System Level Design of Time-Hopping Impulse ModulationMohit JaloriRaghu RajThe University of Texas at AustinProblem Statement• Objectives:– To implement the transmitter, receiver andchannel for the multi user time hopping system.– To evaluate the performance of the system fordifferent pulse shapes and channel impairmentsProgrammableTime DelayDataPNGeneratorChannelPNGeneratorCrossCorrelatorReceivedDataåOur Approach• Multi User Transmitter Section– Generates Gaussian Monocycles, GaussianPulse, Raised Cosine and Manchester Pulse.– Generated gold sequences using 18th orderconnection polynomial.• Receiver Section– Frame Level Syncronization– Sliding Cross-Correlator ImplementationOur Approach (contd.)• Channel– Simulated Rayleigh Fading due to multipathpropagation– Added White Gaussian noise to the transmittedSignal– Neglected Effects due to Doppler frequencyshiftsResults-5 0 5 100.0060.0080.010.0120.0140.0160.0180.020.0220.024SNR (dB)Bit Error RatePerformance comparision of Gaussian, Monocycle, Raised Cosine, Manchester pulse shapesGaussianMonocycleRaised CosineManchesterResults2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7567891011Num ber of MultipathsBit Error Rate (BER)*10-3Performance comparision of Gaussian, Monocycle, Raised Cosine, pulsesGaussianMonocycleRaised Cosine0 20 40 60 80 100 120 140 160-2.5-2-1.5-1-0.500.511.522.5Gaussian Monocycle Pulse0 20 40 60 80 100 120 140 16001234567Gaus s ian P uls e with variance = 20 20 40 60 80 100 120 140 160-0.500.511.522.5Rais ed Cos ine Puls e0 5 10 15 20 25-80-60-40-2002040Spectrum ofRaised Cosime PulseAmplitude (dB)0 5 10 15 20 257891011121314151617Spectrum of Gaussian pulse0 5 10 15 20 25-60-50-40-30-20-10010Spectrum of Gaussian MonocycleFrequency GHzAmplitude (dB)Future Work• Including the effect of Doppler frequencyshifts• Including the forward error correction codes• Feasibility of developing systems capable ofgenerating Gaussian and Raised cosinepulses upto the accuracy of
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