Abstract: To solve the current contradiction between sensing performance and cooperation overhead of cooperative spectrum sensing, a hierarchical fusion cooperative spectrum sensing scheme based on double thresholds with multi-antenna Cognitive Radios （CRs） is proposed in this paper. Additional improvement of local sensing performance of CRs is provided by taking advantage of space diversity gain for employing Square Law Combining （SLC） with multiple antennas. The local sensing results are divided into one-bit and two-bit decisions by setting thresholds. And then by limiting the lowest number of cooperating CRs through Fusion Center （FC）, CRs make a hierarchical report and Fusion Center （FC） makes a hierarchical fusion based on the sensing report. Simulation results show that the proposed scheme achieves a good tradeoff between sensing performance and communication overhead and is more robust to the distance between double thresholds. Also, when most of the detected values fall between the two thresholds, the probability of sensing failure problem caused by malfunctioning CR is greatly reduced.

Key words: cognitive radio network, spectrum sensing, multiple correlated antenna, square law combining, double thresholds

摘要： 针对当前协作频谱感知检测性能和协作开销的矛盾，提出了一种基于双门限能量检测的多天线认知用户分级融合协作频谱感知机制。通过引入多天线平方律合并技术，利用空间分集增益提高了认知节点的本地感知性能，并设置门限将本地感知结果划分为1 bit、2 bit两种，通过融合中心限制参与融合认知节点的最小个数，认知用户分级上传感知结果，融合中心根据上传结果分级融合感知信息。仿真结果表明，该机制较好地实现了感知性能和通信开销的折衷，同时对双门限区间的取值有较好的鲁棒性;当大部分感知数据落入双门限之间时，明显降低了有故障节点时感知失败的概率。

关键词: 认知无线网络, 频谱感知, 多相关天线, 平方律合并, 双门限