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Huawei RNC Capacity dimension

Huawei RNC Capacity Dimension

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RAN Capacity Dimension

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Page 1: Huawei RNC Capacity Dimension

Huawei RNC

Capacity dimension

Page 2: Huawei RNC Capacity Dimension

2

Capacity dimension

Principle for capacity dimension

Input from operator

( Total subscribers in network,

traffic model)

RNC capacity limitation

( Erl, Throughput,BHCA)

Number of WRBS

Subscribers per WRBS

Nodebs per WRBS

Subscribers per Nodeb If Nodebs per

WRBS >100

Radio Network

dimension

Page 3: Huawei RNC Capacity Dimension

3

Traffic Model Parameters

Traffic Parameter Value

BHCA CS per sub 0.6

BHCA total per sub 0.9

CS Voice per sub/BH 16,2mErl

CS Data per sub/BH 1,1mErl

CS Video Telephony call duration/BH 135sec

CS call duration/BH 135sec

Rel.99 PS per sub/BH 580bps

Total PS per sub/BH 1160bps

Timer for CH switching (DCH/FACH) 600-800msec

Location update rate sub/BH 2.2

Ratio of soft/softer HO/BH 0.8:0.2

Proportion of HO/BH 30%

Handover times/call/BH (inter/intra RNC

SHO)

7,0 times/call

PS CH switching 4.0 times/call

Cell update/PSCall 3 times/call

Ratio of UL : DL (Rel.99/HSDPA) 1:3.6

Traffic Model from Vodafone

Page 4: Huawei RNC Capacity Dimension

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Limitation

Limiting factor : throughput capacity 60Mbps/ WRBS

Limiting factor : BHCA capacity 75,000/ WRBS

Limiting factor : NodeB capacity 100 NodeB/ WRBS

Limiting factor : Cell capacity 300 NodeB/ WRBS

120Mbps / 60Mbps = 2 e.g. 2 WRBS

60,000 / 75,000 = 0.8 e.g. 1 WRBS

150 / 100 = 1.5 e.g. 2 WRBS

400 / 300 = 1.3 e.g. 2 WRBS

Page 5: Huawei RNC Capacity Dimension

5

RNC Dimension

RNC types Configure Iub Mbps NodeB Cell STM-1 E1(ATM) E1(IP) FEChannelize

d STM-1

Small Capacity RNC 1WRSS+1WRBS 77 100 300 30 64 64 32 2

Medium Capacity RNC 1WRSS+3WRBS 206 300 900 26 192 192 96 6

High Capacity RNC 1WRSS+6WRBS 461 600 1800 20 384 384 192 12

Traffic capacity

Max. Capacity for different RNC types

Interfaces

RNC Types Configure Subscribers BHCA

Iu

Mbit/s

Iu CS

12.2

AMR Erl

Iu CS Data

Erl

Iu PS I/B

64/128

Mbit/s

Iur

Mbit/s

Small

Capaticy RNC 1 WRSS+ 1 WRBS 95000 85500 50.19 923.4 52.25 28.50 7.654

Media

Capacity RNC 1 WRSS+ 3 WRBS 287000 258300 151.56 2789.64 157.85 86.07 20.623

High

Capacity RNC 1 WRSS+ 6 WRBS 574000 516600 303.10 5579.28 315.7 172.13 46.162

Traffic Capacity

2*63 channalized E1s

VF CALL PROFILE DATAS

Page 6: Huawei RNC Capacity Dimension

6

RNC Capacity Limitation

There define a relationship between CS Erlang and throughput as follows:

1 CS Erlang = 16kbps throughput.

The relation comes from the processing consuming in WFMRb board.

CS Erlang and CS Throughput

For each RNC subrack :

CS throughput + PS throughput <= 60Mbps;

CS throughput < = 40Mbps;

CS Throughput and PS Throughput

Page 7: Huawei RNC Capacity Dimension

7

RNC Capacity Limitation

Supposing each call duration is 120s. The maximum CS throughput is 40Mbps,

equals to 2500Erl.

Erl = BHCA * Call duration /3600

It can derive that : BHCA = 2500/(120/3600) = 75,000

BHCA calculation from CS 40Mbps

1. This index is used to measure the signaling processing capability in WSPUb.

2. The equivalent BHCAconsiders the procedure not only the call procedure, but

also other signalling procedure, including SMS, IMSI attachment, location update,

handover, cell update, URA update, etc.

3. The equivalent BHCA comes from the test data where the WSPUb CPU load is

up to 80%.

