CE-Dimensioning-UMTS

www.huawei.com

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

WCDMA Radio

Network Capacity

Planning

Page1Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

Foreword

WCDMA is a self-interference system

WCDMA system capacity is closely related to coverage

WCDMA network capacity has the “soft capacity” feature

The WCDMA network capacity restriction factors in the radio network

part include the following:

Uplink interference

Downlink power

Downlink channel code resources (OVSF)

Channel element (CE)


Objectives

Upon completion of this course, you will be able to:

Grasp the parameters of 3G traffic model

Understand the factors that restrict the WCDMA network capacity

Understand the methods and procedures of estimating multi-

service capacity

Understand the key technologies for enhancing network capacity


Contents

1. Traffic Model

2. Interference Analysis

3. Capacity Dimensioning

4. CE Dimensioning

5. Network Dimensioning Flow


Contents

1. Traffic Model



4. CE Dimensioning



Contents

1. Traffic Model

1.1 Overview of traffic model

1.2 CS traffic model

1.3 PS traffic model


QoS Type

Data integrity should be maintained. Small delay

restriction, requiring correct transmission

Request-response mode, data integrity must be

maintained. High requirements on error tolerance,

low requirements on time delay tolerance

Typically unidirectional services, high requirements

on error tolerance, high requirements on data rate

It is necessary to maintain the time relationship

between the information entities in the stream.

Small time delay tolerance, requiring data rate

symmetry

Background

download of

Email

Background

Web page

browse,

network game

Interactive

Non re

al-tim

e ca

tegory

Streaming

multimediaStreaming

Voice service,

videophoneConversational

Real-tim

e ca

tegory


Traffic Model

System Configuration

User Behaviour

Service Pattern

Traffic Model Results


The Contents of Traffic Model

Service pattern refers to the service features

User behaviour refers to the conduct of people in using the

service


Typical Service Features Description

Typical service features include the following feature

parameters:

User type (indoor ,outdoor, vehicle)

User’s average moving speed

Service Type

Uplink and downlink service rates

Spreading factor

Time delay requirements of the service


Contents

1. Traffic Model





CS Traffic Model

Voice service is a typical CS services. Voice data arrival conforms to

the Poisson distribution. Its time interval conforms to the exponent

distribution

Key parameters of the model

Penetration rate

BHCA: busy-hour call attempts

Mean call duration (s)

Activity factor

Mean rate of service (kbps)


CS Traffic Model Parameters

Mean busy-hour traffic (Erlang) per user = BHCA × mean call duration

/3600

Mean busy hour traffic volume per user (kbit) = BHCA × mean call

duration × activity factor × mean rate

Mean busy hour throughput per user (bps) = mean busy hour traffic

volume per user × 1000/3600


Contents

1. Traffic Model





PS Traffic Model

Data Burst Data Burst Data Burst

Packet Call

Session

Packet Call Packet Call

Downloading Downloading

Active Dormant Dormant Active


PS Traffic Model Parameters

Traffic Model

Packet Call Num/Session

Packet Num/Packet Call

Packet Size (bytes)

BLER

Typical Bear Rate (kbps)

Reading Time (sec)


Parameter Determining

The basic parameters in the traffic model are determined in the

following ways:

Obtain numerous basic parameter sample data from the existing

network

Obtain the probability distribution of the parameters through

processing of the sample data

Take the distribution most proximate to the standard probability as

the corresponding parameter distribution through comparison

with the standard distribution function


PS User Behaviour Parameters

User Behaviour

User Distribution

(High, Medium, Low end)

BHSA

Penetration Rate


PS User Behaviour Parameters

Penetration Rate

BHSA

The times of single-user busy hour sessions of this service

User Distribution (High, Medium, Low end)

The users are divided into high-end, mid-end and low-end users.



