Low-Complexity Power Allocation Schemes for the Downlink of Nonregenerative Cooperative Multi-User MIMO Communication System

Abstract: Amplify-and-forward (AF) is one of the most popular and simple approaches to transmit information over a cooperative multi-input multi-output (MIMO) relay channel. In this paper, we propose two novel power allocation methods for the downlink of multi-user multi-input multi-output AF cooperative system, which are designed to optimise the sum-rate of the cooperative system according to the weighted sum-rate criterion. The main optimisation problem is not concave and our two methods aim at simplifying it in order to turn it into a concave problem, which can then be easily solved