WO NP2003 E01 1 UMTS Capacity Estimation

UMTS Capacity Estimation

ZTE University

Content

UMTS Service mode Common Capacity Design Methods Uplink Capacity Estimation Downlink Capacity Estimation Estimation Examples

CS Domain Service Model

Key parameter: call frequency, call duration, blocking probability

Average Erlang ＝ call frequency ×duration / 3600

Call DurationCall Duration Call DurationCall Duration

Call SetupCall Setup Call ReleaseCall Release Call SetupCall Setup Call ReleaseCall Release

PS Domain Service Model

Session (WWW)Session (WWW) Session (WWW)Session (WWW)

CallCall CallCall Call (Web Page)Call (Web Page)

ClickClick ClickClick ClickClick

ActiveActive ActiveActive ActiveActiveDormantDormant DormantDormant

PacketPacket PacketPacket PacketPacket

ActiveActive


Dormant status and Active status conversion Every session can contain several packet calls, different

data services and different user types have different features

Resource occupied by packet call varies alone with the burst transmission

PS Service Model - Example

service Bearer rate(kbps)

Mean packet size(byte)

Mean packets in a call

Mean calls/session

Reading time between calls(second)

Email 64 480 32 2 5

www 144 480 25 5 5

Download 64 480 62 2 5

MMS 64 480 32 2 5

Streaming 384 480 267 1 0

Parameter Name Parameter definition Unit

DL Bit rate Downlink service bit rate kbps

DL Mean Packet Size Mean downlink packet size

Byte

DL Mean ＃ Packets Mean downlink packet quantity

DL Mean Calls/session Mean calls of downlink session

DL Reading time between calls

Transmission duration between downlink calls

second

DL Mean packets in a call Mean packets in one downlink session

DL BLER Downlink service quality requirement

DL PS Activity Factor Downlink activating factor


UL Bit rate Uplink service bit rate kbps

UL Mean Packet Size Mean uplink packet size Byte

UL Mean ＃ Packets Mean uplink packet quantity

UL Mean Calls/session Mean calls of uplink session

UL Reading time between calls

Transmission duration between uplink calls

second

UL Mean packets in a call Mean packets in one uplink session

UL BLER Uplink service quality requirement

UL PS Activity Factor Uplink activating factor

BHSA Busy hour sessions attempt


Service Category

Service type Basic characteristic Example

Conversation The time relationship between information entities in the stream must be kept, session mode (small delay, strict delay jitter requirement)

Voice, video phone

Streaming The time relationship between information entities in the stream must be kept

Multimedia data stream

Interactive Request/response mode, data integrity must be kept

Web browser, internet game

Background Data integrity must be kept, high delay tolerance

Email download in background

User Group Classification

Classification principle Based on user consumption capability and consumption behavior

Note: User groups are distinguished by service type, service rate, service quality and service intensity.

User type Group features

High － end High income group, enterprises and managers. Providing high rate access service.

Medium －end

General enterprises and some high income consumers. Providing information inquiry, mobile entertainment and mobile financial services.

Lower － end Middle income class and students. Providing data services such as SMS and some mobile game services

Service Penetration

Percentage of user distribution in different application environments are different

Percentage of high-end, middle-end and lower-end users in different application environments are different

Service model statistic characteristic relates to percentages mentioned above

A B C D

Total 10% 30% 30% 30%

High End 30% 10% 5% 0%

Medium End 40% 50% 40% 10%

Low End 30% 40% 55% 90%

Traffic Analysis for Single Subscriber

CS Domain

Service type

Mean busy hour calls

Mean call duration

Activate factor

Mean speed

(kbps)

Mean busy hour erl per user

Tel. 1.25 72 0.5 12.2 0.025

Video phone

0 (lower end)

0.05 (medium end)

0.1 (high end)

54 1 64 0 (lower end)

0.00075 (middle end)

0.0015 (high end)

Mean busy hour Erl. Per user=mean busy hour calls*mean call duration/3600


PS Domain

Service type Penetration rate

BHSA Mean packet

size (byte)

Mean packets in a call

Mean calls/session

Busy hour throughput

per user （ kbit）

Web service

Low-end user

50% 0.01 480 25 5 4.8

Medium end user

75% 0.02 480 25 5 9.6

High-end user

100% 0.03 480 25 5 14.4

Node: penetration rate means the percentage of UEs which support this service in total UEs.

