Research On Mobile Ad Hoc Network Using Smart Antennas

With the development of Internet and computer networking technology, wireless mobile communication technology is increasingly important to the application of computer networking. Mobile Ad Hoc network is one of the applicable wireless mobile communication technologies. This dissertation focuses on the approach to employ smart antenna in mobile Ad Hoc network nodes, then propose the adaptive beamforming CSMA/CA protocol(ABF-CSMA/CA).Firstly, the character of the Ad Hoc network is synthetically introduced. Some problems of the Ad Hoc network are also presented. For example, when the nodes of the network share the same channel under the control of the distributed multiple-access protocol, the existence of hidden terminal and exposed terminal will seriously influence the utilization efficiency of the channel. On the other hand, the smart antennas has the ability of measuring direction and adaptive beamforming. If the smart antennas are applied in the mobile nodes of the Ad Hoc network, the performance of the network will be highly approved. So the dissertation mainly research on this technology.When the mobile nodes are in the state of waiting, the smart antenna operate in omnidirectional mode. But after the nodes receive the packets of RTS/CTS dialogue, the nodes will be in the adaptively beamforming mode. At this time, the antennas in the receiving and transmitting nodes receive and transmit packets in the directional-antenna mode. Concretely, smart antennas form the digital beam ,namely directional transmit based on the LMS adaptive algorithm. All the process above is defined as the adaptive beamforming CSMA/CA(ABF-CSMA/CA) protocol.Finally, the module of smart antenna is implemented in the simulation environment, then the module of smart antenna is applied in the mobile nodes of the Ad Hoc network. After the analysis of simulation , and compared with the Ad Hoc network using omnidirectional antennas, it shows that the bit error rate and the throughput of the mobile nodes are improved obviously. And the Ad Hoc network with smart antennas can provide higher channel utilization.