一种基于循环谱的共信道多信号调制参数估计方法

共信道多信号的调制参数估计问题已成为通信信号处理领域的一个新兴课题，在非合作通信中是调制识别、信号解调等后续处理的基础。信号经过调制、成形及采样等处理后具有循环平稳性，本文提出了一种基于循环谱和离散谱线提取的调制参数估计方法。该算法利用信号调制参数和循环频率之间的关系，通过提取信号循环谱的谱频率截面上与循环频率相对应的离散谱线，实现对时频重叠的共信道多信号中每个信号分量调制参数的精确估计，主要包括载波频率和码元速率。Matlab仿真BPSK、8QAM两种类型的混合信号结果表明该方法切实有效，可以实现载波频率相差不大时共信道多信号的调制参数估计问题，并且算法计算复杂度小、精确度高、抗噪声性能好，不受频谱重叠度的影响。 

A Method for Modulation Parameters Estimation of Co-Channel Multi-Signals based on Cyclic Spectrum

Modulation parameters estimation of co-channel multi-signals has become a new subject of communication signals processing. In the non-cooperative communication fields, it is the key step and base of subsequent processes, such as modulation recognition, signal demodulation and so on. As is well known, signals exhibite cyclostationary character after modulation, pulse formation and sampling, which is different for those time-frequency overlapped co-channel multi-signals whose modulation parameters are often different from each other. Making use of the character mentioned above, this paper presented a method based on cyclic spectrum and discrete spectrum-line abstraction to estimate the modulation parameters, including carrier frequency and chip rate. The method utilized the relationship between modulation parameters and cyclic frequency, extracted the discrete spectrum line corresponding to the carrier frequency and chip rate in the cyclic spectrum profile to estimate the parameters of each time-frequency overlapped signals. Using BPSK and 8QAM as overlapped simulation signals, Matlab simulation results proved the method effective and accurate. Even when the dispersion of carrier frequencies is very small compared to the chip rate, this method can also be used. Additionally, it is robust to noise and spectrum overlapping extent; at the same time, the sum of computation is small as well.