Doǧan, H.Çırpan, H. A.Panayırcı, Erdal2016-02-082016-02-082006-04http://hdl.handle.net/11693/27200Date of Conference: 17-19 April 2006Conference name: 2006 IEEE 14th Signal Processing and Communications ApplicationsWe consider the design of turbo receiver structures for space-frequency block coded (SFBC/STBC) OFDM systems in unknown frequency selective fading channels. The Turbo receiver structures for SFBC/STBC-OFDM systems under consideration consists of an iterative MAP Expectation/Maximization (EM) channel estimation algorithm, soft MMSE SFBC/STBC 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. © 2006 IEEE.TurkishDecodersKarhunen-Loeve (KL) orthogonal series expansionTurbo receiverBit error rateBlock codesFading channelsIterative decodingMean square errorOptimizationOrthogonal frequency division multiplexingTurbo codesChannel estimationConference Paper10.1109/SIU.2006.1659853