Influence of power allocation and relay location on cooperative system's performance

In this paper, we propose an optimum power allocation method (OPA) which to minimize the the symbol-error-rate (SER) performance for a two-user amplify-and-forward cooperative system. With this optimum and equal power allocation (EPA) methods, we also discuss the impact of relay location to the SER performance and ergodic capacity by making use of two characteristic rectangle and ellipse topologies. With the EPA method, the ergodic capacity and SER curves show an interesting symmetric characteristic and the optimum relay location is just in the middle with respect to the source and destination. While a different conclusion is drown with the OPA method, the optimum relay location is near the destination in this case.