Busy hour throughput per user = BHSA* mean calls in a session *mean packets in a call*mean packet size*8/1000

Equivalent Erl = Busy hour throughput per user / (Bearer rate *3600)


The average traffic according to the Service Model in each

transmission environment is :

Average traffic for each subscriber = ∑ Ratio of subscriber

group* Service penetration * average traffic of this group

Content


UMTS Network Dimensioning Procedure

Capacity Estimation Procedure

Hybrid service intensity analysis The UMTS system provides multiple services and the

hybrid service intensity analysis makes the system capacity consumed by various services equivalent to that consumed

by a single service. Uplink capacity estimation

Estimate the NodeB number that meets the service demand based on the hybrid service intensity analysis.

Downlink capacity estimation It is a verification process. The NodeB transmission power

formula is used to calculate the channel number that can be provided by the current NodeB scale so as to verify whether this channel number can meet the capacity requirement, and if it cannot, stations need be added.

Common Capacity Design Methods

Equivalent Erlangs method

Post Erlang-B method

Campbell method

Equivalent Erlangs Method

Principle: Make a service equivalent to another service and calculate the total Erl.

Example Service A: 1 channel for each connection and the total is 12 erl. Service B: 3 channels for each connection and the total is 6 erl. If 1 erl service B = 3 erl service A, altogether 30 erl service A

shall be equivalent and 39 channels shall be required (under 2% blocking rate).

If 3 erl service A = 1 erl service B, altogether 10 erl service B shall be equivalent and 17 service B channels shall be required (equal 17*3=51 service A channels under 2% blocking rate).

++

Low speed service

equivalent

High speed service equivalent

2 Erl low speed

service

1 Erl high speed service

Capacities meeting the same GoS are different

The calculation result The calculation result is related to the is related to the

equivalent mode equivalent mode

Equivalent Erlangs Method

Post Erlang-B Method

Principle: Calculate the capacity required by each service respectively and add them.

Example Service A: 1 channel for each connection and the total is 12 erl. Service B: 3 channels for each connection and the total is 6 erl. Service A requires 19 channels (under 2% blocking rate). Service B requires 12 service B channels (equal 12*3=36

service A channels, under 2% blocking rate).

These two services require 19+36=55 channels


Suppose services A and B are the same kind, where, Service A: 1 channel for each connection and the total is 12 erl.

Service B: 1 channel for each connection and the total is 6 erl.

Based on the Post Erlang-B method Service A requires 19 channels (under 2% blocking rate).

Service B requires 12 channels (under 2% blocking rate).

Altogether 19+12=31 channels are required.

Based on traditional Erlang-B method

The total traffic of services A and B is 12+6=18 erl and altogether

26 channels are required under 2% blocking rate.

Required channel number estimated through the Post Erlang-B

method is too large.

1 Erl service A

1 Erl service B

++

1 Erl service A and 1 Erl service B

Capacities meeting the same GoS are different

The calculation The calculation

result is too result is too

pessimistic pessimistic


Campbell Method

c

aCCapacity ii

cfficOfferedTra

iii

iii

aerl

aerl

c

2

ic

Principle: Make multiple services equivalent to a virtual service and calculate the capacity on the basis of the virtual service.

iserviceofcapacityCiiserviceofamplitudea

niancevnmeanafactorcapacityc

i...

...*var

*.

3036112 ii aerl

6636112 222ii aerl

Campbell Method

Example Service A: 1 channel for each connection and the total is 12

erl. Service B: 3 channels for each connection and the total is 6

erl

Mean & variance

2.23066

c

63.132.2

30 Traffic Offered cα

Campbell Method

Capacity factor c

Virtual traffic

21 channels (virtual channels) are required to meet the virtual traffic under 2% blocking rate.

Under 2% blocking rate, channel number required by each

service is shown as follows:

Service A:

Service B:

Different channel numbers are required to meet the GOS

requirements of diversified services.

Compared with the former two methods, the calculation result

through the Campbell method is more reasonable.

