Research On MAC Layer Key Technology Of MMW Wireless Ad Hoc Network Instrument Control System

Millimeter wave based wireless ad hoc network technology,on the one hand,it has the advantages of no infrastructure,no center and multi hop communication.On the other hand,it also has the advantages of high communication frequency band,good security and large bandwidth.It has significant application advantages in closed space and highly reflective scenes.In wireless ad hoc networks,MAC layer protocol is responsible for node access control and channel resource allocation.Its performance directly affects the efficiency of the whole network,and its impact on network performance is very important.Therefore,MAC layer protocol is also one of the research hotspots of wireless ad hoc networks.Based on IEEE 802.11 DCF protocol and binary exponential backoff algorithm,combined with the actual background of the project,the thesis studies and improves the MAC layer protocol according to the application environment of complex space and strong reflection of the I＆C system.The specific work of the thesis is as follows:Firstly,the thesis deeply studies the working mechanism of IEEE 802.11 DCF protocol,and analyzes its performance by establishing Bianchi model.Combined with the application background of the project and the analysis of the characteristics of millimeter wave ad hoc network,it is concluded that the traditional RTS/CTS mechanism is not suitable for millimeter wave ad hoc network.For millimeter wave ad hoc network prone to occlusion,a fast reconnection algorithm based on MAC layer of millimeter wave ad hoc network is proposed,By introducing the failure screening mechanism,when the communication failure is judged to be caused by occlusion,the competition window is reduced to improve the probability of rapid recovery of relevant nodes and minimize the impact of occlusion on network performance.Then,the thesis analyzes the principle and performance of binary exponential backoff（beb）algorithm in detail.On this basis,in view of the different importance of controlled equipment in the I＆C system,the important level of controlled equipment is connected with the priority of access channel,and an avoidance algorithm based on the instrument priority of I＆C system is proposed.By introducing rising parameters _iR and falling parameters _dR into the change function of competition window,According to the different priorities of nodes,the above two parameters are flexibly adjusted to improve the probability of nodes with high priority to access the channel first.Finally,through simulation verification and result analysis,the thesis proves the effectiveness of the improved algorithm in the case of sparse deployment of network nodes.