Alpha稳定分布噪声下基于柯西分布的相位键控信号码速率最大似然估计

Cauchy Distribution Based Maximum-likelihood Estimator for Symbol Rate of Phase Shift Keying Signals in Alpha Stable Noise Environment

针对现有的相位键控(PSK)编码信号码速率估计方法在Alpha稳定分布中性能严重退化的问题,该文提出一种基于柯西分布的码速率最大似然估计(CMLE)新方法,该方法可同时估计码速率与定时偏差。CMLE利用窗口法将信号划分为定时偏差窗和多个宽度一定的非重叠且已同步的时域窗,每个窗只包含一个码元符号;在Alpha稳定分布噪声下,利用窗中符号信息构造了基于柯西分布的似然函数,可同时获得定时偏差窗宽与码元符号窗宽的最大似然估计。仿真结果表明,该方法能有效抑制Alpha稳定分布噪声并具有良好的参数估计性能。

In order to solve the problem that the performance of existing algorithms for the symbol rate estimation of Phase Shift Keying （PSK） signals will significantly degrade in the Alpha stable noise environment, a novel Canchy distribution based Maximum-Likelihood Estimator （CMLE） method for symbol rate of PSK signals is proposed. The parameters of the timing offset and the symbol rate can be estimated simultaneously through this method. The windowed procedure is utilized in the CMLE and the noise polluted PSK signal is divided into a timing offset window and the multiple windows with certain width which are non-overlapping and synchronized in the time domain, and only one code symbol is contained in each window; in the Alpha stable noise environment, the symbol in the window is utilized and a likelihood function based on Cauchy distribution is built, then the maximum-likelihood estimation of window width for the timing offset and the symbol rate can be achieved simultaneously. The simulation results show that the proposed method can suppress the Alpha stable noise efficiently and offer superior parameter estimation performance.