Ad Hoc 网络动态时隙分配的混合 MAC 协议研究与仿真

针对 Ad Hoc 网络的节点具有移动性，信道具有多跳共享性的特点，提出动态时隙分配的混合媒体接入控制（media access control，MAC）协议，协议包括时隙分配和时隙竞争2个阶段。在时隙分配阶段，采用静态分配和动态调整相结合的方式，在为每个节点分配固有时隙的基础上，将不共享信道的节点时隙动态地分配给通信节点；在时隙竞争阶段，通过在子帧中设置不同优先级，在不参与通信节点的主时隙中，数据传输子帧被分成实时业务竞争阶段和非实时业务竞争阶段，竞争成功的节点在这个时隙传输数据，提高优先业务节点的接入概率。采用 NS2网络模拟软件进行仿真，结果表明，所提混合 MAC 协议提高了系统的分组投递率，降低了实时业务的平均时延，协议能够充分利用信道空间复用性，减少竞争，提高接入效率，适合 Ad Hoc 网络。

Research and simulation on a hybrid MAC protocol with dynamic slots allocation in Ad Hoc network

According to the mobility of nodes, multi-hopping share of channels in Ad Hoc networks, hybrid MAC protocol with dynamic slots allocation is presented. The protocol includes two stages: slots allocation and slots competition. During the stage of slots allocation, we adopt the combination of static allocation and dynamic adjustment. On the basis of allocating inherent time slot of every node, dynamically allocate the time slots of nodes that do not share channels to the communication nodes; In the stage of competition, by means of setting different priorities in sub-frames, in the main slots of nodes that do not take part in communication, data transmission sub frames are divided into real time services competition stage and un-real time services competition stage, and nodes that compete successfully transmit data at this time slot to improve access probability of preferred business nodes. We simulate the proposed MAC protocol with NS2 network simulation software, and the result shows that the proposed hybrid MAC protocol improves the system packet delivery rate and reduces the average delay real time services. The protocol can improve service quality of real-time services and optimize the whole performance of network.