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为了保证主用户在传输数据过程中不受次级用户的干扰,认知无线电系统中次级用户采用了周期频谱检测技术来检测空闲信道。假设系统中存在多条主用户信道,当检测出当前使用的主用户信道被占用时,次级用户进行频谱切换。频谱切换过程中搜索空闲信道的时间是个随机变量。为了加速频谱切换,采用等增益合并合作频谱检测模式来进行空闲信道的检测,这种模式优化单个信道的检测时间,可以达到使搜索空闲信道平均时间最短的效果。研究了在不同仿真参数的情况下,系统存在相应的最优单个信道检测时间,以及对应最短搜索空闲信道的平均时间。
In order to ensure that the primary user is not affected by secondary users during data transmission, secondary users in cognitive radio systems employ periodic spectrum detection technology to detect idle channels. It is assumed that there are multiple primary user channels in the system. When it is detected that the primary user channel currently used is occupied, secondary users perform spectrum switching. The time to search free channel during spectrum switching is a random variable. In order to speed up the spectrum switching, equal-gain and cooperative spectrum detection mode is adopted to detect the idle channel. This mode optimizes the detection time of a single channel and achieves the effect of shortening the average free channel search time. In the case of different simulation parameters, the system has the corresponding optimal single channel detection time and the average time corresponding to the shortest search free channel.