Umts Fdd Rnp Quick Guide

8/10/2019 Umts Fdd Rnp Quick Guide

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File Name: 2004_07_09_U MTS_FDD_RNP_Q uick_Guide Save Date: 2004-07-20 Revision Number: 003

3DF 01902 3013 VAZZA Edition 01 RELEASEDConfidential 1/58

Radio Network Planning

UMTS FDD Radio Network Planning

Quick Guide


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2/58 Confidential 3DF 01902 3013 VAZZA Edition 01 RELEASED

Table of Contents

RADIO NETWORK PLANNING ...........................................................................................................................1

1 REFERENCED DOCUMENTS....................................................................................................................5

2 REFERENCED TOOLS..............................................................................................................................6

3 LIST OF ABBREVIATIONS......................................................................................................................... 6

4 CONTEXT..............................................................................................................................................7

5 PROCESS OVERVIEW ..............................................................................................................................7

6 INITIAL DESIGN......................................................................................................................................86.1 Basic Link Budget....................................................................................................................................86.2 Positioning and Configuration of Sites in the Radio Network Planning Tool ................................................10

6.3 Performing Predictions........................................................................................................................... 106.3.1 Reliability Level and Coverage Probability............................................................................................ 116.3.2 CPICH RSCP Coverage ......................................................................................................................116.3.3 Traffic Dependent Predictions..............................................................................................................126.4 Issuing of Search Radii .......................................................................................................................... 16

7 ANTENNA SYSTEM PLANNING..............................................................................................................16

8 FIRST DESIGN OPTIMISATION ...............................................................................................................178.1 Predictions............................................................................................................................................ 178.1.1 Pilot pollution prediction.....................................................................................................................178.1.2 Adapt Antenna Tilts and Azimuth ........................................................................................................ 18

9 NEIGHBORHOOD AND SCRAMBLING CODE PLANNING ......................................................................18

10 DESIGN OPTIMIZATION BASED ON MEASUREMENTS ............................................................................ 18

11 SITE CONFIGURATION AND RADIO FEATURES......................................................................................2211.1 Node B Configurations......................................................................................................................2211.2 Detection of Uplink or Downlink Limitation.......................................................................................... 2311.3 Uplink Features.................................................................................................................................2311.3.1 TMA..............................................................................................................................................2311.3.2 4RX Diversity.................................................................................................................................. 2411.4 Downlink Features............................................................................................................................. 2511.4.1 TX Diversity....................................................................................................................................25

11.4.2 High Power Amplifier (HPA)............................................................................................................. 2611.5 Special configurations........................................................................................................................ 2711.5.1 OTSR............................................................................................................................................27

12 ACCURACY OF PREDICTION ................................................................................................................2812.1 Sensitive Parameters for RNP Prediction...............................................................................................2812.1.1 Ec/Io Threshold..............................................................................................................................2812.1.2 Clutter Correction Factors............................................................................................................... 2812.1.3 Shadowing Standard Deviation .......................................................................................................2812.1.4 Eb/No...........................................................................................................................................2812.1.5 Traffic and Load.............................................................................................................................2912.2 Field validation of prediction...............................................................................................................29

APPENDIX A LINK BUDGET ASPECTS........................................................................................................... 30Calculation of Relative Interference................................................................................................................... 30Relation between Eb/No and C/ I...................................................................................................................... 30Uplink Link Budget Parameters and Typical Values............................................................................................. 31Exemplary Basic Uplink Link Budget.................................................................................................................34


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Table of FiguresFigure 1 Overview on Radio Network Planning Steps........................................................................................... 7

Figure 2: Sub-Steps of Initial Design................................................................................................................... 8

Figure 3: Connection between Radius and Intersite Distance................................................................................. 9

Figure 4: Sub-Steps of First Design Optimization...............................................................................................17

Figure 5: Sub-Steps of Measurement Based Design Optimization........................................................................19

Figure 6 Implementing 4RX Diversity................................................................................................................. 25

Figure 7: Equivalent RSCP level to determine suitable intersite distance................................................................ 36

Figure 8 Equivalent RSCP level (after moving site location to reach suitable intersite distance)................................ 36

Figure 9: CPICH RSCP plot for exemplary design (1).......................................................................................... 38

Figure 10: CPICH RSCP level coverage probability per pixel for exemplary design (1)...........................................39

Figure 11: CPICH RSCP plot for exemplary design (1) after tilt and azimuth tuning...............................................40

Figure 12: CPICH RSCP level coverage probability per pixel for exemplary design (1) after tilt and azimuth tuning.. 40Figure 13: CPICH Ec/Io Coverage probability per pixel for exemplary design (2)..................................................41

Figure 14: Downlink coverage probability prediction per pixel for service PS384 for exemplary design (2)..............42

Figure 15: Uplink coverage probability prediction per pixel for service PS384 for exemplary design (2)..................43

Figure 16: Pilot Pollution prediction for exemplary design (2)..............................................................................43

Figure 17: CPICH Ec/Io Coverage probability per pixel for exemplary design (2), with traffic simulation approach(medium traffic) ....................................................................................................................................... 44

Figure 18: Downlink Service Coverage probability per pixel for PS128 for exemplary design (2), with trafficsimulation approach (medium traffic) ........................................................................................................ 45

Figure 19: CPICH Ec/Io Coverage probability per pixel for exemplary design (2), with traffic simulation approach(high traffic).............................................................................................................................................46

Figure 20: : Downlink Service Coverage probability per pixel for PS128 for exemplary design (2), with trafficsimulation approach (high traffic).............................................................................................................. 47

Figure 21 DL power load set in the transmitter table.......................................................................................... 48

Figure 22 UL load percentage set..................................................................................................................... 50

Figure 23 UL load set through reception losses.................................................................................................. 50

Figure 24: Screenshot of Excel Template to derive Area coverage probability .......................................................57

Table of EquationsEquation 1: Calculation of UL reference sensitivity .............................................................................................. 8

Equation 2: Calculation of Maximum Allowable Pathloss (MAPL) in UL.................................................................. 9

Equation 3: Total received Power (total interference)...........................................................................................30

Equation 4: Calculation of relative interference in UL......................................................................................... 30

Equation 5: Relation between Eb/No and C/I in dB........................................................................................... 30

Equation 6: Calculation of Processing Gain ...................................................................................................... 31

Equation 7: Cost-Hata Pathloss formula............................................................................................................ 34

Equation 8: Mapping between Total power used and DL power load................................................................... 48

Equation 9: DL power load % generated by OCNS............................................................................................ 48Equation 10: DL power load in A9155V6 ......................................................................................................... 49

Equation 11: UL interference noise rise............................................................................................................. 49


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3DF 01902 3013 VAZZA Edition 01 RELEASED Confidential 5/58

1 REFERENCED DOCUMENTS

[PCSDef] A9155 V6.2 UMTS Default Parameter Set, L. Sanchez-Perez,3DF 01955 6243 DSZZA 01

[PCSSC] UMTS Scrambling Code Planning Guideline, A. Grtner,

3DF 01902 6010 VAZZA 02

[PCSfl] Fixed Load Simulation with A955V6, L. Sanchez-Perez, internallypublished technical memo

[PCSant] Antenna System Planning, E. Schneider, 3DF 01902 2711 VAZZA 01

[PCSsta] Physical Specification of Standard Antenna Set, U. Birkel,3DF 00995 0000 DSZZA

[PCSa955] User Manual A9155,3DF 01955 6280 PCZZA

[PCSclu] Clutter Classes for Radio Network Planning, T. Mac-Carty,3DF 00993 2000 PGZZA

[PCSotsr] OTSR Radio Network Planning, Draft document, M. Knoedl[PCScov] Reliable 3G WCDMA Radio Network Planning with Coverage Probability

Prediction, Conference Paper for Global Mobile Congress 2004 inShanghai, A. Grtner and M. Hahn

[PCSproc] Radio Network Planning Process for GSM/UMTS, M.Hahn,3DF 00902 3000 DEZZA (Ed: 03)

