EM based MAP iterative channel estimation for turbo coded SFBC-OFDM systems

Conference: TURBO - CODING - 2006 - 4th International Symposium on Turbo Codes & Related Topics; 6th International ITG-Conference on Source and Channel Coding
04/03/2006 - 04/07/2006 at Munich, Germany

Proceedings: TURBO - CODING - 2006

Pages: 6Language: englishTyp: PDF

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Dogan, Hakan; Çirpan, Hakan A. (Department of Electrical-Electronics Engineering, Istanbul University, 34320 Avcilar, Istanbul, Turkey)
Panayirci, Erdal (Department of Electrical-Electronics Engineering, Bilkent University, 06800 Bilkent, Ankara, Turkey)

We consider the design of turbo receiver structures for space-frequency block coded (SFBC-)OFDM systems in unknown frequency selective fading channels. The Turbo receiver structures for SFBC-OFDM systems under consideration consists of an iterative MAP Expectation/Maximization (EM) channel estimation algorithm, soft MMSE SFBC decoder and a soft MAP outer-channel-code decoder. MAP-EM employs iterative channel estimation and it improves receiver performance by re-estimating the channel after each decoder iteration. Moreover, the MAP-EM approach considers the channel variations as random processes and applies the Karhunen-Loeve (KL) orthogonal series expansion. The performance of the proposed approaches are studied in terms of mean square error and bit-error rate. Through experimental results, the effect of a pilot spacing on the channel estimator performance and sensitivity of turbo receiver structures on channel estimation error are studied.