An Improved Hybrid ARQ Scheme in Cooperative Wireless Networks

Hybrid ARQ (HARQ) has been shown to be an effective transmission strategy to improve the performance and capacity of relayed transmission in cooperative wireless networks. In contrast to the conventional HARQ, the retransmitted packets in cooperative systems do not need to come from the original source but could instead be sent by relays that overhear the transmission. This paper proposes an improved HARQ scheme with an adaptive relaying protocol (ARP). The proposed HARQ- ARP scheme combines the retransmission mechanisms (repetition coding and incremental redundancy), the distributed turbo coding (DTC) and the adaptive relaying strategy. They can effectively avoid the problem of both error propagation and noise amplification encountered in current cooperative communication systems. A performance analysis is carried out for the proposed scheme. The analysis and simulation results show that the proposed HARQ scheme can achieve a superior frame error rate (FER) to the existing HARQ relaying methods in all signal to noise ratio (SNR) regions.