Capacity comparison of WCDMA and GSM

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GSM: Capacity is hard blocked, limited by the amount of hardware. TRX number

WCDMA: Capacity is Soft Capacity, it is a interference limited system, we cant get the capacity by the hardware quantity.

The traffic will be affected by following factor1 DL Power 2 Signal quality (Ec/Io, RX level)3 Iub Transmission 4 (OVSF)Code Resource 5 CE ResourceDifferent Capacity Calculation of WCDMA and GSM

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GSM Capacity Calculation FlowTRXTRX1 TRX =8 time soltsErlang-B table Budget ErlangThe utilization can be higher than 100%Case studyThe Traffic is base on TRX time slot amount, there is no other factor affect the traffic, if the time slot is fixed, the Traffic is fixed

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Capacity & Coverage Users Capacity Capacity Cell CoverageCapacity & Quality Capacity Quality (interference ) Quality (Ec/Io , Rx Level ) Capacity Coverage & Quality Quality (Ec/Io ) Cell CoverageWCDMA Coverage Capacity Quality RelationFor a soft capacity limited system, the Erlang capacity cannot be calculated from the Erlang B formula, since it would give too pessimistic results

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1 DL Power 2 Signal quality (Ec/Io, RX level)3 Iub Transmission 4 (OVSF)Code Resource 5 CE Resource

WCDMA Capacity Calculation

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5 W for power control4 W for common channel11 W for Traffic channel1 DL power analysisDL total power is 20WIf DL power utilization is over 75%,DL power congestion.DL Loading=DL used power/Total powerReserved powerUsable power,75% of total powerIf the user use the max service ,one cell can support 2 384K subscriber,one site can only support 6

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3G:The DL Cell power is dynamic. If User is far away the cell or the signal quality is bad, the cell need to use higher power to maintain it service .So the max and min user will be change. The DL power utilization will affect the cell user number and traffic

2G:The DL power is fixed. It will not affect the cell user number and trafficIf one subscriber want to access one cell ,it will increase the DL power utilization. So the DL power is the main resource in WCDMA system.

Question :If the DL power is the main resource, can we use high power RRU to improve it ?how 60W or 80W RRU? Answer:No, we cant do like this. Because the WCDMA is self interference system. If one cell improve its TX power, it will increase the Io, so the Ec/Io will become very bad. In WCDMA, We need to control the coverage to improve the Ec/Io quality 1 DL power analysis

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2 Signal quality analysisCell capacity Cell Interference Cell Ec/Io Cell Ec/Io Cell A Cell BCell capacity

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EbitProcessing GainEchipService Ec / Io= Eb / No PG (Processing Gain)2 Signal quality analysisSpreading and DespreadingIf user TCH Ec/Io is lower than 6.2 dB, the cell cant provide 384k service

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3G: WCDMA is a self interference system The capacity is affected by RX level and Ec/Io. Ec/Io is the main factor to affect cell capacity. 2G: The capacity is affected by RX level.

2 Signal quality analysis

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3 Iub TransmissionIf the DL power isnt in congestion, and the DL Ec/Io is higher than -9.2 dB, then one site throughput can reach 5.8Mbps.As we know, The mobility of subscribers, fluctuation of the radio signals, the variety of service and the complexity of the network system has made Ec/Io and DL power in unstable situation, it is very hard to let the site throughput reach 5.8Mbps. one site cant support 12 users if DL Ec/Io is very bad or DL power is not enough

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4 OVSF ResourceOVSF:Orthogonal Variable Spreading Factor In WCDMA system, Channelisation code uses OVSF code, for keeping the orthogonality of different subscriber physical channels. One cell only has one OVSF tree

SF = 1

SF = 2

SF = 4

Cch,1,0 = (1)

Cch,2,0 = (1,1)

Cch,2,1 = (1,-1)

Cch,4,0 =(1,1,1,1)

Cch,4,1 = (1,1,-1,-1)

Cch,4,2 = (1,-1,1,-1)

Cch,4,3 = (1,-1,-1,1)

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4 OVSF ResourceOne sites OVSF can support 21 384K subs if DL power is enough or the Ec/Io is good.

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5 CE ResourceCase studyIn this case ,users number is limited by the DL CE, because it is 64.But one site capacity can support 256 DL CE, it can support more subs

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DL power is the main resource in WCDMA system.So we need to monitor its utilization, if the DL power utilization is reach 70%,we can say the site utilization is 100%

DL Power Utilization =DL used power/Total power

Summary

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Typical Capacity

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CE Consuming of differenct service

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Ladies and gentlemen, good morning/afternoon. Welcome to (visit Huawei or visit Huaweis booth,) and attending todays presentation. Its my honor to have this opportunity to make an introduction of Huawei Mobile Core Network Solutions to you. During my presentation, you are welcomed to ask any questions at any time. I am happy to answer your questions. As you can see from our slogan, technology changes from time to time but human communications has never stopped. At Huawei, we are sparing no efforts to enable the best communication with our commitment to the telecommunications industry in areas including technology, products and solutions, customer service and others.

The capacity of GSM systems are basically determined by the hardware resources: there are 8 timeslots in each transceiver, therefore the number of voice channels available in one cell would dictate the number of simultaneously connected subscribers The capacity of GSM systems are basically determined by the hardware resources: there are 8 timeslots in each transceiver, therefore the number of voice channels available in one cell would dictate the number of simultaneously connected subscribersThe last but not the least. We want to use this picture to show that in this company we stress teamwork as part of corporate culture. So behind every project, there are over 24000 people supporting it.That is a brief introduction about Huawei GSM. Thank you very much.