WCDMA Indoor Planning

Proprietary and Confidential

INDOOR C/C PROGRAM /

INDOOR PLANNING

Author(s): Kari Heiska, Jukka Liikanen (CS), Jarmo Lehtonen (CS), Jochen Grandell, Karl Tigerstedt

Title: Indoor radio solutions and planning methods

Key words: WCDMA, indoor radio network planning

Document ID: Inp07200

Approved by: Version:

2.0.0

Revision:

NTC/RAS/WCDMA

Indoor Planning Project/Indoor radio solutions and planning methods Inp07 2 (119)

HISTORY

Date Version Author(s) Change Note No./Notes

16.6.1999 0.0.1 KHe first draft

10.12.1999 0.0.2 KHe Dimensioning added, interference scenarios added

13.12.1999 0.0.3 KHe, JLi Planning process + site solutions from GSM added

20.12.1999 0.0.4 KHe Capacity planning method

6.1.2000 0.0.5 KHe RRM added

14.1.2000 0.0.6 KHe, JGr Case studies added

18.1.2000 0.0.7 KHe, KTi Measurements added

17.2.2000 1.0.0 KHe Comments from Ann-Louise Johansson and Kari Sipilä added

12.5.2000 1.1.0 KHe More indoor specific DL modelling theory and detailed planning part added, propagation measurements.

19.5.2000 1.2.0 KHe, JGr TDD interference and GSM/WCDMA co-siting chapters added

29.6.2000 2.0.0 KHe Comments added

DISTRIBUTION

Date Version Delivery

10.1.2000 0.0.5 Project Team

19.1.2000 0.0.7 Review Team

16.2.2000 1.0.0 Lotus Notes

19.5.2000 1.2.0 Distribution in indoor network planning workshop

29.6.2000 2.0.0 Lotus Notes

NTC/RAS/WCDMA 2.0.0 Proprietary and Confidential


TABLE OF CONTENTS

1. Introduction.............................................................................................................................................7

2. WCDMA INDOORS............................................................................................................................8

2.1. Multipath diversity...........................................................................................................................112.2. Power control...................................................................................................................................122.3. Handover..........................................................................................................................................142.4. RRM functionality...........................................................................................................................152.5. Capacity of the CDMA....................................................................................................................162.6. Indoor link budget with WCDMA...................................................................................................21

3. RADIOWAVE PROPAGATION FOR INDOORS.........................................................................24

3.1. Sample measured data......................................................................................................................263.2. Example measurements....................................................................................................................28

4. INDOOR INTERFERENCE SCENARIOS.....................................................................................30

4.1. Other cell interference......................................................................................................................304.2. Own cell interference caused by low dynamic range of the mobile station....................................314.3. Adjacent channel interference used by other operator.....................................................................334.4. Interpath interference.......................................................................................................................38

4.4.1. Interference between GSM and WCDMA..............................................................................394.4.2. Interference between WCDMA FDD and TDD.....................................................................39

5. RADIO RESOURCE MANAGEMENT (RRM) FOR INDOOR...................................................42

5.1. RRM algorithms...............................................................................................................................425.1.1. Power control (PC)................................................................................................................425.1.2. Handover control (HC)..........................................................................................................455.1.3. Packet Scheduling (PS)..........................................................................................................475.1.4. Admission control (AC) and load control (LC)......................................................................48

6. CASE STUDIES..................................................................................................................................50

6.1. Effect of offered indoor user density...............................................................................................516.2. Effect of Pico BS Density................................................................................................................556.3. Comparison between FODS/DAS/Pico...........................................................................................586.4. Effect of the indoor solution to the microcell noise rise..................................................................606.5. Main findings from the system simulation study cases...................................................................62

7. INDOOR MEASUREMENT RESULTS..........................................................................................65

7.1. Diversity measurements (omni antenna, leaky feeder)....................................................................667.2. Headroom in the diversity case........................................................................................................697.3. Coverage with the whole DAS network..........................................................................................707.4. Co-siting measurements (GSM with WCDMA)..............................................................................74

8. NETWORK PLANNING METHODS.............................................................................................77

8.1. Indoor Planning Objectives..............................................................................................................798.2. Area survey......................................................................................................................................808.3. Preliminary Site survey....................................................................................................................818.4. Proper Site Survey...........................................................................................................................82

8.4.1. Propagation Measurement.....................................................................................................838.4.2. Interference measurements.....................................................................................................848.4.3. Typical cell sizes and areas....................................................................................................85

8.5. Detail Planning.................................................................................................................................868.5.1. Detailed capacity and coverage planning..............................................................................868.5.2. Antenna positioning................................................................................................................948.5.3. Planning tool considerations..................................................................................................948.5.4. Pico BS planning....................................................................................................................94



8.5.5. WCDMA BS products.............................................................................................................958.5.6. Cable Power Budget Calculations.........................................................................................958.5.7. System Diagram.....................................................................................................................968.5.8. Floor Plan Drawing...............................................................................................................978.5.9. Photos of proposed antenna locations...................................................................................98

8.6. Frequency and Parameter Plan.........................................................................................................988.6.1. Indoor frequency planning.....................................................................................................988.6.2. SHO parameters.....................................................................................................................99

8.7. Site installation.................................................................................................................................998.8. Optimisation and Verification..........................................................................................................998.9. Basic environmental cases.............................................................................................................100

9. INDOOR SIGNAL DISTRIBUTION METHODS........................................................................100

9.1. Distributed Antenna System (DAS)...............................................................................................1019.1.1. Indoor Antenna Selection.....................................................................................................1029.1.2. Coaxial antenna (leaky feeder, radiating cable)..................................................................1039.1.3. Power Splitter.......................................................................................................................1059.1.4. Directional Coupler.............................................................................................................105

9.2. Fibre optic RF-Distribution............................................................................................................1069.3. Passive repeaters............................................................................................................................1079.4. Active repeaters..............................................................................................................................1089.5. Repeater with Optical Interface.....................................................................................................109

10. REFERENCES..................................................................................................................................111

APPENDIX A MCL MEASUREMENTS................................................................................................113

APPENDIX B. DIVERSITY GAIN IN DAS SYSTEMS........................................................................114

APPENDIX C. MAXIMUM CAPACITY OF DIFFERENT DAS SCENARIOS................................115



ABBREVATIONSAC Admission ControlACLR Adjacent Channel Leakage RatioACP Adjacen Channel ProtectionAGC Automatic Gain ControlATM Asynchronous Transfer ModeAWGN Additive White Gaussian NoiseBCCH Broadcast Control CHannelBER Bit Error RateBPX B Private Exchange BS Base StationC/I Carrier to Interference ratioCCPCH Common Control Physical CHannelCDMA Code Division Multiple AccessCS Circuit SwitchedCN Core NetworkDAS Distributed Antenna SystemDCH Dedicated CHannelDCS Digital Communication System DL DownLinkDPCCH Dedicated Physical Control CHannelDPDCH Dedicated Physical Data CHannelEbNo Bit Energy to Noise density ratioFACH Forward Access CHannelFDD Frequency Division DuplexingFER Frame Erasure RateHC Handover ControlHCS Hierarchical Cell StructuresHO HandOver, Hand Over ControlIPI InterPath InterferenceISI InterSymbol InterferenceIub Interface between RNC and Node B (located in BS)KPI Key Performance IndicatorLAN Local Area NetworkLC Load ControlLOS Line Of SightMEHO Mobile Evaluated Hand OverMRC Maximal Ratio CombiningMS Mobile StationNEHO Network Evaluated Hand OverNLOS Non Line Of SightNMS Network Management SystemNP Network PlanningNR Noise RaiseNRT Non-Real TimeNS Neighbour SetPC Power ControlPCH Paging CHannel



PDP Power Drifting PreventionPS Packet Scheduler (Scheduling)QoS Quality of ServiceRAB Radio Access BearerRACH Random Access CHannelRAN Radio Access NetworkRF Radio FrequencyRM Resource ManagerRNC Radio Network ControllerRNP Radio Network PlanningRRM Radio Resource ManagementRT Real TimeSF Spreading FactorSHO Soft HandOver or Soft Handover OverheadSIR Signal-to-Interference RatioTDD Time Division DuplexingTPC Transmit Power ControlUE User EquipmentUL UpLinkUMTS Universal Mobile Telecommunication SystemWCDMA Wideband CDMA



1. INTRODUCTION

This document describes the main indoor network planning principles of WCDMA FDD system. The work has been done in the Indoor Planning Project which is part of the Pico Coverage & Capacity Program in WCDMA BSS Business Program. This document is targeted for GSM network planners and for WCDMA BSS system development. The more detailed description of the WCDMA network planning in general is documented in [14] so reader is advised to read that document to get more wider understanding on the subject. The main characteristics of the WCDMA system has also been attached to this document to make it more readable for those with no earlier background knowledge on CDMA systems. For those who need more information about the WCDMA system itself, see [2] and the classical articles [5]-[8].In this document the main target has been to collect ideas and solutions for the planning of WCDMA indoor networks. The main focus has been in the radio planning with distributed antenna (DAS) systems. This is because the need for the planning guidelines for DAS systems is more urgent than for the pico BS.

In the first chapter the WCDMA system has been described shortly. The special features and requirements of the indoor environment to the system has also been described. In Chapter 2 the indoor radiowave propagation characteristics have been described shortly. The basic interference scenarios which have to be taken into account in the indoor network planning have been explained in Chapter 3. The radio resource algorithms and parametrization for indoor purposes have been listed in Chapter 5. Chapter 6 shows some indoor simulation results from the Case Study document ([20]) and in Chapter 7 the main results from indoor measurement campaign have been reviewed. More detailled analysis about measurements are documented in [18]. The indoor network planning methods have been described in Chapter 8 and the most commonly used indoor site solutions in Chapter 9.



2. WCDMA INDOORS

The WCDMA network is in most cases interference limited and thus the network planning can be considered as controlling the interference. The increased number of users (or bit-rates) increases the interference in the system which also increases the needed transmitted powers which would be needed to achieve the required performance. Increased power requirements effect also to the coverage and capacity of the system. So it is evident that already in the coverage planning phase the possible load (number of users or used throughput) has to be taken into account. When the load of the cell and therefore the interference, increases, the coverage threshold increases also thus shrinking the coverage area. In order to achieve the required coverage area for a given service level, the coverage areas have to be planned assuming the maximum loading of the system in order to avoid the coverage holes because of the cell breathing effect.

The interference affecting the system can usually be grouped as follows: 1) own cell interference caused by users connected to the own cell,2) other cell interference of the same system caused by users connected to other

cells,- interference from same users within the hierarchical layers, for example from

one indoor sector to another indoor sector- interference between users in different cell layers, for example from outdoor to indoor

3) power leakage from adjacent carrier of the same system,- same operator's interference (usually small)- other operator interference caused by users which are connected to operator

working at the adjacent frequency carrier.4) interference from other systems (like GSM and WCDMA TDD) and 5) interference from other, non-controllable sources.

All these interference types decrease the system performance (coverage and capacity) and have to be minimized if possible in order to increase the spectral efficiency of the network. The own cell interference can be decreased with improved receiver properties (for example with diversity). The other cell interference can be minimized for example with a proper site planning, antenna selections or handover parameter optimization and with frequency planning. The interference coming to the receiver both in uplink and downlink varies also in time. Some inteference sources can be invariant in time whereas other sources can be very peaky, including strong short-term variations. These large fluctuations happen especially with higher bit-rates and with packet transmissions where the transmitter send short packets with a relatively high power. These time dependent effects are controlled by the radio resource management (RRM, Chapter 5) which should be set fast enough to react on these changes. Also the network planner has to be aware of the main time domain effects in order to parametrize the system according to local interference conditions. The capacity of a CDMA cell is not fixed and it can not be planned very accurately. That is, the capacity is dependent on the performance of the receiver in a time varying environment and also on the interference of the other network. One of the most challeging part of the radio network planning is estimating the required traffic, since we



have to know, at least approximately, what kind of services are used, where the users are, what the radio environment is and the radio channel. It is also crucial to know what is the asymmetry of the traffic is in future multimedia services. In web-browsing, for example, the downlink traffic is more intense than the uplink traffic and this have to be taken into account in the network planning also. The WCDMA system supports various services with several bit-rates having also different C/I requirements and thus different cell sizes. Within one service (for example web-browsing) the bit-rate will be changed during the connection controlled by RRM according to temporal changes in propagation channel and interference conditions. The following table shows the planned 3G services grouped according to quality or delay requirements and also according to the operational mode of the connection. Traffic requirements for a indoor cell is quite difficult to obtain because of large number of different services, their QoS criterias, bit-rates and so on. The supported channel bit rates in WCDMA are 15, 30, 60, 120, 240, 480, 960 kbps (in uplink and downlink) and 1920 kbps (in downlink) and the system allocates the bit rate according to requirements of the users and the system capacity at that time moment. The bit rate of packet data can vary during the connection depending on the data rate and power requirements. Different services like speech and data can also be multiplexed to the same connection.

Table 1. Services of 3G system (Table from [10])

Person-to-Person Mobile Internet Corporate AccessTime CriticalInteractive Services

Voice calls Alarm Services Interactive Imagingand Multimedia

Videotelephony (high qual.) Push Information Telemonitoring

Real Time TextMessaging

Traffic Information Alarm services

Navigation Services Push InformationBanking

Near Realtime Services

Text Messaging MMMBrowsing- Media Phone

WWW Browsing - laptop

Voice Messaging E-commerce Transactions Multimedia Messaginge-mail (without attachments) Home LAN Access Fax

Location Triggered Services Interactive E-mail Session

Media Phone BackgroundBack-Up

Company LAN Access

Retrieval (music, magazines)

ScheduledDelivery Services

Image Messaging Mobile Terminated Multimedia Messaging(advertisements)

Laptop Databaseand ScheduleUpdate

Multimedia Messaging E-mail Messagesno attachments

BackgroundE-mail Delivery

MediaphoneSchedule Update

Fax

MMM=Mobile Media Mode



The main system specific features of the WCDMA are listed in the following table. For more information, see [2].

Table 2. Main WCDMA characteristics.

spectrum allocation (Europe) 1920-1980 MHz (UL) and 2110-2170 MHz (DL)

chip-rate 3.84 Mchip/scarrier spacing 5 MHzhandovers soft-HO

intrafrequency hard-HOinterfrequency hard-HOintersystem hard-HO

diversity multipath (RAKE),space/polarization,time

synchronization unsynchronized base stationsused codes scrambling code for user detection

variable spreading code for various bit-rates

modulation QPSKnumber of carriers 3-4 power control frequency 1500 Hzdetection pilot symbols

The WCDMA FDD spectrum allocation in Europe is shown in the . It can be seen that the DCS band is close to the UMTS uplink band so that possible spurious emissions from the DCS (GSM 1800) equipments to the WCDMA uplink have to be taken into account in the co-siting of two systems. Additional UMTS band for WCDMA TDD is also allocated. This will be used especially for indoor purposes but because the standardization of the TDD is quite open the methods how to operate with TDD is unclear.

Figure 1. Frequency allocation of different mobile telecommunication systems.

WCDMA system has several special features that are different from GSM, like the effect of multipath propagation, power control (PC) and soft-handover (SHO). These features are described here briefly.


1800 1850 1900 1950 2000 2050 2100 2150

DCS 1800/DLDECTUMTS/UL

MSSUMTS/DL MSS

DLUL

UMTS TDD

UMTS TDD

1920-1980 MHz 2110-2170 MHz

MHz


2.1. Multipath diversity

Because of the large bandwidth of the WCDMA system, the receiver is, in most of the typical mobile environments, able to separate different multipaths and combine them. In WCDMA the signal bandwidth is 3.84 MHz and therefore the RAKE receiver is able to resolve multipaths with separation of 1/W=0.26s. This means that when the propagation delay between different multipath components is larger than 0.26s (78m) the RAKE receiver combines the usually uncorrelated components introducing some multipath diversity. Because of the decreased variance in the combined signal envelope, the fast power control works better in multipath environment. This gives also better Eb/N0 (bit energy per noise density) performance in uplink and increases the capacity of the cell as well. In picocells the spatial distances are typically small, especially in office environments, so that there are not many multipaths and thereby also multipath diversity gains are usually quite small. Figure 2 shows the measured power delay profile and Figure 3 the rough estimate of the number of channel taps computed from the measurements. The final RAKE finger allocation algorithm was not applied here instead the number of samples which were inside a certain power window were included. The sampling frequency was two times the chip rate in this case.

Figure 2. Measured indoor power delay profile in the case of two DAS antennas.



0.5 1 1.5 2 2.5 30

20

40

60

80

100

number of channel taps

perc

enta

ge

power window = 5 dB

0.5 1 1.5 2 2.5 30

20

40

60

80

100

number of channel taps

perc

enta

ge

power window = 10 dB

Figure 3. Number of channel taps computed from the measurements. This is just an approximate results computed directly from the one measured power delay profile with 1 DAS antenna. 1.5 tap in this means that actually the resolution of the RAKE is better than

1 chip.

In downlink the multipath diversity is also present so that a RAKE receiver in the mobile station would be able to collect the energy from each multipath component. In addition to that, the multipath propagation reduces the DL performance through loss of orthogonality in the radio channel. The spreading codes of different users in the downlink are orthogonal, so that the despreading at the receiving mobile eliminates the interference from other users using the same base station. This is the case when the codes are synchronized and there is only one single channel tap present. In the case of multipaths, the codes are not synchronized since there are shifted replicas of the codes. Hence, different channel taps in the receiver collect also interference from the delayed taps from other users of the BS. This increases the DL interference from the own cell seen by the mobile. This own cell interference is described with orthogonality factor. The orthogonality factor, varies between 0 and 1, so that =1 means that the codes are completely orthogonal and there is no narrowband own cell interference present. The orthogonality in indoor environments is usually quite close to 1 because the channel is more or less a one tap channel.

2.2. Power control

The WCDMA link is designed to maintain constant quality (FER-level). RNC (Radio Network Controller) measures the frame reliability info from the base station and based on this asks BS either to increase or decrease the SIR target of the link. The constant quality is justified by the fact that if the link quality is too good the users causes more interference than needed, which decreases the overall capacity. In this case the RNC asks the BS to decrease the SIR target and if the quality is low the RNC asks the BS to increase the SIR target. This is called the outer loop power control. In the closed loop power control the BS asks the MS to change its transmitting power based on the SIR measurements with a frequency of 1.5 kHz. The measured SIR is compared periodically to the SIR-target sent by the RNC (Figure 5). Thus the mobile station changes its transmitting power every 0.66 ms because of the fast power control. With slow moving terminals, the fast power control is able to follow the fast fading increasing the average transmitted power. The fast power control keeps the received SIR from different mobiles in the cell at a constant level decreasing the required Eb/N0 and thus increasing the own cell capacity. On the other hand, the power peaks will disturb adjacent cells. Figure 4



shows the measured mobile station power as a function of sample number when the mobile moves slowly (~3 km/h). It can be seen that the mobile can follow quite well the fast fading, so that the instant power in dBm looks like the Rayleigh fading turned upside-down. It can be seen that the difference between the minimum and maximum value is about 20 dB. Rx diversity in UL would decrease the effect of these peaks (4-5 dB decrease on average power raise according to measurement data) and therefore it is recommended to use Rx iversity also for indoors if possible. Furthermore, the average cell size is smaller without diversity. This is because we have to leave some headroom so that the fast power control can work properly also at the cell edge. This corresponds to the fast fading margin in GSM. Without the soft handover the single cell headroom is about 9 dB with and couple of decibels above that without UL diversity.

Figure 4. Measured transmitting power (dBm) of the mobile station moving with walking pace. The sample corresponds the spatial distance about 2 m.

2.5 3 3.5 4 4.5 5 5.5 6

x 104

0

50

100

UL

FE

R %

991029_comb1_mrk_sync.mat

UL FER

2.5 3 3.5 4 4.5 5 5.5 6

x 104

-50

0

50

dBm

MS TxP

2.5 3 3.5 4 4.5 5 5.5 6

x 104

0

10

20

dB

sfn

UL Eb/Io setpoint

Figure 5. Uplink FER, Mobile station Tx Power and uplink Eb/N0-setpoint. The x-axis is the system frame number.



2.3. Handover

The mobile selects the used cells (active set) based on its pilot power measurements (or Ec/I0 measurements from the pilot channel) and the BS either accepts or rejects the cell selection. The mobile can be connected to one or more base stations (soft handover) or one or more base station sectors (softer handover) at the same time. In the former case the FER-level for the outer loop power control in RNC is computed with selection combining of signals coming from different base stations. In the latter case the combining (MRC combining) is done at the base station. The soft(er) handover increases the cell capacity because it decreases the interference coming from other cells and it also provides seamless handover across the cell borders. The other cell interference decreases because in SHO the MS gets its required performance with lower transmitting power. In soft(er) handover, the most likely interfering mobiles are at the cell border using the highest Tx powers and they are now power controlled by two (or more) adjacent base stations. On the other hand, the soft(er) handover eats the base station capacity and increases the need for signaling between base station and RNC. Therefore, the planning of soft-handover is very important from the network planning point of view. For indoors the soft handover areas have to be planned carefully in order to avoid large soft handover areas inside buildings. If the soft handover overhead indoors is large, the indoor solution does not sufficiently increase the overall capacity. The soft handover overhead (SHO) is defined as the percentage of soft handover links to the single link users of the base station. Usually the target value for SHO can be for example between 0.1-0.5. The most important planning parameter for the soft-handover is the pilot power strength. The indoor pilot power has to be set to a low enough value to minimize the interference from indoors to outdoors and interference from other indoor cells as well as to minimize the downlink loading. On the other hand if the pilot powers are too low the indoor cell is not able to collect the inbuilding traffic. In addition to the soft handover, the system is able to support hard handovers between different carriers and between different systems (WCDMAGSM handovers, for example). In WCDMA the operator has 3-4 5 MHz carriers so that the flexible utilization of different frequencies has to be possible. Therefore, it is not usually possible to dedicate a frequency for indoor use only which would be the optimal solution from the indoor performance point of view, but we have to design indoor networks to support single frequency hierarchical cell structures (HCS). This means that adjacent micro or macrocell operates at the same frequency. One of the main targets for the indoor planning is to have tolerance against interference from adjacent, larger cells and on the other hand minimize the interference to other cell layers.It is assumed that indoor systems are well suitable for high bit rate transmissions (up to 2 Mbit/s in WCDMA) because cells and path losses are smaller and also because the multipath propagation is relatively small. The interpath interference caused by multipath propagation decreases the performance of the RAKE-receiver when the processing gain is low. Therefore, in the case of multipath propagation the system performance will be lower than in the case of a single propagation path. In typical indoor environments the multipath propagation is not usually a big problem because of the smaller cells and smaller propagation path distances. Thus, it can be assumed that 2 Mbit/s transmission is theoretically possible in some indoor cases like office and residential environments. In large indoor environments like large shopping malls and railway stations it is assumed that multipath propagation is more severe and the system performance is thus lower.



