Study On QC-LDPC-Based Spread Spectrum MIMO Communication Systems

With the development of the wireless communication, how to improve transmission rate andquality under limited bandwidth and bad channel have been the question we have to consider.Combined with recent we can see, multi-input multi-output(MIMO) technology can greatly improvethe quality and speed transmission channel. Since the MIMO technology is put forward, the launch ofthe space-time codes diversity, air separation unit and multiplexing technique about MIMO channelcoding and decoding technology, has become the research focus in the field of wireless.One of the main advantage of the MIMO system is improve the channel capacity, which directlyconvert high data throughput; Another advantage is significantly enhances the reliability of datatransmission, which reduce the bit error rate. And these advantages are attained in without usingincrease the signal bandwidth or increase the signal transmission power.Researches about it have been fruitful on channel coding and spread spectrum and so on. Whileif on the basis of the existing MIMO technology itself, our research on MIMO and the usage ofcoding and spreading on it is quite potential in study and application.This article focuses on the study of the cascade of QC-LDPC/SS/MIMO communication systemthan the general MIMO system superiority in all aspects.The research work in this thesis mainly covers aspects as follows:1. Introduced the basic model of the MIMO channel, studying and analyzing various factors aboutinterference and noise which influence the MIMO system, and take a series of algorithm, includingMMF algorithm, ZF algorithm and MMSE algorithm, and also doing the simulations.2. On the basis of MIMO channel, the author explored the suppression effect of addition ofspreading codes on interference and noise. Introduced principle and course of production of Goldcodes, defined the receiver SNR and SINR, followed by a simulation, and compared the changesbefore and after spread spectrum.3. Studying the structure of check-up matrix, encoding and decoding principle of LDPC code. Andsimulations on these codes are made, so the effect of code length, SNR, code rate and decodingiteration numbers on performance of LDPC codes could be researched. Then designed QC-LDPC,which easy to achieve, and added it into MIMO systems.4. Combined with QC-LDPC code and spread spectrum and MIMO system in order to get the betterperformance of suppressing the interference and noise. After making the comparison with the traditional MIMO system, we find that the performance of concatenated QC-LDPC/SS/MIMOSystems really better than the performance of the traditional MIMO system.