471)2.221(1 C

493)2.221(2 C

Campbell Method

If the reference service is the voice service ：

Campbell Method

voicevoicevoice

serviceserviceserviceservice vNoEbR

vNoEbRAmplitude

*/*

*/*

Content


jtotal

j

jjj PI

P

Rv

WNoEb

)/(

W: indicates the chip rate.

vj: indicates user j’s activation factor.

Rj: indicates user j’s data rate.

Pj : indicates user j’s signal receive power

Itotal: indicates total broadband receive power with

the thermal noise power included in the NodeB.

Uplink Load Analysis

Eb/No the receive signal in the NodeB must reach Eb/No required by the service demodulation.

The receive power at the NodeB receive end should meet

the following formula so that the user signal can meet the

demodulation requirement:totaljtotal

jjj

j ILI

vRNoEb

WP

)(1

1

jjj

total

jj

vRNoEb

WI

PL

)(1

1

Define a connection load

factor Lj:

N

jtotalj

N

jj ILP

11

The total receive power of all N users from

one cell is:



The total receive power at the NodeB receive end consists

of three parts:Notherintatal PPPI

indicates the total interference power of in-cell users.

indicates the total interference power of out-cell users.

indicates the NodeB thermal noise power.

Neighbor cell’s interference factor i

i= Other cell interference /Local cell

interference

inP

otherP

NP

The total user receive power of the NodeB:

Define the noise lifting as the ratio of total broadband

receive power to the noise power of the NodeB:

N

jtataljotherin ILiPP

1

)1(

N

jj

otherintatal

tatal

N

total

LiPPI

I

P

INR

1

)1(1

1


Define the uplink load factor

to be:

The noise lifting can be represented

to be:

N

j

jjj

N

jjUL

vRNoEb

WiLi

11)/(

1

1)1()1(

UL

NR

1

1

)1(10)( 10 ULLOGdBNR


The uplink capacity is limited by interference increase:

25 30 35 40 45 50 55 60 65

2

3

4

5

6

7

8

9

10

11

user number

nois

e r

ise(d

B)

Shanghai dialectShanghai dialect Minnan Minnan

dialectdialect mandarinmandarin

CantoneseCantonese


Uplink Capacity Estimation

In the case of a single service, evaluate the channel quantity provided by every cell according to the load formula and further evaluate the total number of base stations satisfying the uplink capacity requirement.

To budget composite traffic, based on the Campbell algorithm, make different services consumption on the system resource equivalent to the single service consumption on the system resource, and then evaluate the quantity of channels to be provided by every cell according to load formula, and further evaluate the number of base stations satisfying the composite traffic requirement.

R99/HSUPA mixed calculation

During the uplink capacity calculation ,decide how much uplink load will be designed in R99 and HSUPA

By simulation, calculate how much PS throughput can be carried by HSUPA

Calculate how much of the remaining PS service to be carried by R99

Calculate equivalent intensity of services

Calculate the variance, average value and capacity factor of the composite service

System virtual traffic A

Calculate the quantity of equivalent voice channels

in the cell

Quantity of virtual channels in the cell

Virtual service capacity B of the cell

Number of cells

A/B

R99 Uplink Capacity Algorithm

Content


Downlink Load Analysis

To correctly demodulate useful signals, the UE must

overcome interference from the following three

aspects

Nothertatal PPPI )1(

P represents total power of signals from current cell

represents total interference power of signals from the outside of the cell

represents thermal noise power from the UE

represents orthogonal factor of the downlink

otherP

NP


By referring to the derivation means of uplink load

factor, denote the downlink load factors as follows:

N

j j

jjDL i

RW

NoEbv

1

])1[(/

)/(

W represents chip rate at 3.84M chip/s

vj represents activation factor of the user j

jR represents bit rate of the user j

represents the average orthogonal factor in a cell

i represents the average ratio of the NodeB power from other cell to that from this cell


Total downlink power allocation

DL

N

jj

j

b

jMS

TXBS

RW

NE

LWN

P

1

1

0

_

Where, represents the noise power spectrum density on the front of the receiver in the mobile station

represents the average path loss of the cellL

) (suppose KTNFNFKTNMS 290174 =+-+

MSN

46 48 50 52 54 56 58 60 62 64

32

34

36

38

40

42

44

46

user number

Tx P

ow

er

(dB

m)

Public channelPublic channel

Two usersTwo users

One userOne user

Three usersThree users

..

