| Ad Hoc network is a temporary, multi-hop, centerless autonomous system which is composed of a group of mobile terminals with wireless transmitters and receivers. Compared to wired networks, wireless networks have limited bandwidth. The characteristics of multi-hop and the equivalence of the nodes provide the opportunity for nodes in Ad Hoc network to send data at the same time. Dynamic change of the network demand that the MAC protocol should have good adaptability. The diversity of service requires the MAC protocol could meet the service requirements very well. Therefore, designing an reasonable and efficient MAC protocol which can meet the characteristics of the Ad Hoc network is of great significance.Combined with the existing MAC protocols’characteristics and the design requirements in Ad Hoc network, we put forward a hybrid MAC protocol with dynamic slot allocation in Ad Hoc network. The protocol includes three stages. In the stage of service priorities distribution, node service can be divided into real-time and non real-time service. The protocol uses the TOSS code to distinguish the service; In the stage of time slot allocation, in order to adapt to the dynamic change of network load and improve the spatial reuse of network, protocol will finish the allocation of time slot according to the service information of the two-hop nodes. In the stage of the time slot competition and data transmission, other nodes can compete for the time slots which couldn’t be used reasonable. Nodes that Compete successfully can send data. In order to adapt to the dynamic changes of the network load, the protocal uses the method of competitive license to supervise and control the number of nodes to compete the channel.The network simulation software NS2 was adapted to evaluate the overall performance of the network and algorithm performance. The results show that the protocol can improve the quality of service for real-time service and optimize the overall performance of the network. |
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