基于分数阶傅里叶变换的水声信道参数估计

Underwater acoustic channel parameters estimation based on fractional Fourier transform

准确估计水声信道参数,对提高通信系统的性能有着重要的意义。Chirp脉冲有良好的相关性,常被用作信道探测信号。鉴于分数阶傅里叶变换(Fractional Fourier Transform,FRFT)对chirp类信号的处理特性,用chirp信号作为测量信号,FRFT作为后端处理技术,可以得到很好的处理效果。研究了基于FRFT的水声信道多途时延和多普勒频偏参数估计的原理和方法,该方法通过发射具有正、负调频斜率的组合线性调频信号,在接收端根据FRFT幅值输出的峰值位置估计信道参数。仿真结果表明,此方法计算量与FFT相当,且有较高的估计精度。

Accurate estimation of the parameters of underwater acoustic channel is of importance in improving communication system＇s performance.Chirp pulse is usually used as the channel estimation signals as its outstanding correlation characteristic.Fractional Fourier Transform （FRFT） is well suited to process chirp signals.Consequently,it is an advisable approach of underwater acoustic channel estimation to take a chirp as the emitting signals and to adopt FRFT as the processing method of the received signals.The principle and method of estimating underwater acoustic channel multipath time-delay and Doppler shift are studied in this paper.Combined signal including two LFM signals with two contrary frequency modulation slopes is used as emitting signal,and then corresponding parameters are estimated according to the FRFT amplitude peaks of received signal.Simulation results indicate that the proposed method has similar amount of calculation as FFT,and high accuracy.