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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。
In order to reduce the spectrum sensing overhead of wideband Orthogonal Frequency Division Multiplexing (OFDM) cognitive system, a fast spectrum sensing method-hybrid spectrum sensing strategy is proposed. The strategy uses the energy threshold method to detect the existence of active users and detects the spectrum boundary of active users by using wavelet transform and multi-scale analysis. The system design is given and the threshold criteria of two detection methods are given. The simulation results show that the energy threshold method can quickly determine the existence of active users, and the wavelet transform algorithm can improve the correct detection probability of spectral boundaries under additive Gaussian white noise (AWGN) channel and frequency selective fading channel. Hybrid spectrum sensing strategy combines the advantages of the two detection methods, effectively reducing the perceived overhead compared to traditional spectrum sensing methods and is easy to implement.