Client Selection for Coordinated IEEE 802.11ac Multi-user MIMO-enabled Access Points

Although downlink multi-user MIMO (MU-MIMO) technology is included in the IEEE 802.11ac Standard, multi-cell interference in IEEE 802.11ac MU-MIMO networks degrades expected performance gain from the technology due to unplanned deployment of access points. To this end, recent research efforts envision that a central controller coordinates a set of APs to alleviate the multi-cell interference. However, to fully exploit the benefits of the coordinated access points with MU-MIMO, it is essential that clients should be carefully selected to maximize aggregate throughput. While an exhaustive search gives the optimal solution, its computationally infeasibility in large size networks requires another solution. Therefore, in this paper, we formulate a client selection problem for coordinated access points and suggest a polynomial time algorithm. Evaluation results show that our algorithm achieves about 98 % of the optimal aggregate throughput with a moderate computational overhead.