Day1.2 WCDMA RAN Dimensioing

7/30/2019 Day1.2 WCDMA RAN Dimensioing

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1 Nokia Siemens Networks Presentation / Author / Date

For internal use

Radio Network Dimensioning


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Contents

Scope of RAN Dimensioing

Input parameters for RAN dimensioingLink Budget

Parameters

Cell Range Calculation

Load Calculation


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WCDMA Network Architecture

Circuit SwitchedCore Network

GGSN

3GSGSN

GPRS

USIMcard

WCDMAmobile

GSM/WCDMAmobile

RAN

WCDMABTS

WCDMABTS

RNC

RNC

MSC

HLR

MGW

IN SCP

SRR

PS Core Network

(PSTN/ISDN)

InternetTCP/IP)

GSM/WCDMAmobile

CBC


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UTRAN Elements and Interfaces

UTRAN

Iu

Uu

User Equipment(UE)

IurIub

RNC

WCDMABTS

WCDMABTS

WCDMABTS

WCDMABTS

RNC

Core Network(CN)


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RNC

3G-SGSN

GGSN

IP/MPLS/IPoATM-backbone

ApplicationServers

(co-locatedor remote)

support of 3GPP QoS-parametersand mechanisms in UE

UE support of different CH-types

internal delays generated byUE

UE memory [effects TCP kbps]

internal BTS-delays

interleaving/propagation delays

RNC internal delays, 3GPP QoS-support

protocol processing and trans-mission delays, 3GPP QoS-

support

internal processing/queuing delays.

3GPP QoS-support

internal processing/queuing and L1delays

memories/buffer sizes [TCP-effect]

internal delays in WAP-gateways/http-

proxies/servers/etc.

= terminal/NW element HW and SW effects

= network planning/dimensioning effects

site locations,

antenna directions/height/quality

cable length/quality

BTS-capacity

Iu-transmission resourcedimensioning, topology/distances

RNC capacity

HO thresholds

cell's traffic load thresholds

interference/transmission power thresholds

used packet scheduling criteria

used RLC buffer payload thresholds [TCP-effect]

used DCH bit rate allocation steps

allocation of dedicated NRT-capacity

packet core capacity

configuration of RT traffic limits

configuration of interactive queue weights

used HLR QoS-profiles

application server capacity

geographical location [e.g. localizedcontent caching vs. centralized server

transmission/router capacity

geographical locations/distance, number of hop

Example: What affects performance in WCDMA

= application software effects

UDP vs. TCP

supported HTTP/WAP-version

support of optimization features

supported HTTP/WAP-version

support of optimization features


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RAN Dimensioing Scope

DomainNameServer(DNS)

3GSGSN

GGSN

ChargingGateway(CG)

Backbonenetwork

(IP based)

BorderGateway(BG)

FireWall(FW)

LIG

Domain Host ConfigurationProtocol (DHCP)

PacketnetworkInter-PLMN

Network

MGW

Iub

Abis

BSC

NodeB

BTS

Iu-PS

Iu-CS(ATM)

RNC

Iub

IP/ATM/TDM

Backbone

PacketnetworkInternet

IN/SCP SMS

PacketnetworkIntranet

McRANAP(SIGTRAN)

MAP(SIGTRAN)

SS7 (E1)Gb

2GSGSN

BSSAP (E1)

CAP/MAP

(E1)

CAP/MAP(E1)

Exist Connect

New Connect

PSTN/PLMNNetwork

CDS

MSS

2G / 3GHLR


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Network planning process & relation to businessplanning

marketing

business

plan

traffic

assumptions

Network

dimensioning

Code & freq. &

interference plan

transmission

plan

final NW

topology/

architecture

parameter

planning

coverage

plan

Network

optimization


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Radio Network DimensioningOverview

COVERAGE CAPACITY

COMPROMISE BETWEEN COVERAGE AND CAPACITY


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Coverage VS Capacity Dimensioning:Cell Breathing [1/2]

This diagram showscells are unload

This diagram shows whensome cells are loaded

Cell-A

Cell-C

Cell-B

Resu lts =>Coverage Holes!

Cell-A

Cell-C

Cell-B

Cellbreathing


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Coverage VS Capacity Dimensioning:Fixed Uplink Load - To avoid Coverage holes [2/2]

This diagram shows aFixed Uplink Load design

Results => No orMin CoverageHoles!