[PCSmeas] UMTS FDD Measurement Training, R.-M. Goerner

[PCSiub] Iub Analysis Basics, C. Moignard-Dumas, PCS-internal draft

[NDPCSlb] GSM Link Budgets, K. Daniel, 3DC 21150 0293 TQZZA

[NDPCSco] Site Sharing GSM-UMTS RF Aspects, A. Grtner, K. Daniel, Ed. 04,3DC 21019 0005 TQZZA

[ND1] AIRMUST User Guide, PMD (former ND) internal document

[ND2] UMTS Radio Dimensioning, PMD (former ND) internal document

[NDtma] Design Paper: Uplink Analysis TMA, A. Grtner and P. Mendribil,3DC 21151 0013 TQZZA, PMD (former ND) document,available on the ND web http:/ /aww-nd.cit.alcatel.fr/default.htmunderND background/design papers

[ND4div] Design Paper: Uplink Analysis 4RXdiv, A. Grtner and P. Mendribil,3DC 21151 0014 TQZZA, PMD (former ND) document,available on the ND web http:/ /aww-nd.cit.alcatel.fr/ default.htmunder

ND background/design papers

[NDtxdiv] Design Paper: Downlink Analysis Transmit diversity, A. Grtner and P.Mendribil, 3DC 21151 0008 TQZZA, PMD (former ND) document,available on the ND web http:/ /aww-nd.cit.alcatel.fr/default.htmunderND background/design papers

[NDhpa] Design Paper: Downlink Analysis High Power Amplifier, F. Richter,3DC 21151 0002 TQZZA, PMD (former ND) document,available on the ND web http:/ /aww-nd.cit.alcatel.fr/default.htmunderND background/design papers

[NDmteu] Design Paper: Downlink Analysis Mix TEU configuration, F. Richter,3DC 21151 0007 TQZZA, PMD (former ND) document,

available on the ND web http:/ /aww-nd.cit.alcatel.fr/default.htmunderND background/design papers

[NDotsr] Design Paper: Downlink Analysis OTSR, F. Richter,3DC 21151 0003 TQZZA, PMD (former ND) document,


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available on the ND web http://aww-nd.cit.alcatel.fr/default.htmunderND background/design papers

[MPS1] EVOLIUM A9100 Multi-standard Base Station Product Description,3DC 21083 0011 TQZZA

2 REFERENCED TOOLS

[TDmarg] Power Margins and SHO gain, v.1.1, TD/SYT internal Excel Macro,

margins_and_sho_gain (V1.1).xls, P. Agin,available on PCS web http://aww-mnd.alcatel.de/pcs/tools.html

[TDlls] UTRA-FDD Link Level Performance, v.3.0, TD/SYT internal Excel Macro,lls_performance_v3.xls, P. Aginavailable on PCS web http://aww-mnd.alcatel.de/pcs/tools.html

[NDfriess] TMA contribution calculated with Friess Formula, ND internal Excelmacro, Friess-Formula_Ed2.xlsavailable on PCS web http://aww-mnd.alcatel.de/pcs/tools.html

3 LIST OF ABBREVIATIONS

In the following, you can find a list of used abbreviations. Most of them are referring to3GPP notation. Alcatel specific notation is marked especially.

3GPP: 3rdGeneration Partnership Project

AMR: Adaptive Multi Rate

ANRU: ANtenna module with integrated Receiver for UMTS (Alcatel)

BCH: Broadcast Channel

BER: Bit Error Ratio

BLER: Block Error Rate

CPICH: Common Pilot Channel

DL: Downlink

DPCCH: Dedicated Physical Control Channel

DPDCH: Dedicated Physical Data Channel

DTCH: Dedicated Traffic Channel

EIRP: Equivalent Isotropic Radiated Power

ETSI: European Telecommunication Standards InstituteFACH: Forward Access Channel

GPS: Global Positioning System

GSM: Global System for Mobile Communications

HPA: High Power Amplifier

MBS: Multistandard Base Station (Alcatel)

MAPL: Maximum Allowable Path Loss

NF: Noise Figure

OCNS: Orthogonal Code Noise Simulator (Alcatel)

OTSR: Omni Transmit Sectorized Receive (Alcatel)

OVSF: Orthogonal Variable Spreading Factor

PA: Power Amplifier


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The gray fields indicate, that the planning steps consist of sub-steps as visualized anddescribed in the according chapter.

Note that in [PCSproc], one can find an extensive formalized process description, butwhich is rather GSM oriented and does not take into account UMTS specialties tackledin this guideline.

6 INITIAL DESIGN

The Initial Design is the first step in the Radio Network Planning Process. It consists ofseveral sub-steps, shown in overview in Figure 2.

Link Budget

Position and Configurationof Sites in RNP Tool

Intersite Distance

Performing Predictions:CPICH RSCP CoverageCPICH Ec/IoUplink Service CoverageDownlink Service Coverage

Issue Search Radii

InitialDesign

modify siteconfigurationif required

Figure 2: Sub-Steps of Initial Design

6.1 Basic Link Budget

The first planning step consists in determining appropriate values for the intersite

distance in the different morphoclasses. These intersite distance values are required bythe planner to place sites in the radio network planning tool for the first predictions.

In order to get an indicatory value for the inter-site distance, a basic link budget can beelaborated manually. This link budget is calculated for the uplink only, implicitlyassuming that it is the limiting link. It is derived for a fixed interference noise rise,without taking into account the closed-loop dependency between traffic forecast,interference and cell range.

Basic link budget step-by-step:

1. Calculation of reference sensitivity for the limiting service k(in general, theservice with the highest bit rate).

Equation 1: Calculation of UL reference sensitivity

( ) ( ) NFNRN

EysensitivitReference thk

k

bk +++

= log10log10_

0


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with

(Eb/N0)k Required Bit Energy-to-total noise-Ratio in dB for bearer servicek (given for a defined multipath profile, UE speed and BLERvalue)

Rk Bitrate of service k (=useful bit rate at RLC layer)

Nth Thermal noise density (typically 174dBm/Hz)

NF noise figure of node B in dB (guaranteed value for EvoliumNode B is 4dB, typical value for Evolium Node B is 3dB)

2. Fix a value for the relative interference (i.e. the noise rise caused by intracelland intercell interference) perceived by a reference user i of service k. A typicalvalue would be 3dB, approximately corresponding to 50% of cell load (seeappendix for more details)

3. Calculate the Maximum Allowable Pathloss (MAPL)

Equation 2: Calculation of MaximumAllowable Pathloss(MAPL) in UL

[ ] [ ] [ ][ ]

[ ] [ ]

[ ]dB

dBdB

dB_dBm_dBmdB

+

=

Gains

ginsMarLosses

ceInterferenrelysensitivitReferenceEIRPMAPL

i,k

kii,k

where

MAPLi,k Maximum allowable pathloss of mobile i using service k

EIRPi Equivalent isotropic radiated power(i.e. transmit power + antenna gain) of mobile i

rel_Interferencei,k noise rise caused by intracell and intercell interferenceperceived by a reference user i of service k

Losses Sum of all losses in dB (e.g. cable and connector loss,body loss, penetration loss)

M argins Sum of all margins in dB (e.g. shadowing margin,Rayleigh Fading Margin)

Gains Sum of all gains in dB (e.g. antenna gain)

In the appendix, you can find typical values for the above parameters

4. Derive a cell radius out of the MAPL by applying the COST-Hata propagation

model (See Appendix A for calculation formula and typical parameters) or byapplying the method of equivalent RSCP using the planning tool A9155 (seeAppendix A for description of this method).

5. In a homogenous hexagonal network with three-sectored sites, the intersitedistance is corresponding to 1.5 times the calculated cell radius. This can beapplied as approximation to derive a suitable intersite distance out of the linkbudget radius.

R

1.5 R

Figure 3: Connection between Radius and Intersite Distance


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In the Appendix A, you can find an exemplary basic link budget.

Note that a more precise link budget including both uplink and downlink analysis andincorporating a traffic model can be elaborated by using the PMD (Presales MobileDesign) tool AIRMUST [ND1]. AIRMUST is a complex and sophisticated tool developedfor dimensioning purposes. In general, it is not required for Radio Network engineersto be trained for application of this tool since they will perform predictions with the RNPtool A9155 taking into account terrain, realistic sites and traffic. Only in case that theclutter and topo databases are not yet available when a project is started, the toolAIRMUST has to be used to derive search radii. But be aware that it is highly disadvisedto issue search radii without the use of a planning tool (A9155).

