Simulation of Third Generation CDMA Systems - Virginia Tech

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Chapter 3Simulator DescriptionThis chapter describes the simulator designed to evaluate the Bit Error Rate (BER) at theuplink and the downlink of a Wideband CDMA (WCDMA) system. Data is transmitted in aframe by frame basis over a time varying multipath channel. Receiver design incorporatesrake diversity combining. Additive White Gaussian Noise (AWGN) is added at the front endof the rake receiver. Multiple Access Interference (MAI) is generated in a structured wayrather than treating it as AWGN. No error correction coding schemes or antenna diversitytechnique was considered for the basic simulator. However we will show in chapter 4 that thesimulator is very flexible and can be modified to incorporate error correction coding.3.1 SimulatorThe simulator consists of two major subsections:• Uplink Simulator• Downlink SimulatorAs their names indicate, these two subsections implement the uplink and thedownlink of the simulator respectively. The major differences between them are:1. Frame structure2. The way Multiple Access Interference (MAI) is added to the signal of the desireduser28
These differences will become evident as we describe the simulator in the subsequentsections. The following sections contain a detailed description of the WCDMA simulator.3.2 Uplink SimulatorAt the uplink, the base station receiver receives signals from all the mobile stationtransmitters and demodulates them. The signals from different MS follow different channelsto reach the base station. The block diagram of the uplink simulator is shown in figure 3.1.1st InterfererRaisedCosineFilterTimeVaryingChannel2nd InterfererRaisedCosineFilterTimeVaryingChannelNth InterfererRaisedCosineFilterTimeVaryingChannel+MAIDesiredMSRaisedCosineFilterTimeVaryingChannel+RakeReceiverBERCounterGaussianNoiseGeneratorRoot-RaisedCosineFilterFigure 3.1: Uplink SimulatorThe following sub-sections describe each block of the uplink simulator.3.2.1 Desired MSThe desired MS is the user for which the simulator estimates the BER. The desireduser has a dedicated control channel and one data application as shown in Figure 3.2. The29
Page 1 and 2: Simulation of Third Generation CDMA
Page 3 and 4: AcknowledgmentsI would like to expr
Page 5 and 6: 2.9.2. Transmit Diversity Schemes2.
Page 7 and 8: List of Tables1.1 3G Data Rate Requ
Page 9 and 10: 3.9 Implementation of Pulse shaping
Page 11 and 12: Chapter 1IntroductionThe goal for t
Page 13 and 14: 1.3 Third Generation Cellular Syste
Page 15 and 16: 1.4. WCDMA: Air Interface for 3GOne
Page 17 and 18: 1.4.2 WCDMA Key Technical Character
Page 19 and 20: Chapter 2WCDMA Physical LayerThis c
Page 21 and 22: Channelization Code(C D )cos(ω c t
Page 23 and 24: DataPilotTFCI FBI TPCT slot =2560 c
Page 25 and 26: 2.4 Uplink Spreading CodesThe sprea
Page 27 and 28: Figure 2.6: Auto-correlation for Tw
Page 29 and 30: The following block diagram shows t
Page 31 and 32: 0.180.160.140.12Probabilty Density0
Page 33 and 34: ar( 0) = 2vr( 0) + 1 (2.12)mod 4ar(
Page 35 and 36: 2.8 Channel CodingThe main purpose
Page 37: 2.9.2 Transmit Diversity SchemesTra
Page 41 and 42: Dtoffset = 2 (3.15)cHere c is the v
Page 43 and 44: Each ray is split into two rays, on
Page 45 and 46: The pass-band of the pulse shaping
Page 47 and 48: The Rayleigh waveform is generated
Page 49 and 50: This expression can be used directl
Page 51 and 52: e -jϕ1FrameAlignmentResamplingDesc
Page 53 and 54: 3.2.7 BER CounterThe bit error rate
Page 55 and 56: (t)R i ’(t)R i (t)e -jϕ i C SC *
Page 57 and 58: IT+ τT + τi i i I iτ iτ iiiz =
Page 59 and 60: 3.3.2 MAI for DownlinkThe MAI in th
Page 61 and 62: menu is provided which gives the op
Page 63 and 64: up_sim.mpar_up.mat ovsf_gen.m scram
Page 65 and 66: 3.6 Code OptimizationThe simulator
Page 67 and 68: Chapter 4Simulation ResultsThis cha
Page 69 and 70: 10 0 E b/N 010 -1BER10 -210 -30 int
Page 71 and 72: 10 0 Number of Interfererssf=32sf=1
Page 73 and 74: 10 0 E b/N 00 interferer2 interfere
Page 75 and 76: 10 -1 Number of InterferersBER10 -2
Page 77 and 78: constraint length. So for a constra
Page 79 and 80: Table 4.1: Performance Improvement
Page 81 and 82: channel model based on measurement
Page 83 and 84: [7] Kevin Laird, Nick Whinnet, and
Page 85: VitaFakhrul Alam was born in Dhaka,

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