| Medium Access Control (MAC) protocol is an important part in the network protocol stack of Ad Hoc network, and it is mainly used to coordinate nodes to access the shared wireless channel. Whether MAC protocol can utilize the limited wireless resource plays a crucial role in Ad Hoc network performance. With the development of various multimedia services and real-time business, the network bandwidth and delay are required to provide a guarantee, the QoS has become a current research question as a new hot spot. At Ad Hoc network, the functions of MAC layer are that controlling node packet transmission, occupying wireless media and ensuring the overall performance of the network. MAC layer locates on the lower layer of protocol stack, controls packets to be sent and received in the channel, efficiently using the wireless channel is a key factor for that the upper range of protocol and mechanisms get Final protection.On the basis of the MAC protocol, the performance of a variety of MAC protocol is analyzed in this dissertation for Ad Hoc network, Dual-channel and improved handshakes are integrated, design a medium access control (MAC) protocol called DCMAC (dual-channel MAC) for ad hoc networks. Based on receiving control packets, nodes use 3 different network allocation vectors (NAV) in control channel or data channel. The hidden terminal can receive data simultaneously and the exposed terminal can also transmit data. As can be seen through the performance analysis, a comparison with a RTS/CTS based protocol is given. The results show that the DCMAC protocol can improve the throughput. A detailed analysis is proposed on how to guarantee the quality of service at MAC layer in Ad Hoc network. As the technique based on DiffServ, combined the EDCF mechanism of 802.11e and the improved backoff method, using dual-channel to solve the QoS guarantee problem. The result of simulation proves the scheme can improve the throughput of network and the quality of serve for real-time traffic. |
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