Research the outage performance in decode-and-forward cognitive system

An approximate outage probability formulation were derived for decode-and-forward (DF) cooperative relay networks on the premise of guarantee primary user quality of service(QoS) and limit of maximal power in cognitive user. The full space diversity is achieved on optimal relay selection strategy. By Monte Carlo simulation, the rationality of the approximate outage probability formulation is validated. Theoretical analysis and simulation results show that, in cognitive system, number of relay are sources of diversity gain.