A Threshold-Selective Multiuser Downlink MAC Scheme for 802.11n Wireless Networks

The emerging 802.11n standard establishes the integration of MIMO technology in WLANs with the goal of achieving high data rates. However there are still many open issues regarding MAC protocol design for MIMO based systems, especially in order to exploit the multiuser capabilities of the MIMO channel. In this paper we propose a novel MAC scheme that considers an opportunistic channel-aware scheduling policy to achieve simultaneous downlink transmissions to multiple users. In an effort to offer a complete and practicable proposal, our MAC scheme is combined with a low-complexity beamforming technique at the Physical layer in a system where multiple antennas are employed at least at the transmitter side (Access Point). A mathematical model for the throughput performance of the proposed scheme is presented and validated through link-layer simulation results.