Joint iterative channel estimation and decoding in flat correlated Rayleigh fading

• Published in: IEEE journal on selected areas in communications Vol. 19; no. 9; pp. 1706 - 1717
• Main Authors: Komninakis, C., Wesel, R.D.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2001; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Channel estimation; Channels; Correlation; Decoding; Fading; Frequency; Iterative decoding; Iterative methods; Markov models; Mathematical models; Phase shift keying; Probability; Rayleigh channels; Studies; Symbols; Turbo codes; Upper bound
• ISSN: 0733-8716; 1558-0008
• DOI: 10.1109/49.947035

This paper addresses the design and performance evaluation with respect to capacity of M-PSK turbo-coded systems operating in frequency-flat time-selective Rayleigh fading. The receiver jointly performs channel estimation and turbo decoding, allowing the two processes to benefit from each other. To this end, we introduce a suitable Markov model with a finite number of states, designed to approximate both the values and the statistical properties of the correlated flat fading channel phase, which poses a more severe challenge to PSK transmission than amplitude hiding. Then, the forward-backward algorithm determines both the maximum a posteriori probability (MAP) value for each symbol in the data sequence and the MAP channel phase in each iteration. Simulations show good performance in standard correlated Rayleigh fading channels. A sequence of progressively tighter upper bounds to the capacity of a simplified Markov-phase channel is derived, and performance of a turbo code with joint iterative channel estimation and decoding is demonstrated to approach these capacity bounds.