基于分集接收的卫星认知通信动态频谱感知策略

摘要

The efficiency of fixed decision threshold based spectrum sensing was deteriorated because of its inadequate adaptability to channel fading variations. A novel dynamic spectrum sensing strategy based on diversity reception in Nakagami-m channel fading was proposed for satellite cognitive communication, which takes the character as low energy of signals to be detected in satellite network into consideration. The optimized spectrum decision threshold adjusted dynamically according to the channel fading state using an advanced fuzzy C-Means clustering algorithm, and a signal receive scheme based on MRC (maximum ratio combining) and EGC (equal grain combining) diversity reception technology was designed to enhance the receiving SNR (signal to noise ratio) in order to mitigate the influence of weak signal environment on spectrum sensing. The results indicate that the performance of spectrum sensing is improved remarkably especially in low SNR environment by the proposed dynamic spectrum sensing strategy.%针对基于固定判决门限的频谱感知策略无法适应信道衰落变化导致频谱感知效率下降的问题，结合卫星网络中待检测信号能量较低的特点，提出一种 Nakagami-m 信道环境下基于分集接收的动态频谱感知策略。该策略利用改进的模糊聚类算法动态获得频谱最佳判决门限，使得判决门限能够根据信道衰落变化自适应调整；在此基础上利用MRC(maximum ratio combining)与EGC(equal grain combining)2种分集方式增大认知用户的接收信噪比，以减小弱信号环境对能量检测算法频谱检测性能的影响。仿真结果表明：该策略能够有效提高低信噪比环境下的频谱感知性能。