Real-time ray-based channel generation and emulation for UAV communications

A real-time ray-based hardware emulator for Unmanned Aerial Vehicle (UAV) communication channels which suits for the Three-Dimensional (3D) dynamic scenarios and considers the movements of both terminals is developed in this paper. The time-variant channel parameters, i.e., ray delay, ray gain, and ray Doppler frequency are precalculated in the host by using the Ray Tracing (RT) method. Meanwhile, RT simulation dramatically increases the number of valid rays. To address the problem of resource limitation and huge computational burden in the implementation, an efficient ray coefficients generation method based on iteration is proposed and implemented. With the advantages of low cost and high flexibility, a Software Defined Radio (SDR) hardware platform is used to emulate the ray-based UAV channels by utilizing the compact architecture including the Time-Division (TD) scheme and Tapped-Delay Line (TDL) for channel convolution. Finally, hardware measurement results demonstrate that the properties of emulated channel, i.e., Power Delay Profile (PDP) and Doppler Power Spectrum Density (DPSD) consist with the simulated ones, which verifies the correctness of hardware implementation. The proposed channel emulator provides an efficient way for optimization, verification, and evaluation of UAV communication systems.     

无人机协同测控中SC-FDMA技术设计

针对无人机协同任务测控传输的多机接入问题,提出基于分布式任务分配模型的高动态SC-FDMA技术.通过将贪婪原则、信道动态分配机制和多用户接入技术结合,利用集中映射方式设计子信道数目可调的映射规则,配置各无人机节点所占用子载波数目.仿真结果表明,与传统FDMA、CDMA、TDMA、OFDMA等相比,基于SC-FDMA设计...     

运载火箭自适应制导及在线轨迹重构方法研究

结合我国运载火箭发展，梳理了传统制导方法的工程应用历程;针对故障适应性和自主化需求，分析了基于在线轨迹规划的制导方法发展概况。基于伪谱离散和凸优化理论，提出一套适应不同目标轨道的弹道轨道联合在线重构算法框架，并利用在线重构设计一种运载火箭故障导致推力不足后的自适应制导算法，通过数值实验和嵌入式测试，验证了在线重构算法和自适应制导方法的正确性、有效性。