Turbo-like codes over the block fading channel: code design and construction

Transmission of turbo-like codes over block fading channels is addressed. We present a novel construction based on blockwise concatenation that yields maximum distance separable turbo-like codes. We emphasize the importance of blockwise concatenation with respect to standard (serial, parallel or hybrid) constructions that perform well on the fully interleaved (ergodic) fading channel, but may suffer severe degradation in the block fading (non-ergodic) case. We analyze the performance of the proposed codes by means of upper bounds on the maximum-likelihood (ML) decoding error probability and we show that iterative decoding performs very close to ML even for short block lengths. We discuss how the proposed codes approach outage probability and we show that blockwise concatenated codes perform close to outage probability also in the case of long block lengths.