Title :
Non-pilot-aided iterative decoding for joint data recovery and channel estimation in fading
Author :
Komninakis, Christos ; Wesel, Richard D.
Author_Institution :
California State Univ., Los Angeles, CA, USA
Abstract :
Decoding in wireless rapidly fading channels requires that the receiver has access to explicit or implicit channel-state information (CSI). This paper presents a joint channel estimation and decoding scheme for frequency-flat, time-selective Rayleigh fading with relatively high Doppler, that does not require external phase information or even pilot symbols. This system outperforms a pilot-aided iterative channel estimation algorithm that does not decode and estimate jointly. The joint decoding algorithm models the phase trajectory of the channel as a suitable Markov process, the dynamics of which depend on the Doppler rate. At each iteration it considers all possible phase trajectories to determine the maximum a posteriori probability (MAP) value for each bit. This decoding procedure is a natural extension of standard turbo decoding, but introduces a significant complexity increase. Performance is assessed via an upper bound to the capacity of a Markov-phase channel.
Keywords :
Doppler effect; Markov processes; Rayleigh channels; computational complexity; estimation theory; iterative decoding; maximum likelihood decoding; time-varying channels; turbo codes; Doppler; Markov process; Markov-phase channel; channel estimation; complexity; data recovery; explicit channel-state information; frequency-flat time-selective Rayleigh fading; implicit channel-state information; joint decoding algorithm; maximum a posteriori probability value; nonpilot-aided iterative decoding; phase trajectory; receiver; turbo decoding; wireless rapidly fading channels; AWGN; Channel estimation; Fading; Frequency estimation; Gaussian noise; Iterative decoding; Phase shift keying; Rayleigh channels; Signal to noise ratio; Turbo codes;
Conference_Titel :
Signals, Systems, and Computers, 1999. Conference Record of the Thirty-Third Asilomar Conference on
Conference_Location :
Pacific Grove, CA, USA
Print_ISBN :
0-7803-5700-0
DOI :
10.1109/ACSSC.1999.831883