Figure 6. The main network elements, interfaces and handover possibilities : soft handover, 2) single link and 3) softer handover. Usage of six sectors in one BS is

assumed here.

2.4. RRM functionality

The capacity and coverage of a WCDMA network are sensitive to interference fluctuations, so to stabilize the system the interference has to be managed in a controlled way. In addition to above mentioned handover and power control, there are also other radio resource management (RRM) functionalities in the system: admission control, load control and packet scheduling, which are located in the RNC and/or in the BS. The function of all of these algorithms are based on measurements of total received power (PrxTotal) in UL and total transmitted power (PtxTotal) in DL. Admission control (AC) either accepts or rejects to establish new radio bearer based on the interference power in uplink or total transmitting power of the BS in DL. This happens when the new bearer is set up or when the existing bearer is modified (change in bit-rate). The packet scheduler (PS) controls the bit-rates and load of the non-real-time traffic. The packet scheduler estimates the acceptable bit-rates and loading for the new service and also controls the load by changing bit-rates or dropping bearers. The load control (LC) take place only when for some reason the admission control or the packet scheduler can not control the load (PrxTotal, PtxTotal) and the system is driven to an overload situation. For indoors these overload situations might happen more often since the used bit-rates are quite high and interfering users can occur quite close to the indoor base station, which in some cases can cause large interference fluctuations. The current RRM, which is based on the total powers, is not optimal in some indoor cases and therefore new indoor specific RRM algorithms have to be studied.


BS1 BS2 BS3 BS4

RNC1 RNC2

CN

Iur

Iub

Iu

1) 2)3)


2.5. Capacity of the CDMA

Uplink analysisThis chapter presents the basic theoretical backgrounds for estimation of WCDMA capacity. It has been assumed here that the power control works perfectly so that the the mobile station and the base station uses only the minimum needed power in order to get the required performance. Both uplink and downlink loading of the CDMA is presented. The text is based on [7] and [14]. The capacity of one cell can be computed as:

()

()

()

()

1 ()

• I is the total received power from k mobiles (Watts)• S is the received power from one mobile (Watts)• Eb/N0 is the received energy of one bit (J) per noise density (Watts/Hz) threshold to

have a certain bit-error in the receiver • W is the used bandwidth (Hz)• R is the used bit rate (Hz)

This is the pole capacity equation of CDMA, so the capacity is proportional to processing gain and inversely proportional to required Eb/N0. In the case of several cells the capacity equation becomes:

, ()

where fUL is the other-to-own cell interference ratio given by the equation:

()

In this equation and Ga is the sectorization gain. The voice activity is about 0.67 for the voice services (the common channel powers are taken into account) and 1 for the data service with continuous transmission. The sectorization gain comes from the fact that narrow antenna beam decreases the interference level coming



from the adjacent cells compared to multisectoral omni-site. In the case of speech users when R=8000 bps, Eb/N0=8 dB, fUL=0.4, =0.67, Ga=3dB, we will get that the pole capacity would be 143 speech users by applying the capacity formula (Equation 6).

To analyze the cell breathing, which means the decrease of cell area as a function of cell loading, the needed received power from one mobile as a function of cell load is computed here. If the required Eb/N0 for a certain service quality is , Iown is the own cell interference coming from own cell mobile users, Iother is the other cell interference and N is the thermal noise we can write criteria for the received power [14]:

()

()

()

()

This equation gives the UL coverage threshold as a number of users in the system. Figure7 shows how the needed received power at the BS increases and also the size of the WCDMA cell decreases with larger number of users. In the network dimensioning this effect has to be taken into account, so that the cell has to be planned for certain number of users or certain traffic.

Figure 7. Received Rx power as a number of users in UL.



The total interference in UL is the sum of the own and other cell interferences. If we use the previous formula for own cell interference and fUL as the other-to-own cell interference ratio in uplink we get:

()

()

()

, ()

where UL is the loading of the system. Therefore the total system interference at the BS is

. ()

This equation is the total interference level of the system as function of the cell loading. In dB the equation is:

()

So this formula gives the additional loss due to uplink loading which can also be used when computing uplink power budgets

Downlink analysis

The total transmitted power P needed in the base station in order to maintain K simultaneous connections each having a bit rate of Ri and Eb/N0 requirement of i will be computed here. The power criteria for a single user can be written as (from [14] and [15]):

, ()

where W is the chiprate, Li is the path loss from BS to MS, Ioth is the other cell interference, N is the thermal noise and i is the average orthogonality factor. The needed power to get the given quality is then

. ()



By summing this over all users in that cell, we get

. ()

If it is assumed that the affect of an indoor cell affect to the other similar cells, like in the case of many pico BS or centralized BS with many sector, the other cell interference from M other cells around the own cell, Ioth is:

, ()

where Lni is the path loss from cell n to the user i of the own cell and Li is the pathloss from the own BS to the user i. The total power P can be computed from this equation:

, ()

where fDL is the other-to-own cell interference in downlink. In the expression above only the dedicated channel powers are just considered. Figure 8 shows the needed transmitted power from the BS in the case of two service mixing, with various percentage of different services. Also the effect of orthogonality factor has been changed. Orthogonality, of 0.9 means very orthogonal channel with small multipath and =0.6 means non-orthogonal channel with many multipath components.

0 5 10 15 20 25 30 35 40 45

0

5

10

15

20

25

number of users

P (

dBm

)

service1, =0.6

service1, =0.9

service2, =0.6

service2, =0.9

Figure 8. Needed power in the case of service 1 (62% speech, 25% 144 kbps data and 13% 384 kbps data) and service 2 (80% speech, 16% 144 kbps data and 4% 384 kbps

data). The orthogonality was either 0.6 or 0.9.



Downlink analysis of pico BS

Usually the indoor BS has low power, so the DL interference from pico BS to micro/macro mobiles is low. In that case we can write the other cell power as (instead of Eq. 21):

, ()

so other cell powers is a sum of pico cell powers and micro/macro cell powers which are here assumed to be independent the pico BS powers. The needed pico BS power for the traffic channel can be written as:

, ()

where fDL,i is the other cell interference of indoor cells only. From this equation we can see that the capacity of the pico BS is affected only by the indoor cell and the outdoor cells decrease only the coverage. The above equation can be written in the form

, ()

The noise rise term nrDL means how much outdoor interference is above the noise floor and is defined as:

, ()

Thus, it is dependent on the output power of the outdoor base stations and the outdoor-to-indoor path losses. For the dimensioning purposes the mean power can be computed as:

, ()

where is

()

From system simulations the is 104 dB and is 116 dB meaning 12 dB interference margin for DL link budgeting (see Chapter 2.6).



2.6. Indoor link budget with WCDMA

Network dimensioning means the computation of number of hardware equipment and configurations which are needed to meet operators service requirements for a large area assuming average propagation conditions, subscriber information and system properties. Because of high variation of building types, these average numbers are not usually applicable for indoors. Additionally, the usual reasoning for indoor solution is more like capacity and coverage upgrade for smaller indoor area and not for larger area like in micro and macro dimensioning. Therefore, every building has to be dimensioned separately. In the following table there is an example of a WCDMA link budget for 144 kbit/s traffic for indoors. The link budget is for pico BS and any antenna distribution is not assumed here. In here it has been assumed that we have to desensitize the pico cell uplink with the factor of 10 dB in order to decrease the effects of other cell interference and also the effect of users of the own cell which are close to the indoor antenna (see Chapter 4.1). Other link budgets for various data rates in uplink are shown in Chapter 8.5.1.

Table 3. Example indoor link budget: 144kbps Data Service (3km/h, indoor)uplink

Max. TX Power per channel [W] 0.125As above in dBm 21.0TX Antenna Gain [dB] 0.0Body loss of MS in UL / Cable loss of BS in DL [dB] 0.0Transmit EIRP per channel [dBm] 21.0Thermal Noise Density [dBm/Hz] -174.0Receiver Noise Figure [dB] 5.0Receiver Noise Density No [dBm/Hz] -159.0Receiver Noise Power N = NoW [dBm] -93.2Rise Over thermal (Io+No)/No [dB] 4.0Receiver Interference Power I = IoW [dBm] -91.4Total effective noise + interference : I + N [dBm] -89.2Processing gain [dB] 14.3Required Eb/(No+Io) [dB] 2.0Receiver sensitivity [dBm] -101.4RX Antenna Gain [dB] 4.0Cable loss of BS in UL / Body loss of MS in DL [dB] 0.0TPC headroom [dB] 4.0Max. path loss [dB] 127.4

The main differences between GSM and WCDMA link budgets are:

Max Tx powerIn the link budget the Tx power is the maximum transmission power allocated for one link. Therefore it is lower than the total BS maximum power which in this case can be for example 24 dBm.



Required Eb/N0

The carrier–to-interference ratio needed to have required frame error rate level is

, ()

so the needed carrier to interference ratio is dependent on the bit-rate. For example in speech service in uplink the targeted carrier-to-interference ratio can be Eb/N0(dB)-10log10(W/R) = 4.5-10log10(3840000/12200) -20.5 dB. The required Eb/N0 is a function of the mobile speed, the radio channel, the diversity (space, multipath, time) and the used service. The following table gives the simulated received Eb/N0 in different radio channel and with different services. The required received Eb/N0 is larger in DL where space diversity is usually not available. For indoor this is usually the case also in uplink so it can be assumed that the uplink values for indoors would be approximately similar to downlink values. Also the time diversity effects to the Eb/N0 values; with 80 ms interleaving the values are 0.5 dB better in UL and 1.4 dB better in DL.

Table 4. Simulated average required Eb/N0 for different services. Antenna diversity is assumed in UL (from [2]). The required FER level is 10 % for packet services and 1% for speech and CS services.

Service Eb/N0 (UL/DL/DL div.)12.2 kbps, speech 4.5 dB / 9.5 dB / 6.0 dB

64 kbps 2.0 dB / 7.0 dB / 5.0 dB144 kbps 1.5 dB / 6.5 dB / 4.5 dB384 kbps 1.0 dB / 6.0 dB / 4.0 dB 2 Mbit/s - / 6.4 dB (DL, one antenna, =0.89), 3.0 dB

(DL, with Tx diversity, =0.86)

Rise over ThermalThe noise raise over the thermal noise is caused by the other users in the cell and also users from other cells. The noise raise can be computed from the UL loading by NR=10log10(1-) (from Chapter 2.5). The maximum allowed loading is the network planning parameter which can be tuned on cell basis. With lower loading value we would get more stable network but on the other hand the maximum capacity decreases compared to the higher loading cell. With the higher loading value we are on the steep part of loading curve (see Figure 7) and in that case even one additional user can change the cell border remarkably. Typically the maximum loading can be between 0.3 and 0.8 which corresponds to noise raise of 1.5 to 7 dB.

Fast fading marginBecause of the fast closed loop power control of the DPDCH the mobile station power fluctuates rapidly. Especially, in indoor environments, when the mobile speed is low, the power control follows the fast fading causing peaks in the mobile station power. When the mobile station is at the border of the coverage area, the maximum power limits the power control dynamics. In that case the frame error rate exceeds the target level. Therefore, we need some headroom above the mean transmitted power, which should be taken into account also in the link budget. The uplink fading margin is 8.9 dB without soft handover in the case of 3 km/h mobile in the single cell case. In the case of two



adjacent cells the soft handover takes place and this decreases the needed headroom because in that case we will have macro diversity. According to simulations the needed headroom with the soft handover in that case is 3.9 dB ([14]). The functionality of outer loop PC in the end of the call is in Figure 9.

5.7 5.75 5.8 5.85 5.9 5.95 6

x 104

0

20

40

60

80U

L F

ER

%991029_comb1_mrk_sync.mat

UL FER

5.7 5.75 5.8 5.85 5.9 5.95

x 104

15

20

25

30

35

dBm

MS TxP

5.7 5.75 5.8 5.85 5.9 5.95 6

x 104

5

10

15

dB

sfn

UL Eb/Io setpoint

Figure 9. The uplink FER, Mobile station TxP and Eb/N0 setpoint in the end of the call.

Downlink link-budget.

In DL the link budget can be computed roughly from Eq 6 by writing the by , where Lmax/ave is the difference between maximum and average

pathlosses, Lmax is the maximum pathloss and is the interference margin which can be defined as

()

Thus, the maximum allowed pathloss becomes:

()

, ()

For example, when W=384000, Lmax/ave=6 dB, max=0.8, =0.8, fDL=0.2, Pmax=24dBm, N=-100dBm, I=10 dB, throughput T= 2 Mbps and Eb/N0=4dB (384 kbit/s with Tx diversity), the maximum range will be 117.5 dB. The following figure shows the DL coverage as a function of throughput with different parameters values.



Figure 10. The downlink 384 kbps cell range as a function of throughput

3. RADIOWAVE PROPAGATION FOR INDOORS

Mobile networks are increasingly expected to provide coverage also inside buildings, but because of complexity of indoor environments it is not always possible. Radio wave propagation in indoor environment involves external and internal wall penetration, absorption of radio wave energy by furniture, as well as body losses due to the presence of people in the surrounding area. There are reflections from the walls, diffraction from the corners and scattering from the smaller objects like lamps etc. Penetration loss through walls and ceilings depends on the dimensions, on the material parameters as well as frequency.Therefore signal levels in buildings are estimated by applying an empirically measured “building penetration loss” margin. Typical values are 15..25 dB. Big differences between rooms with windows and “deep indoor” exist (10 ..15 dB). This varies from country to country with typical architecture and building materials used.

Pref = 0 dB

Pindoor = -3 ...-15 dB

Pindoor = -7 ...-18 dB

-15 ...-25 dB no coverage

rear side :-18 ...-30 dB

signal level increases withfloor number :~1,5 dB/floor(for 1st ..10th floor)



Due to the complexity of indoor propagation, it has become apparent that indoor planning is difficult and involves statistical estimation. Over the years, several indoor propagation models have been developed, which are based on empirical formulas. Two indoor propagation model types are considered here: 1) a semi-empirical, so called multi wall model (from [24]) and 2) an empirical model. The basic structure of the semi-empirical propagation model is the following:

,

()

where: LFS = free space loss at the distance between MS and BS,Lc = constant loss, used to set the mean error between model and the

measurements to zero.kwi = number of penetrated walls of type i,kfi = number of penetrated floors of type j,Lwi = loss of wall type i,Lfi = loss of floor type j,I = number of wall types,J = number of floor types.

For a given location of the mobile station, the numbers kwi and kfi are determined by

counting all the walls and floors along a straight line connecting MS and BS. The model coefficients Lc, Lwi, and Lfi are optimized according to measurements by using multiple linear regression. The radiowave propagation in indoor environments is very difficult to characterize with a simple empirical model because the building materials, detailed building lay-out and also the closest building environment have an effect on propagation. However, to get a rough estimate of the cell sizes we have used the following, simple empirical propagation model which can be quite easily fit to the measurement data:

()

where d is the distance between Tx and Rx in meters,k is the floor difference between the Tx and Rx antennas,Lf is the average single floor attenuation.

A, B and b are free parameters that can be tuned to fit the model to measurement data, for example. The exponential term in the Equation describes the usual propagation phenomena where the signal attenuation per floor decreases when k >1. This comes from the fact that the radiowave propagates to upper floors usually outside the building and in that case the signal attenuation is lower compares to direct penetration loss through the ceilings. Therefore the parameter b is very sensitive to closest environment of the building.

In this study we have tuned this empirical model by using a more detailed ray-tracing propagation model ([23]). In this case the A value has been fixed to 37 so that the model is usable also in small ranges. Over 7000 receiver points for each of 14 antennas were analyzed to get the average model values. Also the variance between different antennas have been computed. In the ray-tracing propagation model the studied three floor office building has been modeled with vector walls with individual thickness and dielectrical parameters. Also the antennas were modeled with their measured antenna pattern and



gain values. According to the feasibility report ([23]) the used ray-tracing model is quite accurate when compared to measurement results.

Table 5. Fitted parameters for the empirical model

Mean 37 36.7 0.42 8.3Std 0 2.6 0.12 1.6

Slow fading variationsThe slow signal fading around the mean value (log-normal fading) is caused by the environmental changes when the mobile changes its position in the buildings, like obstructed walls, reflections, LOS/NLOS changes, etc. The slow fading variation computed from the ray-tracing results was 4.4 dB.

Diversity gain in DAS antennasIn the case of DAS networks the slow fading coming from different antennas are not correlated and thus this introduces also some gain. Figure 86 in Appendix B shows the cumulated probability of two example antennas in the DAS system computed with the ray-tracing program. The figure shows the slow-fading diversity gain. The main diversity gain computed from all antenna pairs was 4.4 dB for both directional and omni antennas. In the case of DAS systems there is no gain against the fast fading because the signals are combined coherently so that the sum signal is also fading.

3.1. Sample measured data

The table below gives a rough guide of the attenuation for different wall and ceiling materials at 1800 MHz which are to be used in the semi-empirical model shown in the previous chapter. These values are based on existing literature (3,4), and on indoor measurements conducted by Nokia Networks. As far as frequency dependence, losses at 2000 MHz, 1800 MHz and 900 MHz was generally similar.

Table 6 Measured penetration losses of different wall and ceiling types

Material Penetration loss (dB)WallsPlaster Board 3Particle Board 3Glass 4Light Concrete 4Brick 5Concrete 6Reinforced Concrete 12Metal Covered 20Outer wall, large windows 10Outer wall, small windows 15Outer wall, no windows 25Ceilings



Reinforced Concrete 13hollow core slab 15outer ceiling, light 4outer ceiling, medium 15outer ceiling, heavy 30

From the theoretical point of view the signal penetration should be worse at 1800-2000 MHz frequencies than at 900 MHz. In practice this is not proven in all locations due to complexity of the indoor environment. The signal propagates inside building through material, holes/tubes in concrete reinforcement and in free space between limiting elements (ceilings, walls). Typically the material loss is higher in higher frequency, but for example in reinforced concrete the steel structure determines how well the ceiling reflects the signal. Also the separation of wall elements affects to the propagation. Again the tubes and holes in concrete reinforcement are ideal for higher frequency to propagate, so roughly saying the lower frequency propagates through material and higher frequency through holes and tubes. Also the effect of scattering is larger at the higher frequencies when the wavelength is smaller.

0 20 40 60 80 100 120 140 160 180 20060

70

80

90

100

110

120

130

140

distance (m)

path

loss

(dB

)

Path loss functions (directional antennas)

floor1floor2floor3

Figure 11. The distance attenuation computed with the empirical indoor propagation model (Equation 25).

DAS dimensioning example

If the BS maximum power is 37 dBm per sector, the range will be 132 dB (DL link budget, interference margin 10, dB, =0.8, fDL=0.3, total throughput=2Mbps). If the cable attenuation is 10 dB for each antenna element and 115 dB is reserved for path loss for each antenna then the 7 dB was left for splitting which means 5 antennas. From the Figure 12 it can be seen that 115 means 80% coverage probability for 5 floors, so that with 5 antennas we can cover 25 floors. It must keep in mind that this parking house is open environment without any walls inside the building and in more realistic indoor environment the attenuation inside the building is much larger.


2200


Figure 12. The cumulative path loss distributions for each floor from example building (Ruohoparkki). The transmitter was located in the floor 2.

3.2. Example measurements

These measurements are from Nokia Research Centre (NRC) building in Helsinki. The building is steel framed building covered with glass and having large open area in the center of the building. This is in coverage sense quite optimistic case because the attenuation is very low due to large open areas inside the building.

Figure 13. Nokia reseach center (NRC), Helsinki. Tx location is shown in the map (office area A, 2nd floor)

The Figure 14 shows the cumulative probability distribution of the path losses in the NRC building. The measurements have been carried out by using TEMS equipment at 1800 MHz frequency. In every floor the whole building area was measured by walking through the office areas: ABCD. The basement was not covered here. By comparing these distributions to we can see that one pico BS can cover the whole building with throughput of over 2 Mbit/s



service (Five 384 kbps users for example). Interference margin of 10 dB against other cell interference has been taken into account here NRC building in Helsinki is six floor office building having lots of open office areas as well as open space inside it so the attenuation in the building is quite small.

50 60 70 80 90 100 110 120 1300

0.1

0.2

0.3

0.4

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0.6

0.7

0.8

0.9

1

path loss (dB)

prob

abili

ty (

dB)

2nd floor3rd floor4th floor5th floor6th floor

Figure 14. Cumulative path loss distributions measured in NRC building



4. INDOOR INTERFERENCE SCENARIOS

In order to control the interference the main interference sources for indoor environments have to be known. The main interference scenarios associated with the same frequency indoor system are depicted in Figure 11.

Figure 15. The main interference scenarios.

The following interference scenarios have to be taken into account when planning indoor systems:

4.1. Other cell interference

The other cell interference means that the interference originates from mobiles (in uplink) that are connected to other cells, meaning sectors or other base stations. In downlink the other cell interference is the interference which comes to the mobile from other sectors or base stations. From the network planning point of view the other cell interference can be decreased by planning the cells to be as isolated from each others as possible. This means in practice that the signal attenuation between the cells should be large enough. The planner can increase the cell isolation by proper site planning; locating the antennas into different floors in order to maximize the isolation, for example.


Op1 Op2

2)

2)

34)

connectioninterference

1)

cell 2

cell 1 Iown

cell 3

Ioth


Figure 16. The interference scenarios in a case of one carrier WCDMA indoor network.