The target of this planning step is fulfilled, when a typical intersite distance for eachbasic morphoclass is derived.

Note that in case the downlink is expected to be the limiting link (e.g. due to high bitrate services in downlink and/or high downlink load), the uplink link budget approachwill lead to insufficient downlink coverage. In this case it is highly suggested to checkthe intersite distance from downlink point of view after having placed only a few sites,by doing the according predictions (as described in the following sub-chapters) in asmall focus zone defined by the planner.

6.2 Positioning and Configuration of Sites in the Radio Network Planning Tool

First, the project with topo and morpho database as well as the propagation modelhas to be set up. In case of usage of a COST-Hata based propagation model, it maybe required to calibrate the model coefficients (clutter correction factors) bymeasurements, see [PCSclu] for more details.

Then, sites and their configuration have to be entered in the Radio Network Planningtool (namely A9155 v6). If there are existing GSM sites which should be reused, theirposition and height has to be imported first. Roughly respecting the intersite distancefor different morphoclasses derived from the basic link budget or the method ofequivalent RSCP, additional sites have to be positioned according to the well-known

rules of radio network engineering. Adequate antennas and antenna networkconfiguration have to be chosen. Standard antennas and configurations have to beused wherever possible (see [PCSsta]).

Special consideration has to be dedicated to planning measures keeping theinterference between the cell as low as possible (e.g. antenna downtilting or avoidingmain beam directions along open streets or street canyons). Note that UMTS is aninterference limited system, and the network performance is very sensitive tointerference.

Please refer to the Appendix Bfor an exemplary design in the Radio Network PlanningTool A9155. For an according exemplary parameter setting, please refer to thedocument A955 V6.1 UMTS Default Parameter Set [PCS1].

6.3 Performing Predictions

In the following, the RNP predictions to be performed in order to check the coverage in thefocus area are described. Note that in case the prediction results are not satisfyingcompared with the required target, site configurations and/or locations have to be modifiedand/or additional sites have to be placed. Then, the predictions have to be rerun.

However, note that at this early stage of network planning, the planner should not dedicatetoo much time and effort to optimize to the last pixel since some site locations and siteconstraints will still be modified in the acquisition process. It is of no use to have a perfect,but theoretical network.

Keep in mind that all prediction steps described in the following will be re-launched in thedesign optimization step.


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6.3.1 Reliability Level and Coverage Probability

A radio network planning tool has to be able to predict the probability with which a pixel willbe covered in order to give then an indication about the reliability of the coverage over thenetwork area. The radio network engineer has to be able to plan the network in a way, thatthe required coverage probability is reached. However, the derivation of coverageprobability is far more complex for UMTS than in GSM, since the system is interferencelimited. Therefore, it is no more sufficient to look at the statistical variations of one users

received signal, but the variations of the interference have to be taken into account as well.Please refer to the appendix and to [PCScov] for more details.

Since an adequate treatment of coverage probability has not yet been implemented intoA9155, some restrictions resp. workaround rules have to be respected.

In order to calculate the coverage probability for a certain area, it is highly advised to usethe function best reliability level which is offered starting from A9155 V6.2.

This function calculates for each pixel the probability that this pixel is covered according tothe coverage criterion (i.e. covered by CPICH RSCP, by CPICH Ec/Io, by a given service inuplink or by a given service in downlink). This probability is also called local coverageprobability. With the help of the report function offered by A9155 and a short Excelanalysis, the area coverage probability for a certain polygon can then be derived. The areacoverage probability is calculated by averaging the pixel probability values over the focuszone. An according example is shown in Appendix F.

6.3.2 CPICH RSCP Coverage

The first prediction is the only traffic-independent prediction, i.e. no statements about loadhave to be made at this point. It refers to the CPICH RSCP coverage. CPICH coverage is theprecondition for any service coverage. The CPICH RSCP must comfortably reach theminimum required value all over the area to be covered. This can be checked by thederiving the coverage probability: in a first step the probability per pixel, in a second stepthe area probability by averaging over all pixels of this area. When no special requirementfor the coverage probability of CPICH RSCP is given, the planner should follow the rule of

thumb that the coverage probability of CPICH RSCP has to be higher than the requiredservice coverage probability.

Examp le: The required service coverage probab ility for a ll services is 95%. Then, the CPICH

RSCP coverage p robability should be set to 96% at least.

Concerning coverage probability, the CPICH RSCP coverage prediction is very similar to theGSM coverage prediction. With a clutter dependent shadowing standard deviation appliedon the received level, for each pixel the probability can be given that the CPICH RSCP levelat this location will exceed the threshold value. The standard deviation is the same as forGSM and can be derived from the document [PCSclu] or from calibration measurements. Inorder to calculate the coverage probability per pixel by the best reliability function ofA9155 v6.2, a threshold value for the CPICH RSCP has to be set. Note that here, the

required outdoor level has to be given. Therefore, on the minimum possible value, theaccording penetration margin has to be applied, so that the minimum level will also bereached indoors.

Examp le: When the minimum acceptab le CPICH RSCP is 104dBm and the penetra tion loss is

18dB, the RSCP threshold va lue in A9155 V6.2 will be set to 86dBm.

In case that different penetration margins are required for different clutter classes, theplanner can apply the penetration losses to the clutter correction factors. In this case, ofcourse the minimum acceptable RSCP has to be set as threshold.

Summarizing the actions of this planning step:

Apply best reliability function on CPICH RSCP prediction with A9155 to derivecoverage probability per pixel

Apply statistics over the focus area to derive area coverage probability (seeAppendix Ffor example)


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Optional:In order to have a visibility about critical zones etc., perform CPICH RSCP predictionwith A9155 (setting the reliability level to 50%, i.e. no a-priori-margin is applied).Note that this plot does not show a definite coverage border.

If the calculated area coverage probability in the focus zone is below the required value,antenna directions have to be modified and/or sites have to be placed differently (ifpossible) or/and sites have to be added.

The target of this planning step is fulfilled, when the required CPICH RSCP threshold value isreached with the required area coverage probability all over the area to be covered.

Please refer toAppendix Bfor exemplary plots and an according modification of the designbased on the plot.

Note:A design optimization based on the CPICH RSCP prediction should not be carried outcompletely separate from the CPICH Ec/Io predictions described in chapter 6.3.3.3. Sincethere is a trade-off between best CPICH RSCP (i.e. level) coverage and best CPICH Ec/Io(i.e. quality) coverage, measures to increase RSCP coverage may increase interference andtherefore decrease Ec/Io coverage. Therefore, both predictions should be looked at in

parallel.

6.3.3 Traffic Dependent Predictions

The following predictions are traffic dependent. There are two options for considering theimpact of traffic on coverage.

The first is the fixed loadapproach, where one assumes that the load (in uplink anddownlink) is known and equal to a fix value. This approach is typically applied whenno traffic forecast is available, or when the acceptance of the network will beperformed with fixed (virtual) load.

The second is the traffic simulation approach, where out of traffic forecast andservice specific information Monte Carlo Simulations are run which distribute

mobiles randomly over the area and calculate the interference they are producingas well as the power they are needing (in uplink and downlink).

Fixed load approach and Traffic simulation approach mainly differ in the extent of the inputdata and in the calculation complexity, and in their possibility to represent the networkrealistically. The type of results which have to be the outcome of the planning steps isequivalent.

6.3.3.1Fixed Load Approach

In case of fixed load approach, no Monte Carlo simulations are performed.

In downlink the fixed load is modeled by additional transmitted power. The downlink power

load is equivalent to the amount of power used in % of the total available power (i.e. ratioPower used/Maximum Total power). Note that as in the real situation, the downlink powerload includes the common channels.

In the network (e.g. for measurement and acceptance test purpose) the downlink powerload can be emulated with the OCNS feature in the Alcatel node B.

In uplink , the fixed load is modeled by a fixed noise rise perceived by all service users.

In the network, uplink radio load is emulated by means of an attenuator in the uplink pathon the mobile station side.

