A Joint Beamforming based SDMA Protocol for IEEE 802.11n Downlink

• Main Authors: Cheng Guo, Liqiang Zhao, Hui Zhao, Whai-En Chen
• Format: Article
• Language: English
• Published: European Alliance for Innovation (EAI) 2015-09-01
• Series: EAI Endorsed Transactions on Wireless Spectrum
• Subjects: wlan; sdma; beamforming; array antenna; mimo precoding
• Online Access: http://eudl.eu/doi/10.4108/eai.19-8-2015.2260221

To support space division multiple access (SDMA) in the IEEE 802.11n downlink, a joint beamforming based MAC protocol, J-MAC is presented in this paper. An access point (AP) follows J-MAC, which employs multiple array antennas, and user equipments (UEs) follow the IEEE 802.11x standard which employ omni-directional MIMO antennas. J-MAC maintains full compatibility with 802.11x, and UEs do not change any more. In J-MAC, firstly, the AP achieves the weight vector for the array antenna-based beamforming, and updates it periodically. Secondly, before transmitting any data-frame, the AP achieves the weight vector for the MIMO-based beamforming, which should be updated in each transmission. Finally, after getting the joint beamforming, the AP transmits its data-frames to multiple UEs simultaneously. Simulation results show that J-MAC can support the joint beamforming effectively and provide much higher network throughput, lower delay, jitter and packet-loss-rate than DCF does.