Huawei RNC Capacity dimension
Capacity dimension Principle for capacity dimension Input from operator ( Total subscribers in network, traffic model)
RNC capacity limitation ( Erl, Throughput,BHCA)
Number of WRBS
If Nodebs per WRBS >100
Subscribers per WRBS
Nodebs per WRBS
Radio Network dimension
Subscribers per Nodeb
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
Limitation
Limiting factor : throughput capacity
e.g.
120Mbps / 60Mbps = 2
Limiting factor : BHCA capacity
e.g.
60,000 / 75,000 = 0.8
Limiting factor : NodeB capacity
e.g.
150 / 100 = 1.5
Limiting factor : Cell capacity
e.g.
400 / 300 = 1.3
60Mbps/ WRBS
2 WRBS
75,000/ WRBS
1 WRBS
100 NodeB/ WRBS
2 WRBS
300 NodeB/ WRBS
2 WRBS
RNC Dimension 2*63 channalized E1s
Max. Capacity for different RNC types Traffic capacity Interfaces RNC types
Configure
Small Capacity RNC 1WRSS+1WRBS Medium Capacity RNC 1WRSS+3WRBS High Capacity RNC 1WRSS+6WRBS
Iub Mbps
NodeB
Cell
STM-1
E1(ATM)
E1(IP)
77 206 461
100 300 600
300 900 1800
30 26 20
64 192 384
64 192 384
Channelize d STM-1 32 2 96 6 192 12 FE
Traffic Capacity
Small Capaticy RNC 1 WRSS+ 1 WRBS
95000
85500
50.19
Media Capacity RNC 1 WRSS+ 3 WRBS
287000
258300
High Capacity RNC 1 WRSS+ 6 WRBS
574000
516600
VF CALL PROFILE DATAS
923.4
52.25
28.50
7.654
151.56 2789.64 157.85
86.07
20.623
303.10 5579.28 315.7
172.13
46.162
RNC Capacity Limitation CS Erlang and CS Throughput 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 Throughput and PS Throughput For each RNC subrack : CS throughput + PS throughput <= 60Mbps; CS throughput < = 40Mbps;
RNC Capacity Limitation BHCA calculation from CS 40Mbps 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 Equivalent BHCA 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%.
Note: The actual signaling capacity is limited by Integrated BHCA
RNC Capacity Limitation Equivalent BHCA 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) Softer Handover Deletion per RNC (intra/inter RNC)
0.18 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
RNC Capacity Limitation Maximum Subscribers number The maximum number of subscriber depends on the Integrated BHCA, call model and maximum data throughput: Procedure multiplied per Cost
360k
equivalent BHCA(# Subscriber, call model) < Maximum Equivalent BHCA 60M per subRack
Total throughput ( #Subscriber, call model) < Maximum data throughput
Board information WFMRb 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.
Board information WSPUb 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%.
WOSEc 1.
WOSEc board is Iub interface board.
2.
Each WOSEc board can process 60Mbps throughput.
Board Information Summary 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;
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.
