Rerearch On UAV-Assisted Relaying Transmission Schemes Based On Moving Sources

With the development and application of the fifth-generation mobile communication network(5G),more kinds of devices will access the network which is required to provide low-latency,high-speed and high-quality transmission in complex communication scenarios.In the fields like real-time broadcast of sports events,military or industrial real-time communications,higher-speed rail transportation,sources are always moving,leading to time-varying channels which requires dynamic resource allocation.However,traditional static relays are difficult to meet the need.Due to the flexible adjustability of the Unmanned Aerial Vehicle(UAV),they can assist the data transmission effectively.Moreover,when used as a relay,UAV can play its advantages of controllable trajectory,adjustable height,and support for multiple services.In this way,multi-hop transmission in more diversified communication scenarios is completed.In addition,the flexible combination of energy harvesting(EH)can effectively improve the endurance of the UAV relay when performing long-term and long-distance missions,and can carry out additional energy cooperation when performing information cooperation.Based on this,different resource allocation schemes that aiming at solve the problems caused by different motion trajectories of the source can be carried out.The main research and innovation of this paper are as follows:Firstly,from the perspective of information,we design wireless information transmission schemes for multi-hovering UAVs and single-following UAV based on moving sources where the total system power is limited.We have proposed dynamic power allocation for the two schemes based on the optimization target,the symbol error rate(SER).The expressions of the power allocation are detailed derived.The simulations comparing with two typical power allocation schemes that are suitable for static sources show better performance is obtained by adopting our schemes.Also,the comparison of the proposed two schemes are carried out to analyze the optimal number of UAVs in a specific scenario.Combined with caching,a low-consumption implementation is proposed.In detail,the dynamic power allocation list can be written into UAVs’transmitters in advance,which can effectively save signaling consumption when the motion scene is predictable.Secondly,from the perspective of simultaneous wireless information and power transfer(SWIPT),we propose a dual-UAV energy cooperation scheme based on moving sources under EH model.Specifically,accoding to reasonable relay selection strategy,the roles(energy relay and information relay)of the two UAVs are switched flexibly in each period,and on this basis,real-time energy models of the two UAVs during the whole motion of the source are established.With the help of Matlab tools,the optimal solutions of UAVs’ power splitting ratio that maximizes the system throughput in each period is obtained,and then the average throughput performance during the entire motion is obtained.Comparing simulations with the traditional UAV relaying scheme with EH that are suitable for static sources show that not only the instantaneous throughput but also the average throughput of the proposed scheme is superior to that of the compared ones.Moreover,the impact of UAVs’ speed,trajectory radius and relays’ switching frequency on system throughput are also simulated and analyzed,which has reference significance in UAV trajectory design.