An Efficient Algorithm for Optimum Power Allocation in a Decode-And-Forward Cooperative System with Orthogonal Transmissions

We propose an efficient algorithm that computes the maximum achievable rate of a decode-and-forward multi-relay cooperative system with orthogonal transmissions under total power constraint. In P.A. Angel et al. we have argued that in a system with Q relays the optimum rate can be found by solving Q convex problem despite the fact that the optimization problem is not convex and it belongs to a class of problems with variational inequality constraints. In this paper we show that the number of computations can be reduced from solving Q convex problem to solving only [log(Q)] + 1 convex problems. The proposed algorithm facilitates comparisons with competing alternatives in cooperative systems such as the amplify-and-forward or the compress-and-forward strategies