Outage Analysis of Hop-by-Hop Relay Selection in Multi-Hop Cognitive Relay Networks

We propose a hop-by-hop relay selection strategy for multi-hop decode-and-forward (DF) underlay cognitive relay networks (CRNs). In this strategy, taking both maximum transmit power and maximum interference constraints into account, one relay in each decoding set is selected to transmit to the next hop. Relay selection at each stage only depends on the channel state information (CSI) of the following hop. We analyze the performance of the proposed strategy in terms of end-to-end outage probability. Numerical results are presented from analysis which closely match those obtained from simulation. The results are compared to those from other hop-by-hop strategies, showing improved outage probability. Moreover, the numerical results show that the outage probability of the proposed method is very close to that of exhaustive strategy which provides a lower bound for outage probability of all relay selection methods.