4. The maximum equivalent BHCA is 360k and the WSPUb CPU load is 80%.

Equivalent BHCA

Note: The actual signaling capacity is limited by Integrated BHCA

Page 8: Huawei RNC Capacity Dimension

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RNC Capacity Limitation

Basic Signaling Equivalent BHCA

CS BHCA per BM per BH 1.00

PS BHCA per RNC per BH 1.00

Location Area Update per RNC per BH 0.46

Routing Area Update per RNC per BH 0.46

Soft Handover Addition per RNC (intra/inter RNC) 0.26

Soft Handover Deletion per RNC (intra/inter RNC) 0.13

Softer Handover Addition per RNC (intra/inter RNC) 0.18

Softer Handover Deletion per RNC (intra/inter RNC) 0.09

CS Inter-RAT handover per RNC 0.56

PS channel switching per RNC 0.41

SMS per RNC per BH 0.46

Paging per RNC per BH 0.01

RRC REJ 0.15

Equivalent BHCA

Page 9: Huawei RNC Capacity Dimension

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RNC Capacity Limitation

The maximum number of subscriber depends on the Integrated BHCA, call

model and maximum data throughput:

equivalent BHCA(# Subscriber, call model) < Maximum Equivalent BHCA

Total throughput ( #Subscriber, call model) < Maximum data throughput

Maximum Subscribers number

60M per subRack

Procedure multiplied per Cost 360k

Page 10: Huawei RNC Capacity Dimension

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Board information

1. WFMRb board is user plane processing board, handling the user data of

AAL2 cell for Iu/Iub/Iur interface.

2. One RNC subrack contains 10 WFMRb with the maximum capability of

60Mbps for PS throughput or 40Mbps for CS throughput

3. The maximum user plane capability of WFMRb board in RAN5.1 is 6Mbps

for PS packet processing. (MAC layer 7.2M)

4. For CS voice processing, 4Mbps can be handle for each WFMRb board.

5. WFMRb board contributes to the RNC total PS throughput as well as the

CS throughput.

WFMRb

Page 11: Huawei RNC Capacity Dimension

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Board information

1. WSPUb board is signalling processing board which handle the RANAP/

RNSAP/SS7/QAAL2/RRC/NBAP signaling;

2. Each WSPUb board could handle 75,000 BHCA (for typical traffic model) which

does not includes the location update, paging, handover, SMS,

attaching/detaching, etc. procedure.

3. The maximum equivalent BHCA is 360k and the WSPUb CPU load is 80%.

1. WOSEc board is Iub interface board.

2. Each WOSEc board can process 60Mbps throughput.

WSPUb

WOSEc

Page 12: Huawei RNC Capacity Dimension

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Board Information

1. WFMRb and WSPUb are the main boards contributing to RNC capacity;

2. WOSEc board is the Iub interface board which is not the limitation for the

RNC capacity;

3. WMUXb board is the switching board in each sub-rack and is not the

limitation for the RNC capacity;

Summary

Page 13: Huawei RNC Capacity Dimension

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Some analysis for New Year’s eve

1. Between 00:00-00:15, Altogether 21000 CS call attempts processed by

RNC 121, but only 13000 RAB assigned by CN, so somewhere in CN must

be overload.

2. Between 00:00-00:59, Altogether 51055 RRC connect rejected, among

them 49683 belong to SMS, only 1372 belong to voice call.

Conclusion:

Between 00:00-00:15, both RNC and CN are overloaded.

RNC is overloaded (RRC rejection) with only 600 Erlangs because abnormal

high number of SMS and Core network lack of reply.

Page 14: Huawei RNC Capacity Dimension

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RRC EVOLUTION NEW YEAR CHARTS RRC.FailConnEstab.Cong

