A Limited Feedback SDMA Scheme with Dynamic Multiplexing Order

摘要

The employment of a fixed number of active beams in limited feedback SDMA schemes usually results in severe inter-user interferences in sparse networks. Targeting a good tradeoff between the multiplexing gain and the inter-user interferences, this paper proposes a novel kind of limited feedback SDMA scheme, which employs a variable number of active beams, i.e., a dynamic multiplexing order. The proposed two transmit schemes consist of the modification of conventional feedback information and the development of two novel scheduling algorithms based on a maximum likelihood (ML) estimation of possible user interferences. More specifically, the ML estimation utilizes a combination of the feedback partial instantaneous channel state information (CSI) and the long-term channel correlation, and the two new scheduling algorithms select the active beam subset as well as the user group with the criterion of maximizing the estimated sum throughput. Simulation results demonstrate that in sparse networks the proposed SDMA schemes considerably outperform some conventional schemes in terms of the sum throughput, with a comparable feedback overhead.