Cell-A

Cell-C

Cell-B

Cell-

A Cell-D

Cell-H

Cell-E

Cell-F

Cell-

C

Cell-B

Cell-

G

No (or minimum)

coverage holes problems

More cells required

Traffic mobility taken

into account. (Note:dimensioning assumes

uniform traffic

distribution)

eg. Actual ULload = 8%

eg. Fixed ULload = 30%

"actual" Loading,(ie from the traffic

inputs defined indimensioning)


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Input parameters overview

CAPACITY RELATED Spectrum Available

User Profile and Traffic GrowthForecast

Traffic Density Map

COVERAGE RELATED Coverage Regions

Area Type Information

QUALITY RELATED MS Class

Indoor Coverage

Location Probability

Blocking Probability

Gives an Estimation of theEquipment Necessary to Meet theNetwork Requirements

Network Dimensioning Activities

Radio Link Budget Calculation

Cell Size Calculation

Capacity Calculation

Number of Node B, RNCcalculation

Iub, Iur and Iu transmissionCapacity

Input Categories


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Capacity Related Input

The number of subscribers, user profile and spectrum available are the main requirements forcapacity dimensioning

Traffic forecast should be done by analysing the offered Busy Hour traffic per subscriber for different

service bit rates in each rollout phase.Traffic data:

Voice :

Erlang per subscriber during busy hour of the network

Codec bit rate, Voice activity

RT data :

Erlang per subscriber during busy hour of the network

Service bit rates

NRT data :

Average throughput (kbps) subscriber during busy hour of the network

Target bit rates

Asymmetry between UL an DL traffic for NRT Services (Downloading 1/10) should be taken intoconsideration.

Network and Subscribers evolution forecast is also needed.


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Coverage Related Input

Accurate coverage area information should be available

Total coverage area for each rollout phase (km2

) Percentage of the area for each morpho class (Dense Urban, Urban, Suburban andRural)

DENSE URBAN

URBAN

SUBURBAN


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Coverage Related Input

Area type information must be as accurate as possible:

coverage area for each rollout phase

percentage of the area for each morpho-class (DU,U,SU,R)

building penetration loss and fading margin

propagation models for path loss calculation

correction factors for the Propagation Model

Service Scenarios should be defined: which kind of service is to be offered and where (big impact onthe number of sites).

MorphoClass Build Pen Loss Stand Deviation Car Loss Stand Deviation

Dense Urban 18 dB 11 dB

Urban 15 dB 10 dB

Sub Urban 12 dB 9 dB

Rural 10 dB 9 dB

Road 6 dB 7 dB


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Quality Related Input

Blocking Probability: is blocking of call attempts due to lack of availableresources and for CS Services is usually between 1-2%

In the propagation models there is no place to cover the local fluctuations(slowfading) of the strength of the electromagnetic waves, caused mainly byshadowing. It should be done separately.

Fade margin is a function of location probability and standard deviation


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Quality Related Input

Penetration Losses

Signal levels inside the buildings are estimated by applying buildingpenetration loss margins. BPL may vary in different area types.

Pref= 0 dB

Pindoor = -3 ...-15 dB

Pindoor= -7 ...-18 dB

-15 ...-25 dB no coverage

rear side :

-18 ...-30 dB

signal level increases with floor

number :~1,5 dB/floor (for 1st

..10th floor)


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Summary of Dimensioning Inputs

Dense Urban Urban Suburban Rural

Voice # of subs & mErl per sub # of subs & mErl per sub # of subs & mErl per sub # of subs & mErl per sub

CS data # of subs & mErl per sub # of subs & mErl per sub # of subs & mErl per sub # of subs & mErl per sub

PS data # of subs & kbps per sub # of subs & kbps per sub # of subs & kbps per sub # of subs & kbps per sub

Coverage area km2 km2 km2 km2

Location probability % % % %

Standard deviation dB dB dB dB

Fade margin dB dB dB dB

Penetration loss dB dB dB dB

Area correctionfactor

dB dB dB dB

MS / Node Bantenna height

m m m m


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RF Dimensioning Process Flow

Link Budget Calculation

Radio link specific :- Data rate (processing gain)- Average Eb/No- SHO gain in dB

Equipment specific :- MS Power class- MS/BS calc. sensitivity- Antenna gainetc

Load factorcalculation

Propagation specific :- Antenna height- BPL and BPL deviation- Area correction factor

- Lognormal shadowingmargin

Max. allowed path loss

Cell Range Calculation

Max. Cell Range in each areatype

Capacity Estimate

No. of sites / Total supported trafficin each area type

Equipment Requirement

BS HWs / Transmission / RNC

Service specific :-blocking rate- throughput factor

1st guessof amountof trafficper CU

InterferenceMargin

Max. traffic per CU

If fulfill the operator need

If too low capacity


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WCDMA Link Budget


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Link Budget Overview

Building penetrationloss

Body loss

Cable losses

Antenna gain

Noise figure


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WCDMA Link Budget

MS transmit power = 21 dBm

Antenna Gain (example):

