In this paper, a noise reduction orthogonal multi-user correlated delay shift keying (NR-OMU-CDSK) noncoherent communication system based on frequency domain processing is proposed. In NR-OMU-CDSK, chaotic signal generated in frequency domain is converted to time domain through inverse Fourier transform, and then the real and imaginary components of the time domain signal are simultaneously modulated to two phase-orthogonal branches. The transmission rate and security performance of each branch are further improved by switches and Walsh code. In the receiver, moving average filter is used to reduce the variance of interference term in the decision variable, and information bits are obtained through relevant demodulation. The bit error rate (BER) performance of NR-OMU-CDSK is evaluated in AWGN channel and multipath Rayleigh fading channel. The research results show that the theoretical BER is basically consistent with the simulation results. The transmission rate of NR-OMU-CDSK is improved by 4N×100% (N is the number of users), and the signal-to-noise ratio is improved by nearly 4dB for the same BER performance, when NR-OMU-CDSK is compared with conventional CDSK in AWGN channel. Moreover, compared to other multi-user systems, this system has also obvious advantages in various system performance and avoids RF delay line problems.

本文提出了一种基于频域处理的降噪正交多用户相关延迟移位键控(NR-OMU-CDSK)非相干通信系统。在NR-OMU-CDSK中，将频域产生的混沌信号通过傅立叶逆变换转换到时域，然后将时域信号的实部和虚部同时调制到两个相位正交的分支。交换机和沃尔什码进一步提高了各分支的传输速率和安全性能。在接收端，利用移动平均滤波器来减小决策变量中干扰项的方差，通过相关解调得到信息比特。NR-OMU-CDSK 的误码率 (BER) 性能在 AWGN 信道和多径瑞利衰落信道中进行评估。研究结果表明，理论误码率与仿真结果基本一致。NR-OMU-CDSK的传输速率提高了4N ×100%（N为用户数），在AWGN信道下，NR-OMU-CDSK与传统CDSK相比，在相同BER性能下信噪比提高近4dB。而且，与其他多用户系统相比，该系统在各种系统性能上也有明显优势，避免了射频延迟线问题。