基于类间功率谱差的FRFT-TDCS门限判决算法

针对分数阶傅里叶变换域通信系统采用传统门限判决算法难以有效剔除多分量线性调频干扰的问题，根据高斯白噪声和多分量线性调频干扰分数阶傅里叶变换域功率谱特征，提出了基于类间功率谱差的门限判决算法。该算法利用了分数阶傅里叶变换不影响高斯白噪声的统计特性，在分数阶傅里叶变换域的三维频谱上自适应地确定门限值，既可以有效对多分量线性调频干扰频谱剔除，又解决了分数阶傅里叶变换的变换阶次对门限判决带来的不利影响。仿真结果表明，该算法在双极性调制和循环移位键控调制下，对多分量线性调频干扰剔除的有效性，尤其在大干信比情况下，误码率的提升尤为明显，对提高分数阶傅里叶变换域通信系统抗多分量线性调频干扰的能力具有一定的实用价值。

Threshold decision algorithm for FRFT-TDCS based on power spectral difference between classes

In order to overcome the problem that transform domain communication system based on fractional Fourier transform(FRFT-TDCS) with traditional threshold decision method is difficult to eliminate multi-component linear frequency modulation( LFM) interference. According to the power spectrum of Gauss white noise and interference, a threshold decision algorithm based on the power spectrum difference between classes is proposed. The algorithm takes advantage of the fractional Fourier transform that does not affect the statistical properties of Gauss white noise. It can effectively determine the threshold value in the three-dimensional spectrum of the FRFT domain, which can effectively eliminate the interference spectrum and solve the negative influence of the FRFT transformation order on the threshold decision. The simulation results show that the algorithm is effective for jamming in bipolar modulation and cyclic shift keying modulation. Especially in the case of large interference energy-to-signal energy ratios, the improvement of bit error rate is particularly evident. It has practical value for improving the ability of FRFT-TDCS to resist LFM interference.