..

..

Downlink Downlink powerpower

The downlink capacity is limited by transmission

power of the base station


Downlink Load and Scale Analysis

Estimate downlink capacity after analyzing the channel quantity required by uplink capacity, and observe whether the downlink can support the mobile station to work in the designated coverage area and its channel quantity reaches the channel quantity generated by the uplink

Calculate the quantity of equivalent voice channels to be provided by every cell

Calculate the quantity of equivalent voice channels availably provided by every cell

Compare the above two results

Content


Assumed Conditions

Channel environment: downtown area TU 3 km/h System design load: 50% Voice service blocking rate: 2% Interference factor from the adjacent cell: 0.65 Area of the city zone: 40.8 square kilometers

Voice CS64 PS64/64 PS64/128 PS64/384

Data rate(k) 12.2 64 64 64 64

Activity factor 0.67 1 1 1 1

Eb/No 4.2 2.87 1.6 1.6 1.6

Forecast traffic 3000 400 100 5 2

Voice CS64 PS64/64 PS64/128 PS64/384

Data rate(k) 12.2 64 64 128 384

Activity factor 0.58 1 1 1 1

Eb/No 7.7 7.7 7.4 6.4 8

Forecast traffic 3000 400 100 35 20

Uplink:

Downlink:

Assumed Conditions

Input: system load requirement and coverage requirement

Uplink coverage estimation

Downlink coverage estimation

Uplink capacity estimation

Quantity of base stations satisfying uplink coverage

Quantity of base stations satisfying coverage

requirement

Quantity of base stations satisfying downlink coverage

Quantity B of channels provided by the cell

Compare the results and evaluate the larger one

End

Quantity A of channels required by the cell

A<BAdd base stations

Based on traffic model

Based on power

Yes

No

Estimation Flow Chart

Emission end

Maximal emission power (dbm)

Antenna gain (dbi)

Human body loss (db)

Effective emission power

Receiving end

Thermal noise power spectrum density (dbm/HZ)

Thermal noise power (dbm)

Receiver noise coefficient (db)

Receiver noise (dbm)

Interference margin (db)

Bit rate (kbit)

Processing gain (db)

Receiving Eb/No (db)

Receiver sensibility

Antenna gain (dbi)

Line loss

Other

Power control margin

Soft handoff gain

Shade fading margin

Penetration loss

Maximal path loss

Uplink Coverage Estimation1. Uplink budget

2. Calculate the cell coverage radius based on a specific propagation model:

Path loss k1 k2log(d) k3Hms k4log(Hms) k5log(Heff) + k6log(Heff)log(d) k7(diffraction loss) clutter loss

30Heff-6.55k6

-13.82k544.6k2

152.4k1

0.540.540.540.50.65Radius（ Km ）

PS64/384PS64/128PS64CS64Voice　

Uplink coverage is limited by the CS64 kps service

Uplink Coverage Estimation

3. Calculate the quantity of base stations required by uplink Coverage area of the three-sector base station

22 488.05.05.095.138

9KmRS

The quantity of base stations is 40.8/0.488=84

Uplink Coverage Estimation

af amplitudefor 1 amplitudefor ratebit

servicefor servicefor ratebit amplitude Relative

0

0

NE

NE

b

b

Voice: 1

CS64: 64 x 1 x 100.287/12.2 x 0.67 x = 5.76

PS64/64: 64 x 1 x 100.16/12.2 x 0.67 x = 4.3

PS64/128: 64 x 1 x 100.16/12.2 x 0.67 x = 4.3

PS64/384: 64 x 1 x 100.16/12.2 x 0.67 x = 4.3

Equivalent intensity of each service

Variance, mean and capacity factor of the

composite service

Virtual traffic A of the system

Quantity of equivalent

voice channels in the cell

Quantity of virtual

channels in the cell

Number of cells

A/B Virtual traffic A of

the cell



42.010

42.010

42.010

42.010

i

iiaerlmean 1.57663.423.453.410067.540013000

i

iiaerliance 7.182713.423.453.410067.540013000var 2222

Mean

Virtual traffic of the system mean/capacity factor 5766.1/3.17 1818.96(Erl)



