Outage performance of cooperative multihop transmission in cognitive underlay networks

In this paper, we consider a multi-hop transmission using cooperative communication in cognitive underlay networks. Relying on the broadcast characteristic of wireless medium, the secondary destination and secondary relays can receive the data, which is transmitted by the secondary source or by previous secondary relays. In this protocol, at any stage, if the secondary destination cannot successfully decode the data, a successful secondary relay, which is nearest to the secondary destination is chosen to retransmit the data at next stage. We evaluate and compare performance of the proposed protocol with that of the conventional multi-hop transmission. In particular, we derive exact expressions of end-to-end outage probability and their correction is verified by Monte-Carlo simulations.