Performance analysis and relay selection region for interfered opportunistic relaying wireless sensor and ad hoc networks

In this study, the authors investigate the performance of opportunistic relaying (OR) in wireless sensor and ad hoc networks in an interference environment and propose a relay selection region for OR. Assuming that nodes are homogeneously distributed according to Poisson point process, the authors find closed-form expressions of the outage probability and transmission capacity for the OR wireless networks. After this, they further derive the diversity-multiplexing tradeoff (DMT) for OR at finite signal-to-noise ratios (SNRs) and then find an upper bound of source node density to guarantee the diversity gain to be positive, that is, the outage probability of OR decreases as SNR grows. On the basis of these analyses, the authors find out the relay selection region where the transmission capacity of OR is better than that of direct transmission (DRT). The simulation results show that OR does not always perform better than DRT when the density of source nodes is large. In this case, we can improve the performance of OR by selecting the region of relays. In addition, the results show that DMT is degraded as the spatial correlation (interference) increases and OR cannot achieve full diversity order in the interfered network. Moreover, asymptotic analyses show that the proposed framework can also be used for the interference-free situation.