The parameter settings for A9155 and the correspondence to OCNS settings are given inAppendix C. The application of the fixed load approach is described in detail in thedocument [PCSfl]. Please refer to this document for deeper information.

The fixed load approach constitutes an easy way to get coverage results without the need togather traffic forecast data. However, it has to be noted that some important aspects of areal network cannot be reflected by the fixed load approach. All planning efforts targeting tooptimize the network by reducing traffic per cell cannot be modeled.


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Example:

An example constitutes the add ition of a site as an option to increase interference limited

downlink coverage. In a living UMTS network, one opt imization possibility in case of too high

interference consists of adding a site. Since it will o ffer new capacity, the load in the

surrounding cells will become lower and therefore interference will decrease as well. But for a

fixed load scenario, where the same load is mandato ry for a ll cells, the new site adds to the

system high (artif icial) traf fic and therefore brings a lot of interference and only very few new

capacity, so that it might make the interference scenario worse than before. This effect

(called the Fixed Load Trap) w ill occur both in f ixed load p rediction and in measurement

scenarii with fixed load condition.

Also other measures such as downtilting to reduce the cell area to have less traffic in the cellcannot be reflected by the fixed load approach.

Therefore, if severe interference problem are occurring which cannot be resolved withoutadding a site, the usage of the traffic simulation approach for prediction is highly suggested.

Suggestions for Avoid ing the Fixed Load Trap

In order to avoid the above cited vicious circle due to the fixed load and its usage in both

prediction a nd acceptance, and in ord er to nevertheless benefit from some advantages of its

simple applica tion, two p ossible solutions are suggested. Note that their app licationinfluences the definition of the acceptance criteria.

1. Comb ination of Fixed Load and Traffic Simulations Approach:

The first predictions are run w ith Traffic Simulation Approach (Traff ic inputrequired!)

A9155 Tool output gives load values for each cell

Those values can be used as fixed load input i n case of minor design changes

In case of b igger design changes, traf fic simulation can be applied

The downlink load values given as output by A9155 for each cell for the fina l

design are taken as fixed load settings for acceptance

For uplink, one fixed load for the overall network is taken for acceptance

2. Traff ic Simulation f or Prediction, Fixed Load for Acceptance

All predictions are run with Traffic Simulation Approach (Tr aff ic input required!)

The downlink load values given as output by A9155 for each cell for the finaldesign are taken as fixed load settings for acceptance

For uplink, one fixed load for the overall network is taken for acceptance

Caution:

Fixed Load Requirements should not be included a priori in any acceptance criteria in order

to avoid the Fixed Load Trap!Acceptance can of course be done with artificial fixed load, but the load settings should befixed only after the design has been finalized, according to the downlink power load valuescalculated by A9155 for the respective design. Fixed load settings will therefore be differentfor each sector.

6.3.3.2Traffic Simulation Approach

For the traffic simulations, additional input data is required:

A traffic map has to be provided, showing the traffic distribution over thegeographical area.

Traffic profiles have to be given, to define how much which service is usedPlease refer to Appendix Dfor an exemplary traffic forecast and to the A955 v6 usermanual [A955man] for detailed description on how to enter in the Radio NetworkPlanning Tool. Do not underestimate the effort to collect all required input data!


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Within a Monte Carlo simulation , subscribers are distributed over the planning area.The number of users and their requested service are randomly chosen according totraffic map. Power control equations are then solved iteratively.

The predictions base on an interference situation, derived from one simulation or theaverage (or any other probability value) of several simulations. The planner has todecide which option is used.

The application of both the fixed load approach and the traffic simulations approach has toyield the following predictions as an outcome: CPICH Ec/Io, Uplink Coverage and Downlinkcoverage.

6.3.3.3CPICH Ec/Io

The precondition for any service to work is a minimum received CPICH Ec/Io. This value ismobile station dependent.

An analysis of the CPICH Ec/Io has to be performed predicting for each pixel a receivedCPICH Ec/Io value. The prediction is done with a reliability level of 50% (i.e. without theapplication of a shadowing margin).

The shadowing standard deviation for Ec/Io is much smaller than the standard deviation forthe signal alone, and this standard deviation does not only depend on the clutter class, butalso on the amount of extracell interference.

Since this effect of a small shadowing standard deviation is not yet implemented in theA9155 V6.2 predictions, the following workaround is proposed to avoid too pessimisticforecasts:

Before starting the Ec/Io predictions, set the standard deviation for each morphoclass to 3dB.

Create Best Reliability plot on CPICH Ec/Io prediction with A9155 v6.2 to derivecoverage probability per pixel. Note that the threshold for Ec/Io has to be set.

According to experience on the field and Evolium (TD/SYT) simulation results, thevalue should be 15dB. Note that this threshold is independent of the penetrationloss.

Apply statistics over the focus area to derive area coverage probability (seeAppendix F)

Optional:In order to have a visibility about critical zones etc., perform CPICH Ec/Io predictionwith reliability level of 50%. Note that this plot does not show a definite coverageborder.

Note that in A9155, before performing the predictions for Ec/Io, you have to lock other

prediction results previously carried out with the higher standard deviation, namely theCPICH RSCP prediction, to avoid that they are recalculated with the new standard deviationvalues.

The CPICH Ec/Io coverage is highly dependent on the downlink load. Therefore, it is crucialto set the load resp. traffic related parameters correctly in the tool according to the trafficforecast given by the operator.

Since the CPICH Ec/Io prediction considers the impact of intracell and intercell interference,it constitutes a good basis to create an interference optimized network where theinterference is reduced as much as possible. Such an optimized network will also lead tobetter results in the service coverage which is limited by interference as well.

The planner should therefore dedicate effort to modify parameters such as site location,

antenna azimuth and antenna height in order to get reduced interference and good Ec/Iocoverage.

The planner should perform this RNP optimization starting with the cells resp. regions wherethe worst coverage probabilities per pixel are occurring.


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The target of this planning step is fulfilled, when the required CPICH Ec/Io threshold value isreached all over the area to be covered with the required area coverage probability.

Please refer toAppendix Bfor an exemplary plot (at 50% coverage probability).

6.3.3.4Downlink Coverage Prediction

For each service, a downlink coverage prediction has to be carried out.

For both fixed load and traffic simulation approch, service parameters, terminal parametersand mobility parameters have to be set in the planning tool.

In case of fixed load approach, the fixed load is modeled within the power settings (totalpower). For more details please refer to Appendix Cand to [PCSfl]).

For the traffic simulations approach, the load is derived from the Monte Carlo runs. Serviceparameters, traffic parameters and traffic profiles have to be set appropriately beforehand.

In downlink, the ratio C/I which is suffering from various shadowing impact in numeratorand denominator is limiting. The downlink service coverage probability is therefore derivedbased on a shadowing standard deviation for C/I which is significantly smaller than for thepure level.

Since this effect of a small shadowing standard deviation is not yet implemented in A9155V6.2 predictions, the following workaround is proposed to avoid too pessimistic results:

Before starting the downlink predictions, set the standard deviation for eachmorpho class to 3dB (resp. check that this setting is still valid)

Before starting the downlink predictions, disable the limitation coming from CPICHEc/Io by setting the Ec/Io threshold value to 30dB.

Create Best Reliability plot on Downlink Service Coverage with A9155 v6.2 toderive coverage probability per pixel. Apply statistics over the focus area to derivearea coverage probability (see Appendix F)

Optional:

In order to have a visibility about critical zones etc., perform Downlink ServiceCoverage prediction with reliability level of 50%. Note that this plot does not show adefinite coverage border.

When the required area coverage probability is not reached, the planner should modify thedesign, starting with the cells resp. regions where the worst coverage probabilities per pixelare occurring. Antenna directions can be modified and/or sites can be placed differently (ifpossible) or/and sites can be added.

The target of this planning step is fulfilled, when the focus area is predicted to be covered byall required services in the downlink with the required area coverage probability.

Please refer to Appendix Bfor exemplary plots.

6.3.3.5Uplink Coverage Prediction

For each service, which has to be provided in the focus area, an uplink service predictionhas to be carried out.