18 dBi, X-pol, 650horizontal beamwidth,variable electrical tilt

Cable Losses

Body proximity Loss

3 dB for voice services 0 dB for data services

WCDMA Link Budget


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WCDMA Link Budget

Soft HO

Softer HO

Soft HO MDC gain is actually the gain due to less powerrequirement when multiple radio links are there

(relative to that of a single link )This gain is mainly in DL and in UL this gain is negligible

WCDMA Li k B d


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WCDMA Link Budget

MDC Gain: In DL there is some combining gain dueto UE maximal ratio combining:

Soft/softer handovers are included

Average is calculated over all theconnections taking into account theaverage difference of the received signalbranches (and UE speed)

Nokia recommended value = 1.2 dB

MHA gain is used to compensate for the cable

losses

WCDMA Li k B d t


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WCDMA Link Budget

Total noise power in the receiver is a function of:

Boltzmans constant

Temperature

Bandwidth

Thermal Noise = kTB

Noise figure

Nokia recommended values:

Node B MS

Noise Figure 3 dB 8 dB


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WCDMA Link Budget

Processing gain is a function of the system chiprate and service bit rate

Service bit rate Processing Gain

Voice 12.2 kbps 24.98 ~ 25 dB

CS 64 kbps 17.78 ~ 18 dB

PS 128 kbps 14.77 ~ 15 dB

PS 384 kbps 10 dB

WCDMA Link B dget


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WCDMA Link Budget

Interference margin calculated from the UL/DLloading () values. This parameter shows in DL

how much the BTS "sensitivity" is decreased due tothe network load (subscribers in the network) & inUL indicates the loss in link budget due to load.

dBLog 110 10IMargin = dBLog 110 10IMargin =


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WCDMA Link Budget

In order to meet the defined quality requirements (BLER)a certain average bit-energy divided by total

noise+interference spectral density (Eb/N0) is needed.Eb/No depends on:

Service

MS speed

Radio channel

Service bit rate UL Eb/No [3kph] DL Eb/No [3kph]

Voice 12.2 kbps 4.4 7.9

CS 64 kbps 2.0 5.0

PS 64 kbps 2.0 5.0

PS 128 kbps 1.4 4.7

PS 384 kbps 1.7 4.8

* Nokia recommendedvalues


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WCDMA Link Budget

Soft handover gain is the gain against shadow fading.

This is actually the gain in required Eb/No relative to thatof a single link and it is averaged over all radio links inthe SHO area

Nokia recommended value = 2 dB

IPL Correction Factor. This parameter describesthe ratio between the maximum and the averagepathloss. Usually all subscribers are not located atthe cell edge but are distributed through the wholecell coverage area. That is why some gain can beadded in power budget calculation.

Nokia recommended value = 6 dB


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IPL Correction Factor

Worst case scenario Reality MS distributed over the whole area

Users at the cell edge require high power; users closeto the base station need much less power at the

same time

WCDMA Link Budget


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WCDMA Link Budget

UL Power Control Headroom is the parameter todescribe the margin against fast fading. This

parameter is needed because at the cell edge theUE does not have enough power to follow the fastfading dips. This is especially important for the slowmoving UEs.

Nokia recommended value = 1.8 dB


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Load Calculation

L d C l l ti


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Load Calculation

Load factor () predicts the amount of noise rise by treatinginterference as wideband noise.

It is based on Eb/No, number of users, their service bit rate and activity,other cell to own cell interference ratio, the amount of uplink noiserise and orthogonality factor.

Load Calculation


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In order to meet the defined quality requirements (BLER) a certain average bit-energydivided by total noise+interference spectral density (Eb/N0) is needed. So for every userj

and for given bit rate Rjwe have:

, where Ij is the received signal power of user j

Of course subscriberj is not active all the time, that is why the special activity factorjshould be introduced:

jjtot

j

jj

b

II

I

RW

NE

1

0

jtot

j

jj

b

II

I

R

W

N

E

0

Load Calculation


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Using the previous equation we can express the load caused by one subscriberas a part ofthe total load:

, where:

For N subscribers, the load caused in the cell (so called load factor) is:

jjbj

j

NE

RWload

11

1

0

totjj IloadI

N

jjload

Little i


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Little i

The load factor calculation the other cell interferences takes into account theinterference from other cells.

This can be introduced by means of the little ivalue, which describes how muchtwo cells overlap (bigger overlapping more inter-cell interferences).

Iother

Sector Little i

Omni 0.55

3 0.65* Nokia recommended

values

Intereference in DL


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Interference in UL


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Orthogonality


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Orthogonality

Orthogonality [] is a measure how well separate code signals areuncorrelated

In DL the own cell interference are reduced by factor (1-). This is due to thesynchronised orthogonal channelisation codes, which are used in DL.

