Study On The Technology Of Space-time Coding In MIMO System

After entering the new century, the desire of people that is communicating information with each other in a high speed at anytime and anywhere has become stronger and stronger. But because of the limited radio spectrum, more efficient signal processing techniques have been considered to realize the high data transmitting rate. The proposal of MIMO technology could be regarded as a great breakthrough in the field of modern wireless communication. With the introduction of spatial dimensions, which makes a certain correlation between time domain and space domain, the capacity of wireless communication system will be increased greatly as well as the spectrum efficiency in the case of same bandwidth and transmission power. Besides, the MIMO system not only can achieve the considerable diversity gain, but also can change the date rate by combining MIMO technology and space-time coding(STC) technology.The thesis embarks from the environment for mobile communication system, and focuses on the basic theory of MIMO system and STC technology, which comes out the channel capacity of the MIMO system and two designing rules of STC from the perspective of mathematics. Then, it emphasizes on the Space-Time Block Coding(STBC) which is widely used, resulting in the detailed analysis of the principles and performance of the Orthogonal Space-Time Block Coding(OSTBC) and Quasi-Orthogonal Space-Time Block Coding(QOSTBC) as well as the simulation analysis.STC-MIMO-OFDM systems can synthesis the advantages of three technologies to bring better performance gain. In this paper, the group transmitting method used in single antenna system has been introduced into STC-MIMO-OFDM system, which results in the new system that is NSTC-MIMO-OFDM system. A multi-dimensional diversity, including time, frequency, space and modulation diversities can be achieved by the NSTC-MIMO-OFDM system. The thesis proves that the proposed NSTC-MIMO-OFDM systems provide considerable improvement in the bit error performance compared to the STC-MIMO-OFDM system at the cost of a slightly more complicated system structure from the perspective of theory and simulation.