Session Traffic Volume (Byte): Average traffic of single session of the

service

Busy hour throughput per user (Kb):

PS throughput equivalent Erlang formula (Erlang)

)Session

NumPacketCall()

PacketCall

PacketNum()PacketSize(fficVolumeSessionTra ××=

1000/8fficVolumeSessionTraBHSAuser/roughputBusyHourTh ××=

)3600

(_ ∑ ⋅⋅⋅⋅=

ctorActivityFaredRateTypicalBea

nEviromentApplicatioderTypicalroughputUnBusyHourThgRatePenetratinUserOfDiffrentPercentageErlangData



Data Transmission time (s): The time in a single session of service for

purpose of transmitting data.

Holding Time (s): Average duration of a single session of service

Activity factor:

eHoldingTim

issionTimeDataTransmorActiveFact =

eTypicalRatBLER

fficVolumeSessionTraissionTimeDataTransm

1

1

1000/8 ×−

×=

issionTimeDataTransmadingTimeRe)1Session

lNumPackketCal(eHoldingTim +×−=


Contents

1. Traffic Model



4. CE Dimensioning



Basic Principles

In the WCDMA system, all the cells use the same frequency,

which is conducive to improving the WCDMA system capacity.

However, for reason of co-frequency multiplexing, the system

incurs interference between users. This multi-access

interference restricts the capacity in turn.

The radio system capacity is decided by uplink and downlink.

When planning the capacity, we must analyze from both uplink

and downlink perspectives.


Contents


2.1 Uplink Interference Analysis

2.2 Downlink Interference Analysis


Uplink Interference Analysis

Uplink interference analysis is based on the following formula:

NotherownTOT PIII ++=



Receiver noise floor: PN

For Huawei NodeB, the typical value is -106.4dBm/3.84MHZ

NFWTKPN += )**log(10



: Interference from users of this cell

Interference that every user must overcome is :

is the receiving power of the user j , is UL activity factor

Under the ideal power control :

Hence:

The interference from users of this cell is the sum of power of all

the users arriving at the receiver:

ownI

jtotal PI −

jρjP( )

jjjTOT

jNoEb

R

W

PI

PjAvg

ρ1

10 10

/ _

⋅⋅−

=

( )jj

NoEb

TOTj

R

WI

P

jAvg ρ1

10

11

10

/ _⋅⋅+

=

∑=N

jown PI1



:Interference from users of adjacent cell

The interference from users of adjacent cell is difficult to analyze

theoretically, because it is related to user distribution, cell layout,

and antenna direction diagram.

Adjacent cell interference factor：

own

other

I

If =

otherI



( )( )

N

N

jjNoEb

TOTNotherownTOT P

R

WI

fPIII

jAvg

+⋅⋅+

+=++= ∑1

10

/

1

10

11

1

_ ρ

( )jj

NoEb

j

R

WL

jAvg ρ1

10

11

1

10

/ _⋅⋅+

=

( ) N

N

jTOTTOT PLfII +⋅+⋅= ∑1

1

Define:

Then:

( ) ∑⋅+−⋅= N

j

NTOT

LfPI

1

11

1Obtain:



Suppose that:

All the users are 12.2 kbps voice users, Eb/NoAvg = 5dB

Voice activity factor = 0.67

Adjacent cell interference factor f=0.55

jρ



According to the above mentioned relationship, the noise will rise:

ULN

jN

TOT

LfP

INoiseRise

η−=

+−==

∑1

1

)1(1

1

1



Define the uplink load factor for one user:

Define the uplink load factor for the cell:

( ) ( )( )

∑∑⋅⋅+

×+=×+=N

jjEbvsNo

N

jUL

R

WfLf

jAvg

1

10

1 1

10

11

111

_ ρ

η

( ) ( )( )

jjEbvsNo

jj

R

WfLf

jAvg ρ

η1

10

11

111

10_

⋅⋅+×+=×+=


Uplink Interference Analysis Limitation

The above mentioned theoretic analysis uses the following simplifying

explicitly or implicitly:

No consideration of the influence of soft handover

No consideration of the influence of AMRC and hybrid service

Ideal power control assumption

Assume that the users are distributed evenly, and the adjacent cell

interference is constant

Considering the above factors, the system simulation is a more

accurate method:

