Chaotic Communication System of Noise Reduction Improved Multiple User Multiple Ary Correlated Delay Shift Keying

In view of the poor transmission efficiency of Correlation Delay Shift Keying (CDSK) system, this studyproposed a noise reduction improved multiple user multiple ary correlated delay shift keying (NR-I-MUMA-CDSK) basedon Schmidt Orthogonalization Chaotic communication system. The system uses Schmidt orthogonalisation to generate N different sets of orthogonal chaotic sequences at the transmitter side, and then copies the generated sequences P times. It also employed multiple ary information mapping and multi-carrier technology, enabling each user to carry K bits ofdata. It also designed to transmit N sets of user information on a single carrier wave by superimposing N different orthogonal chaotic signal carriers. The transmission rate and energy efficiency of the system were improved. The receiveruses the moving average filter to process the signal, reducing the noise variance from N₀/2 to N₀/2P. This reduces noiseinterference, which in turn reduces the system bit error rate(BER). The theoretical formula derivation and simulationanalysis of the system in Additive White Gaussian Noise (AWGN) and Rayleigh fading channel were carried out respectively. The results show that, compared with CDSK, the system improves the information transmission rate andenergy efficiency. The information transfer rate increases with N and K, and the average bit energy decreases by nearly 100% with K. The effects of different parameters on the system BER were verified by simulation. The results show thatthe system BER is inversely proportional to P and the binary number M, directly proportional to N and R, and consistentwith the deduction of theoretical formulas under both channels. The effects of path number L and path gain on the biterror rate were verified by simulation in Rayleigh fading channel. Compared with many chaotic communication systems, the system BER is greatly reduced, and the system BER decreases with the increase of M, which proves that the systemhas good theoretical value and practical engineering significance.