认知无线电多时隙联合频谱感知方法及优化

摘要

In order to decrease the interference to the primary user (PU) caused by the secondary user (SU) in cognitive ra-dio ,a spectrum sensing method is proposed to cooperatively detect the PU through multi-slot energy sensing of the SU .Each trans-mission frame was divided into several time slots ,and the SU sensed the PU at the beginning of each time slot .The SU could im-prove the performance of detecting PU through combining the multi-slot sensing results .In order to maximize the SU ’ s spectrum ef-ficiency ,the PU state was built as a two-dimensional Markov random process ,and according to this process ,the single-slot sensing time was optimized .The simulation results show that compared to the ”listen-before-transmit”spectrum sensing method proposed by Liang ,the proposed method reduces the interference probability of 28% by only sacrificing the spectrum efficiency of 14% ,and with the increase of the signal-to-noise ratio (SNR ) ,the maximal spectrum efficiency of the proposed method gradually approaches that of the”listen-before-transmit” spectrum sensing method .%为了降低认知无线电中次用户对主用户的干扰，提出了次用户通过多个时隙的能量感知联合检测主用户的频谱感知方法。每个传输帧被分成若干个时隙，次用户在每个时隙的开始进行能量感知，通过合并多个时隙的感知结果，提高次用户对主用户的检测性能。为了最大化次用户的频谱效率，将主用户状态建模为二维马尔科夫随机过程，并根据该过程优化单时隙频谱感知时间。仿真结果表明：相比Liang的“先听后传”频谱感知方法，提出方法仅牺牲14％的频谱效率，却使干扰概率降低了28％；随着信噪比增加，提出方法的最大频谱效率逐渐接近“先听后传”频谱感知方法。