Opportunistic Cooperative Relaying with Backoff-Based Contention

In this chapter, we focus on an opportunistic relaying scenario and develop two distributed cooperation strategies. Both adopt a backoff-based inter-group coordination, while the intra-group contention is based on either the forwarding probability or backoff timer. In particular, we employ stochastic geometry to address the impact of spatial distribution of relays. Considering a Poisson point process for random relays, we derive the probability distributions of the average received signal-to-noise ratio (SNR) and transmission success probability of potential relays. Making use of such statistics and location information, each relay can independently determine its contention parameters such as a backoff time and/or a forwarding probability. We analytically evaluate the relaying performance and validate the accuracy with simulations. The results demonstrate the improvement over a pure probabilistic scheme and the gap to the upper bound of a centralized scheme with the pre-selected best relay.