0

10000

20000

30000

40000

50000

600002

00

6-1

2-3

1 2

1:0

0:0

0

20

06

-12

-31

22

:00

:00

20

06

-12

-31

23

:00

:00

20

07

-01

-01

00

:00

:00

20

07

-01

-01

01

:00

:00

20

07

-01

-01

02

:00

:00

20

07

-01

-01

03

:00

:00

20

07

-01

-01

04

:00

:00

20

07

-01

-01

05

:00

:00

20

07

-01

-01

06

:00

:00

20

07

-01

-01

07

:00

:00

20

07

-01

-01

08

:00

:00

20

07

-01

-01

09

:00

:00

20

07

-01

-01

10

:00

:00

RRC Attemps New year

0

20000

40000

60000

80000

100000

120000

140000

160000

2006

-12-

31 2

0:00

:00

2006

-12-

31 2

3:00

:00

2007

-01-

01 0

2:00

:00

2007

-01-

01 0

5:00

:00

2007

-01-

01 0

8:00

:00

2007

-01-

01 1

1:00

:00

2007

-01-

01 1

4:00

:00

2007

-01-

01 1

7:00

:00

2007

-01-

01 2

0:00

:00

2007

-01-

01 2

3:00

:00

2007

-01-

02 0

2:00

:00

2007

-01-

02 0

5:00

:00

2007

-01-

02 0

8:00

:00

2007

-01-

02 1

1:00

:00

2007

-01-

02 1

4:00

:00

2007

-01-

02 1

7:00

:00

SumaDeRRCAttConnEstabUnknow n

SumaDeRRCAttConnEstabTmStrCall

SumaDeRRCAttConnEstabTmLw PrSig

SumaDeRRCAttConnEstabTmInterCall

SumaDeRRCAttConnEstabTmHhPrSig

SumaDeRRCAttConnEstabTmConvCall

SumaDeRRCAttConnEstabTmBkgCall

SumaDeRRCAttConnEstabReg

SumaDeRRCAttConnEstabOrgStrCall

SumaDeRRCAttConnEstabOrgInterCall

SumaDeRRCAttConnEstabOrgConvCall

SumaDeRRCAttConnEstabOrgBkgCall

SumaDeRRCAttConnEstabOgSubCall

SumaDeRRCAttConnEstabOgLw PrSig

SumaDeRRCAttConnEstabOgHhPrSig

SumaDeRRCAttConnEstabIRATCelRes

SumaDeRRCAttConnEstabIRATCCO

SumaDeRRCAttConnEstabEmgCall

SumaDeRRCAttConnEstabDetach

SumaDeRRCAttConnEstabCallReEst

SMS locUpdate

interRAT

CS call orig

Page 15: Huawei RNC Capacity Dimension

15

Mapping nodeb to SubRack 40 nodeb on SubRack1 Half of NodeB on Cpu1

Page 16: Huawei RNC Capacity Dimension

16

SPU load evolution

CPU WSPU1:1

0%

20%

40%

60%

80%

100%

30/1

2/2

006 0

:00

30/1

2/2

006 4

:00

30/1

2/2

006 8

:00

30/1

2/2

006 1

2:0

0

30/1

2/2

006 1

6:0

0

30/1

2/2

006 2

0:0

0

31/1

2/2

006 1

:00

31/1

2/2

006 5

:00

31/1

2/2

006 9

:00

31/1

2/2

006 1

3:0

0

31/1

2/2

006 1

7:0

0

31/1

2/2

006 2

1:0

0

01/0

1/2

007 2

:00

01/0

1/2

007 6

:00

01/0

1/2

007 1

0:0

0

01/0

1/2

007 1

4:0

0

01/0

1/2

007 1

8:0

0

01/0

1/2

007 2

2:0

0

VS.MeanCPUUtil.SPU

VS.MaxCPUUtil.SPU

WFMRName Time(As hour) VS.MeanCPUUtil.FMRVS.MaxCPUUtil.FMR

WFMR:1:1 01/01/2007 0:00 26% 31%

WFMR:1:12 01/01/2007 0:00 29% 34%

WFMR:1:13 01/01/2007 0:00 26% 30%

WFMR:1:14 01/01/2007 0:00 26% 31%

WFMR:1:2 01/01/2007 0:00 27% 33%

WFMR:1:3 01/01/2007 0:00 26% 31%

WFMR:1:4 01/01/2007 0:00 29% 34%

WFMR:1:5 01/01/2007 0:00 24% 29%

WFMR:1:6 01/01/2007 0:00 27% 33%

WFMR:1:9 01/01/2007 0:00 25% 30%

More space on User plane than Signalling plane

Page 17: Huawei RNC Capacity Dimension

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SPU Dimension using current CPU load

• Total nber of subcribers in network: 1000k

• Erlangs_RNC121/TotalErlangs=2% =>20k Subs in RNC121

• Erlangs for each Nodeb from counters

• Nodeb to SPU map( worse SPU 40 nodeb among 87)

• The cpu load is 8% for common task if the traffic load is 0

• Cpu load with 275 Erlangs=40% at BH and limit is 80%

=> the SPU can handle 275*(80-8)/(40-8)=618 Erlangs

=> If 618/87=7 Erlangs per nodeB => a SPU can handle 550/7=78Nodeb

Erlangs per SPU

=600*40/87=275 Erl

600Erl