4.2. Own cell interference caused by low dynamic range of the mobile station

In this case the indoor cell is disturbed by those mobiles which are close to the base station antenna and having small coupling loss. When the mobile Tx power control is working in its dynamic range and is coming closer to BS antenna the outer loop is decreasing its Eb/N0 target to keep constant quality (FER). However, in some point the real Eb/N0 value can not be decreased anymore because the mobile station power is in its minimum value and so this particular connection gets too good quality. The increased power level of that link can be seen as an interference to other mobile, and thus those mobiles have to increase their Tx powers. The received power from the interfering mobile is:

, ()

which can be for example: -50-45=-95 dBm which can be slightly higher than the nominal Rx power of the system (for example –103 dBm (noise power) + 6 dB (noise raise)). In the case of one interfering mobile with coupling loss of L and minimum power of Ptx, min, assming that the interfering mobile transmits with minimum power, the power equation changes to:

()

()

Figure 17 shows the effect of the minimum coupling loss user computed with the previous equation. The minimum power of the interfering mobile is -44 dBm or -50 dBm.

40 45 50 55 60 65 70 75

-120

-115

-110

-105

-100

coupling loss of the interfereing mobile (dB)

cove

rage

thr

esho

ld fo

r 8

kbit/

s us

er

min MS Tx power = - 44 dBmmin MS Tx power = - 50 dBm

Figure 17. The needed received power for the speech user.



The additional noise rise caused by one interfering users can then be computed by:

, ()

where pr1 and pr2 are the needed received power at the BS with and without the interfering user. When the number of users is large the noise rise is just pr1/pr2,

()

The noise raise caused by one mobile is therefore independent on the bit rates and Eb/N0

values. Figure 18 shows the noise rise caused by one user. So if the system allows 5 dB additional noise rise the minimum allowed coupling loss have to be larger than 50 dB.

35 40 45 50 55 60 65 70 75 800

2

4

6

8

10

12

14

16

18

20

path loss of the interfering mobile (dB)

nr (

dB)

Figure 18. Noise rise caused by one interfering user.

The increase of the coverage threshold also increases the transmitted powers of all mobiles in that cell, which in turn causes a decrease in coverage. The increased mobile powers cause increased interference also to surrounding cells. Changes of the noise rise, because of mobiles passing by a picocell antenna, can therefore cause interference peaks and dropped calls in many cells around the picocell and therefore it would be desirable to decrease these large interference variations. In the RRM algorithms where the controlling actions are based on the total received power, the single interfering mobile causes problems. When the mobile is close to the antenna the noise rise caused by the mobile can be for example 14 dB. If the largest acceptable noise rise value is 10 dB, the RRM controlling functions act and drop users from the interfered cells. Possible ways to cancel the own cell interference peaks are: 1) desensitization of the picocell receiver, 2) new RRM, which would recognize the interfering user and would drop it before it interferes the system, 3) more robust RRM against the interfering peaks and allowing larger noise rises if this is caused by only one large interferer and 4) new antenna solutions where the minimum coupling loss is larger and therefore the noise rise is larger. If the mobile is very close to the indoor antenna also the dynamic of the AGC is limiting. If the total base station power is P and the minimum coupling loss is Lmin, the received wideband RF power is P - Lmin. If this RF power, Prx, max exceeds the maximum input power of the mobile AGC the mobile will be blocked. The maximum power in the



antenna will be between PPilot and Pmax. If the maximum received power of the mobile station input is –25 dBm, PPilot=14 dBm and Pmax=24 dBm, the respective allowed coupling loss, Lmin = P- Prx, max which is then 39-49 dB depending on the instantaneous base station power.

4.3. Adjacent channel interference used by other operator

When one operator have indoor coverage with indoor solution (f1) and another with a distant micro or macrocell (f2) the interference from mobile with f2 to base station with f1

is Ioth=PMS,f2 –CL-ACLR, where PMS,f2 is the transmitting power of the interfering mobile, CL is the coupling loss between indoor base station and the mobile and ACLR is the adjacent channel ratio of the mobile. The worst case situation would then be if PMSf2=24 dB (data terminal), CL=40 and ACLR=33, causing received power of –49 dBm which would cause high blocking rates in indoor cells in UL. In practice the mobile station power would be much smaller and the coupling losses usually above 50-60 dB.

Figure 19. Adjacent channel interference.

Figure 20. The coupling loss values of three indoor antennas. Constant 55 dB areas are shown with white lines.

In the following analysis one example of ACLR/ACP problem is shown:


5 MHz

operator 1 operator 2 operator 3

f1 f2 f3


Figure 21. Adjacent channel interference from picocell to other operator's microcell.

Input data ACS=ACLR=30dB CL1=55 dB from MS to pico base station CL2=130 dB from MS to micro/macro base station Pico output power = 14…24 dBm Mobile station power = 24 dBm DL processing gain of the microcell TCH = 27 dBm, Eb/N0=8 C/I=-19 dB Tx power from the microcell=30 dBm/traffic channel

The maximum allowed interference at the mobile connected to microcell is

30-130(CL)+19(C/I)=-81dBm

so that the minimum coupling loss will be

(14…24)-30(ACS)-(-81 (dBm)) = 65…75 dB.

This causes received interference levels at the picocell of

24-30(ACLR)-(65…75)=-70…-80 dB.

This is about 10-20 dB above the normal operating point for indoor environments. This is the worst scenario from the picocell point of view. Without any desensitization (artificial decrease of the sensitivity of the receiver) and with a normal total Rx power based RRM the indoor cell starts reduce the own cell loading in this case. So we would need additional 10-20 dB desensitization in order to avoid the large interference peaks to the own cell. This reduces our own uplink coverage and also increases the interference to surrounding cells. In DAS systems where there is always 10-20 dB attenuation due to signal distribution cables and therefore the probability that the other operator mobile produces such interference peaks is smaller. One method to avoid this ACLR problem with Rx power based RRM is to increase the PrxThreshold and PrxOffset values considerably (with about 10-20 dB). However, with this method the indoor system might behave very unstable in high load situations i.e. causing call drops and large interference peaks to other cells. Therefore, better method is to desensitize the uplink so that the used transmitting powers are high but the UL interference fluctuations are more stable.

The required power for the microcell user can be computed by the equation:

, ()



where Pm is the power allocated to the microcell user, Lm is the pathloss from the microcell antenna to the mobile, Pp is the power of the pilot channel, Lp is the pathloss from pico base station to the mobile and ACIR is the adjacent channel interferenece. The maximum link specific power is based on the strength of the pilot channel. The maximum power in the microcell for the service having bit rate of R and planned Eb/N0 target of is computed by:

, ()

where is the power adjustment paramter; when =1 (0 dB), the reference service is given the same power as for the pilot channel, when =2 (3 db), for instance, the reference service is given 3 dB less power than for the pilot. Assuming that most of the interference comes from an other operator's pico cell the minimum required pathloss:

()

By using this formula, the outage percentages for a 4 microcell case have been computed. The pathloss data has been obtained from ray-tracing propagation modelling. The outage percentage is the number of served pixels inside the building per total number of pixels. The results are found in Table 7. Results show that for one carrier separation (ACIR=33 dB), the outage is quite large in far away microcells (#2 and #5) but in the case of LOS microcells the outage is low. We can conclude based on the results that if one operator has a indoor solution in some building, also another operator working adjacent carrier have to come quite close to that builing in order to have enough coverage. Situation is better in a case with two carrier separation (ACIR=45). The outage computed here is not dependent on the DL bitrate because also the allocated power increases. Minimum coupling loss was here 45 dB but changing it does not affect to the results considerably.



0 50 100 150 200

80

100

120

140

160

180

200

220

240

1

2

3

4

5

x(m)

y(m

)

Figure 22. Four microcells (operator 1) and one picocell (operator 2).



Table 7. The outage percentages computed using Eq. 41 as an outage criteria. The output power from the picocell is assumed to be 24 dBm.

microcell 2 microcell 3 microcell 4 microcell 5ACIR=33 Poffset=0 8.9 0.2 0 26.4

Poffset=3 12.6 0.5 0 35.2ACIR=43 Poffset=0 1.7 0 0 12.3

Poffset=3 2.7 0 0 15.0

Another possibility is to use throughput or bit-rate based RRM instead. There the UL traffic is limited based on fractional loading:

, ()

where i is the Eb/N0 of the user (planned or measured), Ri is the user bit rate, W is the modulation bandwidth and N is the number of users in the system. With this method the individual other or own operator's users close to the indoor antenna have no influence on the load controlling actions. The high load case occurs when is above a certain limit indicating that there are too many users in the system and based on that the RRM makes controlling actions. Of course, the mobile close to the antenna can in this can disturb the balance of the uplink of the cell raising all transmitted powers in that cell, but it does not have any direct impact on the load controlling actions. Similar methods that can be used in this case were suggested for the own cell interference case (previous chapter)The ACLR problem can also be avoided when two operators have dedicated indoor solutions in the same building . In that case the transmitted powers are low close to the other operator's indoor antenna and the interference is small. Also if the frequency separation between two operator is larger than single carrier-spacing situation would be better. From the micro operator's side the worst case would be that the (C/I) requirement would be about -5 dB (512kbit/s, Eb/N0=4dB). If there is indoor solution inside the building with an other operator the maximum allowed interference is: 30-130+5=-95 dBm which leads to 24(TxP)-30(ACS)-(-95)=89 dB path losses. This means that the whole floor in one building will be blocked by the indoor system in the case of high bit rates in micro. Solution for that would be that either we allocate another frequency for the microcell, using more microcells closer to the building or by using a dedicated indoor solution.



4.4. Interpath interference

High bit rates in WCDMA are obtained with low processing gain, i.e. symbols are spread with shorter codes or/and there are more parallel codes. Therefore, in multipath channels non-negligible intersymbol interference (interpath interference) is caused at high bit rates. In the case of single path transmission the orthogonality of the short codes eliminates the interference from the other code channels. However, if the time dispersion is large enough (> one chip 70 meters) the different code channels and symbols are not anymore orthogonal, which increases the interference. In the case of multicodes, own interference can be quite high depending on the number of multipaths. The effect of multipath propagation is, however, quite difficult to predict because it is strongly location dependent. To study the effect of interpath interference several link level simulations with high bit rates have been performed. Results of the link level simulations are illustrated in Figure23. In these figures the a-vector means the relative tap powers of the multipath channel. The figures show the received and transmitted FER in downlink, 2 MBit/s service as a function of received Eb/N0, respectively. At the 10% FER level the Eb/N0 losses were 1.8 dB and 3.3-4 dB, respectively because of interpath interference (IPI). The figures show also that 0-10 dB differences in tap values have not so much effect on results in the case where the number of fingers is constant. When the Eb/N0 increases the FER values does not decrease because of ISI. The second figure show the FER as a function of transmitted Eb/N0, which gives information about how much interference the BS generates to other users. It can be seen that multipath diversity gain is larger than ISI loss, if FER>3% and the overall gain due to multipath is about 2.5 dB. The diversity gain is largest for channel with two equal taps but the gain is reduced when there are more multipaths. From the link level simulations it can be concluded that transmission works quite well when the receiver is in LOS or behind one corner. However, there are also locations in small microcells with large multipath effects where the required Eb/N0 is above 6 dB. It could be assumed that inside the buildings the multipath propagation or the delay spread is not as big problem as it is outdoors. However, in large open halls or open offices there could be multipath propagation which produce several taps and therefore limits the coverage area of the high bit rate service. To reduce the effect of multipath interference, more advanced receivers have to be implemented for indoors, for example IRC RAKE (interference rejection combining) -receivers.As we can see from the link level results, shown in the figures below, the performance of the ordinary RAKE receiver is strongly dependent on the multipath profile (radio channel). However, from the network planning point of view the analytical prediction of the multipath profile is a complicated task. One possibility of finding out the problematic areas is to use advanced and complicated propagation models like ray tracing. In ray tracing models, all possible radio wave paths from transmitter to receiver are computed. These rays can be reflected or diffracted from walls or ceilings of the building. The indoor ray tracing model also includes the penetrated field strengths. It has been shown that ray-tracing based methods can be used in wideband channel modeling, especially when the receiver is close to the transmitter, but they are usually computationally inefficient for commercial use. When the receiver is further away from the transmitter all the assumptions used in ray-optics are not valid anymore. In that case the rays are not narrow and there are not only reflection and diffraction components but also incoherent



scattering thet can have great effect on the result. Thus, the usability of ray-tracing when the transmitter is far away from the receiver is questionable.

-4 -2 0 2 4 6 8 10 12 1410

-4

10-3

10-2

10-1

100

Eb/No, received (dB)

FE

R

1-path 2-path,a=(0,-10) 2-path,a=(0,-5) 2-path,a=(0,0) 3-path,a=(0,-5,-10) 3-path,a=(0,0,-5) 3-path,a=(0,0,0) 3-path,a=(0,0,-15) 4-path,a=(0,-5,-10,-15)

0 2 4 6 8 10 12 14 16 1810

-4

10-3

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Eb/No, transmitted (dB)

FE

R

1-path 2-path,a=(0,-10) 2-path,a=(0,-5) 2-path,a=(0,0) 3-path,a=(0,-5,-10) 3-path,a=(0,0,-5) 3-path,a=(0,0,0) 3-path,a=(0,0,-15) 4-path,a=(0,-5,-10,-15)

Figure 23. FER vs. received Eb/N0 and FER vs. transmitted Eb/N0

4.4.1. Interference between GSM and WCDMA

Due to the high-bit properties of WCDMA, the standard has been advertised as being especially suitable for office environments. Many office buildings, however, already have a DAS network for a 2nd generation system, such as GSM/DCS in the 900/1800 band. The installation costs of such a DAS network are the most important part of the total costs for providing indoor coverage. Therefore, customers would be very keen on using the existing DAS network for co-siting of GSM and WCDMA. If necessary, the antennas could be changed to dual- or tri-band. The cost of this would, however, be negligible, when compared to cable installations. Another reasoning for co-siting comes from the difficulties in obtaining sites for the base stations in many indoor environments. A combined approach, such as the Nokia UltraSite which combines GSM, EDGE and WCDMA in the same cabinet would be advantageous in such cases. Thus, if the BSs are already co-located for one reason or another, using the same feeder cables for signal distribution would be even more tempting.

In the case of co-siting of GSM and WCDMA, it has to be assumed that the emissions to the WCDMA uplink band is low enough. According to the GSM specifications, the out of band emission can be –36 dBm, so that if we want to have –103 dB received level in WCDMA the needed attenuation between GSM transmitter and the WCDMA receiver has to be over 67 dB. The problem becomes apparent when the WCDMA and GSM signal is put to single co-axial feeder in the case of DAS antennas. In that case the GSM transmission has to be separated well enough from the WCDMA reception in order to avoid additional interference .

4.4.2. Interference between WCDMA FDD and TDD

The WCDMA TDD mode is suitable for indoor environment more than for macro and microcells because of its limited cell range and the interference problems. Also the downlink maximum capacity which is needed in indoor environment is larger in TDD than in FDD. In this chapter the co-siting of TDD and FDD in order to increase indoor



capacity as well as the TDD operator interference to the own FDD band are discussed briefly. shows the interference scenarios between TDD and FDD frequency bands.

Figure 24. Interference between TDD band and FDD uplink band

TDD mobiles and base stations interfere FDD base stations in uplink. So if the distance between TDD and FDD base stations is low there will be direct interference to FDD from TDD BS. The TDD frame is divided in to slots which are allocated according to the required service to different mobiles so that the interfering power is bursty. The interference affects the system performance in two ways: the increment of interference in BS Rx increases the needed MS powers decreasing also the cell range and also increases interference to other cells (higher MS powers). The RRM functionalities in FDD uplink are based on the total received power so that the increment of the total interference effect also on RRM functions. The effect of TDD bursts depends also on the averaging in RRM.Figure 25 shows the effect of distance between TDD and FDD BS to the noise raise in FDD Rx caused by the additional interference. We can see that if the distance is small (< couple of meters) there will be large interference from TDD BS to FDD BS. The interference decreases when the distance between BSs increases but then the TDD MS to FDD BS interference starts to increase. This is caused by the fact that when the TDD cell is larger then also the TDD MS powers are larger and the interference increases. This interference is dependent on the minimum coupling loss (minimum link loss) between FDD BS and TDD MS which can be affected by the appropriate cell planning of the FDD BS.

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Figure 25 Noise rise in uplink with 5 and 10 MHz channel separation.

We can see from these results that when there is larger than 120 meter distance between FDD and TDD BSs (ETSI-propagation model, meaning about 100 dB propagation loss) the noise rise is smaller than 5 dB if the MCL is 60 dB. In the case of 40 dB MCL the distance is only 35 meters about 83 dB link losses) when the separation is 5 MHz and 70 meters (92 dB link loss) when the separation is 10 MHz.



The minimum allowed coupling loss between TDD and FDD BS is 77 dB with 5 MHz separation and 67 dB with 10 MHz separation meaning about 20 and 10 meter minimum distance without line-of-sight. This assumes that ACIR is 42 and 52 dBs. So the TDD and FDD can be almost co-located for indoor environment if we can plan the coupling losses between TDD and FDD antennas so that the MCL requirement is fulfilled. This means that we can have considerably capacity increase due to TDD deployment (50-90% for either UL or DL according to simulations).



5. RADIO RESOURCE MANAGEMENT (RRM) FOR INDOOR

5.1. RRM algorithms

This text is based on the RRM description in [16] and [1]. The main focus here is to emphasize those NP parameters and algorithms which are important from the indoor network planning point of view or where the parameterization is different from the outdoor networks. A more detailed description of the NP related RRM parameters is given in [14]. The RRM algorithms are grouped as follows: Power Control (PC), Handover Control (HC), Packet Scheduling (PS), Admission Control (AC) and Load Control (LC). The RRM algorithms and their locationing within the network elements are shown in Figure 26. Parameter names are from the parameter dictionary, [16].

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Figure 26. Location of the RRM algorithms and the interfaces between network elements (Figure from [1]).

5.1.1.Power control (PC)

UL open loop power controlThe transmit power of RACH is set with the open loop power control. Because the interference level and propagation condition can be change quite rapidly there is a possibility that the MS transmits with too high power at the beginning and generates therefore additional interference. If the user is close to antenna when it starts sending RACH, the own cell interference might be quite high. Therefore, it is preferable to have as small starting value for the preamble as possible (= min power, –50 dBm).

UL fast closed loop power controlUL fast closed loop power control adjusts the transmit power of the MS in order to keep the received Eb/N0 at the set point value. The BS receives the Eb/N0 setpoint from the RNC and compares the measured value to the setpoint value. BS sends the power up (power



down) command to the MS if the setpoint is above (below) the measured value. The power control command is sent in every slot (0.625 ms) so that for low mobile speeds the power control can easily follow the fast fading. The power control step is either 1 dB or 2 dB and for indoors it is recommended to use 1 dB because of the slow channel. The power control dynamics is 65 dB. For indoors where the mobile speed is low and there is little multipath (and possibly no space) diversity, the gains of closed loop power control are quite remarkable. Due to fast power control the received Eb/N0 values are close to the set point and the own cell interference is thus small. On the other hand, the power rise due the compensation of multipath fading is high producing interference to other cells. In soft handover the MS sets its power up if all BSs of the active set ask the MS to increase the power. In softer handover the combined Eb/N0 from the active sectors is used and a common power control command is sent.

DL power controlThe difference between UL and DL fast closed loop power controls is that in DL the MS measures the received and combined SIR with all multipath diversity branches coming from different sectors and sends one power control command to all sectors in the soft handover case. In the case of a low quality link, the different BSs can interpret the PC command differently and thus the powers of these two BS drift away from each others. To prevent the power drifting in DL a power drifting prevention (PDP) algorithm has been developed in Nokia. The PDP algorithm periodically compares the Tx power of the BS to the reference power and corrects the drifting power to that reference power. For the NRT users it is sometimes recommended to use reduced power control in order to avoid unnecessary interference to other cells. This results in an increased FER which increases the re-transmissions, but the total capacity of the system can be improved.

DL power control for NRT trafficBecause indoor traffic concentrates more on the non-real-time traffic it could be assumed that the DL power rise prevention algorithm will give us gain in the system. More information about the algorithm and the parameterization is found in [1].

UL/DL outer loop power control Outer loop power control takes care of setting the Eb/N0 setpoint, so that needed quality of service is achieved with the minimum transmitted power. The outer loop power control runs in RNC. The RNC sends the BS the initial UL Eb/N0 setpoint, its maximum and minimum value and during the call it sends the change of the Eb/N0 setpoint or its new absolute value if required by the quality estimation. The quality of the link can be estimated with frame reliability indicators (FRI). These parameters are important mostly from the basic network functioning point of view and not so much for the coverage and capacity. So by wrong settings of these parameters the call might drop in some locations. Parameters:

EbNoIniSpUL/DLThe parameter defines the initial UL Eb/N0 setpoint for a radio access bearer which is to be used by the power control. This can have the same value as initial planned UL Eb/N0 and is dependent on e.g. bearer type, bit rate, UE speed and QoS. The value is read from the EbNoPlannedUplink-table at bearer set-up and bearer reconfigurationEbNoMaxUL/DL



The parameter defines the maximum uplink/downlink Eb/N0-setpoint for a RAB to be used by the PC. Each service can have its own limit. This parameter will be read from a table holding one value for a different speed / service combination. Other combinations could be interpolated. If we consider the situation where the channel is very weak and the Eb/N0 is set to its maximum value and then the power increase rapidly (for example when the user comes from an elevator to LOS) it might occur that the Eb/N0 is too large for a while and the MS produces large interference to other pico-cells. This can be avoided by decreasing the maximum value of the setpoint.EbNoMinUL/DLThe parameter defines the minimum uplink/downlink Eb/No setpoint for a RAB to be used by the fast PC. Because of the low coupling losses for indoors, it is assumed that those mobiles which are on minimum Tx power (-44 dBm) have also the minimum Eb/N0 setpoint. When the channel changes rapidly the outer loop has to increase the setpoint and stabilize it to its nominal value (8 dB, for example). If the minimum value is very low and the step size is small large UL FER values might occur before the system reaches the new setpoint. So it is preferable to not use too small minimum values. MinStepSizeThis parameter defines the minimum step size of the step of the Eb/No setpoint changes.FER/BERTargetDL /ULThe parameter defines the table with FER/BER target for a RAB which is to be used by the DL/UL outer loop PC. Parameter depends on e.g. QoS, bit rate, speed etc of the RAB. Each RAB can have its own value.

