中文摘要：

在低轨（LEO）微小卫星感知无线电（L-CR）系统中,多个LEO卫星节点具备一定的频谱感知功能,卫星节点通过分布式组网对地面信关站发射的信息进行感知、传输和处理,地面汇聚节点对LEO卫星节点转发信号进行重构。考虑LEO系统中授权频带的主用户（PU）对卫星认知用户（SU）的干扰,认知用户感知到的信号同时存在PU干扰和噪声,地面汇聚节点通过高效的重构算法进行含噪信号恢复是L-CR系统实现的重要问题。论文研究了LCR系统中基于分布式压缩感知的信号重构方法。针对L-CR特点,分别分析了汇聚节点在低信噪比情况下采用凸松弛法中的基追踪去噪（BPDN）、同伦（Homotopy）法和最小角回归（Lars）的重构均方误差（MSE）与重构复杂度。研究表明,BPDN具有最小的重构MSE,但其重构复杂度最高。Lars可以有效折衷重构MSE与复杂度。在此基础上,提出了基于分布式压缩感知的最小角回归（DCS-Lars）信号重构方案。仿真结果表明,所提DCS-Lars方法可以在低信噪比情况下有效重构感知信号,并具有良好的频谱检测能力,同时重构复杂度大大降低。

英文摘要：

In Low Earth Orbit （LEO） micro satellite Cognitive Radios （L-CR） system, multiple LEO satellite nodes are provided with spectrum sensing functionality. They perform sensing, transmission and processing of information from ground gateway station via distributed network. Ground sink reconstructs the original signal from LEO satellite forwarding signals. Considering the interference from the authorized primary user （PU） to the secondary user （SU） satellites in LEO system, SU sensing signal contains PU interference and noise. Hence, the fundamental problem is the implementation of efficient algo- rithm to realize noisy signal reconstruction at ground sink in L-CR system. Signal reconstruction based on distributed compressive sensing （DCS） in L-CR system is studied. According to the characteristics of L-CR system, the reconstruction mean square error （MSE） and the complexity performance are investigated for different convex recovery schemes in low signal to noise ratio （SNR） region respectively. Namely, basis pursuit de-noising （BPDN）, homotopy method and least angle regression （Lars） algorithm. It is indicated that, BPDN has the minimum reconstruct MSE with the highest complexity, whereas Lars algorithm makes a tradeoff between reconstruction MSE and complexity. On the basis of that, signal reconstruction scheme based on DCS- Lars is proposed. Simulation results show that, the proposed DCS-Lars scheme can effectively recover sensing signals in low SNR region with better spectrum detection performance, and reconstruction complexity can be reduced simultaneously.