DCF/DSDMA: Enhanced DCF with SDMA downlink transmissions for WLANs

Multi-user MIMO is a promising technology to enhance the performance of WLANs. However, the MAC protocol of the IEEE 802.11 standard (the DCF MAC protocol) is not able to solve the new coordination and synchronization issues that are needed to enable multiple simultaneous transmissions. This paper presents an enhanced MAC protocol for Downlink SDMA in WLANs where only the Access Point is equipped with multiple antennas. Compared to the traditional WLANs, results show that the proposed protocol is able to exploit the benefit of multiple antennas at the Access Point, providing significant performance gains in terms of throughput and delay as well as the most suitable number of active users that a WLAN can support.