Simulation Environment Construction And Protocol Design Of UAV Ad Hoc Networks

Unmanned aerial vehicles(UAVs)are widely adopted in the military field due to their superior performance,low cost and human casualty avoidance.By imitating the behavior of bees,birds and other animals,a UAV cluster consisting of multiple micro and small UAVs can overcome the defects of single UAV in performing tasks.Thus,UAV cluster become the key research direction of military equipment.The communications insides the UAV cluster are based on the mobile ad hoc network.Routing protocol and MAC protocol are the important problems that need to be solved in ad hoc networks,which are the research focuses of UAV ad hoc networks.In this dissertation,we studied the construction of the UAV application scenarios,routing protocol simulation and MAC protocol design,which provide reference for the research and development of UAV communication equipment.The routing protocols have been widely studied,however,the existing routing protocols are applicable to different scenarios.In order to evaluate whether these routing protocols are applicable to military UAV cluster,it is necessary to build the communication scenarios and motion models for UAV clusters,which are close to the actual application scenes.According to the characteristics of military UAV cluster performing tasks,the application scenarios of UAV cluster can be classified into three types,i.e.,friendly,obstacle and confrontation.The motion models proposed in previous studies focus on random motion of nodes,which does not conform to the rule of UAV motion.In this dissertation,we analyze the related parameters of the publicly reported UAVs.Considering the characteristics of different stages of UAV missions,we build five simulation scenarios,which bring basics for the simulation assessment.In this dissertation,we select the three most widely studied protocols,i.e.,ad hoc on-demand distance vector(AODV),dynamic source routing(DSR)and optimized link state routing(OLSR)protocol as simulation objects.Through OPNET,we construct five simulation scenes,i.e.,“launch successively in one way”,“launch parallelly in three ways”,“two groups flight with obstacle avoidance”,“search and surround the target” and “flight under partial destruction”,to simulate the three kinds of routing protocols respectively.The end-to-end delay,delivery rate and network overhead of each simulation scene are compared and analyzed.Simulation results indicate that each protocol performs differently in different scenarios.Through comprehensive analysis,the routing protocol with the best performance in different scenes is obtained,which provides reference for the protocol switching of UAV cluster communications.MAC protocol is designed for the coordination and use of wireless channel resources.Adopting directional antenna in ad hoc networks can realize space reuse,reduce transmission power and improve communication capacity.Considering directional antenna can only send and receive directional information,there exist problems such as directional hidden terminal,directional exposed terminal and deafness.In this dissertation,a MAC protocol based on hybrid antennas is designed,which uses dual-band,hybrid antenna,power control,position exchange methods.UAVs send control signals and data signals separately through channels with different frequency bands.And the handshake signals are transmitted through the omnidirectional antenna at maximum power,and the data signals are transmitted through directional antenna at optimal power.The node position information is added to the handshake signal,which is used for directional antenna alignment,communication judgment and transmission power calculation.And the judging criteria and computational formula to decide whether to transmit is derived.The problems of directional exposure terminal,directional hiding terminal and“deafness” in directional antenna protocol are solved.Simulation results show that the proposed MAC protocol performans much better compared with the traditional MAC protocols.