Product name

WCDMA RNP

Product versionTotal 12 pages

1.2

WCDMA Capacity Dimensioning Procedure

and Case Study

Prepared by UMTS RNP Date 2007-11-28

Reviewed by Date yyyy-mm-dd

Reviewed by Date yyyy-mm-dd

Granted by Date yyyy-mm-dd

Huawei Technologies Co., Ltd.All rights reserved

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Table of Contents

WCDMA Capacity Dimensioning Procedure and Case Study.......................................................41 Introduction..............................................................................................................................41.1 Huawei capacity dimensioning procedure.........................................................................4

2 CS Capacity Dimensioning Principle and Example.................................................................52.1 Uplink and downlink load factor per connection................................................................52.2 Calculation of CS load.......................................................................................................52.3 Case study.........................................................................................................................6

3 PS Capacity Dimensioning Principle and Example.................................................................63.1 Calculation of PS load........................................................................................................63.2 Case study.........................................................................................................................7

4 HSDPA Capacity Dimensioning Principle and Example.........................................................84.1 HSDPA capacity dimensioning principle............................................................................84.2 Case study.........................................................................................................................8

5 HSUPA Capacity Dimensioning Principle and Example.........................................................95.1 HSUPA Capacity dimensioning principle...........................................................................95.2 Case study.........................................................................................................................9

6 Mixed Services Capacity Dimensioning..................................................................................96.1 Case study.......................................................................................................................10

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WCDMA Capacity Dimensioning Procedure and Case Study

Abstract：This article presents an overview of WCDMA capacity dimensioning. The principle

and procedure of capacity dimensioning for CS service and best effort for PS service is

clearly depicted in the document.

1 Introduction

1.1 Huawei capacity dimensioning procedure

In order to perform capacity dimensioning for multiple CS services, Multidimensional

ErlangB is used for CS services which considers resources sharing among CS services.

Based on the cell target load and traffic profile, the number of subscribers supported by the

cell at target load can be obtained. The procedure for mixed services capacity dimensioning

is illustrated in figure 1, as shown below.

Figure1 Mixed services capacity dimensioning procedure

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2 CS Capacity Dimensioning Principle and Example

2.1 Uplink and downlink load factor per connection

The average uplink load factor of one connection for service :

（1）

The average downlink load factor of one connection for service :

（2）

: WCDMA chip rate.

: Bearer bit rate of the service .

: Average ratio of other cell to own cell base station power.

: Signal energy per bit divided by noise spectral density, required to meet a predefined

Block error rate.

: Activity factor of the service .

: The average power consumed by one connection of the service .

: The maximum power of one cell.

2.2 Calculation of CS load

（1） Calculation of CS peak cell load

CS peak cell load can be calculated by multidimensional ErlangB algorithm.

（2） Calculation of CS average cell load

According to CS traffic profile and the subscribers in the cell, we can easily obtain the

average CS load in the cell.

Traffic per cell of CS service :

（3）

CS average cell load in uplink:

（4）

CS average cell load in downlink:

In downlink the calculation of load should consider the ratio of SHO.

（5）

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: The number of subscribers per cell

: The traffic per subscriber of CS service .

: Soft handover overhead including softer handover.

2.3 Case study

Assumptions:

Subscriber number per Cell: 1000

Voice traffic per user: 0.02Erl

VP traffic per user: 0.001Erl

Overhead of SHO (including softer handover): 40%

Downlink target load: 90%

Maximum NodeB transmission power: 20W

GoS requirement of voice: 2%

GoS requirement of VP: 2%

Uplink and downlink load factor of AMR12.2: 1.1873%, 0.9383%

Uplink and downlink load factor of CS64k:4.9901%, 5.2011%

Then,

Considering the load resources sharing between voice and VP, the total peak

load needed by voice and VP in uplink is = 49.52%, in downlink is

=55.83%

Average load needed by voice in uplink is 1000*0.02*1.1873% = 23.74%, in

downlink is 1000*0.02*(1+0.4)*0.9383%=26.27%

Average load needed by VP in uplink is 1000*0.001*4.9901%=4.99%, in

downlink is 1000*0.001*(1+0.4)*5.2011%=7.28%.