Common channel powersCareful planning of the common channel powers is very important from the capacity and coverage point of view. This is because the common channel powers are relatively large compared to dedicated powers and thus they take a large part of the BS capacity. Common channel powers are not power controlled and the coverage requirements is quite large because they have to be decoded everywhere in the cell area. Those DL common channel powers which are RNP parameters are listed here:

PCPICHtxPwr This is the transmission power of the common pilot channel which is used for neighbor measurements and MS channel and SIR estimation. All other common channel powers are computed based on this powerOther common channel powers:

PtxPrimaryCCPCH , carries BCCH.SCCPCHtxPwr ,carries PCH and FACH.PSCHtxPwr, primary synchronization channel.SSCHtxPwr, secondary synchronisation channel.AICHtxPwr, indicator for the acquisition by BS of the RACH preamble.PICHtxPwr, carries the paging indicators which tell UE to read the paging message from the associated secondary CCPCH channel.CPICHToRefRabOffset

The parameter defines the offset between the CPICH transmission power and the DL transmission power for the reference service maximum DL power allocation. This is then used in the determination of the maximum downlink power for every bearer. The planning of these powers are described in Chapter 8.5



5.1.2.Handover control (HC)

Four types of handovers can occur in WCDMA:

Soft handovers Intra-frequency hard handovers Interfrequency hard handovers and Intersystem handovers

In soft handover the MS is connected to two or more cells simultaneously to ensure seamless handovers and little interference to other users since the MS is always connected to the best cell. Soft handover is the main handover type in WCDMA. Intra-frequency hard handover can be defined between BSs served by different RNCs and then a inter-RNC soft handover is not possible in that case. Interfrequency hard handover is the handover between different carriers in the case when the same cell has two or more carriers and the load of the carriers has to be balanced or in the case of two cells having different carrier. To enable the interfrequency handovers, the mobile station have to measure the adjacent carriers as well. Parameters.

Cell layerIt is crucial for the effective usage of picocell that the RAN is aware of the cell layer of each user because the interaction of cell layers, especially when they are using the same frequency, is assumed to need modified parameterization. This means more indoor specific handover and load controlling parameters for example.ServingCellLayerThis parameter indicates the cell layer of the serving cell in a hierarchical radio network structure. The cell layer info is either pico, micro or macro.IntraFreqMeasControlThis parameter determines the parameter set which is used to control the intra-frequency measurements.WCDMA neighboring cells for intra-frequency measurementsNumber of neighboring cells. In the case of high rise offices, this figure can be quite high. The value is between 1 and 64. Also carrier frequency, scrambling code and the handover connections of neighboring cells will be listed for the intra-frequency handovers.

Soft handover ( SHO)Cell borders are the main source of other cell interference because of high transmitting powers. In soft handover the MS is connected to several cells and it needs less transmitting power because of selection combining. Thus in the soft-handover the mobile causes also less interference to the network. The mobile measures the received levels (actually power of despreaded symbols/total received power) from neighboring BSs and selects the best candidates for the active set and sends that information to RAN. The final decision about the active set is done in RRM algorithms running in RNC. If the strength of the picocell transmitted Pilot is 14 dBm and the macrocell pilot power is 30 dBm, the pathloss difference in the point where the powers are equal is 16 dB. This corresponds to distances for example about 58 meters from the pico (coupling loss is 110 dB) and 485 meters from the macro (coupling loss is 126 dB), respectively computed by using simple propagation models. If the noise level of the macrocell is –96 dBm and we are using 384 kbit/s services, the needed transmission power of the MS before the soft handover to pico is 22 dBm. This causes 22-110 dB=-88 dBm received power in the pico



cell base-station which is much more than the nominal received power level. This has to be taken into account in the detailed planning.In the following the main soft-handover parameters are shown. The handover parameters can be set differently in the case of not real time traffic (NRT).

AsSizeRT/NRT The maximum size of the active set for an real time connection. The RNC sends this value to the MS. Value is between 1 and 8.WindowAddRT/NRTIf the difference between strongest PCPICH channel (pilot channel Ec/I0) and the PCPICH channel of the neighboring cells is below Window_add the MS suggest RNC to take that channel to the active set. WindowDropRT/NRTIf the difference between strongest PCPICH channel to PCPICH channel in question is below Window_drop MS starts the drop timer.DropTimerRT/NRT If the difference between strongest pilot channel to the pilot channel in question is below WindowDropRT longer than DropTimerRT the BS will be put to the neighbor set.CompThresholdRT/NRTThe weakest active set channel can be replaced by the strongest neighbor channel if pilot(active)<pilot(neighbor)+T_comp when active set is full.

All these SHO parameters are very important from the indoor planning point of view. It has to be ensured that those outdoor mobiles which would cause large interference to indoor cell will be part of indoor active set so that indoor cell is able to control their transmitting powers. The purpose of indoor solutions is to make sure that the indoor cell takes all of the traffic inside the building. Therefore, ideally the handover take place immediately when the user goes indoors. In GSM with hard handover this has been ensured with proper parameterization so that the indoor link budget has been improved artificially. This means that even if the pilot signal (BCCH) is quite low compared to outdoor cells, the mobile moves to indoor. In WCDMA the mobile takes the indoor cell to the active set when the pilot power is within a certain window relative to strongest pilot. One proposal is that we will tune the handover parameters so that when the mobile takes the indoor cell to its active set it drops the macro/micro cell from the active set. Problems arise because slowly moving indoor mobiles take the macrocell to its active set quite often; this is when the indoor pilot decreases because of the fast fading. Then a cell layer specific handover algorithm has to be used. The following changes of the parameterization can be used, for example in the case when a pico cell is in the active set of the mobile:- decrease the Window_drop for macro cell- decrease the T_tdrop for the macrocellThis is because it is preferable to take macro cells away from the active set inside the building. When the picocell is in the active set we should also prevent the macrocell from coming to the active set because of large variations in pilot powers:- decrease the WindowAddRT- increase the T_tdropIn the case of high speed mobiles it is preferable to take the picocell to the active set as early as possible in order to avoid large interference peaks to the picocell. So Window_add should be large for the fast moving mobile in the case of picocells.



Intra frequency hard handoverOne possibility to force the mobile to indoor cell is to define the handover between outdoor and indoor as a hard handover. This increases the uplink loading of the outdoor network but on the other hand decreases the downlink load. There should be some hysteresis between hard handover between outdoor and indoor; the parameters should be set so that the outdoor to indoor is more likely to happen with the same Ec/I0 values than the indoor to outdoor handover. The following parameters are defined for the hard handover:

HardHoRequiredParameter indicates whether the handover from the serving cell to a neighboring cell is performed as a hard handover.EcIoMarginIntra-frequency hard handover is possible if following calculation is true.AveEcIoDownlink + EcIoMargin < AveEcIoNcell.IntraFreqAveWinParameter determines the averaging window of periodic intra-frequency measurement reports. The averaged values are used in the decision algorithm of intra-frequency hard handover.

Inter frequency handoverIt is probable that in some cases the indoor cell is at different carrier than the outdoor cells. In those cases the interfrequency hard handover between micro and pico or macro and pico takes place and it has to planned separately. Usually, the inter frequency handover will be done because of the load or quality reasons but in the case of picocells the handover reason is usually that we want that traffic inside the building will be in the indoor cell. One possibility to do that is to have location based inter-frequency hard handover so that the mobile will enter the slotted mode only when the mobile is close to the building and start doing other frequency measurements.Hard handover is needed for example when the inter RNC soft handover is not possible. Inter frequency handover is a hard handover between different carriers and it is evaluated in RNC. If there is possibility to perform inter frequency handovers the RNC asks the MS to start periodical inter frequency measurements and reporting.

Inter-system handoverThe inter system handover is a hard handover between WCDMA and GSM systems to complement the coverage areas of both systems. The decision algorithm for the WCDMA to GSM system is located in RNC and from GSM to WCDMA in GSM BSC.

5.1.3.Packet Scheduling (PS)

Packet scheduler determines the optimum length and size (bit rate) for the packets in the NRT traffic. The PS main functionality is to decide whether or not a requested packet with a certain bit rate can be sent or not. The decision is based on the measured PrxTotal (in UL) and PtxTotal (in DL) and the estimate loading of requested new service. Related indoor planning parameters for the PS are:

DeltaPrxMaxUp /DeltaPtxMaxUpThe maximum allowed increase of received/transmitted power in UL/DL relative to PrxTot/PtxTot. Value is between 0-3 dB and 0-5 dB, respectively. In the case of large interfering peaks caused by minimum power mobiles, the total received power can increase rapidly and so it is preferable that all interference power tolerance



related parameters should be quite high (3 dB). The worst case happen when the mobile is very close to the indoor antenna when it starts the pre-ambling. DeltaPrxMaxDown, DeltaPtxMaxDownThe maximum allowed decrease of received/transmitted power in UL/DL reactive to PrxTot/PtxTot. The value can be between 0-3 dB and 0-5 dB, respectively. Maximum values for these parameters is is suggested for indoor environments because of larger interference variations.

5.1.4.Admission control (AC) and load control (LC)

The admission control (AC) either accepts or rejects to establish a new radio bearer based on the interference power in the uplink or total transmitting power of the BS in DL. This happens when the new bearer is set up or when the existing bearer is modified (changed in bit-rate). The load control (LC) take place only when for some reason the admission control or the packet scheduler can not control the load (PrxTotal, PtxTotal) and the system is driven to overload situation.The packet scheduler determines the optimum length and size (bit rate) for the packets in NRT traffic. The PS main functionality is to decide whether or not a requested packet with a certain bit rate can be sent or not. The decision is based on the measured PrxTotal (in UL) and PtxTotal (in DL) and the estimated loading of the requested new service. Figure 27 shows the functioning of admission control, load control and packet scheduler as a function of the total transmitter power of the base station (DL) or the total received wideband power (UL).

Figure 27. Basic functioning of admission control, load control and packet scheduling (Figure from [1]).

Admission and load control related parameters:PtxAbsMaxDLPlanned maximum downlink transmission power of the radio link used in the downlink power allocation. The allocated power cannot exceed the value of this parameter. The parameter is controlled on a cell basis. This is not the physical limit but the planned maximum.PtxTarget/PrxTarget



Target for total transmitted power/ total received wideband power in a cell. A downlink/uplink bearer is not admitted if the estimated non-controllable power exceeds this threshold. PtxTarget/PrxTarget is used to calculate PtxTargetBS/ PtxTargetBS which is the first overload threshold for BS and RNC.PtxOffset/PrxOffsetTarget for total transmitted power / total received power can be exceeded by the value of PtxOffset/PrxOffset before load has to be decreased. An uplink bearer is not admitted, if the estimated total received power exceeds the sum of this parameter and PtxTargetBS/PrxTarget. PtxOffset/PrxOffset is used to calculate PtxTargetBS/PrxTargetBS, which is the first overload threshold for BS and RNC.Ptx_threshold/ Prx_thresholdOverload threshold for total transmitter power in DL or received total wideband interference power of the cell in UL. If the power exceeds the threshold, LC starts to perform overload control actions in BS and RNC. This parameter should be set to a very high number for indoors. Otherwise the system starts to drop users when one user is very close to the indoor antenna. PtxMeasAveWindow/PrxMeasAveWindowNumber of frames used for long term averaging at BS of the short term (frame based) averages of PtxTotal /PrxTotal measurements. The results are sent to RNC in RRI messagePrxNoiseNoise level in the BS digital receiver when there is no load (thermal noise + noise figure + effect of possible desensitization). Parameter is needed in noise-rise calculations. ULLoadEstMethodACThe parameter defines the UL power increase estimation method of AC if there are different methods used for AC, LC and PS.Ptx_DPCH_maxThe parameter defines the absolute maximum physical transmission power of a dedicated physical channel independent from a unit. It is defined by the physical limitation of the channel.PtxDPCH_minThe parameter defines the absolute minimum physical transmission power of a dedicated physical channel independent from a certain service or speed. It is defined by the physical limitation of the channel unit.



6. CASE STUDIES

Some indoor case studies from [20] have been added into this document in order to get more concrete picture of indoor capacity and coverage in practical network planning cases. The studied scenario is the simple office scenario shown in Figure 28-Figure 30. The simulations have been done with npsw/i which is the indoor system simulator described in more detail in [17]. Four different indoor planning cases are shown in Chapters 6.1-6.4. The overall conclusions about the study cases are summarized in Chapter 6.5.

Title:floor1.epsCreator:MATLAB, The Mathworks, Inc.Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

Figure 28. First floor of Simple Office with neighboring buildings and antenna locations within the 1st floor.

Title:floor2.epsCreator:MATLAB, The Mathworks, Inc.Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

Figure 29. Second floor of Simple Office with antenna locations within the 2nd floor.Title:floor3.epsCreator:MATLAB, The Mathworks, Inc.Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

Figure 30. Third floor of Simple Office with antenna locations within the 3rd floor.



6.1. Effect of offered indoor user density

Background: In this case the required indoor traffic that is profitable to support through the indoor network built with different signal distribution systems will be studied. Two outdoor scenarios were considered: two close microcells (Cells 3 and 4) and one far microcell (Cell 2). The used outdoor scenario is hen in Figure 31. In each case 6 different indoor solutions were considered:

Microcells only microcells + 1 sector DAS with 6 antennas microcells +3 sector DAS with 6 antennas microcells +1 pico BS located in the middle floor microcells +3 pico BSs, 1 in each floor microcells +6 pico BS, 2 in each floor

Figure 31. The used microcell scenario.

The initial traffic density of the scenario was low. In that study area there were only 30 mobiles; 21 of those were speech users with 8 kbit/s and 9 were 144 kbit/s data users. In the initial MS distribution only 3 mobiles were inside the studied building.

Simulation parameters:BS TxMax: 24 dBm (pico), 37 dBm (das)Max power per link: 21 dBm (pico), 30 dBm (das)Pico BS Pilot: 14 dBm, 25 dBm (das)Pico BS noise figure: 5 dBm + desensitizationDesensitization: 10 dB in pico, 0 dB in DASMicro BS TxMax: 37 dBmMicro BS Pilot: 23 dBmMicro BS noise figure: 5 dBmMicro BS common channel other: 23 dBmWindow_add: -3 dBChannel: PedestrianChannel orthogonality: 0.92Service: Mixed (70% 8 kbit/s, 30% 144 kbit/s)UL max interference: 7 dBMS minimum power range: -44…21 dBmCable attenuation 10 dB in 1 sector case



8 dB in three sector case0 dB in pico BS

Simulations have been done with npsw/i version 1.0.0 (ver. 3.0.0. in npsw)

The used bit rates in the mobiles were distributed as follows: 70% speech and 30% 144 kbit/s data. Symmetrical traffic has been assumed here meaning that the uplimnk and the downlink bit-rates are equal, which might not be the case in practice. The mobiles were put to outage randomly, so that in the final capacity results the same bit-rate distribution was assumed. The outage has been defined as the percentage of the mobiles which are in outage after the npsw/i run from all mobiles inside the building. In the following table the quality criteria is that the the indoor outage has to be below 20%.

Table 8. The maximum indoor capacity (=number of users). The maximum allowed outage was set to 20%.

Two close microcells One far microcell1 DAS antenna 20 186 DAS antennas 22 193 sector DAS 58 371 pico 39 403 pico 116 1036 pico 147 156

Table 9. Indoor penetration: the percentage of users using indoor cell from all served indoor users

Two close microcells One far microcell1 DAS antenna 47 1006 DAS antennas 78 1003 sector DAS 81 1001 pico 51 883 pico 75 996 pico 83 100

The indoor penetration in the case of two close microcells is usually below 70 %, so that less than 70% of the indoor users are connected to indoor cells and microcells handle the large part of the indoor traffic. In the second case when there was only one far microcell the penetration was almost 100% except in the 1 pico case when the indoor penetration was 88%. Results:Figure 32 shows how much the closest microcells can take the indoor traffic when the indoor penetration increases from 8 users to 63 users. The indoor outage is 0% with 38 users and 9.7% with 43 users. So the maximum throughput was about 1.8 and 1.9 Mbit/s to maintain good quality. The qood quality here means that the outage percentage is below 20% from all users located inside the building so actually this is the measure for good indoor quality whether it is provided with either pico or microcells.



Figure 32. The microcell throughput as a function of indoor mobile users and the respective noise rises.

In the next case the indoor base station with a DAS system having totally 6 antennas was simulated. The results are shown in Figure 33. The capacity in that case was 22 users and 78% of the users inside the building were using the indoor site. In that point the microcells take about 1200 kbps and the picocell 1100 kbps from indoors. So the total throughput is about 2300 kbps. This is only slightly more than in the case of microcells only (2000 kbps in that case). On the other hand the average noise rise in the microcell uplink decreases from 6 to 3.5 dB when using this indoor solution.

Figure 33. The microcell and picocell throughput as a function of indoor mobile users and the respective noise raises in the case of 1 sector DAS with 6 antennas.

In the case of three sector DAS antenna with two antenna heads per sector (attenuation to the antenna is 8 dB) the capacity was 58 users. The results are shown in the Figure 34 from where we can find that the indoor throughput is about 3000 kbps through the 3 indoor cells and 1900 kbps through the microcells, totally 4900 kbpsIn Figure 35 the simulation results with 6 picocells are shown. With 147 users the picocell throughput is about 7000 kbps and the microcell indoor throughput is 2000 kbps totally 9000 kbps. 83% of all the users inside the building are served by indoor cells. The average noise rise in picocell is about 3 dB and in the microcells about 3 dB.



Figure 34 The microcell and picocell with 3 sector DAS system. The throughput is as a function of indoor mobile users.

Figure 35. The microcell and picocell throughput and noise raises in the case of 6 pico as a function of indoor mobile users.

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When we study the case of one microcell far away from the target building the situation is more straightforward (Figure 36). The outdoor cell does not take traffic from indoor and it is more like coverage limited case (in 1 pico BS case).

6.2. Effect of Pico BS Density

Background: In order to estimate the total capacity of a pico BS network the effect of the other cell interference as a function of the base station density has to be understood. In this study case the number of basestations has been increased from 1 to 12. The BSs have been selected so that the supposed interference increase between additions of BSs is as small as possible. The numbers there in Figure 37 refer to the order of installations of BSs in the study, so that BS number 1 was used in the first simulation round, 1 and 2 in the second and so on. The pico BSs were added to the simulation scenario as uniformly as possible.

Simulation parameters:Simulation scenario used: Scenario 1Number of antennas: Pico [1...14], Micro [3 4]

antennas 9, 5 13, 8, 11, 14, 10, 1,12, 3, 4, 11,2 in Figure 28-Figure 30

Pico BS TxMax: 24 dBmMax power per link: 21 dBmPico BS Pilot: 14, 17 dBmPico BS noise figure: 5 dBm +10 dB desensitizationMicro BS TxMax: 37 dBmMicro BS Pilot: 23 dBmMicro BS noise figure: 5 dBmMicro BS common channel other: 23 dBmT_add: -3 dBChannel: PedestrianChannel orthogonality: 0.92Service: 384 kbit/sUL max interference: 7 dBEb/N0 (UL) 1.4 dBEb/N0 (DL) 4.0 dBMS minimum power range: -44…21 dBm



Simulations have been done with npsw/i version 1.0.0 (ver. 3.0.0. in nps/w)

Results:The results (Figure 38, Figure 39) show that when the number of picocells is increasing the number of users per cell decreases from about 6 users to 3-4 users per cell. This is because the decreased isolations inside buildings cause increased interference from other picocells. The results also show that the main part of the interference comes from picocells and not from the outer microcellular network. The pico network is more balanced when we used 14 dBm Pilot powers instead of 17 dBm. In the 17 dBm case the DL becomes the limiting direction and the downlink coverage decreases when the number of pico BSs increase because of interference from the pilot channel. When using a power of 14 dBm powers in Pilot and also the other common channels the coverage is always above 90% for a 1 Mbit/s user. Only when two picocells are put in LOS the coverage will be slightly below 90%. Figure 42 shows the total number of microcell users after DL iteration for 14 dBm and 17 dBm Pilot case. Results show that when using 14 dBm Pilot instead of 17 dBm we will get better capacity for microcells also. The traffic channel powers will be about 1 dB lower in the 14 dBm pilot power case than for 17 dBm case.The initial number of users was high, so that the load control of the npsw/i was used to remove users from highly loaded cells. The quality of the network was determined by computing the UL and DL coverages. Only one mobile station distribution for each base station scenario was used which explains the large random variation of the one simulation.

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Figure 38. Users per cell, total number of users and DL indoor coverage as a function of number of pico cells. In the case of 6 pico BS two different BS scenario were used. Pilot

power here was 17 dBm.



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Figure 39. Users per cell, total number of users and DL indoor coverage as a function of number of pico cells. In the case of 6 pico BS two different BS scenario were used. Pilot

power here was 14 dBm.

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Figure 40. The other-to-own cell interference as a function of number of pico BS.



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Figure 42. Total number of users in microcells (#3 and #4) as a function of picocell users.

6.3. Comparison between FODS/DAS/Pico

Background: In this simulation the maximum capacities of three indoor systems (DAS, FODS and pico BS) have been analyzed and compared with the same indoor scenario. It is assumed that the Pico BS is high capacity solution for indoors and DAS systems are for providing indoor coverage. However, in the WCDMA BS release 1 we could have up to 6 sectors in one BS which can also be used for indoors so it could be cost efficient to use many sectors through present GSM coaxial DAS systems instead of using many Pico BS. In this study these two approaches are compared as well as the fiber optical distribution system (FODS). The simulation parameters are shown below:

Simulation parameters:Simulation scenario used: Indoor BS with DAS Number of antennas: Pico 3 antennas per floor, Micro (Cells 3 and 4

in Figure 31)



BS TxMax: 24 dBm (pico), 37 dBm (i_das)Max power per link: 21 dBm (pico), 30 dBm (i_das)Pico BS Pilot: 14 dBm, 25 dBm (i_das)Pico BS noise figure: 5 dBm + desensitizationDesensitization: 10 dB –20 dB (pico), 5 dB (i_das)Micro BS TxMax: 37 dBmMicro BS Pilot: 23 dBmMicro BS noise figure: 5 dBmMicro BS common channel other: 23 dBmT_add: -3 dBChannel: PedestrianChannel orthogonality: 0.92Service: Mixed (70% 8 kbit/s, 20% 144 kbit/s, 10% 384 kbit/s)UL max interference: 7 dBMS minimum power range: -44…21 dBm

Simulations have been done with npsw/i version 1.0.0 (ver. 3.0.0. in nps/w). DL Eb/N0

values were used when simulating the uplink performance of DAS system. In the case of DAS there is no Rx diversity assumed.

