Reaearch And Implement Of The Coding And Carrier Synchronization Technique For MT-DS-CDMA Communication

There is noise and fading in the wireless channel, also with frequency offset, which would cause the distortion and the error judgement of the signal. So we need to deal with the received signal as to gained useful information to the best of out abilities. We can adopt carrier synchronization technique to recovery coherent carrier, also we can take error control coding to detect and correct the error bit.We figure out the basic principle of channel coding, focus on the characteristic of convolutional coding and interleave-coding. Furthermore, we analyze the reason which cause frequency offset, and then introduce the usual method of carrier synchronization through enumerate the harm of frequency offset. Then, we analyze the characteristic of Decision-Directed Loops and Non-Decision-Directed Loops, and figure out the simulate result about Squaring loop and Costas loop.We propose a proper coding scheme and carrier synchronization algorithm of MT-DS-CDMA system, on the basis of summary on communication system coding and carrier sync techniques. Moreover, the theoretical performance of carrier sync algorithm is deduced, and simulation results of convolution coding and carrier sync algorithm under PN synchronization and PN asynchronization are presented. After algorithm simulation, we finished the FPGA hardware implement and system test, the bit error ratio of (2,1,8) convolution code reach to 10^-5 when E_b/N₀=4dB under AWGN channel, also the carrier sync algorithm have good astringency within small frequency offset from -250Hz to +250Hz, so the results achieved system design requirements.