Evaluation of generalised relay selection in the presence of feedback delay for multi-hop relaying

In this work, the impact of outdated channel state information because of feedback delay is evaluated for the performances of several generalised relay selection schemes. Multi-hop amplify-and-forward relaying is considered over Rayleigh fading channels. Numerical results show that different relay selection schemes suffer from different performance degradations when the hop index increases. Interestingly, for generalised relay selection, numerical results also show that selecting more relays does not necessarily lead to better power outage probability and bit error rate performances. These observations provide useful guidance on relaying system designs.