一种适用于主用户信号随机出现和离开的能量频谱感知方法

针对认知无线电系统中主用户信号随机出现与离开时的频谱感知问题，提出了一种新型的能量感知方法：该方法首先假设主用户信号的随机出现和离开服从泊松随机过程，当认知用户准备接入时，该方法先将从待测频段上接收到的样本能量按照泊松离开概率进行线性合并，然后计算相应的判决门限并判断待测频段是否有主用户信号，如果没有则接入并使用待测频段。当认知用户使用频段时，将接收到的样本能量按照泊松到达概率进行线性合并同时计算相应的门限，再判断主用户信号是否随机出现，如出现则退出当前使用频段。仿真结果表明，相比传统能量感知方法，所提新的能量感知方法能够在主用户信号随机出现与离开的情况下有效工作。

Energy Based Spectrum Sensing Method with Random Presence and Absence of Primary User's Signal

In order to address the problem of spectrum sensing with random presence and absence of primary user''s signal in cognitive radios, a novel energy based spectrum sensing method is proposed. The method first assumes that the departuring process and the arriving process of the primary user''s signal are possion random processes. When a cognitive user tries to access a spectrum, the energy of the collected samples is combined linearly according to the departure rate of Possion random process and then the corresponding threshold is calculated to decide whether there is a primary user or not. If the primary user is absent, the cognitive user accesses and the spectrum is used. When the cognitive user is using the spectrum, it also combines the energy of the collected samples linearly according to the arrival rate of Possion random process and calculates the corresponding threshold to test whether the primary user is arriving or not. If the primary user is arriving, the cognitive user vacates this spectrum immediately. Simulation results show that compared with traditional energy based detection method, the proposed method can work efficiently with random presence and absence of primary user''s signal.