小波域的频率扩展信道的信号检测

Signal detection in FFD channels in wavelet domain

由于海洋动力学和目标起伏引起发射信号包络的时变衰减,相应于频域就是频率扩展,这种信道称为频率扩展信道,又名快速衰落信道(FFD)。在FFD信道中,理想信道的最佳检测器——匹配滤波器的性能将有所下降,Baggenstoss已经证明FFD信道的最佳检测器是分段副本相关器(SRC)。近年来出现的小波变换具有和宽带相关处理相似的计算结构,所以文章拟从连续小波变换的理论和性质出发,推导FFD信道小波变换域最佳检测器的形式,并针对一个仿真算例,进一步用Monte-Carlo实验计算出该检测器的性能曲线,结果表明该检测器的性能优于小波域的副本相关器。

Fast fading distortion can occur as a result of dynamics of ocean environment or target fluctuation. Modulation of the transmitted waveform changes in a time-varying fashion. This is equivalent to frequency spreading in the frequency domain. In an FFD channel, the expected performance gain is often unachievable. Baggenstoss has proven that the optimum LRT detector of an FFD channel is a segment replica correlator(SRC). The computation structure of wavelet transform is generally similar to that of broadband processing. Thus, based on the continuous wavelet transform theory and its properties, the optimum detector of FFD in the wavelet domain is proposed in this paper, termed wavelet domain segment replica correlator(WDSRC). Simulation results show that the performance of WDSRC is superior to that of wavelet domain replica correlator(WDRC).