Abstract: Two-stage cooperative spectrum sensing that used both soft combining and hard combining need to send much unnecessary information to fusion center in the second stage. Concerning this problem, this paper proposed an improved algorithm by estimating Signal-to-Noise Ratio (SNR). The improved algorithm selected traditional two-stage scheme to improve the performance of spectrum when SNR was low and selected hard combining scheme to decrease the number of sending data when SNR is high. The simulation results show that the proposed algorithm decreases much unnecessary soft information being sent to fusion center at the cost of a little loss in performance of detection as compared to an existing two-stage cooperative spectrum sensing algorithm.

Key words: Cognitive Radio (CR), soft combining, hard combining, cooperative spectrum sensing, two-stage scheme, detection probability

摘要： 针对同时使用硬合并和软合并的两步协作频谱感知方法在第二步的软融合时仍需向融合中心发送大量不必要数据的问题，引入了接收信噪比估计，提出了一种改进的两步协作感知算法。改进算法在低信噪比情况下使用传统的两步协作检测提升检测性能，在较高信噪比情况下则采用硬融合策略来减少发往融合中心的信息量。仿真结果表明，改进算法和传统的两步协作检测算法相比，能在几乎不损失检测性能的情况下，显著减少不必要的数据传送。

关键词: 认知无线电, 软融合, 硬融合, 协作频谱感知, 两步法, 检测概率