For both fixed load and traffic simulation approch, service parameters, terminal parametersand mobility parameters have to be set in the planning tool.

In case of fixed load approach, the interference created by the fixed uplink load is treated asadditional loss for the prediction. For more details and parameter settings, please refer to[PCSfl]).

For the traffic simulations approach, the interference is derived from the Monte Carlo runs,so it is crucial to perform these runs before the prediction. Service parameters, traffic

parameters and traffic profiles have to be set appropriately beforehand. Refer to theappendix for an exemplary traffic forecast.


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8 FIRST DESIGN OPTIMISATION

Figure 4 shows in overview the different sub-steps of this planning step .

(Real) Position andConfiguration

of Sites in RNP Tool

Performing Predictions:CPICH RSCP CoverageCPICH Ec/ IoUplink Service CoverageDownlink Service CoveragePilot Pollution Prediction

Adapt Antenna Tiltsand Azimuths

(if required)

First DesignOptimization

Figure 4: Sub-Steps of First Design Optimization

When the exact location, of all sites is known along with configuration of node B andantenna system, a first design optimization has to be carried out. First, the predictionshave to be run to see the as is status. Then, if necessary, modifications of antenna tiltand azimuth can be carried out.

8.1 Predictions

The above described predictions have to be re-run with all known site coordinates(Location, Antenna Height, antenna orientation):

CPICH RSCP Coverage

CPICH Ec/Io

Uplink Service Coverage Prediction

Downlink Service Coverage Prediction

In addition, a pilot pollution prediction has to be performed:

8.1.1 Pilot pollution prediction

A polluting cell is a cell which meets all the criteria to enter the active set of a mobile(for soft handover) but which cannot be admitted in the active set of the mobile due tothe active set size limitation.

Since the algorithms for cells to enter or to leave the active set are containing a certainhysteresis, the content of the active set may not always be the same at a given location,even if the radio conditions are the same. The active set will depend on the history ofthe mobile and cannot be given unambiguously at a certain snap shot in time.

For RNP purposes not the entire algorithm (requiring the history of the mobile) isconsidered, but a simplified criterion is used: The indicator is the received CPICHquality given by the parameter Ec/Io. The cell received with the highest Ec/Io isassumed to be serving cell, i.e. it is in the active set. Cells with a Ec/Io value, which isnot more than xdB (typically 3dB) lower than the best Ec/Io, are assumed to be in theactive set as well if the active set size is not exceeded. If the active set size is alreadyreached, such a cell is classified as polluter.

A polluting cell acts as pure interference and is not of use for the mobile at the given

pixel. The radio network planning has to avoid that a multitude of equally suited cellshaving the potential to enter the active set are received. The number of potential activeset cells should be equal to or less than the maximum active set size, in order to avoidpilot pollution. The lower the pilot pollution, the better is therefore the quality.


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It is highly important to eliminate polluting cells or at least to reduce the received signalof polluting cells to a minimum for each pixel. The maximum active set size should beset to three (more than three mobiles will not bring additional macro diversity gain).

The planner has to run the pilot pollution prediction with A9155 V6. It will show areaswhere the fourth, fifth, sixthetc CPICH is received with a Ec/Io level high enough toenter the active set. The planner will have to reduce the according Ec/Io level by tuningthe antenna parameters as described below.

8.1.2 Adapt Antenna Tilts and Azimuth

In order to reduce pilot pollution and/or improve the C/I situation in critical areas, theantenna downtilt of the polluting resp. interfering cell can be increased. As a rule ofthumb, one can state that the downtilt in UMTS should be at least 1-2 higher than thevalue a planner would chose for GSM (for detailed tilting guideline see [PCSant]). Note

that tilt changes with a difference of 2 compared to the previous value do not makesense, since the modification effort (requiring on-site tuning) does not stand in relationto the effect.

In some cases a modification of the antenna azimuth may help to decrease pilotpollution and interference in critical zones. The precondition is of course that an

azimuth modification is allowed. Note that building constraints or co-siting with anexisting GSM BTS may limit the azimuth modification potential or even fix the azimuth

to a given value. Azimuth modifications of 10 compared to the previous value donot make sense.

After modification of the antenna parameters, the pilot pollution prediction has to bere-run, in order to visualize the improvement and in order to check if no regionsbecame worse than before.

The target of this planning step is fulfilled, when the focus area is predicted to be covered byCPICH (RSCP and Ec/Io) and all required services with the required area coverageprobability, where critical areas of pilot pollution and interference have been ameliorated.

9 NEIGHBORHOOD AND SCRAMBLING CODE PLANNING

The next step consists in neighborhood planning. It is highly important to defineappropriate neighbors for each cell, respecting the maximum number of neighbors inthe neighbor list. The current restriction of Evolium UTRAN (R2) is 14 neighbors (forintra-frequency handover only). The restriction in R3 is 14 neighbors for intra-frequency handovers, 12 neighbors for inter-frequency handover (hard handover)towards other UMTS FDD carriers, 12 neighbors for inter-system handover (UMTS-GSM hard handover) and 1 neighbor for blind handovers.

A potential neighbor missing in the neighbor list may lead to high interference andsignificantly decrease network quality. Neighborhood planning with A955 v6 isdescribed in [PCSa955], chapter VII.8.2.

After establishing the neighbor list, the scrambling code planning has to be executed.Please note that the existing neighbor list is a precondition for the scrambling codeplanning. The scrambling code planning is described in detail in [PCSSC]. Here, basicson scrambling codes are explained and a tool based method as well as a manualmethod for code allocation are given.

10 DESIGN OPTIMIZATION BASED ON MEASUREMENTS

Once the network (resp. a continuous network region) is installed and on air, themeasurement based optimization process can start. It is visualized in overview in Figure5.

The goal of the measurements is to identify problems related to

CPICH level coverage (RSCP)

CPICH quality (Ec/Io)


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Pilot pollution

Handover definition (Neighbors)

DefineMeasurement Areas

Define MeasurementTest Cases

Perform Measurements

Analyze Results

Modify Design

Re-launch

Predictions

MeasurementBased DesignOptimization

Figure 5: Sub-Steps of Measurement Based Design Optimization

In order to reach this goal, the following sub-steps are to be carried out.

Define Measurement Areas

First, the regions and routes have to be defined on the map where measurements(and, consequently, the measurement based optimization) should be carried out.

In the first UMTS networks, there used to be a sub-division of the network into so-called clusters of around seven sites. The advantage of such a relatively smallnetwork region is the lower complexity, the drawback is that there are a highnumber of border regions between the clusters which are not optimally treated.

When sub-dividing into clusters, it is important not to define the clusters at an earlystage of the network planning process in a rigid way, but with high flexibility duringthe TOC (turn-on-cycle). As soon as a contiguous area of around seven node B ison air, they can constitute a cluster to be measured.

Define Measurement Test Cases

Measurement test cases have to be fixed. In general, 3G scanner measurements incombination with trace mobile measurements on a dedicated channel areperformed. The 3G scanner measurements give the received CPICH RSCP andEc/Io values for all received cells. The UE measurements give (among others) thedownlink SIR and the BLER on the dedicated channel and the cells in the active set.In addition, they give an indication on critical points of network quality by call

drops, reduced bit rate etc.

Iub measurements are suggested as well, since they will bring importantinformation about the uplink (i.e. uplink SIR) (see [PCSiub]).

Note that the settings of the network (office data, OCNS power) have to beknown at the time of the measurement, otherwise, no analysis is possible.

Perform Measurements

Measurements have to be performed according to test cases. Please take care ofdetailed documentation (e.g. on office data settings, on measurement conditions,points and routes....). GPS coordinates have to be traced along with themeasurements. For more information on measurements, please refer to

[PCSmeas]. Analyze Measurement Results and Modify Design


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The measurement result analysis has to identify critical points and the reason forthem being critical. In the following, typical problem sources and the potentialcountermeasures resp. design optimization measures are listed:

o CPICH level (RSCP) coverage

CPICH coverage problems occur when the pathloss is getting too high andthe received CPICH level (RSCP) is dropping below the minimum required

value.

