Analysis And Design Of UAV Multiple Medium Access Protocol Based On Directional Antenna

UAVs play an important role in observation,cruise,military,communications,logistics,agriculture and other fields for their advantages of small size,low cost,and hardly affected by working environment.As the scale of UAVs network continues to expand,traditional omnidirectional UAVs network is increasingly affected by network capacity and transmission bandwidth.Therefore,the use of directional antennas in UAVs network is more and more popular in civilian and military fields to improve the performance of UAVs network by making full use of the spatial reuse of directional antennas.In order to take full advantage of directional antennas,we must design suitable multiple medium access protocol for directional UAVs network.Based on the characteristics of different transmission scenarios in UAVs network,this paper designs two kind of directional multiple medium access protocol.They are directional Low-latency and High-reliability multiple medium access protocol in time-efficient scenario and purely directional time-division multiple medium access protocol in heavy-load scenario.In order to meet the requirement for low latency and high reliability in time-efficient scenario,this paper designs directional low-latency and high-reliability multiple medium access protocol,which provides high-priority missions with short access delay and high transmission reliability guarantees.In this protocol,we have finished the analysis of priority threshold using stochastic geometry theory.Firstly,we use Poisson point process to model the distribution of users’ position in network,and use the method of spatial arrival to unify the distribution of position and missions,Secondly,we use calculus theory,combinatorial mathematics,and probability theory to derive the probability distribution of channel statistics that one user hears in a time window,and derive the relationship between user medium access probability(MAP)with channel statistics.After completing the derivation of MAP,we have worked out the relationship between data packet’s transmission success rate and burst transmission success rate by Poisson point process theory,Laplace transformation and turbo encoding theory.Finally,we get the relationship between transmission success rate of one packet and priority threshold.In order to meet the requirement for network throughput in heavy-load missions,we proposed purely directional time-division multiple medium access protocol.This protocol uses directional time-division and frequency-division hybrid multiple medium access mechanism,and takes full advantages of directional antenna’s spatial reuse to realize the parallel transmission of multiple links by using time slot multiplexing algorithm based on coloring theory,which improves the overall network throughput.Firstly,the communication link-based time slot division strategy is used to schedule the time slot and directional antenna beam.Secondly,by studying the interference model of directional antennas,the principle of time slot multiplexing is determined.Thirdly,in order to finish distributed time slot multiplexing calculation,this protocol uses a directional broadcast mechanism to complete the network maintenance and the diffusion of the two-hop neighbor connection relationship.Finally,a time slot multiplexing algorithm based on coloring theory is designed.This algorithm uses the maximum matching algorithm and the maximum matching algorithm based on transmission requirements to finish the multiplexing calculation of time slots,using as few time slots as possible to transmit as many communication links as possible in parallel,and improves overall network throughput.Finally,the implementation of two protocols and the construction of corresponding simulation scenarios are finished by OPNET.We have evaluated performance of the two protocols in terms of network throughput,delay,packet loss rate,and spatial reuse.Simulation results show that the two protocols proposed in this paper can significantly improve the performance of the UAVs network.