Huawei RNC Capacity Dimension

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Huawei RNC

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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

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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

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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

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RNC Dimension

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

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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;

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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

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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

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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

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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.

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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

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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;

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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.

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RRC EVOLUTION NEW YEAR CHARTS

RRC.FailConnEstab.Cong 0 10000 20000 30000 40000 50000 60000 2 0 0 6 -1 2 -3 1 2 1 :0 0 :0 0 2 0 0 6 -1 2 -3 1 2 2 :0 0 :0 0 2 0 0 6 -1 2 -3 1 2 3 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 0 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 1 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 2 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 3 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 4 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 5 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 6 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 7 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 8 :0 0 :0 0 2 0 0 7 -0 1 -0 1 0 9 :0 0 :0 0 2 0 0 7 -0 1 -0 1 1 0 :0 0 :0 0

RRC Attemps New year

0 20000 40000 60000 80000 100000 120000 140000 160000 06 -1 2-31 2 0: 00 :0 0 06 -1 2-31 2 3: 00 :0 0 07 -0 1-01 0 2: 00 :0 0 07 -0 1-01 0 5: 00 :0 0 07 -0 1-01 0 8: 00 :0 0 07 -0 1-01 1 1: 00 :0 0 07 -0 1-01 1 4: 00 :0 0 07 -0 1-01 1 7: 00 :0 0 07 -0 1-01 2 0: 00 :0 0 07 -0 1-01 2 3: 00 :0 0 07 -0 1-02 0 2: 00 :0 0 07 -0 1-02 0 5: 00 :0 0 07 -0 1-02 0 8: 00 :0 0 07 -0 1-02 1 1: 00 :0 0 07 -0 1-02 1 4: 00 :0 0 07 -0 1-02 1 7: 00 :0 0 SumaDeRRCAttConnEstabUnknow n SumaDeRRCAttConnEstabTmStrCall SumaDeRRCAttConnEstabTmLw PrSig SumaDeRRCAttConnEstabTmInterCall SumaDeRRCAttConnEstabTmHhPrSig SumaDeRRCAttConnEstabTmConvCall SumaDeRRCAttConnEstabTmBkgCall SumaDeRRCAttConnEstabReg SumaDeRRCAttConnEstabOrgStrCall SumaDeRRCAttConnEstabOrgInterCall SumaDeRRCAttConnEstabOrgConvCall SumaDeRRCAttConnEstabOrgBkgCall SumaDeRRCAttConnEstabOgSubCall SumaDeRRCAttConnEstabOgLw PrSig SumaDeRRCAttConnEstabOgHhPrSig SumaDeRRCAttConnEstabIRATCelRes SumaDeRRCAttConnEstabIRATCCO SumaDeRRCAttConnEstabEmgCall SMS _locUpdate interRAT CS call orig

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Mapping nodeb to SubRack

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SPU load evolution

CPU WSPU1:1 0% 20% 40% 60% 80% 100% 0 0 6 0 :0 0 0 0 6 4 :0 0 0 0 6 8 :0 0 0 6 1 2 :0 0 0 6 1 6 :0 0 0 6 2 0 :0 0 0 0 6 1 :0 0 0 0 6 5 :0 0 0 0 6 9 :0 0 0 6 1 3 :0 0 0 6 1 7 :0 0 0 6 2 1 :0 0 0 0 7 2 :0 0 0 0 7 6 :0 0 0 7 1 0 :0 0 0 7 1 4 :0 0 0 7 1 8 :0 0 0 7 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%

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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