Diversity and Delay-Limited Throughput Analysis for the Effective Cooperative ARQ Protocols with Opportunistic Distributed Space-Time Coding

The paper investigates effective protocols and the corresponding performance for cooperative automatic retransmission request (ARQ) that uses the decode-and-forward (DF) opportunistic distributed space-time coding (ODSTC). According to the analysis, the delay-limited throughput enjoys significant enhancement even using one or two active relays only for ARQs than using direct retransmissions. Besides, allowing the non-active relays to overhear the DSTC signal sent by active relays during ARQs also leads to a better throughput via ODSTC. Nevertheless, in the high or the low SNR regimes, simple schemes without overhearing may provide almost the same performance offered by a scheme with overhearing despite the much inferior diversities. These features may be further explored to enhance the overall system throughput for multiple access systems using only limited system resources.