Optimal Relay Assignment and Power Allocation in Selection Based Cooperative Cellular Networks

We consider a system with a single base station communicating with multiple users over orthogonal channels while being assisted by multiple relays. Several recent works have suggested that selection, i.e., a single relay helping the source, is the best option in terms of the resulting complexity and overhead. However, in a multiuser setting, optimal relay assignment is a combinatorial problem. In this paper, using the sum rate as our design metric, we develop a convex optimization problem that provides an extremely tight upper bound on performance. We also provide a heuristic to find a close-to-optimal relay assignment. Simulation results using realistic channel models demonstrate the efficacy of the proposed scheme.