Nokia recommended value: [] = 50%

Load Calculation


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After introduction of the little i the load factor in the cell will be:

In DL the own cell interference is reduced by factor (1-). This is due to the synchronisedorthogonal channelisation codes, which are used in DL:

N

j

jloadi1

N

j

jjDL loadi 1

Ortogonality factorj is between 0.4 and 0.9Typical values:

ITU vehicular subscriber (Macro Cell) j=0.6

ITU pedestrian subscriber (Micro Cell) j=0.9

Power Rise


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Power Rise

For UEs located in the other cells the power increase caused by Fast LoopPC procedure is harmful for the own cell interference conditions

Non-fad ing channel Fad ing channel

Transmitted power

Received power

Power rise

Average transmitted power

Non-fad ing channel Fad ing channel

Transmitted power

Received power

Power rise

Average transmitted power

Nokia recommended value:[pwr_r ise] = 0.7 dB

Load Calculation


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Because of power rise in the UL load calculation, the little ishould be corrected (little iismultiplied by pw_r iseparameter)

UL load affects the noise level at the Node B receiver. Noise Rise

A typical cell load value for dimensioning ranges from 30% to 70 %.

50% is a good compromise between the number of sites and the offered capacity.

Breathing effect: UL load limits the Coverage.

0

2

4

6

8

10

12

14

16

18

10

20

30

40

50

60

70

80

90

95

98

loading/%

loss/dB

N

j

jUL loadirisepw_1

Interference Margin vs Load Factor


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Interference Margin vs Load Factor

20

10

6

1.25

3

25% 50% 75% 99%

IMargin [dB]

Load factor

20

10

6

1.25

3

25% 50% 75% 99%

IMargin [dB]

Load factor

The graph showsrelationship betweenthe interference marginand the load factor.

Nokia recommendsloading between 30% to

70% for optimumperformance

50% uplink loadingrepresents a good

trade-off betweencoverage and capacity

Cell Loading Calculation


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1. Traffic per CellErlang or kbit/s

4. Interfering Channels(=physical channels*activity factor)

5. Fractional Load

3. Physical Channels(=traffic channels*SHO)

2. Traffic Channels

Traffic per cell is usually defined in terms of Erlang forvoice and real time (RT) data services and in terms ofkbits/s for non real time (NRT) data

The blocking probability is typically assumed to be 2% forcircuit switched services.



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g

Evaluation of the physical channel requirement per carrierfor each service class. This is completed separately forUL and DL.

Evaluation of interfering channels per cell for each serviceclass. This requires a direct multiplication of thephysical channel requirement with the correspondingservice activity factor.



5. Fractional Load


2. Traffic Channels

Soft handover overhead (SHO)

Nokia value = 40%

assumption: 30% = 2-wayconnections

5% = 3-way connections

Therefore: (1 * 0.65) + (2 * 0.30) + (3* 0.05) = 1.4


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Code Channels Calculation


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5. Fractional Load


2. Traffic Channels

Hardware Channels

HW channels are implemented on channel cards(WSP cards)

The signal processing unit (WSP) in the Node B

performs RX and TX code channel processing,coding and decoding functions.

Amount of WSPs shall be planned according to thetraffic on the BTS.


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BTS Power


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The link budget provides the average BTS TX power per connection for eachservice class. The BTS TX power per connection is defined from the averageDL isotropic path loss.

The total BTS TX power is obtained by summing up the TX power required for allservice classes and common channels

For dimensioning, the amount of power allocated for common channels is 20% ofthe maximum BTS TX power.

NODE B POWER

COMMON CHANNELS

TRAFFIC


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Dimensioning Results


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Required HW channels (BTS processing capacity)

LoadRequired BTS TX

power

TRAFFICErlang or kbit/s

TRAFFICErlang or kbit/s

TRAFFIC CHANNELSTRAFFIC CHANNELS

PHYSICAL CHANNELSPHYSICAL CHANNELS

INTERFERING CHANNELSINTERFERING CHANNELS

FRACTIONAL LOADFRACTIONAL LOAD

FRAC. LOAD OF THESERVICE CLASSES

FRAC. LOAD OF THESERVICE CLASSES

TOTAL LOADUL & DL

TOTAL LOADUL & DL

REQUIRED BTS TXPOWER

REQUIRED BTS TXPOWER

Limiting factors:

The following criteria should be considered:

Uplink load < Maximum uplink load

DL load < 1

BTS TX power < Maximum BTS TX power

Number of channel units < Max number of channelunits

Dimensioning Results


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RF DIMENSIONINGRESULTS

Number of base stations

Configuration of base stations

Number of subscribers per area

mErl / subs for voice and RT data

mErl / sub for NRT data

Iub/Iur/Iu INTERFACEDIMENSIONING

RNC

DIMENSIONING


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UL Fractional Load Calculation


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Cell Load Calculation


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Day1.2 WCDMA RAN Dimensioing

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