Static simulation: Monte_Carlo method

Dynamic simulation


Contents


2.1 Uplink Interference Analysis

2.2 Downlink Interference Analysis


Downlink Interference Analysis

Downlink interference analysis is based on the following

formula:

NotherownTOT PIII ++=



Receiver noise floor: PN

For commercial UE, the typical value is -101dBm/3.84MHZ

NFWTKPN += )**log(10



:Interference from downlink signal of this cell

The downlink users are identified with the mutually orthogonal

OVSF codes. In the static propagation conditions without multi-

path, no mutual interference exists.

In case of multi-path propagation, certain energy will be detected

by the RAKE receiver, and become interference signals. We define

the non-orthogonal factor to describe this phenomenon:

ownI

TXjown PI ×= α)(

α



: Interference from the downlink signal of adjacent cell

The transmitting signal of the adjacent cell NodeB will cause

interference to the users in the current cell. Since the scrambling

codes of users are different, such interference is non-orthogonal

Hence we obtain:

otherI

TXjother PfI ×=)(



Ec/Io for User j is:

10/)(10/

10/

10/

10)(1010

)(10)(

NN

PCLTX

j

PCL

TX

CL

j

j Pf

P

Pf

P

Io

Ec++×+

=+×+=

αα



Under the ideal power control:

Then we can get:

jjj

NoEb

R

W

Io

Ecj

ρ1

)(10 10

)/(

××=

j

TX

PCL

TXj

NoEb

j RW

PfP

P

Nj

/

)10

(1010/)(

10

)/( +

++×××=

αρ



Define the downlink load factor for user j:

Define the downlink load factor for the cell:

maxP

PTXDL =η

j

TX

PCLTX

j

NoEb

jj RW

Pf

P

P

P

P

Nj

/

)10

(1010/)(

max

10

)/(

max

+

++×××==

αρη



According to the above mentioned relationship, the noise will rise:

( )N

DLMax

N

otherownN

N

total

P

CLPfNo

P

IIP

P

INoiseRise

/ηα ××++=++==


Contents

1. Traffic Model



4. CE Dimensioning



Capacity Dimensioning FlowDimensioning Start

Assumed Subscribers

CS Peak Cell Load(MDE)

YesYesYesYes

NoNoNoNo

CS Average Cell Load PS Average Cell Load

=Target Cell Load?

Dimensioning End

Total Cell Load

Load per Connection of R99

HSPA Cell Load

LoadLoadLoad,LoadmaxLoad HSUPAavgPSavgCSpeakCSUL_totalcell ++= −−−−

CCHHSDPAavgPSavgCSpeakCSDL_totalcell LoadLoadLoadLoad,LoadmaxLoad +++= −−−−


Contents


3.1 R99 Capacity Dimensioning

3.2 HSDPA Dimensioning


Capacity Dimensioning Differences

GSM

Hard blocking

Capacity --- hardware dependent

Single service

Single GoS requirement

Capacity dimensioning ---ErlangB

WCDMA

Soft blocking

Capacity --- interference dependent

Multi services (CS&PS)

Respective quality requirements of

each service

Capacity dimensioning ---

Multidimensional ErlangB


Multidimensional ElangB Principle (1)

Multidimensional ErlangB model is a Stochastic Knapsack Problem.

“Knapsack” means a system with fixed capacity, various objects arrive at the

knapsack randomly and the states of multi-objects in the knapsack are

stochastic process.

Then when various objects attempt to access in this system, how much is the

blocking probability of every object?

K classes of services

Blockedcalls

Callsarrival

Callscompletion

Fixed capaciy


Multidimensional ElangB Principle (2)

Case Study: Two dimensional ErlangB Model

The size of service 2 is twice as that of service 1

C is the fixed capacity

n2

Blocking States of Class 1

C

C-b1

n1

n2

Blocking States of Class 2

C

C-b2

n11 2 3 4 5 6

1

2

3

1 2 3 4 5 6

1

2

3

n2

States Space

C

n11 2 3 4 5 6

1

2

3

Ω


CS Capacity Dimensioning (1)

CS services

Real time

GoS requirements

Multidimensional ErlangB

Resource sharing

Meeting GoS requirements

Capacity

Blocking probability Cell Loading

?MDE

Channels......

