Communication Relay Planning Methods For Unmanned Aerial Vehicle Swarms

Taking the Unmanned Aerial Vehicles(UAV)swarms as the research object,this paper focus on the instability,disturbance and fragile chain phenomenon of UAV-UAV communication and the UAV-GCS(Ground control station)communication.The paper introduces the relay communication UAVs to improve the UAV communication network,and studies the communication relay planning method of the UAV swarms.Firstly,a basic communication model conforming to the characteristics of the UAV is established,and the UAV communication relay planning problems are divided into an air-ground communication relay planning and an air-to-air communication relay planning.Then,for the air-ground communication relay planning,the problem of relay communication in multiple UAV task points and the problem of air-ground communication link maintenance of single mission UAV in complex scenes are studied.Finally,for the UAVUAV communication network,from the perspective of different network communication indicators,the initial deployment and the online real-time planning algorithms of the UAV relays are proposed.The main work and contributions of this paper are as follows:(1)An air-ground relay planning algorithm for multiple mission pointsAccording to the basic model of the wireless channel,considering the UAV mission environment,antenna gain,multipath effect,etc.,a channel model conforming to the UAV characteristics is established.The mission points have time sequence,that is,the mission time of the mission points is different,and the communication time with the ground control station is different.Based on this,the air-ground communication relay problem is decoupled.Firstly,regardless of the time sequence,the static relay is adopted,and the full-time coverage of all mission points is realized with the least number of UAV relays,and the deployment positions of the UAV relays are determined.Based on the static relay deployment position,with the scheduling of task points,multiple task areas with non-overlapping time domains can be assigned to one dynamic relay,and dynamic relay planning can be converted into multiple relay point allocation problems with time windows.The designed algorithm compares the minimum number of relays and the deployment allocation of different mission altitude planes,different scenarios(urban,suburban,etc.)and the relayed UAV communication capacity,which proves the effectiveness of the algorithm.The designed algorithm compares the minimum number of relays and the relay allocation modes under different mission altitude planes,different scenarios(urban,suburban,etc.)and different UAV relay communication capacity,which proves the effectiveness of the algorithm.(2)Air-ground UAV relay planning algorithm in complex scenesThis section focuses on the problem of broken communication links between unmanned aerial vehicles and ground control stations in complex scenes.Firstly,two difficulties in air-ground relay communication are analyzed,including the occlusion of obstacles on the line of sight of the communication nodes and the influence of communication jammer.A communication jammer detection method and a threedimensional jammer localization algorithm based on received signal strength(RSS)are proposed.The air-ground communication relay planning architecture is then designed,which is divided into an offline global path pre-planning phase and an online adjustment phase in which sudden obstacles or jammers occur.In the offline global planning phase,the minimum number of UAV relays is solved and the individual drone paths are planned.The online adjustment phase is based on the model predictive control method to evade away from the sudden obstacles and communication interference timely.The simulation compares and analyzes the performance of the global path planning algorithm under two different known obstacle environments,and further verifies that when there are sudden obstacles and communication interference,the UAV can quickly locate the interference and effectively avoid it,thus maintaining high quality communication.(3)UAV relay planning architecture for UAV-UAV communication linksAiming at the problem of communication quality between UAV swarms in collaborative tasks,an UAV-UAV relay planning architecture is proposed.The planning architecture is divided into two parts,a collaborative mission drone and a relay communication drone.The planning architecture consists of two parts,collaborative mission UAVs and UAV communication relays.The Kalman filter method is used to estimate the motion state of the mission UAVs.Three types of communication link performance metrics are considered,including global message connectivity,worst link connectivity,and β-weak link connectivity.Based on the minimum spanning tree,an optimal UAV relay communication topology is generated.The planning algorithm is divided into relay initial deployment position optimization and online relay path adjustment algorithm based on model prediction control.The simulation experiment compares the performance of the relay communication link using different numbers of UAV relays.Furthermore,under different communication performance index standards,Monte Carlo experiments are carried out to verify the stability of the algorithm.In the real-time adjustment phase of the relay path,the communication quality of proposed algorithm is compared with that of random motion and hover around the initial position,indicating that the proposed algorithm can achieve higher communication quality.