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为了获得认知无线电系统更高的频谱利用效率,基于最小总错误概率准则推导了软判决协作频谱感知最优判决门限的闭合表达式,并且分析了各种频谱感知参数对最优判决门限的影响.理论分析表明,所提出的最优门限可以获得虚警概率和漏检概率2种性能指标的折中.从仿真结果可以看出,平均信噪比和软判决方案对最优判决门限影响较大,而样本数量对最优的判决门限几乎无影响.对于MRC和MDC两种软判决方案,随着协作用户数量的增加,最优判决门限值随之增加并且趋近于某一极限值.而对于EGC软判决方案,协作用户数对其最优门限值影响很小.
In order to obtain higher spectrum utilization efficiency of cognitive radio system, the closed expression of the optimal decision threshold of soft-decision cooperative spectrum sensing is derived based on the minimum total error probability criterion, and the influence of various spectrum sensing parameters on the optimal decision threshold is analyzed The theoretical analysis shows that the proposed optimal threshold can obtain the compromise of two kinds of performance indexes: the false alarm probability and the missed detection probability.From the simulation results, it can be seen that the average signal to noise ratio and the soft decision scheme affect the optimal decision threshold But the number of samples has little effect on the optimal decision threshold.For both MRC and MDC soft decision schemes, as the number of cooperative users increases, the optimal decision threshold increases and approaches a certain limit For the EGC soft decision scheme, the number of cooperative users has little effect on the optimal threshold value.