Total average load needed by voice and VP in uplink is

=23.74%+4.99%=28.73%,

In downlink is =26.27%+7.28%=33.55%

3 PS Capacity Dimensioning Principle and Example

3.1 Calculation of PS load

The following procedure shows how to calculate the PS average load.

（1） Calculation of PS average cell load for UL

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(6)

Where is the number of equivalent channels for service

(7)

: Throughput per user for service .

: PS data retransmission for service .

: PS burstiness ratio.

（2） Calculation of PS average cell load for DL

Calculation of PS average cell load for DL is almost same as that for UL except that

the impact on the load due to SHO should be considered in DL.

3.2 Case study

Assumptions:

Subscriber number per cell: 1000

UL PS64k throughput per user: 50kbit

DL PS64k throughput per user: 100kbit

DL PS128k throughput per user: 80kbit

Overhead of SHO (including softer handover): 40%

PS traffic burst is 20%

Retransmission rate of R99 PS services is 5%

Activity factor of PS is 0.9

Uplink load factor of PS64k: 4.3072%

Downlink load factor of PS64k and PS128k: 3.3139%, 6.6454%

Then,

Load for UL PS64k is

Load for DL PS64k is

Load for DL PS128k is

Total average downlink load needed by PS is 2.82%+2.26%=5.08%

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4 HSDPA Capacity Dimensioning Principle and Example

4.1 HSDPA capacity dimensioning principle

For HSDPA capacity dimensioning, average HSDAP cell throughput can be calculated

based on available resources like power and codes for HSDPA and cell average radius.

The following figure shows the procedure. Of course, the required power of HSDPA to

guarantee HSDPA cell average throughput requirement can also be calculated.

Figure2 HSDPA capacity dimensioning procedure

4.2 Case study

Assumptions:

Subscriber number per cell: 1000

Traffic model of HSDPA is 1200kbit

HSDPA traffic burst is 25%

Retransmission rate of HSDPA is 10%

Then,

Target of HSDPA cell average throughput is

Based on the target HSDPA cell throughput and cell radius, the needed power for

HSDPA including that for HS-SCCH is 10.37%

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5 HSUPA Capacity Dimensioning Principle and Example

5.1 HSUPA Capacity dimensioning principle

Similar with capacity dimensioning of HSDPA, average HSUPA cell throughput for input

load or the load needed by HSUPA to achieve certain throughput can be calculated. The

following figure shows the procedure of calculating HSUPA cell throughput from input load.

Figure3 HSUPA capacity dimensioning procedure

5.2 Case study

Assumption:

Subscriber number per cell: 1000

Traffic model of HSUPA is 700kbit

HSUPA traffic burst is 25%

Retransmission rate of HSUPA is 10%

Then,

Target of HSUPA cell average throughput is

Based on the target HSUPA cell throughput and cell radius, the needed load for

HSUPA is 25.22%

6 Mixed Services Capacity Dimensioning

PS service is the best effort service which is used in mixed services capacity dimensioning.

Best effort means that the packet service can utilize the resource that is available, but there

are no guarantees on “blocking probability”.

Figure 4 illustrates the resource occupation by CS and PS services.

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Uplink load HSUPA actual cell load

Maximum rate of single user

HSUPA cell throughput

HS-DPCCH loadR99 loadA-DCH load

Cell Radius Ec/N0Ec/N0R

User rate at distance r

Figure4 Resource shared by CS and PS

According to the previous calculation we can obtain the actual total cell load by the formula:

When the actual total cell load equals to the cell target load, the number of

subscribers is the capacity of one cell.

6.1 Case study

Based on the assumption and calculation of previous case study, the total load

can be obtained easily using the formula above (assuming downlink load for

CCH is 20%):

=Max (49.52%, 28.73%+1.31%+25.22%) =55.26%

= Max (55.83%, 33.55%+5.08%+10.73%) +20%=75.83%

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