composite service




Quantity of virtual channels

in the cell

Number of cells

A/B

Virtual traffic A of the cell

Capacity factor variance/mean 3.17

Variance


Quantity of equivalent voice channels availably provided by the cell

N

j

o

bj

N

EvR

Wf

1*

1*1

1*)1(

%50 65.0f

Get the quantity of equivalent voice channels N 54

Where, and



composite service





in the cell

Number of cells

A/B

Virtual traffic A of

the cell




composite service





in the cell

Number of cells

A/B Virtual traffic A of the cell

Quantity of virtual channels in every cell

c

aCCapacity ii )(

Quantity of virtual channels in the cell (54 1)/3.17 16

Virtual traffic of every cell

Look up the Erl B table, and provide 9.83Erl for 16 virtual channels in the case of 2% of call loss ratio




composite service





in the cell

Number of cells

A/B Virtual traffic A of the cell


Number of cells=Virtual traffic of the system/virtual traffic of every =1818.96/9.83=186

Number of three-sector base stations=186/3=62

Downlink Capacity Estimation

Integrate uplink and downlink coverage budget and uplink capacity budget to determine that there are 84 base stations currently and authenticate whether downlink power meets the requirement.

Quantity A of channels to be provided by the cell

Average traffic of every cell


Quantity of virtual channels in every cell

Determine the number of stations

Quantity B

of channels availably provided by the ce;;

End A<BYes NO

Add base

stations

Voice: 3000/84/3 11.9 Erl

CS64: 400/84/3 1.59 Erl

PS64/64: 100/84/3 0.4 Erl

PS64/128: 35/84/3 0.14 Erl

PS64/384: 20/84/3 0.079 Erl

Average traffic of various services in every cell


Quantity A of channels to be

provided by the cell




in every cell

Quantity B

of channels availably provided by the cell

End

A<B

Yes


Virtual traffic of every cell Equivalent service intensity of each service on

the downlink Voice: 1, CS64: 7.8, PS64/64: 7.3 PS64/128: 13.1, PS64/384: 50 Mean of composite traffic

Variance of composite traffic

355.19=50 0.079+13.1 0.14+7.3 0.4+7.8 1.59＋ 11.9var 2222 iance

Traffic factor capacity factor variance/mean 355.19/33.04 10.75

Virtual service capacity of the cell mean/capacity factor 33.04/10.75 3.07 (Erl)

33.04=50 0.079+13.1 0.14+7.3 0.4+7.8 1.59＋ 11.9 mean







in every cell

Quantity B


End

A<B

Yes


c

aCCapacity ii )(

Quantity of equivalent voice channels: 7 10.75 1 76

Quantity of virtual channels in every cell Look up the Erl B table and obtain that

the quantity of virtual channels required by 3.07 Erl virtual traffic is 7

Quantity of equivalent voice channels to be provided by every cell






in every cell


Quantity B


End

A<B

Yes


Calculate the quantity of channels availably provided by every cell based on power

])1[(/

)/(*1

/

)/(***

1

1

jj

N

j j

jj

N

j j

jjN

RW

NoEbv

RW

NoEbvLP

P

P represents the maximum service transmission power, which is 13 W

represents the noise power spectrum density on the front of the mobile station receiver, and its value is -169 dBm

L represents the average path loss, which is evaluated by subtracting 6 dBm from the maximum path loss

j represents orthogoal factor, which is 0.6 for the multipath channel

represents interference factor from an adjacent cell. It is 0.65 for the three-sector antenna macro cell

j

Obtain that the quantity of equivalent voice channels actually provided by every cell is 71

NP






in every cell


Quantity B

of chann

els availa

bly provided by the cell

End

A<B

Yes


Comparison The quantity of channels to be provided by

every cell is 76 The quantity of channels actually provided

by every cell is 71 There are 84 base stations currently, and it

cannot satisfy downlink capacity requirement, and some stations should be added.






in every cell


Quantity B


End

A<B

Yes


Iterative calculation

726588

717287

717286

717685707684

697683

Number of channels provided

Number of channels required

Number of base stations

If there are 88 base stations, the uplink and downlink coverage capacity requirement can be met

In the case, the base station coverage radius is

488.095.1/88/8.40 Km


WO NP2003 E01 1 UMTS Capacity Estimation

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