Simulation of Third Generation CDMA Systems - Virginia Tech

More documents

Recommendations

Info

filter. This Doppler filter imparts correlation to the time domain samples according to theDoppler spread. The Doppler spread is a function of the mobile speed. The waveform comingout of the Clarke’s model waveform generator has a Rayleigh amplitude distribution and auniform phase distribution between [0,2π]. The mean value of the amplitude is unity. Wemultiply this waveform by the amplitude of the corresponding path and use that as theRayleigh waveform in the time varying channel of figure 3.5.N-τ samplesτsamplesN samples = 1 FrameτsamplesN-τ samplesN samples = 1 FrameFigure 3.6: Implementation of Delay of τ SamplesFigure 3.7: Interpolation Noise in the Rayleigh Waveform. (The Factor of Interpolationis Five)36
The Rayleigh waveform is generated at a sampling rate equal to the chip rate.Samples for higher sampling rate is constructed by interpolation. This reduces the simulationtime significantly at the expense of an injection of a small amount of noise. The noisegenerated as a result of interpolating the Rayleigh waveform is insignificant as shown inFigure 3.7.The Rayleigh waveform can be generated at the symbol rate rather than at the chiprate. This will reduce the simulation run time even more. Even for a relatively large Dopplerspread of 223 Hz which corresponds to a mobile speed of 120 km/h, the interpolation noiseremains below –30 dB for the worst case scenario of a sampling factor of 8 and a spreadingfactor of 256. This noise does not cause any measurable change in the BER.3.2.4 Addition of NoiseThe Additive White Gaussian Noise (AWGN) added at the front end of the receiver isgenerated by a Gaussian random number generator. The variance of the noise distributiondepends on the Signal to Noise Ratio (SNR) or E Nb0at the receiver front end. The noisevariance is also a function of the spreading factor, signal amplitude and sampling rate i.e. thenumber of samples per chip. The calibration of noise is discussed in the following section.3.2.4.1 Calibration of NoiseLet us assume for the time being that no pulse shaping is employed. Figure 3.8a and3.8b show the chip and the double sided noise spectrum.37
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 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: The pass-band of the pulse shaping
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,

Simulation of Third Generation CDMA Systems - Virginia Tech

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?