To enhance the performance of opportunistic cooperative relaying systems

this paper proposes the power allocation algorithms aiming at minimizing the outage probability.The optimization model of the system is constructed and proved to be a convex optimization problem.Then the optimal power allocation algorithm and its operation steps are presented.Furthermore a simple and effective near-optimal power allocation strategy is developed

which only depends on the average channel gains of the relays and thus incurs little overhead.Simulation and numerical results show that significant performance gains can be achieved by the two proposed power allocation algorithms.