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UBC Theses and Dissertations

Performance analysis of Viterbi decoding in Rayleigh fading with channel estimation errors Lin, Dingyi


Previous studies on the effect of channel estimation errors on the bit error rate (BER) performance of Viterbi decoding (VD) concern various types of fading channels with additive white Gaussian noise (AWGN), modulation and interleaving schemes. Pairwise error probabilities (PEP) have been derived using Laplace transform. Studies of VD on fading channels with impulsive noise and perfect channel estimation are also available in the literature. In this thesis, the BER performance of unquantized VD with BPSK is analyzed for a frequency-nonselective slow Rayleigh fading channel with AWGN and Gaussian distributed channel estimation errors. Closed-form expressions for the PEP are derived. Upper bound and lower bound on the BER are obtained. It is shown that channel estimation errors have the same effect on BER as channel noise. Computer simulation results show that the upper bound is fairly tight. In practice, the channel might be estimated using pilot symbols, together with various interpolation filters. It is shown that the channel estimation error variances are usually unequal for different data symbol positions. The BER performance of VD optimized for unequal estimation error variances is compared with that of VD optimized for equal variances using computer simulation. The BER performance of VD in Rayleigh fading and impulsive noise with channel estimation error is also studied. The optimal metrics are derived for VD in Rayleigh fading with Gaussian channel estimation errors, for Laplacian noise and Gaussian mixture noise. The BER performances of VD’s for various scenarios are compared.

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