Results:Result tables are shown in Appendix C. In the first network scenario each floor has 2 antennas, so we have a total number of 6 antennas for one sector. The attenuation from the BS output to the antenna input is 15 dB; for each antenna head we must have one 1:2 splitter and one 1:3 splitter, which causes attenuation of about 8 dB. The resulting 7 dB comes from the attenuation of the co-axial cable and the needed adapters. Results show that if no diversity is used the capacity of a passive DAS network is not very good but the coverage is 100% for both UL and DL. This is based on the assumption that the DL Eb/N0s can be used to model the non-diversity situation in UL. The DL coverage is good because we do not have high DL interference present in this scenario. Table 21 shows the results with 3 sectors with and without UL diversity. It can be noticed from the results that if we do not have diversity in UL the capacity is even less than the differences in EbN0s because the other cell interference is about three times as large compared to the diversity case. In the non-diversity case the larger headroom is assumed. If no diversity is used in DAS the antenna placement might be difficult because of increased interference to microcells (about 3 dB more noise raise in microcells in the no diversity case). The DL performance is better in DAS case than with pico because of the large output power (5W). The base station does not need desensitization because of the large attenuation of the feeder cables. The MCL is typically about 55 to 60 dB with the feeder network. Table 22 shows the result with pico BS with one antenna per floor. If we compare these results with previous results with DAS antenna we can conclude that if we had diversity in DAS the performance would be even better than with pico BS because of the better signal distribution. The DAS network would cause much less interference to microcell layer and also to other sectors. In practice the UL diversity is quite difficult to implement with coaxial DAS networks because we would need to duplicate the HW (cables, splitters, antennas). Larger output power in Pico cells can provide 10% larger DL coverage area. The DL performance is typically worse in PicoBS than in DAS. This is because of the large output power of DAS base station.



As a target area of DAS networks we could have economical co-siting within current GSM DAS networks, good indoor coverage and moderate capacity. Table 23 shows the results from simulations where we have tested the applicability of letting pico BS to feed a local DAS network. Results show that the DAS network would provide only slightly better DL coverage than the pico BS with single antenna. High signal attenuation due to the DAS network (cables and splitters) causes decrease of DL coverage with Pico BS compared to case where DAS is feeded by a high power BS.

Table 24 shows the respective simulations with Pico + FODS. In the first case it was assumed that there was no UL diversity available in FODS and therefore the interference levels were quite high. In the following simulations it has been assumed that the UL diversity is available. According to simulations the DL performance is lower than in outdoor BS + DAS case but better than in Pico + DAS case because now we do not have any attenuation in the cables. Anyway, the UL is limiting because of the small dynamic range of the mobiles. However, by further desensitization we could shift the minimum required mobile station Tx power to the used range. Even when using three antennas per floor this causes too much interference to the microcells. If there are many minimum coupling loss mobiles in some sector we can desensitize only that sector with about 2-3 dB more than the others. However, if the desensitization difference is too high all the other sectors begin to suffer. One possibility is to desensitize also the microcells but according to the results then the interference from outdoor to indoor increases and then the indoor capacity begins to drop. If we do not se the desensitization at all, the problem moves to radio resource management, where the algorithms and parameters have to be more tolerant against large noise raises.

6.4. Effect of the indoor solution to the microcell noise rise

Background: The effects of desensitization, minimum MS Tx power and minimum coupling loss to the UL noise rise of microcells was studied here. In the default case, no desensitization was assumed, so the indoor network is affected by high variations of the uplink noise. The speech service was used here to avoid random effects of the minimum power users, so in this case there is always lots of minimum power mobile users close to the indoor antennas. Hard blocking was also used here. Hence, a maximum number of channel cards in the base station was assumed.

Simulation scenario used: Scenario 1Default number of antennas: Pico: 6 pico BS (2 per floor), 2 Micros (Cells 3

and 4 in Figure 31)Pico BS TxMax: 24 dBmMax power per link: 21 dBmPico BS Pilot: 14 dBmPico BS noise figure: 5 dBmMax UL noise raise: 30 dBMicro BS TxMax: 37 dBmMicro BS Pilot: 23 dBmMicro BS noise figure: 5 dBmMicro BS common channel other: 23 dBmT_add: 3 dBChannel: Pedestrian



Channel orthogonality: 0.75 (micro), 0.92 (pico)Default MCL: 45 dBDefault MS min Tx power: -44 dBmDefault BS desensitization: 0 dBService: 8 kbit/sHard blocking: on, 64 users per cellEb/N0 (UL) 1.4 dBEb/N0 (DL) 4.0 dBMS minimum power range: -44…21 dBm

Results: The results show that in DL the interference from pico to micro is very small. In principle the DL capacity of micros can also increase when adding more picos but in this case the building is so close to the micros that this effect can not be seen. In the case of only one cell the other cell interference is zero and all the interference comes from non-orthogonality. In that case the interference is small and therefore also the required power is small. In a more realistic scenario the DL interference is more uniformly distributed so in that case there might occur also an increase of microcell capacity when using picocells.The 20 dB desensitization of pico BS increases the uplink noise rise in microcells by 2.2 dB. If we do not have any indoor solution the microcell noise raise is 2.2 dB so that the total effect of indoor solution to microcell noise is 4.4 dB. If we could use antennas for indoors which provides larger coupling loss at small ranges (MCL 4560) we would gain also in microcell link budget by 1.7 dB.

Table 10. Effect of number of pico BS to DL capacity. Speech users.

Number of Pico BSs Micro users Pico users Total number of users0 5291 508 113 621.03 525 357 882.06 528 692 1220.09 524 933 1457



Table 11. Effect of desensitisation to the noise raise in microcells. Speech users, 6 pico BSs.

Desensitisation (dB) Average micro noise rise (dB)

Average pico noise rise (dB)

0dB 4.4 18.15dB 4.8 13.710dB 4.3 8.415dB 5.8 5.720dB 6.6 3.0

Table 12. Effect of minimum coupling loss to the noise raise in microcells. Speech users, 6 pico BSs.

MCL Average micro noise rise (dB) Average pico noise rise (dB)35dB 5.8 19.345dB 4.4 18.155dB 3.7 14.960dB 2.7 12.0

Table 13. Effect of number of pico BSs to the noise raise in microcells. Speech users, 6 pico BSs.

Number of pico BSs Average micro noise rise (dB)


0 2.21 2.6 15.23 3.6 14.96 4.4 18.19 5.3 18.6

Table 14. Effect of minimum mobile Tx power to the noise raise in microcells. Speech users, 6 pico BSs.

Mobile min power Average micro noise rise (dB)


-44dBm 4.4 18.1-50dBm 2.5 12.3-55dBm 2.0 8.4-60dBm 1.7 5.0-100dBm 1.6 1.8

6.5. Main findings from the system simulation study cases

The conclusions and learning points of the study cases are also grouped into the two categories discussed, i.e. BS configuration and network planning cases. It must, however, be reminded that such a division is ambiguous and serves only as a general guideline.



BS configuration study cases

In here are listed the findings when comparing different radio signal access methods. The pico BS means a small WCDMA base station with relatively low output power. The system simulations with DAS and FODS have been done by assuming high output power base stations (5W). Based on the BS configuration study cases in [20], the following main conclusions can be drawn: The choice of a 24 dBm maximum Tx power for the Pico BS seems to be a

reasonable choice, since additional power does not increase capacity but on the other hand reduced power starts to decrease capacity rapidly. This true for the UL limited cases with symmetrical data flow and with quite high orthogonality factors.

Even a small change in the MS TxP dynamic range (65 dB 70 dB) would significantly increase capacity of picocells because of the own cell inteference decrease. However, as such an increase in the dynamic range is quite unlikely, the effect of Pico BS desensitization was also studied. The results show that a 10 dB desensitization would bring the benefits (in terms of Pico BS capacity) of a 10 dB increase in the dynamic range (65 dB 75 dB). However, a 5 dB desensitization would only result in a marginal capacity increase for the 65 dB dynamic range case. Desensitization naturally "eats" users from outside microcells, so the overall capacity increase in the network scenario simulated is less significant.

DAS network results in general: - Coverage (UL/DL) is not limiting, but the capacity is relatively low (no Rx diversity,

one sector, 2 antennas/floor, 6 antennas/sector):- The large output power of the simulated DAS network (5 W) leads to a better DL

performance than with Pico BSs, and no desensitization is necessary due to the high attenuation of the feeder cables (no Rx diversity, three sectors, 2 antennas/floor).

- UL diversity would make the performance of a DAS network generally better than that obtained with Pico BSs, but in practice UL diversity is difficult to implement due to the requirement of duplicated HW (cables, splitters, antennas).

- Economical co-siting with GSM DAS networks is one important target area.- FODS would be beneficial for WCDMA because of possibility to have UL and DL

diversity. Also the implementation of FODS is easier than of DAS systems. Pico BS results in general:- Performance in DL is typically worse than in a DAS system due to the higher output

power of the latter.- Capacity of a Pico BS network is of the same order or slightly lower than a DAS

network with UL diversity (UL diversity by assumed in Pico BS in all cases).- If a Pico BS is used to feed a local DAS network, only a slightly better DL coverage

is obtained when compared to a Pico BS with a single antenna.- If a Pico BS is used to feed a FODS network, the DL performance is worse than in

outdoor BS + DAS case but better than in Pico + DAS case. The reason for this is lack of cable attenuation in the FODS system. UL diversity for FODS is assumed in the simulations, since it should be possible to implement with a relatively low cost.

Increasing the number of antennas per floor also increases the risk of having mobiles transmitting at a minimum power. If a sector is suffering from many minimum coupling loss mobiles, a extra desensitization of 2-3 dB is needed for that sector (when compared to other sectors). A larger difference will start to disturb the other sectors.



The use of a Pico BS in co-existence with a co-axial DAS network was also investigated due to the enhanced capacity of such a combination. In general, due to the cable losses of the DAS network, the DAS users interfere with the Pico BS in UL because of the high MS Tx powers of the DAS users. If pico BSs are desensitized, the interference from DAS users is reduced but instead the Pico BS users start causing high interference to the DAS network. On overall capacity maximum is obtained when the DAS network's pilot powers are reduced in order to decrease the DAS cell area. It can be noted that the desensitization of a Pico BS should be set so that the sensitivity difference is equal to the difference in EIRPs of the Pilot powers of Pico BS and DAS.

There were no significant differences in the results if antenna types (omni vs. directional) were varied.

Network planning study casesBased on the network planning study cases, the following main conclusions can be drawn: The total capacity was investigated as a function of the Pico BS density in the

network. The results show that when the number of picocells increases, the number of users per cell decreases from roughly 6 384 kbps users to 3-4 384 kbps users per cell. This is due to the increased interference from other picocells resulting from decreased in-building isolation. In fact, the main part of the interference comes from picocells instead of the outdoor microcellular network. The results also show that by using 14 dBm Pico BS Pilot power instead of 17 dBm a more balanced network is obtained.

Plug&Play network:- The basic task was to investigate whether adequate capacity and coverage is

obtainable with very simple planning rules, thus implying small planning and installation costs. Simple network planning rules were also presented.

- The results show that if the traffic is uniformly distributed and the noise rise in- every cell is equal, the Pilot powers are the same and the BSs can be uniformly distributed. In addition, if the services used are 384 kbps or smaller, the variance between cells is mainly caused by the network scenario and MS locations, and not the service.

- Indoor cells are most likely interfered by other indoor cells, as the microcell users tend to transmit with relatively low powers due to being in LOS to their microcell.

- The effects of hot spots was investigated by placing high bit rate users in different areas of the network. The results show, however, that the indoor network is quite stable (in terms of coverage, capacity and throughput) and the differences in input traffic do hot have a significant effect.

- Capacity gain from detailed planning was found to be quite small in pico cells. Such detailed planning should be focused on minimizing the UL interference for micro cells, whereas indoor capacity and coverage is quite easily obtained by employing simple planning rules and default values.

The DL interference from pico to micro cells is negligible. However, a 20 dB desensitization of pico cells increases the UL noise rise by roughly 2 dB. The micro cell link budget could be improved by almost 2 dB if antennas with a higher coupling loss at small ranges could be used for pico cells.

If the SHO window is increased (from 3 to 6 dB), the other cell interference in UL increases only slightly.



7. INDOOR MEASUREMENT RESULTS

In this chapter the key findings of the first WCDMA experimental indoor system measurements have been reviewed. The more detailed description about the measurements is in [18]. The aim of these indoor measurement was to study the basic WCDMA features for indoor environments giving support for indoor radio planning problems with WCDMA. The measurement environment (Nokia networks premises in Upseerinkatu 3) is a typical office made of concrete and brick with quite small working rooms and long corridors. A dedicated indoor signal distribution and antenna network has been installed at that site in order to provide a flexible, easily configurable indoor test environment.The used WCDMA base station was the Helmi base station used in the Nokia's experimental test system. The more detailed description about the experimental system can be found from the basic macro measurement report [12] and Helmi descriptions [19]. For mobile station mobility, a dedicated measurement trolley containing experimental WCDMA mobile (Dumbo), a battery, and two laptops for the data gathering and measurement software controlling purposes has been used. The used measurement set-up is shown in Figure 43.

The used indoor distribution network includes: Passive distributed antenna system (DAS) with 7 omni antennas with 2 dBi gain

installed on the ceilings Fiber Optical Delivering System (FODS) with one main unit (MU) and one remote

unit (RU). Uplink diversity antennas. Space diversity used, the distance between antennas was

about two meters. Leaky feeder. The length of the leaky feeder segment was about 30 meters. Two

parallel leaky feeder was used and so the diversity with that can also tested.

The experimental data includes measurements covering following indoor specific problem areas:

space diversity in uplink Rx, multipath diversity, passive DAS antenna solutions, functionalities of optical signal distribution systems, coverage, path losses, ceiling and elevator attenuation, RAKE receiver functionality in indoor multipath channel, functionality of fast closed loop and outer loop power control for indoor

environments.

In the following chapters these questions have been analyzed shortly.



Figure 43. Measurement network setup.

7.1. Diversity measurements (omni antenna, leaky feeder)

In the diversity measurements the same path along the corridors was measured three times with omni and with leaky feeder antennas (used measurement route in). In the omni-antenna case both antennas were measured walking the same route twice. The antenna branches were connected in that case to the Tx/Rx connector of the BS. In the diversity case the other antenna was connected to Tx/Rx branch and the other was connected to Rx diversity branch. The average diversity gains (=average decrease of MS TxP) as well as the average uplink Eb/N0-setpoints were recorded.The example measurement result from the non-diversity case is shown in the Figure 45. The diversity gain has been estimated in the case of two antenna case: omnidirectional and leaky feeder. The diversity gain was computed as difference between mobile station Tx powers in one antenna gain and in diversity case in every averaged measurement point. The original recorded data was average so that the distance between adjacent samples was 1 meter. The locations of the measurement points were computed based on the recorded marker points along the measurement route. Those averaged measurement points were removed from the analysis where the transmitted power was below -30 dBm which was considered as real minimum power of the mobile station. The distributions of diversity gains are in . The average uplink Eb/N0 setpoint values in the stable part of the Eb/N0 in the middle of the measurement line was also computed with and without diversity. The results are collected to the Table 13.



Figure 44. Measurement route in the diversity measurement. Measurement line goes from floor 2 to floor 3 and then back to floor 2.

Table 15. Average Eb/N0 setpoint and diversity gain values.Average Eb/N0-setpoint in uplink

(dB)Diversity gain

(dB)



Omni antenna1 11.34.5 dBOmni antenna2 12.0

Diversity with omni 12.0Leaky feeder1 12.3

4-5 dBLeaky feeder 2 11.0Diversity with leaky 11.9

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Figure 45. The effect of power control in the single antenna and leaky feeder antenna cases. No diversity used here. The RxP has been average over ones superframe (640 ms).

The RxP units are dBus which are 113 dB above dBms.

Figure 46. Distribution of the diversity gain. Left: omni antenna, right: leaky feeder. In the leaky feeder case the antennas were installed to different side of the tower so that also

the gain against slow fading can be seen in these figures.

Figure 47 shows the power delay profile of single antenna and leaky feeder in dB scale. This data includes only those power delay profiles which are at the marker position along the measurement route shown in the Figure 44. It can be seen that because of the time dispersion the signal is spread over several chips. No significant multipaths, reflections or diffractions can not be seen in these results which was noticed to be common in all these measurements. This power delay profiles are so called fat-fingest which are quite common for indoor environments where there are lots of scattering and reflecting objects between the transmitter and receiver. Also the RAKE receiver has have capabilities to collect maximum energy from this environment.



Figure 47. Relative PDP, of omni antenna and leaky feeder antenna without diversity.

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Figure 48. UL FER, MS TxP and UL Eb/N0 setpoint measured along the measurement route (Figure 44). Single omni antenna case.

7.2. Headroom in the diversity case

The headroom can be defined as the needed MS Tx power above the mean power to obtain the required FER level. Two examples of the signal behaviour at the cell edge are shown in Figure 49. The left and the right figure were without and with the uplink diversity, respectively. It can be seen that the fading is much larger in the case without diversity and it drops faster and quite suddenly compared to the diversity case. It can be seen also that in both cases the uplink is working quite a long time and the TPC works hits the maximum power level (35 dBm) without dropping. In the non-diversity this length in meters is about 8 meters and with-diversity case it is about 12 meters, assuming the 3 km/h walking speed.



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Figure 49. Uplink FER, mobile station Tx power and the UL Eb/N0 setpoint in the diversity measurement. In the left figure there is only one antenna case without diversity and in the right figure the diversity antenna was used. The time scale in these two figures is approximately the

same.

According to measurements the coverage of the leaky feeder was limited to the same or the next floor whereas the omni-antenna coverage was several floors in the Upseerinkatu tower. In the measurement case shown in Figure 39 the coverage to the central part of the UPS is not large; the call drops approximately in the center of the central building. This is mainly because there is only a quite narrow corridor between those two buildings (tower and the center part) and the attenuation due the outer walls is very large.

The dedicated Pilot channel transmission power was 29 dB. In these measurement the antenna attenuation was 20 dB and the cable + adapter attenuation is about 5 dB. The signal strength at the antenna is then about 7 dBm. The minimum coupling loss can be computed is then (Figure 45) 7dBm-(65dBu-113)=55 dB. In the case of the leaky feeder the minimum coupling loss is 7dBm-(51dBu-113)=69 dB. So there is 14 dB difference in MCL. So this is the pathless between BS and MS antenna feeders. The maximum path loss is according to measurements is 152 dB after which the call is dropped.

7.3. Coverage with the whole DAS network

The coverage of whole antenna installation was also tested. Figure 63 shows the received power and transmitted power along one measurement route. All the measurement routes



in the 7 antenna case cover almost whole Upseerinkatu 3 building showing that with this antenna scenario the speech coverage is large. The mobile station is in its minimum power when we are very close to the antenna. The minimum power areas are smaller in the 7-antenna case as in 1 antenna case because of cable losses due to signal splitting.

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Figure 50. 7-DAS, MS TxP vs. RxP, route 1

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Figure 51. 7-DAS, UL FER, MS TxP and Eb/Io setpoint, route 1



Figure 52. 7-DAS, power delay profile, route 1.

It can be seen thateven in this 7-antenna case the time dispersion is not very large so there is only one significant multipath tap present. The Eb/N0 setpoint in this example is better than in the case of single antenna case when the antenna is in the tower (Figure 44). One possiblereason for that would be the channel and the RAKE allocation would be different.Figure 53-Figure 55 show the transmitted power of the mobile along the measurement route in the 7-DAS case. In the DAS cases the system was UL limited.

Figure 53. 7-DAS, MS TxP profile, route 1, 2nd floor



Figure 54. 7-DAS, MS TxP profile, route 1, 3rd floor

Figure 55. 7-DAS, MS TxP profile, route 1, 4th floor

In the case of fiber optical distribution system which was also tested the system was DL limited. This is because of limited output power of the FODS system (max 23 dBm EIRP). Figure 56 shows the UL performance in the case of FODS. Because the UL and DL are separated in the FODS system there are abnormal power control effects in some cases because of unbalanced UL and DL. Usually the FODS system worked reasonably well together with WCDMA.



1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

x 104

0

50

100

UL

FE

R %

iv8.mat

UL FER

1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

x 104

-50

0

50dB

m

MS TxP

1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

x 104

0

10

20

dB

sfn UL Eb/Io setpoint

Figure 56. FODS, UL FER, MS TxP and Eb/Io setpoint, route 1

7.4. Co-siting measurements (GSM with WCDMA)

Many office buildings already have a DAS network for a 2nd generation system, such as GSM/DCS in the 900/1800 band. The installation costs of such a DAS network are the most important part of the total costs for providing indoor coverage. Therefore, customers would be very keen on using the existing DAS network for co-siting of GSM and WCDMA. If necessary, the antennas could be changed to dual- or tri-band. The cost of this would, however, be negligible, when compared to cable installations. Another reasoning for co-siting comes from the difficulties in obtaining sites for the base stations in many indoor environments. A combined approach, such as the Nokia UltraSite which combines GSM, EDGE and WCDMA in the same cabinet would be advantageous in such cases. Thus, if the BSs are already co-located for one reason or another, using the same feeder cables for signal distribution would be even more tempting.

The GSM and WCDMA signals must be fed into a single cable for the experiment. Thus, a wideband combiner must be employed for this task. Since the motivation for the experiment was to test the WCDMA system performance and not on RF-specific measurements, any combiner fulfilling the basic requirements could be used. A Rojone 800-2000 MHz combiner was available for the experiments, the basic characteristics of which are shown in TAB. The basic measurement set up including the combiner and all connections needed for the experiment is shown in Figure 57.

Parameter ValueFrequency range 800 – 2000 MHzIsolation 20 dB min adjacent ports, 30 dB min non-adjacentReturn loss 20 dB minTransmission loss 6.5 dB 1.0 dB maxInsertion loss 1 dB typical (included in transmission loss spec)Power 100 Watts per port



Figure 57. WCDMAGSM co-siting measurement set-up.

