Joint and iterative detection and decoding of differentially encoded COFDM systems

Abstract

Divsalar and Simon showed that with multi-symbol differential detection, the performance gap between two-symbol differential detection and coherent detection of differentially encoded phase shift keying can be closed. To close this gap for single-carrier differentially encoded phase shift keying with interleaving and convolutional encoding, Peleg et al. proposed a joint and iterative multi-symbol detection and decoding scheme that regards the differential encoding as inner component code of a serially concatenated code. Several data-, audio- and video-broadcast systems are differentially encoded multi-carrier systems and use time multiplexing of the transmitted services to reduce receiver complexity. The commonly used receiver-structure for these systems does not perform joint and iterative multi-symbol detection and decoding. The present work extends the use of the single-carrier iterative decoding scheme proposed by Peleg et al. to demodulate differentially encoded multi-carrier systems. A novel two-dimensional block-based demodulation is proposed that maintains both the multi-symbol differential detection coding gain and the reduction in receiver complexity by time-multiplexing. Simulations show that with comparable receiver-complexity, the proposed multi-carrier scheme outperforms the single-carrier scheme by ≈ 0.9 dB. Furthermore, the receiver complexity can be reduced up to a factor of four and a half compared to the single-carrier scheme. Finally, the proposed multi-carrier scheme outperforms ”classical” two-symbol differential detection with soft-decision Viterbi-decoding by ≈ 2.8 dB with one iteration and by ≈ 1.2 dB without iterations.