Problem indication:

RSCPBest< RSCPmin(RSCP of Scanner preferred), where RSCPministhe threshold value for CPICH RSCP reception

and/or

There is a call drop or significant bit rate reduction in a regionwhere the CPICH RSCP monitored by the scanner is very low.

Countermeasures:

Adapt antenna direction(azimuth and/or tilt) of best possibleserverPotential Problem of this solution:

There is a trade-off between CPICH level and CPICH qualitycoverage. This measure enhances RSCP but may decrease Ec/Io

Add new site

Increase the CPICH Powerof the cell with RSCPBest.Potential problems of this solution:

The interference for other cells may be increased. In addition,there is less downlink power for the DCH (i.e. the traffic channels)left. This means a reduced capacity.

o CPICH quality

CPICH quality problems occur in case of high interference. The receivedCPICH Ec/Io is dropping below the minimum required value. The CPICHquality is in contrary to the CPICH level coverage depending on the intra-cell load, the extra-cell load and the interference caused by extra-cellCommon Channels.

Problem indication:

((Ec/IoBest< Ec/Iomin) AND (RSCPBest> RSCPmin)) (to be measuredby Scanner)

and/or

There is a call drop or significant bit rate reduction in a regionwhere the Ec/Io monitored by the scanner is very low and wherethe RSCP has still a high enough value.

Countermeasure:

Reduce the own cell sizeif the reason for low Ec/Io is mainlyintra cell load, to reduce the load (does not work in fixed loadscenario!). Note: In this case, another cell has to overtake theremaining load.Possibilities to reduce own cell size are

1. increase downtilt

2. reduce CPICH transmit power(Note that in this case, not only the load and therefore Io isreduced, but also the useful signal, i.e. Ec is reduced, so thatthere may be no amelioration of the situation)

Reduce cell overlap of serving and interfering cellif thereason for low Ec/Io is extra cell load, by changing


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1. antenna tilt,

2. antenna azimuth

3. antenna height

4. CPICH transmit power.

First try to change the interferer (reduce Io). If this is not possible,

change server (increase Ec).

Adding a site:If the reason for low Ec/Io is both extra-cell andintracell load, then adding a site will decrease the load in theserving cell and in surrounding cells and will therefore decreaseboth intracell interference and extracell interference (does notwork in fixed load scenario!Therefore, adding a site shouldalways reduce the fixed load requirements for acceptance.)

If the reason is low Ec and Io is close to No, then the CPICH levelcoverage is the problem (see above)

o Pilot Pollution (CPICH pollution)

Pilot pollution occurs if more received cells are fulfilling the criteria to enter

the active set than the number allowed by the active set size. The criterionis the received CPICH (=pilot) quality given by the parameter Ec/Io. Thecell received with the highest Ec/Io is assumed to be serving cell, i.e. it is inthe active set. Cells with a Ec/Io value, which is not more than YdB(typically 5dB) lower than the best Ec/Io, are assumed to be in the activeset as well under the condition that the maximum active set size (typically3) is not exceeded. All other cells fulfilling the Ec/Io criterion are polluters.

Problem indication:

More than X CPICHs detected by Scanner with Ec/Io within theinterval [Ec/IoBest Y, Ec/IoBest](Typically: X=3; Y=5 dB)

Countermeasure

Identify the cells received within [Ec/IoBest Y, Ec/IoBest]

Decide which cells should not be received within[Ec/IoBest Y, Ec/IoBest] and change their design

Increase Ec/IoBestby changing design of best server

Following ranking is valid for design changes:1. Adapt antenna tilt (i.e. reduce interference)

2. Adapt antenna azimuth (i.e. redirect interferers towards lesscritical regions)

3. Adapt antenna height (i.e. reduce interference)

4. Adapt pilot power

o Neighbor definition

Missing handover definitions (i.e. missing neighbors) can lead to severquality problems and call drops, since the missing neighbor is not only notserving the mobile but in addition producing high interference.

Problem Indication:One of the best cells shown in the 3G scanner measurement which shouldbe in the active set according to the active set criterion does not enter theactive set of the mobile.

Countermeasure:

Declare missing neighbor definition at OMC if the cell with theEc/Io which is reported by the scanner and which is fitting theactive set criterion is wanted to be in the active set.


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Note that the limitation for intra-frequency neighbor declaration inR2 and R3 is 14 neighbors per cell. In case this number is alreadyreached, an already declared neighbor has to be replaced by themissing cell. One should preferably replace the cell which isreceived with the weakest Ec/Io according to the scanner. Thenumber of monitored cells is limited to 32, the number of node Binvolved in the Active Set is limited to 4 in R2.

Change the cell design of the according cell, if this cell is notwanted to be in the active set

Re-Launch Prediction

The predictions described in chapter 6.3 have to be re-launched with the modifieddesign.

The planner has to repeat the loop (design modificationprediction) until he issatisfied with the result (interference sufficiently low, coverage acceptable). Theaccording design changes compared with the design at the time of the measurementshave then to be documented and proposed by the planner.

11 SITE CONFIGURATION AND RADIO FEATURES

11.1 Node B Configurations

The Evolium A9100 MBS UMTS (Node B V2) offers a multitude of configurations (see[MPS1]). The difference between the configurations lies mainly in the number ofsectors, the number of ANRU1(which contains the receiving functionalities), the numberof TEU2(which contain the transmitting functionalities, namely the power amplifier) andthe number of base band boards (responsible for the base band processing). Inaddition, the number of used carriers per sector has to be known.

The number of sectors as well as the number of carriers per sector has to be defined bythe Radio Network Planner.

In addition, the number of TEU per sector has to be known for Radio Network Planningsince it impacts the transmit power per sector and carrier, and defines if there istransmit diversity or not (Note that TX diversity feature is described below in paragraph11.4.1in more detail).

For the typical case of a three-sector site, Table 1 shows the possible node Bconfigurations in R3, for the usage of a medium power amplifier (MPA) which offers20W at antenna connector.

# sectors # carriers # cells Txdiv power/sector

in W

power/cell

at antenna

output in W

power/cell at

antenna output in

dBm (to be used

for RNP)

configuration number

of

antennas

Cabinet

Families

3 1 3 No 20 20 43,0 3x1 20W 6

MBI-3, MBI

5, MBO1,

MBO2

3 2 6 No 20 10 40,0 3x2 20W 6

3 1 3 Yes 40 40 46,0 3x1 40W TXdiv 6

MBI-3 (DConly), MBI-

5, MBO2

3 2 6 Yes 40 20 43,0 3x2 40W Txdiv 6

3 sector 3 ANRU3 PA 20W

3 ANRU

6 PA 20W

Table 1: Possible node B configurations for three-sector site in R3

As one can clearly derive from the table, in case of multicarrier operation, theavailable power per sector has to be divided between the carriers. This means thatwhen upgrading from one to two carriers, the downlink capacity is not doubled, since

1ANRU = ANtenna module with integrated Receiver for UMTS

2TEU = Transmitter Equipment for UMTS


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the power per cell is only half as before. An option constitutes in that case to upgradeto two TEU per sector, but then, the planner has to consider the TXdiversity feature.

Note that for R5, a 3x3 configuration (i.e. 3 sectors x 3 carriers) is planned, however itis not yet definitely fixed in the roadmap.

11.2 Detection of Uplink or Downlink Limitation

In the following chapters, features are presented which lead to an enhancement of theuplink or the downlink performance. Uplink features are only worth to be appliedwhen the uplink is limiting, whereas downlink features offer an enhancement of theoverall performance (coverage or capacity) in case the downlink is limiting. Therefore,before thinking about the application of the features, the planner has to be sure aboutthe limiting link and the enhancement he wants to achieve.

In order to derive the limiting link, the uplink and downlink service coveragepredictions are to be looked at. A strong indication for the limitation is the areacoverage probability for the focus zone: The link with the smaller area coverageprobability for the most demanding service can be considered as limiting.

11.3 Uplink FeaturesIn the following, optional features are shortly presented which lead to an enhancementof the uplink performance. The planner can introduce them on certain cells or in awhole area in if the uplink coverage is limiting and has to be increased. It does notmake sense to apply those features if the downlink is limiting.

In the following, the features are shortly depicted, and their impact on the RNP and therequired installation and hardware is shortly described.

