EM based MAP channel estimation for turbo/convolutional coded SFBC/STBC-OFDM systems


Dogan H. , Çırpan H. A. , Panayirci E.

IEEE 14th Signal Processing and Communications Applications, Antalya, Turkey, 16 - 19 April 2006, pp.105-106 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume:
  • Doi Number: 10.1109/siu.2006.1659853
  • City: Antalya
  • Country: Turkey
  • Page Numbers: pp.105-106

Abstract

We 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.