Research On SDMA Protocol Based On Joint Beamforming In IEEE802.11n Wireless LANs Downlink

The new generation WLAN IEEE802.11n employed new technologies to enhancePHY and MAC, improving the downlink transmission rate and throughput, but it stillonly concentrates on point-to-point transmission. When there is a line-of-sight (LOS)component between the transmitter and receiver, transmitter which employs arrayantennas is capable of achieving SDMA and providing array gains. In addition, MIMObeamforming could improve the transmission quality. Through the employment of arrayantennas and MIMO beamforming in802.11n PHY layer, the key research of this thesisis a new WLAN MAC protocol to support SDMA communications based on jointbeamforming (J-BF). The main contributions are as follows:(1) By using joint array antennas beamforing and MIMO beamforming in802.11nPHY layer, the downlink transmission quality is researched and the performance thatJ-BF counteracts multiuser interference is analysed.(2) On the basis of DCF protocol, J-MAC is proposed, which is capable ofsupporting J-BF effectively and realizing downlink SDMA communications.J-MAC maintains full compatibility with802.11x and the User Equipments (UEs)do not change any more. Simulation results show that J-MAC supports the SDMAeffectively in the downlink and improves the system performance of802.11nsignificantly.