The WCDMA and GSM co-siting tests were done in Upseerinkatu premises by using WCDMA experimental base station (Helmi) and GSM1800 BTS. The signal was combined into the same DAS feeder with wideband combiner. The same route were measured with WCDMA collecting transmitted power values of the WCDMA phone and changing the incoming Tx powers of the BCCH channel of the GSM network in every measurement route. With 30 dB attenuation in GSM network the GSM coverage was very poor but with 0 dB attenuation the measured Rx values were above –70 dBm so there was strong signal everywhere in the cell area inside the building. The possible intermodulation causes interference to the WCDMA uplink band causing noise rise in the WCDMA BS Rx. This causes increment of the MS Tx powers because of SIR-based closed loop power control. Figure 58 shows the measured transmitted powers of the WCDMA along the measurement route. It can be seen that the interference does not have large effect, if any, to the mobile powers. In here it has to keep in mind that the BTS was a prototype having better outband emission properties than with a real product.



-20

-15

-10

-5

0

5

10

15

20

25

0 5 10 15 20

Marker point # along route

Mo

bile

Tx

P (

dB

m)

No GSM signal

GSM signal with30 dB attenuation

GSM signal with 0dB attenuation

Figure 58. Transmitted powers of the WCDMA mobile along the measurement route in the WCDMA-GSM co-siting test.



8. NETWORK PLANNING METHODS

There are normally two reasons why to build an indoor site. One is to improve the poor indoor coverage and the other is to free capacity to outdoor cells. The micro/macro layer is the basic coverage and capacity solution also for indoors especially with lower bit rates. Because of the high-density micro layer in cities the indoor coverage is normally adequate. Anyhow quite often the outdoor cells are congested because of the traffic coming inside a building. By implementing an indoor cell it is a good possibility to free capacity to outdoor cells. Also the frequency planning with indoor becomes easier; for indoor antenna the output power (EIRP) is low and walls increase the path losses that the therefore the interference area of the indoor cell is much more limited than in the case of outdoor cell. Usually, the dedicated indoor network is a special solution in cases where the micro/macro layer can not provide sufficient capacity and coverage for indoors or all the micro/macro capacity are used in one or two buildings with high data rate and/or high user density. It should be pointed out that indoor areas are anyway very important when thinking the whole network performance: the penetration losses from outdoor to indoor are large and therefore the coverage problems are typically inside the buildings. Approximately 80% of the mobile users are indoors and in the case of data users this figure can be even higher. In WCDMA where the coverage and capacity is more closely related to each others and the interference control is essential the importance of indoors is maybe even higher and the different cell layers (macro, micro, pico)are more tightly related to each other. Also the cell borders are quite often indoors so that the selection of suitable handover parameters in order to avoid dropping or high interference is critical. In WCDMA there is only three or four bands available for the operator so that indoor and outdoor networks are more likely in the same frequency band. Therefore, it is not possible to totally separate indoor and outdoor network planning from each others and the indoor network deployment is part of the optimization and evolution of the whole network. The key performance indicators (KPIs) of the outdoor network has to followed (Network management system (NMS) data, measurements, customers feedback), and decision of the dedicated indoor solution is based on that. Before decision of the indoor network deployment the outdoor network KPIs should be studied. At least the following questions should be answered:

What are the reasons for the problems in the outdoor network (coverage, capacity, bad quality, delays, low throughput, etc.)

Location of problem areas/problem cell?

After this we should clarify how to use indoor solutions in order to increase micro/macrocell capacity and coverage? In the following some basic cases are reviewed.

In some cases, indoor coverage problems can be solved by down-tilting or re-orientating rooftop antennas towards the target building. Indoor coverage can be also provided by using outdoor micro cells. Because of complexity of indoor propagation and the attenuation caused by external building wall, signals from neighboring outdoor sites may not be able to provide sufficient indoor coverage nor the quality. In these situations, antennas and BS’s must be installed inside the building itself. Because of majority of the calls are made inside buildings, the indoor solution is also good way to increase capacity.



Some high-rise buildings the indoor solution is only way to solve interference problems and provide good quality inside buildings. Naturally the indoor site solutions are more complex than the outdoor sites; usually huge number of antennas and other RF-components are needed. For the tower type of office buildings, for example typically two antennas per floor are needed, so if we have buildings with 60 floors, roughly 120 antennas are needed. Good indoor planning ensures also that indoor solution is well integrated into overall network through the interference planning, parameter planning, frequency planning, and optimization, e.g. via tuning the RNP parameters optimally for indoor solution. Optimization takes place after the implementation of the indoor solution.On the other hand the mobile phone has become an essential tool for personnel who spend considerable working time outside their offices. GSM operators are looking for solutions that allow them to address the business customers need for wireless solutions with PBX-type services, competitive tariffing and advanced cost and service management. Migration of a considerable part of voice traffic from fixed networks to mobile networks by complementing and replacing the PBX is an opportunity for mobile operators. It enables operators to offer PBX-comparable tariffing and enhance mobile penetration and usage. In addition to the traffic in offices, mobile usage outside the low tariff area increases due to the greater mobile penetration.

Coverage holes in microcellsIt should be clarified whether the UL or DL coverage is the problem in micro/macro layer. In uplink it should be find out what is the reason for low coverage. Possible reasons can be for example large interference from high bit rate users in adjacent cell, wrong Pilot power settings in adjacent cells, etc. One way to increase the indoor coverage in micro/macro layer is to decrease the PrxTarget value and thus loose the UL link budget This increases the blocking probability for RT services and decreases bitrates for NRT services, but if the UL capacity is not a problem we could do that. Also adjustment of the soft-handover parameters (increasing the adding window for example) should increase the UL coverage if the downlink coverage/capacity is not a problem. Also reorienting or re-locating the microcell antennas are possibilities to increase the indoor coverage. If there is an existing indoor solution near the microcell, the possible interference from indoor users to micro/macro layer can be possible reason for UL coverage problems in microcells. In practice an indoor solution is in many cases the only possibility in order to provide acceptable indoor coverage. If the DL coverage is the problem and we don't have any possibilities to increase any link specific transmission powers the indoor solution for one distant building with relatively high capacity would free up the available transmission power from macro/micro layer. This should be taken into account also in the indoor planning process that before any indoor installation the loading of each candidate building should be find out to find out the current capacity need. Also the possibility to segment buildings so that only those buildings which require largest Tx powers from each micro/macrocell should be built first. In some cases the indoor solution is the only possible way to provide indoor coverage, for example carages, tunnels, metro stations, etc. places where the penetration losses from outdoor to indoor is very high. In such places the planning of indoor coverage is quite easy from the interference point of view because those indoor environments are isolated from the other network and thus the interference is small. In those cases the WCDMA planning process follows quite close to the GSM planning process.



Capacity problem in microcellsFrom the micro/macro point of view the possible ways to free up capacity is usage of additional carrier or usage of more cells. However, in practice there is usually no free carriers available and adding new cells increases the other cell interference which in turns decreases the capacity and coverage. In such situations the indoor solution would be quite usable. However, when the building with high capacity requirements is close to microcells the same frequency planning might be quite difficult. Problems arise for example because the indoor users disturb closely located microcell in uplink direction. In that case we might have to use another frequency for indoors in that case.Because of different building structure and different existing outdoor network environments, indoor planning procedure may vary case by case. Also customer expectations and requirements can vary a lot. This section describes the basic indoor planning process which is described in Figure 59.

Figure 59. Indoor planning procedure.

8.1. Indoor Planning Objectives

In WCDMA the QoS requirements have to be set for each service for a given building. Services with higher bit rates and lowest frame error rate (FER) requirements need more power and thus have lowest coverage probabilities. The real time (RT) data have larger FER requirements than the non-real time data (packet data). On the other hand NRT data will include new QoS requirements, like delay and throughput requirements. The site density have to be determined according to service with tightest requirements. It is assumed that indoor solutions will be provided for those buildings (areas) with largest capacity and bit-rate requirements. The speech and lower bit rate services will be covered with outdoor WCDMA network or with existing GSM network. Naturally, there will be dedicated indoor solutions for lower bit rate in environments where the outdoor network


Detail Design and Documentation

Preliminary Site Survey

Indoor Planning Objectives

Area Survey

Proper Site Surveyservice distribution, p (R)Eb/N0(R)average interference, fUL

maximum loading, max, UL

unsymmetricity,

Optimization and Verification

Frequency & parameter plan


can not provide any services like garages, metro tunnels etc. The QoS requirements for the WCDMA indoor planning requirements are:

Services available in the building Minimum quaranteed bit-rate and its coverage (usually high, 95%) Peak bit rate and its coverage (for example 2 Mbit/s in DL close to antenna) Delays, average and peak throughput for NRT-services Call blocking for RT-services

It is very important that both the operator and Nokia have a same opinion why indoor solution is needed and it is also necessary that customer understand Nokia planning process and real meaning of the indoor solution. In many cases indoor is a good solution for solve capacity, quality and coverage problems, but usually it is also very expensive and time consuming solution. The first task when defining indoor planning objectives is to find out customers’ expectations and requirements. As an example it essential to understand whether Customer expects the entire building to be covered or only certain most important parts of it. Also share of responsibilities (including nomination of contact person for target building), project time schedules etc. will be agreed. The output of this task is a list of requirements for Indoor planning criteria and other information mentioned above. The indoor site objectives should be discussed together with the customer and documented so, that objectives are clear for everybody. The process should show:

Customer and Nokia participants Responsibility sharing, including nomination of contact person for target

building/site, access permission and floor layouts etc. Who is responsible for Radio Network Planning, Installation planning and who

is going to do installation work etc. Procedure how and when to order equipment Project time schedules Planning criteria How to indoor site is documented and what documentation is sent to customer

8.2. Area survey

Area survey should be made to help customer to select possible indoor site candidates. Idea of area survey it to locate traffic hot spots, locations without coverage at all or poor coverage, basements, underpasses etc. and buildings where interference problems occur, for example high-rise buildings. During area survey all data should be collected from possible site candidates what needed to identify target indoor site clearly, like building picture/photo, name, address and contact information. Also the reason why the building is into list should be presented. After the area survey the list of possible indoor site candidates should be accepted to the customer. In cases where the customer is already specified the target indoor sites, there is no reason for the area survey.

The following list shows possible high traffic locations; place where people work, travel and spend time. The approximative current speech traffic values are also shown.

Airport (~103 Erl/hour) Shopping Malls (~100 Erl/hour) Office Buildings (~40 Erl/hour) Exhibition center (~30 Erl/hour) Hotels, restaurants, subways etc.



The data rate requirements can be for example 300 Mbit/month/user for an office user. For a large building including 1000 users this means about 500 kbit/s average bit rate from the office. Naturally the peak bit rate is much larger than that and the bit rate distributions are very difficult to characterize. The NRT data traffic is assumed to be unsymmetric, so that in web-browsing service, for example, the DL data throughput can be 10 times larger than the UL data throughput. If the amount of non-real time vs. real time services is assumed to be about 2:1, the total data flow is approximately distributed as 1:7 (UL:DL)During area survey all data should be collected from possible site candidates what are needed to identify target indoor site clearly:

Building or site picture/photo Building type, size and number of floors Name and Address Contact information (contact person, phone number) The process should show: The customer and Nokia participants The way how the Indoor sites are selected Traffic hot spots Poor coverage locations Bad quality locations (interference) Other reasons (image etc.) How many sites are selected for one site candidate Used tools (NMS statistic, maps, Tom) Site candidate acceptance (Customer and Nokia)

8.3. Preliminary Site survey

Idea of preliminary site-survey is to know the selected indoor sites/buildings in terms of existing coverage and building structure. It is also giving us clear picture what is the optimal indoor solution for the target building and what are possible and not possible site solutions for example because of installation limitations. After pre-survey it is possible to create a draft plan, estimate the number of needed antennas, BS’s and sectors. After that a draft indoor design solution will be made to estimate approximate budgetary cost if needed. Before preliminary site survey, the customer introduces the indoor solution concept for the building owner, get the permission for install indoor equipment, like BS, antennas etc. Access to the building is needed and floor layouts should be get before the preliminary site survey. Preliminary site survey is needed to get familiar with the building structure and layout. It is also needed to identify possible antenna locations, cable routes, raisers, BS location and possible installation limitations

Outdoor network topology In preliminary site survey the original coverage inside the building, location of black spots or bad quality areas are also identified and measured. Preliminary interference analysis could be made to resolve the possible frequency re-use inside the target building. Also soft handover zones (indoor-outdoor, indoor-other building, under ground connections, entrances to the car park etc.) will be identified and located. Also the capacity estimation should be done. The traffic distribution of the existing outdoor network should be clarified in order to avoid the uplink interference from outdoor to indoor cell.



Also the other operator network topology would be beneficial to know. If the adjacent channel is allocated to another operator the uplink interference from other operator mobile users would be extremely high and in the worst case it would block our indoor network totally. On the other hand our own network will cause so called dead zones around the indoor cells which might block the other operator in downlink before they interfere to our cell (Chapter 4.3)Original coverage and quality measurement should be performed at least in three locations, downstairs, middle of the building and top of the building. This is because the neighbor channel list is changing when moving vertically inside building. It is possible to make interference analysis at same time and solve the frequency usability inside the building.

Traffic estimationThe traffic estimation is roughly based on the type of the building and estimation number of subscribes inside the building. There are no accurate traffic estimation methods, but as rule of thumb, the estimation for speech users can be as simple as below:

Subscriber number = people inside the building operator mobile penetration

Traffic = subscriber number traffic per subscriber.

The speech traffic per subscriber can be for example 24 mErl and the data traffic can be for example 15 Mbit/day on the average. From this data traffic 30% can be RT data and 70% NRT (packet) data. So if we have a building with 1000 users and the penetration is 25% the total number of Erlangs needed for speech is 0.2510000.024=6 erlangs. The needed data traffic can be 0.25100015=3750 Mbit/day. From this we would need to know the peak data capacity, which can be quite difficult to estimate. With this information and possible hot spot information. The NRT traffic is usually asymmetric so that the DL traffic is higher than the UL traffic.

8.4. Proper Site Survey

Due to complicated building structure, different wall material and furniture inside the building, it is difficult to predict the wave propagation very accurately. Received signals inside the buildings are sum of multiple signal components caused by obstruction, reflection, and diffraction from floor, ceiling, wall and other object. Indoor propagation measurement will be done to verify our proposed antenna locations and giving us clear picture which are effective cell sizes with certain EIRP power. Possible additional measurement like downlink total interference measurements and Pilot power measurement from other cells are also needed. The additional purpose is to find suitable EIRP power for the Pilot channel because the cell selection, signal estimation and other common channel powers are based on that. The Pilot power should not be too high because therefore the Pilot itself increases the interference from the picocell. In the case of large Pilot powers those mobiles which are far away from the picocell or even outdoor to be connected to picocell. This increases also the interference power from picocell users to outdoor network (see Chapter 6). With too small Pilot powers the indoor users will be connected to outdoor networks and the indoor solution does not have enough penetration.

During the site survey the co-operation between radio network planner and the installation planner (IPE) is important. The installation planner has the idea of possible cable routes and cable installations and they can define the possible installation problem



at the site. The Radio Network Planner seeks for the optimum antenna locations and together with installation planner they make the preliminary routing plan where the installation planner has responsibility to estimate cable lengths. The final BS location and common riser location should be confirmed during the survey or at least before final designs and documentation. In many buildings it is allowed to use only public areas for the antenna installations i.e. corridors and halls and that creates own problems. For example, some hotels might be difficult to provide good coverage inside guestrooms, if it is allowed to use only corridors for antenna installations.

8.4.1.Propagation Measurement

Narrowband indoor propagation measurement will be done to measure propagation conditions inside the building, verify proposed antenna locations and giving us clear picture which are effective cell sizes with certain EIRP powers. These measurements can be done by using a test transmitter and a mobile as a receiver. Test transmitter measurements are based on the test antenna installed at the same location as the possible real one. External omni or panel antenna can be connected to the test transmitter. Transmitting power should be as close as possible to the expected real one. The measurement should be performed in the same floor as antenna and also up and/or downstairs to get the idea of cell sizes overall with one antenna location. RNP decides the best test antenna location and makes the measurements. The measurement results are used for deciding the optimal antenna locations, the amount of antennas required and the actual EIRP level needed. Widband channel measurements will also give us information for planning purposes. These measurements with the bandwidth larger than the chip rate will give us information about the time dispersion of the indoor channel which is important especially in the detailed downlink coverage and capacity calculations. For the average orthogonality the similar method as in [9] can be used in order to simulate the value. In practice either we use some commonly used average orthogonality values or the proposed network planning tool described in Chapter 8.5.2. The default values for orthogonality can be 0.9 for office environment where the dealy spread is low and 0.8 for shopping centres with somewhat larger dealy spread. The pathloss measurements are also possible to perform by using the wideband measurement tool but usually the dynamic range for the wideband sounders are not enough because of higher noise levels. For the pathloss measurements at least 80 dB dynamics is required. Additionally, these wideband channel sounders are not very practical to use and they are also expensive.



8.4.2. Interference measurements

From the downlink loading equation (Chapter 2.5) it can be seen that the power of one cell effects to the power of all other cells in the system. This is true especially when there are many adjacent same layer cells, for example pico cells. The other cell interference, fDL, fUL in equation (11 and 22) has to be guessed or the test transmitter measurements have to be defined to cover not only the assumed own cell area but also in the other cell areas as well.

Figure 60. Measurement of indoor isolation, fDL.

The the other-to-own cell interference inside the building for cell j in the measurement point i can be computed as:

,

()

where M is the expected number of sites inside the building, Lli is the pathloss from site l to the measurement point i. N is the total number of measurement points. The interference from outside is not possible to measure with the test transmitter, but it is possible to measure roughly before any indoor implementations assuming that the indoor solution has only minor effects to the powers of outdoor base stations. The downlink noise rise was expressed in Chapter 2.5 as:

where KM is the number of outdoor BS, PM,k is the Tx power of those outdoor base stations, N is the noise level and Lk,i is the linkloss from outdoor BS (index k) to indoor MS (index i). This is the same as the WB received power divided by the noise level. The interference margin that is used in dimensioning can be estimated as:

, ()

where


L2i

cell 2

cell 1 L1ij


Then the DL interference can be computed as:

()

and

()

()

where Pc,i is the NB test transmitter measurement result from the own cell area, P0 is the transmitting power of the test transmitter and the PWB,i is the wideband interfernece power (total receved power) in the measurement point i.

8.4.3.Typical cell sizes and areas

We can’t say any exact values for these because every building is the own individual. These are the approximation values based on the measurement performed in the projects today. Cell size depends on:

Building type (Open Office, shopping center etc.) Wall attenuation, number of walls, wall material etc. Attenuation between floors Used System (Fiber optic, distributed antenna, repeaters etc.) Antenna type (panel \ omni \ coaxial antenna) Output power Antenna Gain Original coverage inside the building Installation limitations (cable risers, place of BS etc.) Etc.

Next table will describe what kind of coverage areas has been achieves so far in the projects done (numbers from GSM which approximately gives the 144 kbit/s cell sizes in WCDMA).

Table 16. Approximative cell sizes in various indoor environments

Floor Type TX_EIRP Cell size (Omni/Panel) Cell Area

Open Office 30-50mW 60-80m/ 30-40m up to 2500m2

Typical European 30-50mW 40-60m / 20-30m 2000m2



High rise(1 floor)

up/downstairs

30-50mW 25-35m / 20m up to 1500m2

+ 1000-1500m2

Shopping Mall 30-50mW 100-120m / 50-60m 3000-5000m2

10mW Decrease of 10-20% - 10%...20%

8.5. Detail Planning

Detail planning and documentation starts immediately after site survey when all the equipment locations are confirmed, like BS room, raisers etc. A power budget calculation and network system design should be completed with the antenna position drawings. The flowchart in shows the proposed detailed coverage and capacity planning method for indoors.

8.5.1.Detailed capacity and coverage planning

The capacity planning in WCDMA is different from GSM. In GSM the capacity (erlangs) can be computed with a certain blocking probability and with a certain number of Trx. However, in WCDMA the offered capacity depends on the used services (bit-rates), radio channel, the interference and RRM functionalities. It is therefore case and environmental dependent and also impossible to calculate beforehand very accurately. Also, the definition of capacity is different because in WCDMA the number of simultaneous users depends also on the functionality of RRM algorithms. For example, if the required bit rate in a one time moment is too large the packet scheduler can drop the bit rate but the data calls are not dropped. Also, a user can be accepted to the system by the admission control in a one time moment with a certain bit rate but not with any higher bit rate. The WCDMA macro and microcell planning is based on the planning tool, where the detailed propagation environment as well as the user distributions can be taken into account. For indoor there are no such tools and so we have to simplify the detailed planning procedure as much as possible. In here the proposed capacity planning method is based on the number of users and service distributions as well as the average values of assumed interference and Eb/N0 performance. The local propagation environment is taken into account by using narrowband propagation measurements. More detailed planning should also take include other cell interference, Pilot power measurements from other cells around the building as well as the wideband channel measurements (Chapter 8.4). However, this is not a very realistic method to find the capacity of the system because it is not possible to characterize the service distributions accurately. From the operator point of view the main requirement for the indoor network is usually the ability to maintain a certain, predefined average/peak throughput. One possibility to compute the total throughput of the data network in the dimensioning phase is to check only how many high bit-rate users (384 kbit/s) it is possible to have inside the building with a certain number of sectors. The detailed planning procedure according to flowchart in the Figure 62 will be described here.



DL capacity planning

In here the indoor capacity has been defined as "throughput through the indoor network". Figure 61 clarifies this definition. It is therefore clear that the large soft handover areas inside the building between outdoor and indoor networks decrease the indoor capacity.

