Abstract: The MAC protocol for supporting the application of smart antennas in the mobile Ad Hoc network(MANET) is studied. An adaptive beamforming CSMA/CA protocol(ABF-CSMA/CA) is proposed. In ABF-CSMA/CA, the RTS/CTS dialogue is used and training sequences are transmitted just before RTS and CTS packets, so the temporal reference beamforming(TRB) can be performed. An improved virtual carrier-sense mechanism is also proposed to enhance collisioin avoidance(CA) and obtain efficient space division multiple access(SDMA). In this scheme, every node has two kinds of network allocation vector(NAV)- o NAV and b NAV. A theoretical analysis of channel utilization is presented. Results show that the ABF-CSMA/CA protocol can support the application of smart antennas effectively and rpovide higher channel utilization.

Key words: mobile Ad Hoc networks, smart antennas, multiple access protocol, performance analysis