Design Of Multi-channel PCSS System Based On MQAM

Spread Spectrum Technologies are widely used in military confrontation and civil communication because of its high electromagnetic hidden,high adaptability to wireless channel and multiple access capability.Compared to the traditional Direct Sequence Spread Spectrum,Parallel Combinatory Spread Spectrum which was developed from the Soft Spread Spectrum has advantages of strong information transfer capability and high bandwidth efficiency.Parallel spread spectrum sequence,which is added from selected pseudo random sequences,is a multi-value sequence,So we can use the multi band digital modulation mode.For example,MPSK,MQAM,MASK or MAPK etc..All these modulation methods have high spectral efficiency,but MQAM can make good use of signal space,the anti-noise performance of which will be better than M-ASK,M-FSK,M-PSK etc..So,it is widely used.in,large capacity digital microwave communication system,cable TV network data transmission,satellite communications and other fields.The PCSS software simulation platform based on MATLAB and mathematical models of 16 QAM were built.Demonstration and design the main parameters of symbol rate,The chip rate and spread spectrum sequence periodic sequence,carrier frequency.For multi-channel MQAM modulation based on parallel combinatory spread spectrum communication system requirements,design and optimizate the autocorrelation and cross-correlation sequences with good properties set.Under the assumption that the synchronization and Gauss white noise channel conditions,Simulation analysis of the main performance of the system,and make a comparison with parallel combination spread spectrum communication system with single channel.