Channel Modeling And Simulation For UAV Relay System Based On GPUs

In recent years,unmanned aerial vehicle(UAV)has found a wide range of applications because of the development of science and technology.In modern wars,relay networks use UAV as relay node in investigation and communication.However,due to the complexity of environment and the mobility of UAV,it is difficult to measure the UAV relay channel,and many UAVs should be produced in order to deploy the relay networks that will cause high cost and low efficiency.Therefore,it is important to simulate the propagation characteristics of UAV relay channel in laboratory environment.The main work of this paper is as follows:Firstly,the basic theory for wireless channel is introduced briefly.In addition,the common modeling method of UAV communication channel is analyzed thoroughly.The deterministic model and statistical model of UAV communication channel are given.Meanwhile the the statistical properties of received signal is analyzed in fading channels.On this basis,a multi-hop relay channel model based on UAVs is established.Based on the proposed channel model,the statistical properties of the cascaded propagation path loss and the cascaded probability density function(PDF)of channel fading are derived.Moreover,the theoretical performance of a UAV-based relay system(such as the outage probability,bit error rate(BER),and channel capacity)is also analyzed.Then,Central Processing Unit(CPU)and Graphics Processing Unit(GPU)are analyzed and compared in the aspects of the characteristic and application domain.In addition,a channel fading simulation method based on sum of sinusoids(SoS)theory is introduced detailedly.However,the computational cost will increase sharply as the accuracy of the simulation method for channel fading increases.In order to ensure the efficiency and quality of channel fading simulation,an efficient generation method for Gaussian random processes is implemented on GPUs.Based on the proposed method,a new real-time generation method for multi-path shadowing composite fading is presented.The simulation results show that the time consumption of the GPU implementation is far less than that of the CPU implementation while the high accuracy is kept.Finally,a UAV relay channel simulation software based on GPUs is designed and developed by using the multi-hop relay channel model and real-time generation method for multi-path shadowing composite fading.The functions of channel simulation software include user configuration interface and relay channel simulation.In addition,the detailed tests are carried out for software functions and the UAV relay channel generated by channel simulation software is analyzed using Matlab.The results show that UAV relay channel simulation software designed in this paper can meet the performance requirement.