天地一体波束形成关键算法研究

In hybrid terrestrial-satellite mobile communication system, in order to decrease the heavy burden of power consumption, weight, cost and signal processing due to the great number of array elements on-board, it's necessary to study space-ground integrated beamforming technology and transfer all or part of beamforming tasks from satellite to gateway on earch. Moreover, the anti-jamming and anti-interception performances are also improved. Two realization structures, the ground-based beamforming (GBBF) and the hybrid on-space/on-ground beamforming (HSGBF), are involved in the space-ground integrated beamforming technology architecture. In this project, some key algorithms will be studied as follows. Firstly, for the uplink HSGBF, a feeder signal dimension reduction method and an unitary beamspace beamforming algorithm will be studied. Secondly, for the efficient utilization of limited transformation band width of feeder link, a code division multiplex method and a wavelet packet division multiplex method will be studied. Thirdly, for the dynamic transformation scenario, a new fast uplink LMS-like beamfroming algorithm will be derived. Fourthly, a cost function with several introduced error effects will be designed and a robust uplink ground-based beamforming algorithm based on Support Vector Machine (SVM) will be studied. Finally, for the downlink GBBF, a joint power control and beamforming optimization model will be established under the requirement of anti-interception and a recursive solution algorithm will be presented based on uplink and downlink duality theorem. Through the research of this project,the space-ground integrated beamforming technology architecture will be spreaded and developed further and a technical support can be provided for the construction cause of our country in this field.

在星地混合移动通信系统中，为降低因星载阵元数量大而导致的卫星功耗、质量、造价和信号处理负担加重，有必要研究天地一体波束形成技术，将全部或部分波束形成任务转至地面信关站完成，同时提高系统的抗上行干扰和防下行截获性能。该技术体系包括地基波束形成和天基-地基混合波束形成两种实现架构，本项目拟针对其中的关键算法开展研究，内容包括：面向天基-地基混合上行波束形成，研究星上降维方法和酉波束空间波束形成算法；为适应馈电链路有限传输带宽，研究码分复用和小波包分复用方法；针对动态传输场景，推导新型类LMS快速上行波束形成算法；设计引入各种误差效应的代价函数，研究基于支持向量机的稳健上行波束形成算法；面向地基下行波束形成，在防截获条件下构建功率控制与波束形成联合优化模型，并依据上行和下行对偶原理推导迭代求解算法。通过研究，力求促进天地一体波束形成技术体系的完善，为我国在该领域的建设事业提供技术支撑。

在星地混合移动通信系统中采用天地一体波束形成技术，可降低因星载阵元数量大而导致的卫星功耗、质量、造价和信号处理负担加重，并提高系统的抗上行干扰和防下行截获能力。本项目围绕天地一体波束形成关键算法，从以下四个方面开展研究：一是星上降维与波束空间波束形成算法，设计了基于二维离散傅里叶变换的静态降维矩阵，并对阵元空间降维至随机酉波束空间再进行自适应波束形成的UB-RLS算法进行了研究，降低了波束形成运算量；二是馈电链路传输多路复用方法，主要研究了码分复用、小波包分复用和基于正交多速率调制的多路复用方法，显著提高了馈电链路传输的频谱利用率；三是快速与稳健上行自适应波束形成算法，通过研究以CS-LMS算法为代表的类LMS快速自适应波束形成算法与波束形成器设计来提高对动态环境的适应性，通过研究基于支持向量机的稳健上行波束形成算法来提高对波达方向估计误差等非理想效应的适应性；四是功率控制与下行波束形成联合优化算法，提出了基于保密速率约束条件的多用户下行波束形成算法、单用户窃听信道的鲁棒性掩蔽波束形成算法以及保密速率最大化迭代预编码算法，以发送功率最小化或保密速率最大化作为优化目标，在多约束条件下构建问题模型，并采用半定规划等方法求解，达到抗截获和防窃听之目的。通过研究，为星地混合移动通信系统在波束形成算法方面提供了技术参考。