Figure 61. Indoor capacity definition

Assuming that we want to have throughput of T (kbps) through the indoor cell we must have ability to support (1- pOutSHO)M connections with average bit rate of R, where pOutSHO

is the probability of soft-handover between indoor and outdoor network so that (1-pOutSHO) MR=T. The maximum downlink loading can be computed as:

()

so it is a sum of fractional loadings from not soft-handover users, soft-handover users and the loading beacause of the common channels. If the SHO probability between indoor cells is assumed to be pInSHO, then the total soft-handover probability when assuming that indoor and outdoor sho-probabilities are independent is:

()

The fractional loadings can be computed as:

()

()

()

In practice it is not allowed to run the system up to maximum capacity in order to avoid the non-stability but we need to set the maximum loading for example DLmax=0.8. The


outdoor BS1 outdoor BS2


number of sectors needed for the required downlink capacity is then (putting the denominator to zero):

, ()

For example if we require 5 Mbps for a certain building and the outdoor SHO probability is 20% then the network has to planned for 5 Mbps/0.8=6.25 Mbps, which means approximately 16 384 kbps users. If the SHO probability between indoor sites is 15% then pSHO is 0.32. The loading for the NSHO users is 1.3665, loading for the SHO users is 0.7266 and the loading for the common channels is 0.1047. Then, the total loading is 2.75, which means that we would need 3 indoor sites. These numbers are based on link and system level simulations. It can be noticed that these numbers are just averages so with careful indoor dimensioning we have to take also the variance of orthogonality and other cell interference into account. The Eb/N0 values here are transmitted values and are therefore larger than the received Eb/N0 values because those include the power rise because of fast fading.

The output power needed in the BS in order to have K simultaneous connections using bit rate Ri is:

, ()

where: K is the number of mobiles in the cell,W is the modulation bandwidth,i is the required Eb/N0 in the mobile for a given error rate. This includes also the fast fading margin and the SHO gain if the mobile is in SHORi is the bit rate for mobile i ,Li is the path loss for mobile i ,N is the noise power,i is the voice activity for mobile i ,i is the orthogonality (0<<1), usually the average orthogonalitynrDLi is the noise rise in DL explained in Chapter 2.5 max=max[Li(1+nrDL,i)],fDL,i is the other-to-own cell interference in downlink.

It can be seen from that equation that the denominator of this equation can go to zero meaning that in some point the BS needs infinite transmission powers in order to maintain the K users. Therefore, the absolute maximum capacity can be found setting the denominator to zero. This means in practice that the power of the cell in order to keep the required link performance depends on the own cell and other cell interference as well as the background noise. The own cell interference depends on the own cell powers because of non-orthogonality and other cell powers because of finite isolation between cells. Therefore, the cell powers are connected to each others and have to be solved through the previous equation.



Figure 62 Detailed planning for indoors.

UL capacity planning

The number of sectors in uplink can be computed from the uplink loading equation:

()

where fUL is the other-to-own cell interference ratio in uplink including the effect of power rise in adjacent cells. For example, when assuming that in UL the speech=8 dB, data=5 dB,


UL capacityservice, throughputEb/No

average interference, fUL

maximum loading, max, UL

unsymmetricity,

DL capacityservice, throughputEb/N0, SHO-gainssoft-handover probabilities (indoor/outdoor)average orthogonality, average interference, fDL

maximum loading, max, DL

number of sectors needed

UL coveragemaximum bit-rate for continuous coverage, Rmax

maxUL

maximum path loss, LmaxUL

estimation of noise raise because of minimum power mobiles, nrMCL

maximum quranteed bit rate in the case of minimum power mobile, Rmax,MCL

Propagation measurementsHot-spotsBuilding structureMCL proposed antenna locations,

path-loss measurements, L (dB)WB-interference measurements

DL total powersInput data: Li,nrDL,i ,maxDL, , fDL,Eb/N0, service Pilot power EIRP per antenna, PEIRP

DL coveragePEIRP ,Lmax, maxDL, , fUL, RmaxDL

Needed CPICHToRefRabOffset


f=0.7 the sectors needed for UL direction is 5.966 when using the same service distribution as before. In here it has not been taken into account that the traffic might be unsymmetrical so there is more DL traffic (for example web browsing) than UL traffic. The effect of soft handover to the average Eb/N0 performance has not been assumed here. Soft handover gives gain in UL direction to decrease the needed mobile station transmitting powers and decreasing also the interference from adjacent cells. In DL the gain of SHO is more questionable because of the DL power control problems in the case of two (or more) links. Additionally, the soft handover increases the required number of channels and the total Tx power of the BS. According to indoor system simulations fUL is between 0.2 and 1.0 so it varies a lot depending on the used scenario and whether the UL diversity is used or not. The interference increase without diversity can be about 6 dB higher than without diversity so the fUL can be for example 0.2 with diversity and 0.7 without diversity.

Figure 63 shows the simulated distribution of downlink other-to-own cell ratio in picocell environments for various antenna scenarios. In the 6 sector case there was 6 antennas, one for each sector and two sectors/floor. In this case the other-cell interference is quite large indicating that the interference from the same floor is higher than interference from other floors. This depends naturally on the local propagation conditions and can not be generalized. It can be also seen that the most of the interference comes from inside the building if there is more than one sector. This is of course dependent on the building type and the indoor cell scenario. Interference is not so much correlated to the path loss because of the interference from other floors. So there can be high other cell interference values also quite close to the indoor antenna.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

fDL

prob

abili

ty 6 sectors, 6 antennas3 sectors, 3 antennas3 sectors 9 antennas 2 sectors, 9 antennas1 sector, 9 antennas

Figure 63. The distribution of other-to-own cell retrieved from simulations in the case of different distributed antenna scenarios.

Also the variance of the service mix, soft handover as well as the used values for and fDL/fUL effect to the needed capacity. Figure 64 shows the dimensioning results computed with the indoor dimensioning program. The program generates randomly the bit rates and soft handover for the mobiles assuming a given average bit-rates and soft handover probability. Eb/N0 setpoints and voice activities are set according to bit rates.



0 2 4 6 8 10 120

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

number of needed sectors

prob

abili

ty

i=0.2, SHOpr=0.2i=0.5, SHOpr=0.2i=0.2, SHOpr=0 i=0.5, SHOpr=0

Figure 64. The distribution of needed sectors when the service distribution was 60 8kbit/s speech, 30 64 kbit/s data, 7 144kbit/s and 2 384 kbit/s data.

UL coverage

When the number of sectors are computed the problem is to distribute the signal around the building so that the BS can support the traffic. The proposed antenna location depends on the locations of traffic hot-spots if they are known, building structure and the maximum allowed noise raise because of minimum power mobiles. In the uplink coverage part we have to compute the maximum allowed pathloss in order to have coverage for minimum required bit rate, RminUL. From the uplink link budget (Table 17) we get that if we want to have 144 kbit/s continuous coverage, the maximum pathloss is 124 dB. This can be verified with the narrowband test transmitter measurements where the proposed cell area were measured with hand portable measurement system. The measurement route should ideally include sample measurements uniformly everywhere in the cell area. If the maximum pathloss is above the required we either have to change the proposed cell area, antenna location or antenna gain.

Table 17. UL link budget for the UL coverage analysis in detailed planning

Service 8 kbit/s 144 kbit/s 384 kbit/sMobile max. power 21 dBm 21 dBm 21 dBmantenna gain + body loss 0 dBm 0 dBm 0 dBmEIRP 21 dBm 21 dBm 21 dBmNoise floor -108 dBm -108 dBm -108 dBmBS noise figure 5 dB 5 dB 5 dBNormal uplink noise raise 7 dB 7 dB 7 dBProcessing gain 27 dB 14 dB 10 dBEb/N0 UL, no div. 8 dB 5 dB 5 dBRx antenna gain 2 dB 2 dB 2 dBTPC headroom 4 dB 4 dB 4 dBAssumed cable losses 8 dB 8 dB 8 dBReceiver sensitivity -105 -95 -91Maximum allowed pathloss 126 dB 116 dB 112 dB


calculation parameters =0.9 fDL=0.2, 0.5 pSHO=0.2,0 (sh probability) max=0.8 average service: 50% 8kbps, 30%

144 kbps, 20% 384kbps no of users=6-8


The noise raise of the minimum power mobiles depends on the minimum coupling loss between mobile (Equation 30) and the base station so the feeder and splitter losses has to be taken into account roughly. If the minimum coupling loss measured with the test transmitter is for example 40 dB we have to add the feeder loss (which is for example 8 dB) so that the total coupling loss in 48 dB. From Figure 18 it can be seen that this causes additional noise raise of about 10 dB. This means that the required pathlosses increases 10 dB in the above link budget and the minimum quaranteed bit-rate decreases. Actually it depends on the RRM how the system behaves in this situation. If the received power exceeds the threshold value which should set very high value in the indoor case, the system begins to decrease the bit rates of the NRT users and drop NRT and RT users.

DL total powersAfter the measurements we have to plan the needed EIRP for the proposed antenna to support the traffic in downlink. The total power estimated for one sector is then:

()

The suggested approach for the downlink power allocation is the following. We can use the measured path loss from the test transmitter located in the proposed actual antenna location and use these pathloss values when setting the EIRP of each antenna. In the following figure there is an example of this calculation without outdoor cell interference. Figure 65 shows the pathloss curve which is assumed to be the measured pathloss in the building and the route of the test mobile, respectively. The assumed test transmitter is located in the middle of the building. In reality these path loss values have been retrieved from the ray-tracing pathloss model.

0 50 100 150 200 250 30040

50

60

70

80

90

100

110

120

distance along measurement route (m)

path

loss

(dB

)

40 60 80 100 120 140

120

130

140

150

160

170

180

190

200

1

2

3

x (m)

y (m

)

Figure 65. The "measured" path loss and the respective measurement route with the test transmitter.

In here we have located mobiles randomly along the measurement routes 1000 times, so that in each time the linklosses, soft handover probabilities and service distribution has been set randomly with three different number of users. Figure 66 shows the respective cumulative distributions, where its possible to check the EIRP at for example 95% probability. In this example it is about 14 dBm.



-40 -30 -20 -10 0 10 20 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Needed EIRP power (dBm)

prob

abili

ty

6 av. users, P(>0.8)=0.317 av. users, P(>0.8)=0.418 av. users, P(>0.8)=0.54

Figure 66. The calculated Tx power distribution over 1000 simulations runs.

Pilot power planning The pilot power determines the cell area, and effects also to the downlink capacity of the system. The needed power for the downlink coverage can be computed with:

()

For example when the CCHt=10 dB, RCCH=16, =0.9, fDL,max=0.5, max=Lmax=120 dB, the needed Pilot power will be 6.8 dBm. In the optimization and parameterization part we have to make sure with measurements that the inbuilding mobile takes the indoor cell into its active set. This is the EIRP pilot power which have to come out from the antenna, so the base station power should be EIRP added by cable losses.

DL coverageThe maximum allowed powers for dedicated channels are computed based on the pilot power. The network planner have to set the offset between the pilot power and maximum reference service power. The required power can be calculated as:

()

In here the P is the total needed EIRP computed previously. Orthogonality is the average orthogonality and the interference is the average interference as before. In our example case we will put ref=8.5 dB, Rref=144000 and the 95%=107dB, then the needed power for the reference service is –4.0 dBm. The maximum powers for each bit rate is computed based on the reference service power. The network planner can change the maximum powers with the CPICHToRefRabOffset. The initial value for that parameter can be computed with

()


calculation parameters =0.9 i=0.25 pSHO=0.2 (sh probability) ohSHO=0.3 (sh overhead) max=0.8 service: 50% 8kbps, 30%

144 kbps, 20% 384kbps


And is in our example case 6.8-(-4.0) dB= 10.8dB. So this is a network planning parameter which can be tuned in order to increase the DL coverage if needed. Of course then the capacity then decreases.

8.5.2.Antenna positioning

In the antenna location planning the following items has to be taken into account: capacity hot-spotsThe antenna should be located to the hot-spot area if it is possible to know that where are the mobile users inside the building and what are their most commonly used services. proposed cell areaThe indoor antennas should be installed so that the antenna covers the whole proposed cell area. handovers from outdoors to indoorsIn some cases the antennas will be located so that the users make handovers to indoor cells immediately after the mobile enters to the building. interference from outdoorsIf the interference from outdoor to indoor is large, the UL interference can be minimized by locating the indoor antenna far away from the building edges and other outside interference sources.minimum coupling loss values (MCL)If possible the indoor antenna should be located so that the coupling losses between MS and the BS antenna is above the planned threshold value. The MCL can also be decreased with a proper antenna selection and splitting.cable routing and installationsThe antenna installation and visibility questions are also important in practice. So it is not possible to install the indoor antenna optimally, but the building lay-out and also the building owner might be limiting.

8.5.3.Planning tool considerations

Short considerations about the needed indoor planning tool will described here. The planning tool can be used for the UL and DL capacity and coverage planning and optimization. This could be some kind of indoor planning toolbox containing:

Narrowband transmitter (or several of them for estimating fDL) planning software WCDMA phone for WB noise measurements and capable for narrowband test

transmitter measurements also. measurement PC for the receiver

The test system must be able to measure path losses from the test transmitter(s) and WB DL interferences from the outdoor network. The planning software should be able to calculate the EIRP for a coverage probability of a given service.

8.5.4.Pico BS planning

The one of the most important targets of the pico BS development is make it easy to plan. This means that installation and network planning time and work efforts are relatively low compared to DAS planning. Possible features would be that after the installation pico BS performs:



automatic frequency allocation common channel power allocation handover control other RRM parameter tuning.

8.5.5.WCDMA BS products

The following table (from [11]) shows the number of antennas needed with a certain number of TRx per sector and number of sectors per BS. Different colors shows the respective SW and HW release.

TRXs/ sector

Number of sectors1 2 3 4 5 6

1234

Available in first releaseAvailable with Rel1 HW and Rel2 SWAvailable with Rel2 HW+SW in single cabinetAvailable with Rel2 HW+SW and two cabinets chained together

The indoor planner can increase the capacity by increasing the number of sectors. It is also possible to increase the number of TRx per sector (add new carriers) but it might be quite difficult to find an appropriate frequency for the new carrier in practice.

8.5.6.Cable Power Budget Calculations

Cable power budget calculation specifies the system gains and distribution losses from BS to each radiating point (antenna) of the system. It should be check against the target EIRP and will be used as to determine whether the system is logical choice or not.



Usually the possible output powers from the distribution networks are between 10-100mW, (10-20dBm), because normally we have several splitters and couplers and cable losses in the network = total antenna line loss. If the maximum needed EIRP seems to be to high, it is possible to decrease BS output power. Using reasonable antenna EIRP is also possible to avoid leaking outside the building. Picture below shows the simple DAS network and the respective power budget sheet.

Figure 68. Power budget calculation sheet of the network in Figure 67.

8.5.7.System Diagram

The system diagram presents layout of feeder cable routing and the type and placement of RF components such as splitters and couplers. It also identify splitter and coupler types, cable length, loss and type, number of antennas per floors and antenna type. All antennas and other RF-components should be named like below.


15 dB

13 dB

BTS

A1

A5

A4

A3

A2

1/2"

Figure 67. Example simple DAS network.


A-F2-2 A = antenna, F2=floor 2, 2nd antenna in that floor.C-B1-1 C = coupler, B1=basement 1, 1st coupler in that floor.

Figure 69. Example system diagram.

8.5.8.Floor Plan Drawing

The floor plan drawing is to present antenna locations in every floor and identify antennas so, that there is no misunderstandings between drawings, power Puget calculations and system diagram. Also the cable routes, raisers and other RF-component should be included for the floor plan



Figure 70. Example floor plan drawing.

8.5.9.Photos of proposed antenna locations

It is important that both installation planner and building owner knows exactly where the antenna is proposed. That why is important to take picture all proposed antenna locations and mark the exact antenna location to the picture. It is also important to clarify antenna type (omni, panel).

8.6. Frequency and Parameter Plan

In the parameter and frequency plan phase it should be checked that the default indoor parameter set fits to the current environment. The frequency plan needs to be done so that it fits for the whole network. The parameter plan can be done before or during site installation. In indoor environment one of the key functions is to keep calls in indoor cells whenever possible, optimize the power levels according to the indoor environment and to be sure that in the case of one frequency micro/macro/pico scenario minimize the possible interference from indoor to outdoor networks.

8.6.1. Indoor frequency planning

The ideal way to handle indoor networks is to dedicate some frequency for the indoor use only. Single buildings in the planning area can still be integrated into the total network, but the more indoors there are in area, the more difficult it becomes to plan the network without interference problems between indoor and outdoor networks. Dedicated frequency for the indoor use only makes the indoor solution independent from the outdoor network and makes it easier to manage. On the other hand when the traffic densities are low for indoors it is maybe not possible to use dedicated indoor frequency. The problems might occur when using the same frequency in closely located pico and microcells. Because the indoor user density is large the interference from pico cell



mobiles to microcell base station might be quite large and therefore the different frequencies would be preferable. Of course the re-use=1 can be used also in this case but the parameterization, like setting pico cell Pilot powers or desensitization factor is more difficult.Another problem might come when using pico cell and adjacent macrocell at the same frequency. In that case the large transmitting powers of the macrocell mobiles cause interference to picocell in uplink. On the other if the macro and pico are close to each other the macrocell will interfere picocell in downlink direction. Therefore it might be difficult to balance the macrocell and picocell borders.

8.6.2.SHO parameters

Target of the handover parameterization is on the other hand minimize the interference caused by wrong cell selection and on the other hand minimize also the soft handover overhead in the base station in downlink. Because the indoor Pilot powers are low compared to outdoor Pilot powers the traffic has to be directed to indoor with proper handover parameterization. Also some hysteresis has to be set in order to avoid multiple handovers between pico and micro/macro layer. When a fast moving mobiles is close to the building with pico cell the mobile does not have time to take the pico to its active set. Large transmitting powers of the macro cell mobile cause therefore high interference peaks to the pico cell. Therefore, the mobile has to prioritize the picocell when updating the active set by a certain factor. The cell layer identification has to be included in handover control information between BS and MS. The handover parmetrization is shown in 5.1.2.

8.7. Site installation

During the site installation phase the radio network planner should follow up installation work in the case of modifications needed. All the changes must be accepted by RNP and documented carefully.

8.8. Optimisation and Verification

The optimization is taking place when the whole indoor site implementation process is completed and the site is first on air. The installed system has to verify and optimize with field test measurements. The main objective of the coverage check is to verify whether the actual design criteria’s for the coverage are fulfilled. Of course, the coverage depends on the current traffic of the system and the bit rate used in the coverage test. One possibility is to measure with lowest bit rate and to estimate the required power what would be needed with higher bit rates. Another possibility is to use as high bit rate as possible and then follow the offered bit rate in various building locations and use that as an optimization and verification criteria. This method is more dependent on the instantaneous traffic in that cell so these measurements have to be performed over large enough time span and/or in different time of the day.The handover check will be done in those building locations where there exist handovers between indoor and outdoor or between several indoor cells. Also handovers in lifts will be checked. Based on network statistic and field test results, parameters setting are to be tuned to gain the best achievable quality and performance out of the existing installation. Finally, when the acceptance test and fine-tuning are completed the result and final report are given to the operator concerned to be checked against the planning criteria for final acceptance.



8.9. Basic environmental cases

The basic indoor environments and their specific requirements for the system and the signal distribution network is reviewed here.

Office (normal)In the regular office environment the capacity requirements is assumed to be high. There might be also quite close outdoor cell quite close to the building and it has to make sure that the interference from indoor to outdoor is in acceptable level. Another problem might occur with outdoor highways where the fast moving mobile users are connected to macrocell. These might produce large interference in indoor cells. In those cases the handover parameters have to be set to prioritize the indoor layer so that the indoor cell is seen as a larger cell from the macrocell mobile point of view. In the case of distributed antenna systems the uplink diversity would be beneficial in order to minimize the indoor to outdoor interference problems.

Office (High-rise)In the high rise office the office users might be in LOS (or nearly LOS) to many outdoor cells. This cause increase of DL interference so the required BS powers might be quite high. Also the Pilot powers should be set so that the indoor floor is not in soft handover shared by many outdoor cells. This decrease the capacity and coverage of the outdoor network. This can be avoided by appropriate setting of SHO parameters. Another problem with the high rise buildings is the elevators. Elevator walls are covered with thick reinforced concrete and the elevator cage itself is metallic so that the overall attenuation might be quite large. This can be avoided by dedicating one indoor sector for the elevator only. However, with this solution the handovers from elevator to other floor might cause large and fast interference to indoor cells.

Public premises (shopping malls, etc.)In the public premises the propagation environment is quite different from the regular office case; the cell sizes are larger and the radio channel is assumed to be more frequency selective with more multipath components. In LOS environments the capacity increment by adding more same frequency base station will be more difficult because of large soft handover areas and high other cell interference. In order to have enough coverage the signal has to be distributed with coaxial or optical antenna network. The interference between pico and other cell layers is highly dependent on locations of other cell as well as on the building materials.

Railway/metro stations, airports, carages, etc.In metro tunnels the signal has to be distributed with leaky feeders or with distributed antenna system. The other cell interference is low so the planning is quite close to GSM indoor planning: There is usually no need to worry about interference between cell layers. In airports the long feeder length are needed for the signal distribution and therefore the fiber-optical distribution would be beneficial.

9. INDOOR SIGNAL DISTRIBUTION METHODS

This part presents different kind of indoor solutions used in Nokia, and give short overview of indoor equipment. There is no exact rule, which solution is best for which indoor. All systems has it’s own benefits and limitations, and which one is selected is up



to planner, customer and indoor environment. The following are various indoor solutions which has been implemented by Nokia. The signal distribution is crucial in the case of indoor systems because the planning and implementation takes large part of the costs of the indoor solution.

Figure 71. Signal distribution methods for indoors.

Possible indoor solutions can be: DAS (Distributed Antenna System) Coaxial antenna (belongs to DAS) Passive Repeaters Active Repeaters Repeater with optical interference FODS (Fiber-Optic Distribution System)

In the following these solutions are introduced shortly.

9.1. Distributed Antenna System (DAS)

Distributed antenna systems are typically used to cover indoor sites which needs to add capacity, quality or coverage. DAS is most commonly used indoor solution, and it is suitable for almost all environments. DAS is connected to the outdoor or indoor BS and then the RF signal is distributed to several antennas by using splitters/coupler with coaxial cable. Following example presented typical DAS system where couplers and splitters are used to distribute signals to the various antennas.



