A grouped multi-user diversity scheme based on adaptive space division multiplexing

In the multi-user multiple-input multiple-output (MIMO) systems employing space division multiplexing (SDM), the downlink capacity is limited by the spatial channel resources. In this paper, a novel grouped multi-user diversity (GMUD) scheme is proposed on the basis of adaptive SDM. In view of the characteristics of SDM algorithm, the scheme first divides all users into groups in such a way that the users whose principal right singular vectors have the least cross correlation are put into the same group. Then using a novel adaptive SDM scheme, the attainable capacity of each group is computed, and the channel is allocated to the group with the maximal capacity. Simulation results show that the proposed GMUD scheme can not only provide fair resource utilization, but also dramatically improve the system capacity due to the adoption of multi-user diversity and adaptive spatial channel allocation.