Joint mode/route selection and power allocation in cellular networks with cooperative relay

In a cellular network with cooperative relaying, each node may choose to communicate with the source node directly or use the cooperative communication mode with the assistance of a relay node. The transmission mode (either direct or cooperative) and the transmit power of the source and relay nodes affect not only performance of individual links, but also the overall system capacity. In this paper, we propose a cross-layer design that jointly considers the transmission mode/relay node selection (MRS) with power allocations (PA) in order to optimize the network capacity. This is first formulated as an optimization problem for a cellular system, where the same frequency channel can be reused in different cells. We then design a low complexity heuristic MRS scheme based on the link and interference conditions of the source and potential relay nodes. Given the transmission mode and relay node (if the cooperative mode is chosen) of each link, the transmit power of the source and relay nodes are solved by the geometric programming method. Numerical results are demonstrated to verify the effectiveness of the joint MRS and PA method.