FRFT-TDCS应对多分量LFM干扰的最优阶次选择算法  

Optimal order selection algorithm for FRFT-TDCS with multi-component LFM interference signal

作　　者：孙乐[1] 张衡阳[1] 魏军[1] 余侃民[1] 宋爱民[1] 

机构地区：[1]空军工程大学信息与导航学院,西安710077

出　　处：《计算机应用研究》2017年第10期3121-3124,3148,共5页Application Research of Computers

基　　金：国家自然科学基金资助项目(61202490);航空科学基金资助项目(20150896010)

摘　　要：针对FRFT-TDCS应对多分量LFM干扰信号时的变换阶次选择问题,提出了一种以寻求最大可用带宽为标准的FRFT-TDCS最优阶次选择算法。首先分析了LFM干扰信号在FRFT域内不同阶次下的频谱分布特征,对其能量聚焦时的展宽、位置以及幅值进行了量化;然后通过预设门限对不同变换阶次时的干扰频谱进行标记并统计,选择使可用子载波个数最多的变换阶次作为系统最优阶次;最后对CSK解调模型进行推导,得出了系统误码率与基函数自相关函数之间的关系,证明了增加系统可用子载波个数可以降低误码率。仿真结果表明,该方法在应对多分量LFM干扰时,可以自适应确定系统最优阶次,降低基函数的峰值和均值,提高发射波形的LPI、LPD性能,有效降低系统误码率。To deal with the transform order selection problem for FRFT-TDCS system with multi-component LFM interference signals, this paper proposed an optimal order selection algorithm which could achieve the maximum available bandwidth. Firstly, it analyzed the spectrum distribution characteristics of LFM interference signals under different orders in the FRFT domain, and it quantified the energy bandspread, location and amplitude of the LFM interference signal, Then, it could tag and count the interference spectrum in different transform order using the preset threshold, and it chose the optimal order which could maximize the number of available subcarrier. Finally, it obtained the relationship between the system BER and basis function autocorrelation function by deriving the CSK demodulation model, and it proves that the increase of system available subcarrier number can reduce the BER. The simulation results show that, the proposed method can find the most optimal order when dealing with multi-component LFM interference signals, the basis function generated under this transform order can achieve the lowest peak and mean value, improves the system performance of LPI and LPD, and effectively reduces the system BER.

关 键 词：分数阶傅里叶变换 变换域通信系统 多分量LFM干扰信号 最优阶次 

分 类 号：TN911.4[电子电信—通信与信息系统]