7/f

RF7/8” 10m

RF7/8”

RF7/8”

RF7/8”

RF7/8”

RF7/8”

35m

10m

10m

15m

35m6/f

4/f

8/f

RF7/8”

RF1/2”

RF1/2”

RF7/8”

RF7/8”

30m

10m

10m

15m

15m 6/f

4/f

8/fRF1 1/4” (100m), 8/f

2/f

1/f

RF1/2” (80m)

RF1/2”

15m

RF7/8”

15m

10m

2/fRF7/8”

RF7/8”(100m)

RF1/2” (60m)

GARAGE

G/f

G/f

entrance radiatorRF7/8”

35m RF1/2”

15m

10 dB directional coupler

Kathrein omni (dualband)

Kathrein dir. panel

10mRF7/8”

RF1/2”

15m

RF7/8”10m

RF7/8”10m

Figure 72. Example implementation of DAS network.

Benefits Capacity evolution Maintenance free

(only passive elements) Planning is easy

Limitations No uplink diversity High system loss Difficult installation

9.1.1. Indoor Antenna Selection

Antenna technology offers a whole variety of indoor antennas, ranging from omni and panel antennas to coaxial antennas (Radiating cable, leaky feeder). These antennas are normally small, not very visible to the public, and come in the required colors.

Omni antennas are normally used in wide-open area, such as conference halls, seminar rooms, hotel lobbies.

Panel antenna should be used in areas where strong coverage is required and the area concerned is large. In terms of providing corridors coverage, an omni and the panel antenna does not exhibit significant differences due to the physical structure of area. However, the latter provides further coverage due the greater antenna gain.

Coaxial antenna should narrow dim building, particular in Asian type office tower (horizontal) or narrow shopping mall with long queue of shops, tunnels and underground.



Figure 73. Kathrain omni Antenna,2dBi (left), Kathrain Panel Antenna, 7dBi (right).

As seen, these antennas are small with a dimension of only 200mm and 155mm respectively. Hence, in most cases, it is possible to hide such antennas on top of the ceiling plasterboards, or flushing it on the wall with colors similar to the wall.

9.1.2.Coaxial antenna (leaky feeder, radiating cable)

Coaxial antennas are modified cables from conventional feeder cables. There exist two different kind of coaxial antennas: modified corrugated model and slotted model. Corrugated model is just modified so that the other side or two opposite sides from the corrugated feeder cable is saved open from the top of the corrugation. The slotted model has different shaped/sized/distanced slots in the outer conductor, which will effect into the radiation performance of the cable i.e. longitudinal loss/coupling loss. The value is frequency dependent. Possible to used almost all kind of indoor environment, excellent solution for tunnels, narrow buildings etc. Place where there is metal ceiling, it is impossible to use coaxial antenna. Following present one indoor solution with coaxial antenna.


Benefits No Rx blocking risk Wide band Provide homogenous coverage

Limitations Higher installation cost Need suitable place where to

install

Figure 74.One possible implementation of leaky feeder.

The total attenuation of the leaky feeder from the antenna input to the receiver is a sum of the attenuation loss between antenna connector and the radiating point and the coupling loss from the radiating point to the receiver point. The manufacturer gives usually these 0two values, where the coupling loss is measured with dipole antenna from two meter away from the leaky feeder. The following table shows some characteristics of different antenna types.

Table 18. Coupling loss and attenuation of the leaky feeder at 900 and 1800 MHz frequencies (NK-cables)

Cable type Coupling loss (dB) (95%) Attenuation (dB/km)

900 1800 900 1800

RFX ½" 81 88 87 129

RFX 7/8" 80 87 50 75

RFX 11/4" 85 86 35 56

RFXT 5/8" 79 85 58 89

RFXT 7/8" 77 80 50 80

The attenuation from the cable to the receiver point can be is shown in the following figure (results from [22]):

0 5 10 15 20 2535

40

45

50

55

60

65

70

75

80

85

distance (m)

path

loss

(dB

)

leaky feeder 7/8" RFXTfree space loss

Figure 75.Leaky feeder measurement in open area environment, the used frequency was 1800 MHz.

Figure 76. Two possible leaky feeder scenario.

Figure 76 shows two possible utilization of leaky feeder in WCDMA indoor. In the scenario shown in the left figure the leaky feeder goes around the building so that those mobiles which are in the center part of building use the largest Tx power. This scenario can be used when there are same frequency outdoor cells close to the building and we want to minimize the interference to those cells. In the right figure the leaky feeder is located on the center of the building. With this kind of scenario we can minimize the DL interference when we are far away from the micro/macro cells and there are lots of interfering mobiles close to the building.

9.1.3.Power Splitter

Power splitter is passive component divide energy from transmitter (BS) to several branch of cables or antennas. Most common splitters are symmetrical which divides the input power evenly to its outputs. The most often used splitters in indoor are 2-way, 3-way and 4-way splitters.

Figure 77.Two way splitter.

9.1.4.Directional Coupler

Directional coupler is also passive component which divides the input signal into through port and coupled port. Typical couplings are 6, 8, 10, 13, 15, 20 and 30 dB. Coupler is normally used in DAS to branch out a coupled signal and is then fed out into branch. The through port signal will then continue as a backbone to distribute the signal to the rest of the system without too much insertion loss.

Figure 78. Directional coupler.

9.2. Fibre optic RF-Distribution

The Nokia fiber optic distribution system (FODS) creates cellular coverage throughout a building or a campus of buildings. The fiber optic system uses small fiber optic remote units (RU) to feed the antennas that can be connected to the RU, mounted to the ceiling or wall to provide coverage to a certain sector of the building. These antennas are connected by optical fibers to an RF distribution main unit (MU), which provides the interface to the cellular system through connection to either a base station or a repeater. Table 19 shows the specification of the WCDMA FODS and Figure 79 shows the simplified block diagram of the FODS.

Table 19. Main characteristics of the WCDMA FODSFrequency 1920-1980 MHz UL,

2110-2170 MHz DL

2 W (33dBm)

1 W (30dBm)

1 W (30dBm)

1033dBm (2W)

23dBm (200mW)

32dBm (1.5W)

Max fiber optics length 1.5 kmRF gain DL 10 dBMax output power of RU 23 dBmMax RF input level 13.5 dBmNoise figure 9-11 dBRF gain UL 27 dB

Figure 79. Fbre-optical distribution system (FODS)

Figure 80. WCDMA FODS main unit (left) and the remote unit (right).

Benefits:Possibility to use diversities both in uplink and downlinkRelatively easy installation vs. coaxial cableCable losses very low, useful for long distancesSignal transmission immune against EMC disturbanceUsage of existing cabling

Limitations:DC power supply is required for remote antennas Because of active components, long term maintenance is neededLow EIRPHigh equipment cost

BS MU RUDL

ULL

LUL

RF

RF

optical

By using optical fiber as the carrier media, it possible to distribute the antennas throughout the building without concern to the distance between antennas and BS. Also, the implementation of optical fiber is less costly than for coaxial cables. The FODS consists of an RF distribution MU and up to 24 fiber optic RUs, that can have either one internal antenna and one external antenna, or two external antennas.

9.3. Passive repeaters

Passive repeater is a good solution, when extending coverage to small area. It repeats selected frequencies from the outdoor cell in the indoor cell. Passive repeaters do not add any capacity. Good way to add coverage places where no extra capacity needed, like underpass, underground car parks etc. Picture below shows an example of passive repeater solution in medium size building.

Figure 81. Working principle of passive repeater (figure from [4]).

If antenna B has received level of –50 dBm, based on picture above, the signal level received from the indoor antenna will be approximately –25dBm. However, because this method does not actually repeats the signal, several disadvantages are obvious. Firstly, it is dependent on the outdoor signal received level. Secondly, the repeated signal will be attenuated by the feeder loss. Also, all signals from different BS’s including the competitor network BS’s will be repeated.

Benefits Inexpensive solution, which usually requires only feeder cable and antennas. No active components Easy to install No power control and AGC problems

Limitations There is strong dominant outdoor server (C/I is good enough) The feeder run is short The area to be covered is small with little or no obstruction

9.4. Active repeaters

Active repeaters are solution for covering black spots, like tunnels, parking halls and other underground locations.Benefits (active repeaters over the passive repeaters).

Does not require high-received signal from donor cell (-70...-80dBm). Because the signal is actively repeated, longer feeder cable can be used A repeater may be channel/band selective. This means that preferred channels

may be selected for repeating. Also, channel filters could be used to prevent exploitation by a competitive network operator.

Limitations When planning repeater solution, network planning must take care of RF

limitations and antenna isolation. RF problems may occur with band selective and wide band repeaters?? The active component have to be good ACP characteristics AGC in UL? Good isolation between Rx and Tx of the repeater

Figure 82. Working principle of passive repeater (figure from [4]).

Picture above illustrates an application example of a repeater system. Also the EIRP of each indoor antenna based on typical feeder loss, antenna gain and repeater gain of 82 dB are shown. Assuming that antenna B receives a level of -60 dBm and cable loss of 4 dBm/100m, the output from the repeater will yield 28 dBm. This in turn is divided by a 3-way splitter which introduces a further 4 dBm loss per branch. Therefore, based on these calculations, the EIRP of antenna X, Y and Z are 22.2 dBm, 22.8 dBm and 22.8 dBm respectively.

9.5. Repeater with Optical Interface

This solution is good for places where capacity requirements are low and the area to be covered is large, like long tunnels and large underground locations. RF repeater with optical interference allows long distance transmission. RF repeater with optical interference is an active device, which amplifies the signals between MS and BS. Can be

used together with coaxial antenna and distributed antenna system. Following there is typical configuration of the optical repeater system.

Benefits Like other repeaters, it uses outdoor donor cell, and does not require connection to

RNC Possible to install several repeaters into system Possible to large coverage areasLimitations Network planning must take care of RF limitations and antenna isolation, to avoid

antenna coupling and interference, active device.

MUMU

RURU

RURU

RURUDL RF

UL RF30%/70% 50%/50%OPTICAL UL/DL

MULTIDROP

MUMU

RURU

RURU

RURUDL RF

UL RFOPTICAL UL/DL

POINT-TO-POINT

Figure 83 Optical repeater.

10. REFERENCES

[1] RRM/RNP Cleanup project: RRM Overview, DocID BCU08, ver. 1.0.1. June 1999.

[2] Harri Holma, Antti Toskala: WCDMA for UMTS.

[3] Hasse Sinivaara: Indoor planning, Work Instructions, 1997

[4] PBK Yap: Indoor planning and solutions, ver. 8.0, 1997

[5] Gilhousen, K.S., Jacobs I.M., Padovani, R., Viterbi, A.J., Weaver, L.A., Wheatley, C.E.: On the Capacity of a Cellular CDMA system, IEEE Transactions on Vehicular Technology, Vo. 40., pp. 303-312, May 1991.

[6] Joseph Saphira: Microcell Engineering in CDMA Cellular Networks, IEEE Transactions on Vehicular Technology, Vol 43, No. 4, November 1994.

[7] Andrew Viterbi: CDMA-Principles of Spread Spectrum Communications, Addison-Wesley Publishing Company, 1995, 245 p.

[8] Andrew Viterbi: Erlang Capacity of a Power Controlled CDMA System, IEEE Journal of Selected Areas in Communications, Vo. 11, No. 6, pp. 892-899., August 1993.

[9] Kari Sipilä: Interference Study, ver. 2.0.0. Neptune R2.

[10] Hannu Pikkarainen: Mobile Data Applications.

[11] Jukka Peltola: "Helena Program, Nora BS, Product definition", version 1.0.4.

[12] Grandell J., Holma H., Salonaho O., Skog K., Soldani D., Wacker A., "Single Link Measurement Campaign with the Nokia WCDMA Experimental System", Doc ID: BMW03010.doc, Nokia Networks, 1999.

[13] Mika Raitola: "WCDMA Radio Network Performance R1-Results of WCDMA Link Level Simulations", version 1.0.1, Wesicco document WPW05.

[14] Neptune R2: Network planning manual, ver. 1.0.0

[15] Kari Sipilä, Zhi-Chun Honkasalo, Jaana Laiho-Steffens and Achim Wacker: "Estimation os Capacity and Reuired Transmission Power of WCDMA Downlink Based on a Downlink Pole Equation, Proceedings of Vehicular Technology Conference, VTC2000.

[16] Parameter dictionay, ver. 0.0.6, editor: Jaana Laiho Steffens. Plug&Play Radio Network program, WCDMA business program.

[17] K. Tigerstedt , K. Heiska: Npsw/i feature description, ver. 1.0.0, October.1999.

[18] K. Tigerstedt, K. Heiska. Indoor measurements, ver. 1.0.0., January 2000.

[19] L. Ståhle: Helmi Validator BS Architecture, Slide set, Experimental system training, 15.3.1999.

[20] J. Grandell, K. Heiska. Indoor case studies, ver. 1.0.0., January 2000.

[21] RAS/SD/SP: Sonera Pico-cell indoor trial test report, ver. 1.0.0, January 1999.

[22] Jari Qvintus: Nps/i 2.0.1, Leaky cable measurements, test report, 1997.

[23] Kari Sipilä: Feasibility of Ray-tracing in Radio Network Planning Tools for Indoor Environments, NRC, ver. 1.0.0, January 1996.

[24] Lähteenmäki, J.: NPS/i propagation models, Report, 10.5.1995.

APPENDIX A MCL MEASUREMENTS

The minimum coupling loss depends on the used antenna, antenna installation, mobile user and its position. The following figure shows the measurement set-up for the minimum coupling loss measurements. The transmitter was Ericsson Tems test transmitter working at 1800 MHz frequency. The transmitted signal was attenuated with 6 dB in order to be at the operating range of the receiver. The transmitter operated at the test channel and the measurement mobile was tuned to measure that channel with TEMS measurement software.

Figure 84. MCL measurement set-up.

Two different antenna were measured: omni with 2 dBi gain and directional panel antenna with 6 dB gain. The omni antenna was located to the roof and the panel antenna was located at the 1.3 m height from the ground. Three different lines were measured : Measurement 1: Worst case with directional, very close to antenna (< 5 cm)Measurement 2: With omni antenna. In the beginning the worst case (< 5cm), casual walk in the end (1-2 m away from the antenna)Measurement 3: Directional antenna, Casual walk (always 1-2 m away from the antenna)Measurement results are shown in

0 200 400 600 800 1000 1200 140030

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coup

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Measurement 1

0 500 1000 150030

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ConclusionsFigure 85. MCL measurement results.

user closer to BS antennaMS closer to BS antenna

Tems 1800TxP=22 dBm

L=16 dB PC + measurement software

Mobile

In measurement set 1 casual walk in the beginning of the measurement when the minimum distance was 0.5-1.0 meters, minimum coupling was 40 to 50 dB, whereas the MCL was 32 dB when MS antenna was 3-5 cm from the directive antenna (end of the measurement line). In the measurement set 2 the situation was about the same as in the first set. The worst case MCL=30 dB and with the casual walk 40-50 dB. In the third measurement set only casual walk around the antenna was tested. The minimum distance was about 1.0-1.5 m. It can be seen that the shadowing loss due to users head was about 15 dB.

APPENDIX B. DIVERSITY GAIN IN DAS SYSTEMS

Two antennas in DAS system introduce some slow fading diversity gain. This is needed if we want to compute the needed number of radiators in DAS system for a large area (=many buildings). The diversity gain has been computed with ray-tracing data by taking pairs of linkloss maps computed with two antenna locations. The effect of distance attenuation was neglected by subtracting the mean value from every pixel of those maps. The mean value was computed over 9 pixels around the calculation pixel. So the rest of the variation was caused by the slow fading caused by attenuation due to walls, ceilings, multiple reflections and so on. Figure 86 shows the example distribution of the slow fading of two antennas and the sum signal of these two antennas. The diversity gain was assumed to be the difference between the sum and the mean value of these two antennas.

Figure 86. The diversity gain in the two antenna DAS system.

APPENDIX C. MAXIMUM CAPACITY OF DIFFERENT DAS SCENARIOS

Table 20. Capacity of single sector DAS network. One microcell and DAS with 6 antennas (2 per floor)

UL diversity in micro cells, no diversity in DASUsers UL

Users DL

i Total BS powers (dBm)

DL cov %1 Mbit/srq. Tx pow.

UL cov.512 kbit/s

DAS 17 17 0.0054 26.51 100/ 100 67 67 0.0045 29.22

UL diversity in DAS and micro DAS 35 36 0.0048 27.0 100/ 100 44 43 0.1043 28.8

Two microcell and DAS with 6 antennas (2 per floor)UL diversity in micro cells, no diversity in DAS

DAS 17 18 0.1044 27.4238 100/ 1001 27 26 0.0567 29.2602 23.8 dBm2 4 4 2.6958 28.1245

UL diversity in micro cells and DASDAS 27 29 0.0103 27.9483 100 1001 35 33 0.1132 29.0609 24.8 dBm2 14 14 1.4004 28.7185

Table 21. Capacity of three sector DAS network. Two microcell and DAS with 3 sectors (6 antennas total, 2 per floor), 10 dB attenuation, F=10 dBm

UL diversity in micro cells, no diversity in DASUsers UL

Users DL



UL cov.%512 kbit/s

DAS1 4 4 0.5012 29.5368 100 100DAS2 16 16 0.4312 29.6321 26.0 dBmDAS3 12 12 1.3015 29.00101 18 18 1.3657 28.52852 13 13 1.7703 28.5069

63 63UL diversity in micro and macro

DAS1 20 21 0.0867 29.4543 100 100DAS2 28 29 0.2405 29.5607 26.4 dBmDAS3 24 23 0.2670 29.35961 39 39 0.1372 29.1231

2 31 30 0.5195 29.0229142 142

Table 22. Capacity of three pico BS with variable desensitisation and maximum BS Tx power values.UL diversity in micro and pico cells (F=15 dB)

Users UL

Users DL


DL cov %1 Mbit/s, DL cov. (1Mbit/s)

UL cov.%512 kbit/s

Pico1 17 20 0.2894 19.6899 87.17 % 100Pico2 17 17 0.1114 19.2057 Needed max Pico3 20 17 0.7218 18.1121 power1 33 33 0.1301 29.0642 per link2 31 31 0.1224 29.1709 24.4 dBm

total 118 118UL diversity in micro cells and picocells (F=20 dB)

Pico1 18 22 0.2727 82.6 % 99.7Pico2 31 31 0.0968 Needed max Pico3 15 15 0.2667 power1 26 26 0.0385 per link2 28 24 0.1667 25.2 dBm

total 138 138UL diversity in micro cells and picocells (F=20), Max BS power=27 dBm

Pico1 18 22 0.2727 92.0 % 99.7Pico2 31 31 0.0968 Needed max Pico3 15 15 0.2667 power1 26 26 0.0385 per link2 28 24 0.1667 25.2 dBm

total 165 165

Table 23. Capacity of three pico BS feeding DAS network. In here it is assumed that we can have UL diversity. UL diversity in micro cells and picocells (F=20), Max BS power=24 dBm.DAS system in every floor (2 antennas/floor), L=7 dB

Pico1 22 23 0.1074 20.8623 83.8 % 100%Pico2 26 27 0.2997 20.4948 Needed max Pico3 18 16 0.4471 18.58531 31 31 0.2291 28.7343 per link2 7 7 2.6297 28.2221 24.2 dBm

total 104 104UL diversity in micro cells and picocells (F=20), Max BS power=27 dBmDAS system in every floor (2 antennas/floor), L=7 dB

Users UL

Users DL



UL cov.%512 kbit/s

Pico1 22 23 0.1074 20.8623 94.1 % 100%Pico2 26 27 0.2997 20.4948 RequiredPico3 18 16 0.4471 18.5853 power1 31 31 0.2291 28.7343 Link 2 7 7 2.6297 28.2221 24.25 dBm

total 104 104UL diversity in micro cells and picocells (F=10), Max BS power=27 dBmDAS system in every floor (2 antennas/floor), L=7 dB

Users UL

Users DL



UL cov.%512 kbit/s

Pico1 18 17 0.0705 19.0564 94% 100%Pico2 17 14 0.4310 18.6011Pico3 20 19 0.1050 18.93171 50 52 0.0835 29.26632 31 34 0.2103 29.2764

total 136 136

Table 24. Capacity of three pico BS feeding FODS network. UL diversity in micro cells and no diversity in picocells (F=11), Max BS power=23 dBm. Pico BS feeding FODS RU in every floor (2 antennas/floor), L=0 dB

Users UL

Users DL



Pico1 9 9 0.0789 19.63 91%Pico2 11 11 0.7531 17.71 Required per. Pico3 8 5 1.2911 17.92 Link1 49 49 0.0576 28.96 22.33 dBm2 21 24 0.8115 28.90

total 98 98UL diversity in micro cells and in picocells (F=11), Max BS power=23 dBmPico BS feeding FODS RU in every floor (2 antennas/floor), L=0 dB

Pico1 9 5 1.2702 17.56 90.2Pico2 22 26 0.1426 19.03 Required Pico3 22 20 0.1730 18.41 power per 1 36 36 0.0836 29.80 link2 37 39 0.3285 29.26 23.4 dBm

total 126 126UL diversity in micro cells and in picocells (F=11+5), Max BS power=23 dBmPico BS feeding FODS RU in every floor (2 antennas/floor), L=0 dB

Pico1 8 8 0.1204 18.04 90Pico2 27 27 0.1408 18.76 Required Pico3 20 20 0.2279 18.01 power per 1 49 49 0.0824 29.10 link

2 24 24 0.1645 28.84 23.3 dBmtotal 128 128

UL diversity in micro cells and in picocells (F=11), Max BS power=23 dBmPico BS feeding FODS RU in every floor (3 antennas/floor), L=0 dB

Pico1 16 17 0.1584 22.00 96.4Pico2 7 8 1.2943 20.59 Required Pico3 18 14 0.5966 18.71 power per 1 40 40 0.0522 28.97 Link2 22 24 0.2233 28.96 18.0 dBm

total 103 103UL diversity in micro cells and in picocells (F=11+5), Max BS power=23 dBmPico BS feeding FODS RU in every floor (3 antennas/floor), L=0 dB

Pico1 17 16 0.1331 19.1865 97.2Pico2 17 18 0.5560 19.7934 Required Pico3 16 18 0.2339 18.8083 Power per 1 35 34 0.0424 29.5378 Link2 32 31 0.3391 28.8441 17.1 dBm

Total 117 117

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