A novel multiple access protocol for mobile ad hoc networks with smart antennas

Smart antennas technology is one of the hot-spot in the research areas of wireless communications. However, its applications to the mobile stations do not receive wide attention. In this paper, the approach to employ smart antennas in mobile ad hoc network (MANET) nodes is presented. An adaptive beamforming CSMA/CA protocol (ABF-CSMA/CA) is proposed. In ABF-CSMA/CA, RTS/CTS dialogue is used to distribute channel reservation information. Training sequences are transmitted just before RTS and CTS packets based on non-persistent CSMA, so the temporal reference beamforming (TRB) can be performed by the source node and the destination node. An improved virtual carrier sense mechanism is also proposed to enhance collision avoidance (CA) and obtain efficient space division multiple access (SDMA). Theoretical analysis of channel utilization of the proposed protocol is presented. Analysis and simulations show that ABF-CSMA/CA protocol combining with smart antennas can provide higher channel utilization.