Energy-aware cooperation strategy with uncoordinated group relays for delay-sensitive services

Due to channel fading and user mobility in wireless networks, quality-of-service (QoS) provisioning for multimedia services requires great effort. It is even more challenging to support the fast-growing multimedia services in a green manner. As a promising technique, cooperative communications make use of the broadcasting nature of the wireless medium to facilitate data transmission, and it can achieve energy saving. To support the delay-sensitive multimedia services in an energy-efficient manner, we consider a new framework in this paper where multiple source-destination pairs share a group of relays with an energy constraint. We also propose an effective uncoordinated cooperation strategy, which is based on the backoff timer. The theoretical performance bounds of the proposed strategy are derived with respect to the collision probability and the transmission success probability. As shown in the numerical and simulation results, the proposed strategy outperforms a probability-based uncoordinated strategy in terms of average packet delay, delay outage probability, and energy consumption. Further, we investigate the scalability of our proposed strategy and find that it can be deployed in a large-scale network.