Research On Mac Protocol In Ad Hoc Networks

Ad Hoc Network is a self-organizing multi-hop networks, and access protocol it's an important part of the Ad Hoc network protocol. Due to the matters of resources lack, the correspond between nodes is not easy, and the node's characteristic such of mobility, the access procotol is hard to make efficient use of channel resources. Therefore, how to design an efficient access agreement becomes a major part of this paper.In order to solve the problem of packet conflict in the traditional analysis of access protocol, this paper simulates two kinds of representative protocols: distributed coordination protocol and the enhanced distributed coordination protocol. The results show that distributed coordination protocol to enhance network performance, but there is no reasonable use of network resources. And the enhanced distributed agreement established a transport stream according to the probability of species allocated bandwidth priority mechanism, but still exists the problem of packet collisions which result in network performance problems.As analyzing the advantages and disadvantages of the above, this paper presents the concept of integrated distributed agreement.To improve the performance of network, first we should find the reasons causing packet collisions. We found through indepth analysis of existing settlement mechanism research mainly adopts handshake mechanism to avoid conflict, but the nodes are often not correct receive control packet, thus forming "masked nodes", Meanwhile, current implementations of the RTS/CTS mechanism may give rise to situations where a large number of nodes are unnecessarily refrained from transmitting packets for long periods of time. Simulation proves the existence of the two problems and the results show that those problems reduced the network performance.In order to solve the above two problems, thesis proposes a comprehensive distributed procotol and carries on the modeling。The CDCF procotol to adopt the RTS validation mechanism, this mechanism evaluate the state of channel before send a packet. Simulation results show that this protocol can be very good solution to these two questions with the minimum cost in a certain extent improve the network performance.