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Adaptive Reduced StateTransition Viterbi Differential Detection of MAry DPSK Signals Transmitted over Gaussian and Frequency Nonselective Rayleigh Faded Channels
Fumiyuki ADACHI
Publication
IEICE TRANSACTIONS on Communications
Vol.E82B
No.1
pp.156164 Publication Date: 1999/01/25 Online ISSN:
DOI: Print ISSN: 09168516 Type of Manuscript: PAPER Category: Mobile Communication Keyword: Mary DPSK, differential detection, Viterbi algorithm, fading, adaptive channel estimation,
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Summary:
Adaptive maximum likelihood differential detection implemented by a reduced statetransition Viterbi algorithm (called adaptive 3state RSTVDD) is presented for adaptive reception of Mary differential phase shift keying (DPSK) signals transmitted over additive white Gaussian noise (AWGN) and frequencynonselective Rayleigh fading channels. The adaptive 3state RSTVDD comprises 1DD, a differential encoder, and reverse modulator, followed by reducedstate (3state) Viterbi DD (RSVDD) with adaptive phase reference estimation. The adaptive 3state RSVDD detector estimates the sequence of phase errors of the 1DD output. The phase reference estimator is an adaptive least mean square (LMS) filter with a stepsize that adapts to changing channel conditions. The final detected symbol sequence is the modulo2π sum of the 1DD output phase sequence and the detected phase error sequence. The bit error rate (BER) performance of Mary DPSK, M=4, 8, and 16, in the AWGN and Rayleigh fading channels is evaluated by computer simulation to show that adaptive 3state RSTVDD can achieve almost the same BER performance as the previously developed adaptive Mstate RSVDD. Since the number of trellis states is reduced to three irrespective of M, the adaptive 3state RSTVDD has lower computation complexity and it is particularly useful for Mary DPSK with M8.


