Research On MAC Protocol For Wireless Ad Hoc Networks Used For Directional Antennas

Wireless ad hoc networks have attracted widespread attention due to their low cost and the ability to perform complex tasks collaboratively,and are widely used in scenarios such as intelligent transportation and military battlefields.Media Access Control(MAC)provides a reliable and effective scheduling and coordination mechanism for wireless ad hoc networks,but the existing MAC protocol that introduces directional antennas has a long time to discover neighbors and the time slot scheduling process control frame is too long.many questions.Time Division Multiple Access(TDMA)protocol can support parallel transmission of a large number of nodes through a reasonable time slot allocation and scheduling algorithm,reduce conflicts and delays,and improve the overall throughput of the network.However,the existing TDMA protocol brings a large amount of control frame overhead due to antenna beam alignment,and channel resource allocation is unbalanced.Based on the above problems that need to be solved urgently,this paper makes corresponding improvements to the time slot reservation mechanism and time slot scheduling mechanism of fast networking.The main research work is as follows:1、Aiming at the difficulty of beam alignment in wireless ad hoc networks due to frequent switching of beam directions by directional antennas,an improved algorithm for fast networking time slot reservation is proposed.The algorithm is based on the directional antenna model.Firstly,the change of the electrical signal is used to realize the rapid switching of the beam direction.Secondly,the access time slot table is reserved for the network nodes,and the sending and receiving status is set according to the time slot table.Finally,the scheme of the auxiliary discovery mechanism is introduced,through Nodes communicate with their own neighbor node information,know the location information of potential neighbor nodes,and perform beam alignment,so as to improve the probability of network node discovery,reduce the cost of time slot reservation control frames,and accelerate the node network access process.The simulation results show that the improved algorithm for fast networking time slot reservation can complete the initial function of the network in fewer time slots,reduce the overhead of control frames,and increase the speed of networking.2、Aiming at the problems of excessive time slot scheduling control frame overhead and unbalanced channel resource allocation caused by directional antenna beam alignment,an improved dynamic distributed TDMA scheduling algorithm is proposed.Based on the local two-dimensional time-frequency scheduling table maintained by each network node,the algorithm dynamically schedules time slots through 1-hop neighbor time slot usage information,and sorts link service information according to information length and priority.The scheduling table selects the most suitable time slot to dynamically adjust the allocation of channel resources,so as to realize the rapid network access of network burst services,reduce the overhead caused by beam switching,improve space utilization,and ensure fair allocation of time slot resources.The simulation results show that the improved dynamic distributed TDMA scheduling algorithm can effectively avoid the interference of concurrent links due to its low cost of dynamic allocation of resources,thereby reducing the end-to-end delay performance of the network and improving network throughput.Compared with the High Dynamic Media Access Control(HD-MAC)algorithm,it can be seen that the improved dynamic distributed TDMA scheduling algorithm can flexibly adapt to network topology changes,reduce end-to-end delay,and improve network throughput.