Research On Energy-saving Deployment Algorithm For UAV Relay

With the diversification of relay network scenarios,the limitations of traditional terrestrial relay deployment are gradually exposed.On one hand,not only the deployment period is long,but the resources consumption is expensive.On the other hand,once the ground relay network is deployed,the deployment location cannot be changed at will,and the ground relay deployment needs to be considered that the link between UAV will experience multiple obstacle or various fading issues,while the UAV's flexible and fast deployment features make the UAV relay deployment the best choice to replace the traditional ground relay.Different from the ground relay node,the UAV relay has the characteristics of energy limitation,so the deployment of the UAV relay network needs to consider the energy saving problem.In addition,existing researches focus more on how to use the mobility of UAV to achieve data transmission between long-distance nodes and the accessibility of data between nodes,which is only applicable to transmissions with high tolerance delay and not applicable to real-time data transmission in emergency scenarios.Real-time data transmission needs to rely on the UAV relay network,so the energy-saving deployment problem of the UAV relay network has important research significance.This paper first studies the UAV relay energy-saving deployment strategy in the deployment area without obstacles under the emergency scenario.It is proved that the most energy-saving way of UAV deployment in this scenario is uniform deployment,and then the optimal deployed number is solved for the one-way and the two-way relay respectively.The simulation results show that the optimal deployment strategy proposed in this paper significantly reduces the energy consumption compared to the least number of UAV deployment strategy.Then,the existing UAV relay deployment algorithm in the deployment area with obstacles under the emergency scenario has the disadvantages of poor energy saving effect and low deployment success rate.In this paper we proposed an energy-saving deployment scheme based on bipartite graph theory.Firstly,the line-of-sight communication between the adjacent UAV and the safety of the UAVs are guaranteed,and the total energy consumption of the UAV is minimized as the objective function.The optimization problem is NP-hard problem and it is difficult to solve directly.Therefore,this paper considers decomposing the optimization problem into two problems: the problem of minimizing the total energy consumption of the process of the UAV assisted relay and the problem of minimizing the total energy consumption of the process of UAV deployed to the relay location.In the problem of minimizing the total energy consumption of the process of the UAV assisted relay,the connectivity-based search algorithm is used to transform the energy-saving relay deployment problem with obstacles to the energy-saving relay deployment problem without obstacles,then we determine the deploy number and the optimal relay location of the UAV.In the problem of minimizing the total energy consumption of the process of UAV deployed to the relay location,we use the least weight matching strategy from the set of UAVs available for relaying to select which UAV serve as relay and determine the corresponding relationship of relay location and relay UAV,which balance the flight distance of the UAV,thereby reducing the total energy consumption of the UAV.Finally,simulation results show that,compared with the existing algorithms,the proposed algorithm not only reduces the total energy consumption of the UAV,but also ensures the success rate of UAV relay deployment and reduces the time complexity of the algorithm.The decision time of the proposed algorithm is controlled at the second level,which is suitable for emergency scenarios.