Abstract: This paper proposed a cooperative automatic repeat request (ARQ) mechanism with multiple relays based on communication distance, in order to achieve high energy efficiency, saturation throughput rate and reliable transmission simultaneously. Considering the characteristics of traditional ARQ mechanism and dividsion of network layer packets into link layer frames, a Markov chain model was built for analyzing the characteristics of the saturation throughput rate,packet dropping probability,average delay and energy efficiency with the different communication distance. On the otherhand,a cooperative ARQ based on the Markov model was established for performance analysis and evaluation of the mechanism proposed in this work. Especially, a linear WSNs model was considered. hhe mathematical analyses show that compared with the traditional ARQ the proposed cooperative ARQ can perform better in terms of saturation throughput rate, reliability and energy efficiency.

Key words: Wireless sensor networks, Cooperative communication, Automatic repeat request, Markov chain, Performance evaluation