Design And Simulation Of Space-Time Coding Cascaded To LDPC In MIMO System

MIMO system can improve system performance remarkably and provide dependable wireless transmission link by using multiple sending antennas and receiving antennas. The system can increase the capacity and availability of frequency spectrum of communication system exponentially without the increase of bandwidth. The next generation communication systems (4G) need provide enhanced data rate and high quality communication for Internet and kinds of multimedia service. So how to supply high rate and high quality communication by using efficient signal processing and coding technique in MIMO system has been paid more and more attentions, it will be one of the key technology in 4G communication system. At the same time, the space-time coding technology which can resist channel fading and increase channel capacity and the efficient channel coding(such as LDPC, Turbo code) have developed rapidly, which have been research highlight in the coding theory in the wireless communication field.This thesis firstly introduces the background, history and present situation of MIMO system and space-time coding technology. Then the thesis discusses the channel capacity of MIMO system, studies and compares the design solutions,code and decode methods and performance of three kinds of space-time code. The thesis researches the LDPC which is a kind of channel coding approach to the Shannon bound, study the hard-decision decoding and soft decision decoding, then analyze and compare the complexity and performance of the two decoding schemes.This thesis focuses on the design of the space-time coding cascaded to LDPC system and the system's coding and decoding scheme, presents the LDPC-ASTBC system and LDPC-DSTBC system. The independent iterative decoding algorithm and joint iterative decoding algorithm were proposed for the LDPC-DSTBC system. At last the thesis uses MATLAB software to simulate the systems mentioned in the previous sections, analyzes the simulation results. The simulation results show that the cascade system not only improves the performance of space-time coding tremendously, but also improves the performance of LDPC to some degrees. In the two sending antenna and one receiving antenna MIMO system, the LDPC-ASTBC system and LDPC-DSTBC system can obtain 20dB gain more than the space-time coding system and about 2 dB gain more than the single LDPC. The LDPC-ASTBC system performs about 1.5dB better than the LDPC-STBC system. The joint iterative decoding algorithm used in LDPC-DSTBC system performs about 2 dB better than the independent iterative decoding algorithm.