Reduced-Complexity User and Data-Stream Scheduling for Multiuser MIMO Downlink

Abstract

We consider the scheduling problem in multiuser multiple-input multiple-output (MIMO) systems with successive zero-forcing precoding and coordinated transmit-receive processing. Focusing specifically on the problem of user and data stream scheduling, we allow variable number of data streams per user. Optimal scheduling employing exhaustive search for a constant number of streams per user is already combinatorially complex, and is further compounded by allowing for a variable number of streams per user. We consider a suboptimal metaheuristic scheduling algorithm based on simulated annealing, an algorithm which has shown to provide quick and relatively good solutions to combinatorial optimization problems. We introduce various parameters and examine their impact on the performance of the algorithm. Simulated annealing is shown to offer comparable results at a fraction of the computational cost of the exhaustive search. Our contributions to this area are emphasized in the conclusion and future areas of work are discussed.