RRC EVOLUTION NEW YEAR CHARTS RRC.FailConnEstab.Cong 60000 50000 40000 30000 20000 10000 0 0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
0 0 :
1 2
2 2
3 2
0 0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
0 1
0 0 :
1 3 2 1 6 0 0 2
0 0 :
1 3 2 1 6 0 0 2
0 0 :
1 3 2 1 6 0 0 2
0 0 :
1 0 1 0 7 0 0 2
0 0 :
1 0 1 0 7 0 0 2
0 0 :
0 0 :
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
0 0 :
0 0 :
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
0 0 :
0 0 :
1 0 1 0 7 0 0 2
0 0 :
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
0 0 :
1 0 1 0 7 0 0 2
0 0 :
1 0 1 0 7 0 0 2
RRC Attemps New yea r
SMS
locUpdate
CS call orig
160000
SumaDeRRCAttConnEstabTmStrCall SumaDeRRCAtt ConnEstabTmLw PrSig
interRAT
140000
SumaDeRRCAttConnEstabUnknow n
SumaDeRRCAttConnEstabTmInterCall SumaDeRRCAtt ConnEstabTmHhPrSig
120000
SumaDeRRCAttConnEstabTmConvCall
100000
SumaDeRRCAttConnEstabTmBkgCall
80000
SumaDeRRCAttConnEstabReg
60000
SumaDeRRCAttConnEstabOrgStrCall SumaDeRRCAttConnEstabOrgInterCall
40000
SumaDeRRCAttConnEstabOrgConvCall
20000
SumaDeRRCAttConnEstabOrgBkgCall SumaDeRRCAttConnEstabOgSubCall
0 0 0 : 0 0 : 0 2
0 0 : 0 0 : 3 2
0 0 : 0 0 : 2 0
0 0 : 0 0 : 5 0
0 0 : 0 0 : 8 0
0 0 : 0 0 : 1 1
0 0 : 0 0 : 4 1
0 0 : 0 0 : 7 1
0 0 : 0 0 : 0 2
0 0 : 0 0 : 3 2
0 0 : 0 0 : 2 0
0 0 : 0 0 : 5 0
0 0 : 0 0 : 8 0
0 0 : 0 0 : 1 1
0 0 : 0 0 : 4 1
0 0 : 0 0 : 7 1
1 3 2 1 6 0 0 2
1 3 2 1 6 0 0 2
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
1 0 1 0 7 0 0 2
2 0 1 0 7 0 0 2
2 0 1 0 7 0 0 2
2 0 1 0 7 0 0 2
2 0 1 0 7 0 0 2
2 0 1 0 7 0 0 2
2 0 1 0 7 0 0 2
SumaDeRRCAttConnEstabOgLw PrSig SumaDeRRCAttConnEstabOgHhPrSig SumaDeRRCAtt ConnEstabIRATCelRes SumaDeRRCAtt ConnEstabIRATCCO SumaDeRRCAtt ConnEstabEmgCall SumaDeRRCAttConnEstabDetach SumaDeRRCAttConnEstabCallReEst
Mapping nodeb to SubRack 40 nodeb on SubRack1
Half of NodeB on Cpu1
SPU load evolution
FMRName
VS.MeanCPUUtil.SPU
CPU WSPU1:1
VS.MaxCPUUtil.SPU
100% 80% 60% 40% 20% 0%
0 0 : 0
0 0 : 4
0 0 : 8
6 0 0 2 / 2 1 / 0 3
6 0 0 2 / 2 1 / 0 3
6 0 0 2 / 2 1 / 0 3
0 0 : 2 1
0 0 : 6 1
0 0 : 0 2
6 0 0 2 / 2 1 / 0 3
6 0 0 2 / 2 1 / 0 3
6 0 0 2 / 2 1 / 0 3
0 0 : 1
0 0 : 5
0 0 : 9
6 0 0 2 / 2 1 / 1 3
6 0 0 2 / 2 1 / 1 3
6 0 0 2 / 2 1 / 1 3
0 0 : 3 1
0 0 : 7 1
0 0 : 1 2
6 0 0 2 / 2 1 / 1 3
6 0 0 2 / 2 1 / 1 3
6 0 0 2 / 2 1 / 1 3
0 0 : 2
0 0 : 6
7 0 0 2 / 1 0 / 1 0
7 0 0 2 / 1 0 / 1 0
0 0 : 0 1
0 0 : 4 1
0 0 : 8 1
0 0 : 2 2
7 0 0 2 / 1 0 / 1 0
7 0 0 2 / 1 0 / 1 0
7 0 0 2 / 1 0 / 1 0
7 0 0 2 / 1 0 / 1 0
Time(As hour)
eanCPUUtil axCPUUtil.
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
SPU Dimension using current CPU load
•
Total nber of subcribers in network: 1000k 600Erl
•
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%
Erlangs per SPU =600*40/87=275 Erl
=> 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