AMR12.2k

CS64k

Multidimensional ErlangB Model


CS Capacity Dimensioning (2)

Comparison between ErlangB and Multidimensional ErlangB

Multidimensional ErlangB - Resources shared

High Utilization of resources

ErlangB - Partitioning Resources

Low Utilization of resources


Best Effort for Packet Services

PS Services:

Best Effort

Retransmission

Burst Traffic

PS will use the spare load apart from that used by CS

Total Load

CS Peak Load

CS Average Load

Load occupied by CS

Load occupied by PS

Load

Time


Capacity Dimensioning

Average load:

Peak load:

Query the peak connection through ErlangB table

jjj LoadFactorTrafficdAverageLoa ×=

∑=N

jTotal dAverageLoadAverageLoa1

jjj LoadFactorPeakConnPeakLoad ×=

)( jTotal PeakLoadMDEPeakLoad =


Case Study (1)

Common parameters:

Maximum NodeB transmission power: 20W

Subscriber number per Cell: 800

Overhead of SHO (including softer handover): 40%

Retransmission of PS is 5%

R99 PS traffic burst: 20%

Activity factor of PS is 0.9

Power allocation for CCH is 20% in downlink


Case Study (2)

Traffic Model, GoS and load factors:

4.21%

4.99%

1.18%

Load Factors (UL)

0

0

50

0.001

0.02

UL

N/A0PS384 (Kbit)

5.94%N/A100PS128k (Kbit)

2.96%N/A100PS64k (Kbit)

4.65%2%0.001CS64k (Erl)

0.83%2%0.02AMR12.2k (Erl)

Load Factors (DL)GoS DL


Case Study (2)

Uplink Average Load Downlink Average Load

AMR12.2k:

0.02*800*1.18%=18.88%

CS64k:

0.001*800*4.99%=3.99%

PS64k:

50*800*(1+5%)*(1+20%)/0.9/64/3600

*4.21%=1.02%

CS&PS uplink average load:

18.88%+3.99%+1.02%=23.89%

AMR12.2k:

0.02*800*(1+40%)*0.83%=18.59%

CS64k:

0.001*800 *(1+40%)* 4.65%=5.2%

PS64k:

100*800*(1+5%)*(1+40%)*(1+20%)/0.9/

64/3600*2.96%=2.01%

PS128k: 2.02%

CS&PS downlink average load:

18.59%+5.2%+2.01%+2.02%=27.82%


Case Study (3)

Uplink Peak Load Downlink Peak Load

AMR12.2k:

Traffic=0.02*800=16Erl

Peak Conn= ErlangB(16, 2%)=24

Peak Load=24*1.18%=28.32%

CS64k:

Traffic=0.001*800=0.8Erl

Peak Conn= ErlangB(0.8, 2%)=4

Peak Load=4*4.99%=19.96%

CS Peak Load: 42.53%

AMR12.2k:

Traffic=0.02*800*(1+40%)=22.4Erl


Peak Load=31*0.83%=25.73%

CS64k:

Traffic=0.001*800 *(1+40%)=1.12Erl


Peak Load=5*4.65%=23.25%



Contents


3.1 R99 Capacity Dimensioning

3.2 HSDPA Dimensioning


HSDPA Capacity Dimensioning (1)

HSDPA Capacity Dimensioning

The purpose is to obtain the required HSDPA power to satisfy the

cell average throughput.