11.3.1 TMA

A tower mounted amplifier (TMA) can be used at a UMTS base station (node B) toimprove the effective receiver system noise figure when a long length of feeder cable is

used. The reduction in the receiver system noise figure is translated into animprovement in the uplink power budget. This can be interpreted as compensating thelosses of the feeder and connectors between the antenna and the input of the basestation. A reduced loss in the uplink path will lead to an increased uplink coverage.

TMA is a widely used feature already in the deployment phase of a network.

The typical coverage gain, i.e. the reduction of the number of sites required to cover agiven area, is of around 30%-40% compared to the case where no TMA is used.

The TMA reduces the total noise figure of the reception chain which contains aselements the TMA, node B, cables and connectors, and perhaps diplexers or filters. Thecalculation of the resulting noise figure is done by the Friess Formula. The Friessformula is included in the A9155 v6 algorithms. The usage of a TMA has to be

declared by the planner in the tool, where the amplifier gain as well as the noise figureof the TMA device have to be given. Note that in downlink, the TMA will lead to aninsertion loss (typically 0.5 dB). Otherwise, the downlink should not be impacted by the

TMA, it is e.g. not advised to modify CPICH transmit power because of TMA usage.

To get a better feeling about the impact of the Friess formula, there is a Friess FormulaExcel Tool [NDfriess] available as well on the PCS intranet.

The fixed nominal gain of the Alcatel TMA for UMTS has been specified to be 10-12dB.Therefore, in general, there is an excess gain = amplifier gain feeder cable loss.

Due to this excess gain the blocking behavior and the intermodulation performance ofthe base station will degrade by the amount of excess gain, which might causeproblems with in-band blocking due to close UMTS mobiles. Since the 3GPP

requirements apply also for the system including the TMA, the blocking requirementshave to be fulfilled for the whole reception chain.

In the Evolium MBS UMTS Node B, this potential problem has been resolved in thefollowing way:


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In case there is a TMA, the amplification in the node B is reduced by the amount of theaccess gain, so that the inband blocking performance stays the same. This reductionhas to be executed when installing the site. The reduction depends on the feeder cableloss of the according site.

This amplification reduction is resulting in a slight increase of the node B noise figure.

This means that the entire reception chain including the TMA will still have a better

noise figure than the node B, but not as good as the Friess Formula using the nominalnode B noise figure implies.

When the feeder losses are lying in the range of 2-4dB, the following rule of thumbcan be applied:

The TMA can be considered by setting the uplink feeder losses to zero and by keepingthe node B noise figure as total receiver chain noise figure.

In A9155 this can be done by not specifying any TMA but by reducing the uplink lossesby the amount of the feeder loss.

For the antenna system planning in case of co-siting, the planner has to be aware thatfeeder sharing solutions are definitely not possible, if more than one TMAs are used(e.g. one TMA for GSM and one for UMTS), since otherwise neither DC feed nor alarmhandling are possible and the TMAs would not work. Therefore, if a TMA is requiredfor each system, use separate feeders.

It is neither possible to use a GSM1800/UMTS broadband antenna with one diplexerand common feeder in combination with a TMA because of interleaved uplink anddownlink signals of the two systems.

More details on co-siting can be found in [NDPCSco].

For more information on the TMA and its impact on network design, please refer to[NDtma].

11.3.2 4RX Diversity

4RX diversity is implemented in the Evolium UMTS MBS starting from R4.

Receive antenna diversity consists in using several antennas in the receiver instead ofonly one. The 2-way antenna receive diversity (2RxDiv) is already used with EvoliumNode-Bs per default. Extending this feature on 4 receive antennas is resulting in the socalled 4-way diversity (4RxDiv). This feature is belonging to the smart antennaconcepts.

Antenna diversity primarily is introduced to reduce the fading effects, in order toincrease the receiver sensitivity under fading conditions. In principle antenna diversity isbased on combining decorrelated signals containing the same information bymaximum ratio combining (MRC). The more uncorrelated reception branches are used,the higher the diversity gain will be.

In a UMTS system, the diversity gain is manifested by a reduction of the requiredreceived uplink Eb/No . Compared to the 2RxDiv, the 4-RxDiv will allow an additionalgain on required Eb/N0of around 2.5dB for all services (at 3dB noise rise, i.e. at 50%of load). This Eb/No gain is translated in a gain in uplink coverage.

The typical coverage gain, i.e. the reduction of the number of sites required to cover agiven area, is of around 30%-40% compared to the case of 2RXdiversity.

In case the intersite distance is already fixed, 4RXdiversity will enhance the uplinkcapacity of the cell by about 60%.

Note that in case the uplink load is very high when introducing the feature, the gainwill be significantly smaller.

In the planning tool A9155, the gain on Eb/No thanks to 4RXdiversity can not beentered directly. (In the tool, Eb/No is a global parameter, whereas the reduced Eb/Nois only specific to some cells). Therefore, the gain has to be modeled for the affectedcells in the uplink losses (note: a gain is a negative loss).


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The uplink losses are to be reduced by2.5dBby the planner in case of 4RX diversity.

The 4Rx diversity has also an impact on the antenna engineering. Note that comparedwith standard 2Rx diversity, two additional antenna branches have to be installed,corresponding to either two additional single polarised antennas or one cross-polarised antenna.

In order to apply 4RXdiv, the decorrelation between 4 antennas (resp. antenna

branches) has to be guaranteed. This can be obtained by combining space andpolarisation diversity, i.e. spatially separating 2 cross-polarised antennas:

Distance d

Rxdiv1 Rxdiv2 Rxdiv3 Rxdiv4

SpaceDiversity

PolarisationDiversity

PolarisationDiversity

Xpolantenna 2

Xpolantenna 1

Figure 6 Implementing 4RXDiversity

For the distance rules to achieve decorrelation in case of space diversity, please refer to[PCSant].

For more information on 4 RX diversity and its impact on network design, please referto [ND4div].

11.4 Downlink Features

In the following, optional features are shortly presented which lead to an enhancementof the downlink performance. The planner can introduce them on certain cells or in awhole area in if the downlink power is limiting resp. downlink capacity has to beincreased. It does not make sense to apply those features if the uplink is limiting (i.e.enough downlink power is available.

In the following, the features are shortly depicted, and their impact on the RNP and therequired installation and hardware is shortly described.

11.4.1 TX Diversity

TX diversity (STTD) is implemented in Evolium UMTS MBS in the node B V1 and againstarting from MBS R3 (note that it is not implemented in R2).

The transmit antenna diversity techniques consists in using at the transmitter severalantennas, broadcasting complementary signals. The aim of transmit diversity is toalleviate fast fading and therefore to increase the capacity of the downlinktransmission. Several transmit diversity techniques have been standardized in the FDDmode of UMTS for two transmit antennas, which can be subdivided in two maingroups: the open loop transmit diversity (e.g. STTD = space-time transmit diversity)where no feedback information is sent from the UE to the Node B, and the closed looptransmit diversity where weighting information is periodically sent from UE to Node B.

The closed loop TX diversity is performing beamforming and is therefore a smartantenna technique.

In order to implement TX diversity, a second power amplifier (i.e. a second TEU) has tobe installed in the node B. (Note: having two TEU necessarily means that you have

TXdiv).

The performance gain of the TX diversity feature consists of three aspects:


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reducing the required transmit power for each downlink channel (transmit powerraise to fast fading is decreased)

improving the required received Eb/No (i.e. reducing required radio quality)

doubling the transmit power by adding a power amplifier (TEU)

The gain due to the first and second point depends on the multipath channel and the

speed as well as on the TX diversity type used. For example, the gain is higher for aPedestrian A multipath channel (which is typical for microcellular environment) and forlow speed, than for Vehicular A multipath channel (which is typical for themacrocellular environment) and for high speed. Closed loop brings in general betterperformance than open loop.

The capacity gain due to the double transmit power highly depends on thepropagation loss and therefore on the cell size. For small cells (i.e. cells which havealready a high capacity), a 3dB gain on power brings negligible gain on capacity. Forlarge cells (i.e. cells which have a low capacity) the capacity gain is more significant.

