Joint optimal resource allocation schemes for downlink cooperative cellular networks over orthogonal frequency division multiplexing carriers

This study concentrates on the study of a downlink cooperative cellular (DCC) network in which an access point is located in the centre of each cell and two relay stations are installed in the border between both sectors of a cell to obtain higher cell‐edge throughput. To optimise the network efficiency, a joint optimal subcarrier and power allocation scheme is proposed which initially derives the highest achievable rate for a single‐legacy user (LU), then, through further evaluation and analysis, this is generalised to the case of a multiple‐LU environment. Next, to maximise the overall throughput and ensure fairness, a multi‐objective lexicographical optimisation problem (MLOP) is formulated to maximise the minimum LUs rate while improving the overall throughput. As the proposed MLOP is a mixed‐integer non‐linear problem, finding optimal solutions is impractical and in general, there is no standard method for optimally obtaining a solution. Hence, two efficient algorithms are introduced in this study. Simulation results confirm that the proposed algorithms achieve a fair and near‐optimal performance for the multi‐LU DCC network based on two relay channels, which makes them desirable in practice compared to some of the sub‐optimal well‐known algorithms investigated in this study.