HS-DSCH will use the spare power apart from that of R99

Dedicated channels (power controlled)

Common channels

Power usage with dedicated channels channels

t

Unused power

Power

HS-DSCH with dynamic power allocationt

Dedicated channels (power controlled)

Common channels

HS-DSCH

Power3GPP Release 99 3GPP Release 5

Pmax-R99


HSDPA Capacity Dimensioning (2)

Capacity Based on Simulation

to simulate Ior/Ioc distribution in the

network with certain cell range

to simulate cell throughput distribution

based on Ec/Io distribution in the cell

Dimensioning Procedure

0.00%

0.50%

1.00%

1.50%

2.00%

2.50%

3.00%

3.50%

4.00%

4.22

2.98

2.04

1.39

0.96

0.66

0.45

0.31

0.21

0.14

0.1

0.07

0.05

0.03

0.02

0.01

0.01

0.01 0 0 0 0

Ioc/Ior

Distribution probability

DU Cell coverage Radius=300m

Conditions of Simulation

Channel model-TU3

5 codes

Simulation

Ec/Io distribution

Ior/Ioc distribution

Cell coverageradius

Cell averagethroughput

Ec/Io =>throughput

HSDPA PowerAllocation


Case Study

Input parameters

Subscriber number per cell: 800

HSDPA Traffic model: 1200kbit per subs

HSDPA Retransmission rate: 10%

The power for HS-SCCH: 5%

Cell radius: 1km

HSDPA cell average throughput:

The needed power for HS-DSCH including that for HS-SCCH is 18.38%

kbps293%)01(1*3600

1200*800 =+


Case Study

Uplink Total Load of the Cell :


CS&PS average load: 23.89%

Downlink Total Load of the Cell :


CS&PS average load: 27.82%

HSDPA load is 18.38%

CCH load: 20%

66.20%%. MAX

LoadLoadLoadLoadLoadLoad CCHHSDPAavgPSavgCSpeakCSDLtotalcell

=++=

+++= −−−−

%20%)38.188227%,33.42(

,max_

%4%. MAX

LoadLoadLoadLoad avgPSavgCSpeakCSULtotalcell

53.2)8923%,53.42(

,max_

==

+= −−−−


Contents

1. Traffic Model



4. CE Dimensioning



Overview

Definition of a CE:

A Channel Element is the base band resource required in the Node-B to

provide capacity for one voice channel, including control plane signaling,

compressed mode, transmit diversity and softer handover.

NodeB Channel Element Capacity

One BBU3900

UL 1,536 CEs with full configuration

DL 1,536 CEs with full configuration


Huawei Channel Elements Features

Channel Elements pooled in one NodeB

No need extra R99 CE resource for CCH

reserved CE resource for CCH

No need extra CE resource for TX diversity

No need extra CE resource for Compressed Mode

reserved resources for Compressed Mode

No need extra CE resource for Softer HO

HSDPA does not occupy R99 CE resource

separate module for HSDPA

HSUPA shares CE resource with R99 services

No additional CE resource for AGCH RGCH and HICH


CE Dimensioning Flow

),( _______ HSUPAULAULPSULAverageCSULPeakCSTotalUL CECECECECEMaxCE +++=

),( _______ DLADLPSDLAverageCSDLPeakCSTotalDL CECECECEMaxCE ++=

Dimensioning Start

CS Average CE

Channel Elements per NodeB

Dimensioning End

--Subscribers per NodeB--Traffic model

PS Average CECS Peak CE (MDE) HSPA CE


CE Mappings for R99 Bearers

8 10 PS384k

4 5 PS144k

4 5 PS128k

2 3 PS64k

2 3 CS64k

1 1 AMR12.2k

DownlinkUplinkBearer

Channel Elements Mapping for R99 Bearers


R99 CE Dimensioning Principle

Peak CE occupied by CS can be obtained through multidimensional ErlangB

algorithm

Average CE needed by CS and PS depend on the traffic of each service, i.e.

Average CE = Traffic * CE Factor

CEResources...

...

AMR12.2k

CS64k

Multdimensional ErlangB Model

Total CE

CS Peak CE

CS Average CE

CE occupied by CS

CE occupied by PSand HSPA

CE

Time

CE resource shared

among each service


HSDPA CE Dimensioning

In uplink, no CE consumption for HS-DPCCH if corresponding UL DCH

channel exists

In uplink, CE consumed by one A-DCH depends on its bearing rate

In downlink, A-DCH is treated as R99 DCH.