Note that TX diversity is applied on both dedicated and common channels, thereforethe CPICH benefits as well from a TX diversity gain.

For Vehicular A environment and STTD TX diversity, the following values of capacitygain can be expected for typical cell ranges and the case of on carrier as a rule ofthumb:

Dense Urban Urban/Suburban Rural

Capacity gain

through diversity

~8% ~10% ~12%

Capacity gain

through 2ndPA

(for typical cell sizes

and one carrier)

~0%-2% ~1%-8% ~2%-11%

Typical Total Capacity

Gain

~8% ~15% ~20%

Table 2 Typical gain in capacity through adding the TXdiversity feature

When using A9155, the planner has to take into account TX diversity as following:

doubling the available TX power per sector (i.e. using 46dBm instead of43dBm)

deriving downlink Eb/No values for TX diversity from the tool [TDlls]. Thedifference between values valid without TXdiversity and those valid withTXdiversity is the achieved gain on Eb/No GTXdiv

reducing uplink losses in A9155 by this gain GTXdiv(Note that in the planningtool A9155, the Eb/No values for TXdiversity can not be directly entered, sincein the tool, Eb/No is a global parameter, whereas the reduced Eb/No is only

specific to some cells). Note that A9155 does not take into account the gaindue to reduction of transmit power raise for fast fading.

For more information on TX diversity and its impact on network design, please refer to[NDtxdiv].

11.4.2 High Power Amplifier (HPA)

The High Power Amplifier (HPA) is implemented in Evolium UMTS MBS starting fromR3.

The High Power Amplifier (HPA) is a 52W amplifier, offering 40W at antennaconnector. This means that the power is doubled compared to the Medium PowerAmplifier.

The HPA is often promoted as a means to increase downlink capacity compared to thesituation, where only one TEU with MPA is used. However, if the intersite distance issmall and the existing capacity is already relatively high, the gain in capacity is


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negligible. In case the intersite distance is relatively high and high propagation lossesare to be overcome, HPA will bring some gain.

Dense Urban Urban/Suburban Rural

Capacity gain

through HPA instead

of MPA (for typical

cell sizes and one

carrier)

~0%-2% ~1%-8% ~2%-11%

The table implies that there is no gain brought by HPA in Dense Urban environment.But note that this gain is referring to capacity gain in a typical dense scenario, wherepropagation losses which are to be overcome are relatively low. However, if e.g. TMAand 4RX diversity is implemented to improve the uplink and the uplink bit rate is limitedto 64kbit/s while in downlink, 384kbit/s are allowed, the propagation losses to besupported by the downlink will be high and the HPA may be of interest (see [NDhpa]for more details)

Note that the High Power Amplifier does not allow TXdiversity operation. It is notallowed to have more than one TEU with HPA per sector.

When the planner decides that more downlink power is required (e.g. because of anupgrade from one to two carriers) he has the choice of either installing two TEU withMPA (including TX diversity operation) or to install one TEU with HPA. Both options offera total power of 40W at antenna connector, however, the first solution offers a

TXdiversity gain in addition.

Note that when applying HPA to overcome propagation losses, the absolute CPICHpower has to be doubled compared to the default settings. When only capacityenhancement is targeted, the standard settings should be kept in order to have themaximum possible power available for dedicated channels.

The HPA is implemented in Evolium UMTS MBS starting from R3. In R3, there is onlyone TEU allowed when HPA is used, in R4, one TEU with HPA and one TEU with

standard PA will be allowed. In this case, TX diversity is not applicable. In some specialcases, such a mixed TEU configuration may be interesting for a scenario with threecarriers per sector. For more information on the mixed TEU configuration, please referto [NDmteu].

11.5 Special configurations

11.5.1 OTSR

OTSR is implemented in Evolium UMTS MBS starting from R4.

OTSR stands of Omni Transmit/Sectorized Receive and denotes a UMTS Node B

configuration where the site is an omni site in the downlink and a 3 sector site in theuplink. Compared with the classical 3 sector configuration, the uplink is not modified.However, there is one downlink sector only, of which the signal is split by a powersplitter onto the three antennas.

In OTSR, the downlink therefore constitutes an omni cell (with one scrambling codeonly). The three sector antennas together with the power splitter can be looked at as aquasiomni antenna system, which has a (slightly degenerated) omni pattern. Theantenna gain of this configuration (3 18dBi 65 antennas with power splitter) is~12dBi. Uplink constitutes a three sectorised configuration (therefore 3 cells per site),where the receive gain of the base station antennas is 18dBi.

OTSR constitutes a low cost configuration. Compared with the classical three-sectorconfiguration, the hardware costs of two TEU are saved. The advantage of this

configuration therefore does not lie in the RNP domain, but uniquely in the costdomain.

The downlink capacity of an OTSR site is around 2.5 times lower than the capacity of athree-sector site. The configuration therefore constitutes a pure coverage solution. But


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even when not foreseeing any traffic, the low power per antenna (~6.5W) may lead toa downlink coverage limitation.

For more information on OTSR and its impact on coverage and capacity refer to[NDotsr].

For detailed explanation how to take into account OTSR for Radio Network Planningusing A9155, please refer to [PCSotsr].

OTSR is implemented in Evolium UMTS MBS starting from R4. It is possible to run OTSRwith a TEU including an MPA or and HPA. Also the TXdiversity operation is thinkable,but in this case only one TEU is saved compared to the case of a three-sectorconfiguration. So the question is if this saving is worth the drawbacks in this case.

12 ACCURACY OF PREDICTION

12.1 Sensitive Parameters for RNP Prediction

In the following, very sensitive parameters for RNP prediction are shortly presented. Adifferent set of values for these parameters may lead to significantly different results.

Therefore, one has to keep in mind which values have been taken and why.

12.1.1 Ec/Io Threshold

The Ec/Io coverage is the precondition for any service to work. The minimum requiredEc/Io value has therefore high impact on the prediction results. The lower this thresholdvalue, the higher the Ec/Io coverage, and vice versa.

Note that this value is mobile station dependent. According to experience on the fieldand Evolium (TD/SYT) simulation results, the value has been set to 15dB.

12.1.2 Clutter Correction Factors

For the propagation model, the setting of clutter correction factors (also called morpho

correction factors) is required. The accuracy of prediction depends on appropriatevalues. In some cases, a calibration may be required, however, for typical scenarii, thecalibration database can be consulted. Please refer to [PCSclu] as a basis for decision.

12.1.3 Shadowing Standard Deviation

Due to long term fading variations of the signal known as shadowing, the receivedpower level is varying. The variation can be modeled as a random variable with lognormal distribution of zero mean and a standard deviation that is characteristic on theenvironment. Please refer to Appendix E for details on the coverage probability whichdepends on the standard deviation.

12.1.3.1Standard deviation of Power levelsThe standard deviation for power predictions is dependent on the clutter class. Typicalvalues for urban areas are 7dB-8dB, see [PCSclu].

12.1.3.2Standard deviation of CPICH Ec/Io

The standard deviation for Ec/Io is much smaller than the standard deviation for thesignal alone, and this standard deviation does not only depend on the clutter class, butalso on the amount of extracell interference. Derived from Ville Orange (Lille)measurements, this standard deviation is set to 3dB. Note that the standard deviationfor all C/I limited predictions (e.g. downlink coverage due to downlink powerlimitation) is assumed to have a lower standard deviation as well.

12.1.4 Eb/No

The Eb/No (Bit-energy-over-total-noise) has a considerable impact on the servicecoverage. The values for each service are to be taken from TD/SYT simulation results(see Appendix A for examples). Note that field trials have found values in the same


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order of magnitude as the simulated values. Therefore, simulated values are validatedby the field. All simulated values are given by the tool [TDlls].

12.1.5 Traffic and Load

Coverage is highly dependent on the fixed load chosen or the traffic forecast taken asan input. Note that load or traffic forecast parameters are the most unreliable ones in

the input parameter set.

12.2 Field validation of prediction

A9155 v6 CPICH predictions (RSCP prediction and Ec/Io prediction) have beenvalidated by Ville Orange (Lille) measurements.


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The Processing Gain (in dB) can be calculated as follows:

Equation

Umts Fdd Rnp Quick Guide

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