Multipath-Based User Selection Scheme for Multiuser Beamforming in MIMO Distributed Antenna Systems

An efficient multipath-based user selection (MPUS) algorithm for multiuser beamforming in multiple-input multiple-output (MIMO) distributed antenna systems (DAS) is presented in this paper. Motivated by the idea behind the M algorithm of MIMO detection, in this paper, we generate a scheduling tree having M nodes. From each of the M retained nodes, the M "best" users having the largest branch metrics are extended, and of the M² contenders that result, only the M best are retained before advancing to the next level. Meanwhile, to limit the search range, candidate groups are firstly generated by QR decomposition. In the last stage, the best scheduling path having the largest sum rate is selected as the output. The sum rate performance evaluation of the proposed algorithm is given by computer simulation and its complexity is evaluated by measuring the total number of floating-point operations (flops).