Design of Distributed Multiple Turbo Codes for Block-Fading Relay Channels

In this paper, we consider the half-duplex relay channel. We seek to design multiple turbo codes to minimize the information outage in the block fading channel. An analysis on the diversity order of the relay channel, which depends on the time sharing variable and the rate of the code, is given for practical modulations. We also give a code structure for the multiple turbo codes to achieve the full diversity when it is achievable. The codes are optimized using the extrinsic information transfer (EXIT) chart analysis, based on the convergence thresholds of the iterative decoding tailored for relay channel. Numerical examples shows that with our design technique, the achieved frame error rate is within 0.7dB of the information outage. To reduce complexity, a suboptimum code search approach is proposed, resulting codes which perform 1dB away from the information outage.