Two-Level HARQ for Turbo Coded Cooperation

Wireless networks can exploit an implicit distributed diversity by the use of cooperative systems thanks to the broadcast nature of the radio link. Cooperation leads to improvements in terms of throughput and/or performance and decreases the sensitivity to channel variations. In this paper, a practical approach for a two-user cooperative wireless network is proposed based on a particular hybrid automatic repeat request (HARQ) protocol and turbo coded cooperation. In particular, we propose a two-level ARQ protocol where decision on retransmission is conditioned by two levels; first by the feedback from the destination and second by the feedback from the partner node. The proposed two-level ARQ protocol, combined with turbo coded cooperation, is designed to guarantee inter-user channel improvement through the relay-level ARQ, and consequently better overall system performance and higher throughput by controlling retransmission at destination side.