No additional CE needed for HS-DSCH and HS-SCCH

One HSDPA link need

one A-DCH in uplink and

downlink respectively

HS-DSCHHS-SCCHHS-DPCCH

Associated Dedicated Channels

Site 1 Site 2


CE Mappings for HSDPA Bearers

1 CE---DL A-DCH (DPCCH)

---3 CEUL A-DCH (DPCCH)

---0 CEHS-DPCCH

0 CE---HSDPA Traffic

DownlinkUplinkTraffic

HSDPA Channel Elements Consumption


Case Study (1)

Input Parameters

Subscribers number per NodeB: 2000

Overhead of SHO: 30%

R99 PS traffic burst: 20%

Retransmission rate of R99 PS: 5%

PS Channel element utilization rate: 0.7

Average throughput requirement per user of HSDPA: 400kbps

HSDPA traffic burst is 25%

Retransmission rate of HSDPA is 10%

0

0

50

0.001

0.02

UL

N/A1200HSPA (kbit)

N/A80PS128k (kbit)

N/A100PS64k (kbit)

2%0.001CS64k (Erl)

2%0.02AMR12.2k (Erl)

GoS DLTraffic Model


Case Study (2)

Uplink CE Dimensioning Downlink CE Dimensioning

AMR12.2:

Traffic =0.02*2000*(1+30%) = 52Erl

Peak CE =ErlangB(52,0.02)*1= 63 CE

Average CE =52*1=52 CE

CS64:

Traffic =0.001*2000*(1+30%) = 2.6Erl

Peak CE =ErlangB(2.6,0.02)*3 = 21 CE

Average CE =2.6*3=9 CE

Total peak CE for CS: 80CE

Total average CE for CS: 52+9=61CE

AMR12.2:

Traffic =0.02*2000*(1+30%) = 52Erl

Peak CE =ErlangB(52,0.02)*1 = 63CE

Average CE =52*1=52CE

Traffic of VP:

Traffic =0.001*2000*(1+30%) = 2.6Erl

Peak CE =ErlangB(2.6,0.02)*2 =14CE

Average CE =2.6*2=6CE

Total peak CE for CS: 74CE

Total average CE for CS: 52+6=58CE



CE for PS64k:

Total CE for R99 PS services:

4CE

4CE5%)(1*20%)(1*30%)(1*3*3600*0.7*64

50*2000 =+++

CE for PS64k:

CE for PS128k:

Total CE for R99 PS services:

4+4=8CE

CE for HSDPA A-DCH:

3CE10%)(1*%)52(1*1*3600*400

1200*2000 =++

4CE5%)(1*20%)(1*30%)(1*2*3600*0.7*64

100*2000 =+++

4CE5%)(1*20%)(1*30%)(1*4*3600*0.7*128

80*2000 =+++

Case Study (3)


Case Study (4)


Total CE Total CE

CE MAX

CECE

CEMaxCE

ULAveragePSULAverageCS

ULPeakCSTotalUL

80)461,80(

)

,(

____

___

=+=

+

=

CE 743)858 Max(74,

)CECECE

,CE(MaxCE

DL_ADL_PSDL_Average_CS

DL_Peak_CSTotal_DL

=++=

++

=


Contents

1. Traffic Model



4. CE Dimensioning



Network Dimensioning Flow

UL/DL Link Budget

Cell Radius=Min (RUL, RDL)

UL/DL CapacityDimensioning

Satisfy Capacity Requirement?

Capacity Requirement

Adjust Carrier/NodeBNo

Yes

CE Dimensioning

Output NodeB Amount/NodeB Configuration

Coverage Requirement

start

End

Thank youwww.huawei.com

CE-Dimensioning-UMTS

Documents

multidimensional

packet call

extra ce resource

ideal power

network dimensioning

avg j10

cl pn

ps average