宽带认知OFDM系统的混合频谱感知技术  

Hybrid spectrum sensing scheme for wideband OFDM cognitive radios

作　　者：侯炜[1] 张林[1] 山秀明[1] 

机构地区：[1]清华大学电子工程系,北京100084

出　　处：《清华大学学报（自然科学版）》2010年第10期1690-1694,共5页Journal of Tsinghua University(Science and Technology)

基　　金：国家"八六三"高技术项目(2006AA10Z261;2006AA10A301;2007AA100408)

摘　　要：为降低宽带正交频分复用(OFDM)认知系统的频谱感知开销,提出了一种快速频谱感知方法——混合频谱感知策略。该策略利用能量阈值法检测是否存在活跃用户,利用小波变换多尺度分析法检测活跃用户的频谱边界。进行了系统设计并给出了两种检测方法的阈值准则。仿真结果表明:能量阈值法能够快速判断活跃用户的存在性,而小波变换法则可以在加性Gauss白噪声(AWGN)信道和频率选择性衰落信道下提高频谱边界的正确检测概率。混合频谱感知策略融合了两种检测方法的优点,相比传统频谱感知方法有效降低了感知开销,并且易于实现。This paper presents a fast spectrum sensing scheme,hybrid spectrum sensing scheme,to reduce the sensing overhead of wideband orthogonal frequency-division multiplexing（OFDM） cognitive radios.The scheme utilizes energy based method to detect the presence of active users and exploits wavelet transform to locate the spectral edges of the received signal.The thresholds for the two methods used in the hybrid scheme were also analyzed in this paper.Simulations show that the energy detection method can fast perform user presence detection,while the wavelet method can be used to detect the spectral edges of occupied spectrum blocks in both additive white Gaussian noise（AWGN） and frequency-selective fading channels.Compared with the conventional methods,the hybrid spectrum sensing scheme can effectively reduce the sensing overhead with easy implementation.

关 键 词：认知无线电 频谱感知 正交频分复用(OFDM) 小波变换 

分 类 号：TN911[电子电信—通信与信息系统]