OFDM-UAV中继广播通信系统航迹优化方法

Trajectory optimization method for the OFDM-UAV relay broadcast communication system

为了提高无人机中继广播通信系统的性能,针对频率选择性衰落信道,考虑基站到无人机以及无人机到用户的全通信链路,提出了基于正交频分复用(OFDM)技术的无人机中继广播通信系统航迹优化方法。首先提出了基于OFDM的无人机中继广播通信传输模型,对单用户节点中断概率和系统平均中断概率进行理论分析并给出近似计算公式;然后以平均中断概率最小化和最大用户中断概率最小化为优化准则,提出无人机的航迹优化方法并分析了各因素对系统中断性能的影响;最后通过计算机仿真,证明了所提航迹优化方法正确有效。研究表明:在多径信道下,基于OFDM的无人机中继广播通信系统能有效克服频率选择性衰落,且译码转发方式下的连通性优于放大转发方式;基于平均中断概率最小化准则得到的系统中断性能优于最大用户中断概率最小化准则。

To improve the performance of the unmanned aerial vehicle(UAV)relay broadcast communication system,taking into consideration the entire communication links from the base station to the UAV and from the UAV to the users,the orthogonal frequency division multiplexing(OFDM)based trajectory optimization method is proposed for the UAV relay broadcast communication system with frequency selective fading channels.First,the OFDM-based UAV relay broadcast communication model is provided.Then,approximate calculation formula for the interruption probability for a single-user node and that for the system average interruption probability are theoretically derived.Furthermore,two trajectory methods for the relay UAV are proposed based on the optimization criteria of minimizing the average interruption probability and minimizing the maximum user interruption probability.The effectiveness and correctness of the proposed optimization method are demonstrated by computer simulations,which indicates that the OFDM-based UAV relay broadcasting communication system can effectively overcome frequency-selective fading,and achieve better connectivity under the decode-and-forward transmission mode than the amplify-and-forward mode in multipath channels.The interruption performance of the system,derived based on the criterion of minimizing average interruption probability,surpasses that obtained by minimizing the maximum user interruption probability criterion.