Simulation of Third Generation CDMA Systems - Virginia Tech

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2.2 shows the spreading and modulation for a downlink user. The downlink user has aDPDCH and a DPCCH. Additional DPDCHs are QPSK modulated and spread with differentchannelization codes.cos(ω c t)Scrambling Code(C SC )p(t)DPDCH/DPCCHSerialtoParallelChannelization Code(C ch )jp(t)sin(ω c t)Figure 2.2: Downlink Spreading and ModulationWe can observe some differences between the spreading and modulation in thedownlink and that in the uplink. The data modulation is QPSK in downlink whereas it isBPSK for the uplink. The data rates in the I and Q-channels are the same in the downlinkwhereas data rates in the I and Q-channel of the uplink may be different. The scramblingcode is cell specific in the downlink, whereas it is mobile station specific in the uplink.As in the uplink, Square-Root Raised Cosine filters with roll-off factor of 0.22 areemployed for pulse shaping. The pulse shaped signal is subsequently upconverted as shownin Figure 2.2. The OVSF codes and the scrambling codes are described in sections 2.4 and2.5 respectively.2.2 Uplink Frame StructureFigure 2.3 shows the principal frame structure of the uplink dedicated physicalchannels. Each frame of 10 ms is split into 15 slots. Each slot is of length 2560 chips,corresponding to one power control period. The super frame length is 720 ms; i.e. a superframe corresponds to 72 frames.12
DataPilotTFCI FBI TPCT slot =2560 chips, 10×2 k bits (k = 0..6)Slot 1 Slot i Slot 15T f =10 msFrame 1 Frame i Frame 72T super =720 msFigure 2.3: Frame Structure for Uplink DPDCH/DPCCHPilot bits assist coherent demodulation and channel estimation. TFCI stands fortransport format combination indicator and is used to indicate and identify severalsimultaneous services. Feedback Information (FBI) bits are to be used to support techniquesrequiring feedback. TPC which stands for transmit power control is used for power controlpurposes. The exact number of bits of these different uplink DPCCH fields is given in [6].The parameter k in Figure 2.3 determines the number of bits in each slot. It is relatedto spreading factor (SF) of the physical channel asSF= 256k2(2.1)The spreading factor thus may range from 256 down to 4. The spreading factor isselected according to the data rate.13
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: Channelization Code(C D )cos(ω c t
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 and 38: 2.9.2 Transmit Diversity SchemesTra
Page 39 and 40: These differences will become evide
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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