Reception of M-ary Orthogonal Negacyclic Code Shift Keying Signals Based on Odd Discrete Fourier Transform
Игорь Александрович Гепко · Radioelectronics and Communications Systems · 2022
Abstract In this paper, the idea of “deep upgrade” of the Cyclic Code Shift Keying (CCSK) is further developed. It is proposed a new method of information transmission for M-ary spread spectrum communication systems, which is orthogonal negacyclic shift keying (ONCSK) based on odd-periodic complementary sequences. The method combines the noise immunity of orthogonal signal systems, the simplicity of signal processing of CCSK and the computational efficiency of FFT, as well as high structural security. The developed digital reception processing algorithm is based on computation of odd correlation functions and application of odd discrete Fourier transform. The scalability of the length of the base code N makes it possible to implement a CDMA system that is adaptive in terms of the frequency band used, the spreading factor, and the data transmission rate. ONCSK noise immunity gain in compare to CCSK is valuable for applications such as satellite and deep space communication systems, transform domain communication systems, and IoT. In channels with forward error correction (FEC) coding, ONCSK scheme performs better than CCSK with a much larger spreading factor and many times more computationally complex FEC codec. Refined sizes of ensembles of complementary sequences for different lengths N are determined and structural security characteristics of bipolar spread spectrum signals based on them are studied, including aspects, which are specific to ONCSK.