Research And Design Of PN Code And Error-Correcting Code In The Spread Spectrum Communication System

In spread spectrum communication systems,anti-interference,anti-multiple path, anti-interception,multiple access communication and synchronization are all in relation to the used spread sequences.So,the spreading sequence designs are one of the key points of the spreading spectrum communication systems.In this thesis,related to the theory of spreading sequence we investigated the lower bounds on the correlation functions of spreading sequence set,sequences design with optimal Hamming correltion functions.Several classes of notable spreading sequences have been studied.This paper analyzed the balanced Gold sequence and its generation method,and we gives an improved method which is faster; several generation methods of M sequence were discussed,based on this,a new method can obtain M sequence with any length and amount was given; There are different effects coming with different models in the chaotic systems realized with finite precise.Besides,in the comparison we study the PN codes'performance of balance,performance of auto-correlation,performance of cross-correlation,performance of sidelobe,performance of peak value,as well as simulation.With the development of communication technology,the require of higher reliability for data transmission increase dramatically.Since Error-Correcting code can enhance such reliability,it has been attached much importance.The Error-Correcting code discussed in the paper are Reed-Solomen code and Convolution code.As the two codes are very common,in the base of introduce the basic theory,we have the software realization of common coding and decoding process.The decoding of RS in frequency domain is much simpler than in time domain,for optimize we create a list of element in Galoias fields to make it convenient,furthermore,we compared the performance of error-correcting between algorithm in frequency domain and in time domain.The Viterbi algorithm was discussed base the butterfly plot,the deducing of calculation in branch metric unit and path metrics unit discussed,as to optimize the whole add-compare-select unit.