Singular Value Decomposition Optimizes Multi-Level Orthogonal Code Index Modulation DCSK System

To improve the bit error rate (BER) performance of the differential chaotic shift keying (DCSK) system, this letter proposes a multi-level orthogonal code index modulation DCSK (MOCIM-DCSK) system. A set of mutually orthogonal reference signals is generated using the Gram-Schmidt algorithm, with each reference signal carrying code index bits and modulation bits for the transmission of information signals. Additionally, to further enhance the system’s reliability, singular value decomposition (SVD)-aided detection is introduced, successfully suppressing additive white Gaussian noise (AWGN). The BER formulas of MOCIM-DCSK system over AWGN channel and multipath Rayleigh fading channels is derived, and the complexity of MOCIM-DCSK system is compared with other systems. Simulation results validate the correctness of the theoretical derivations and demonstrate the outstanding BER performance of the system. Furthermore, the application of SVD to the MC-DCSK system provides additional evidence of its advantages and versatility in enhancing BER performance.