The Study Of Space-Time Coding In MIMO Communication Systems

Future wireless communication systems demand for higher communication quality and data rate, which makes people develop more effective technology of coding, modem, and signal process to improve quality and spectrum efficiency. The technique of space-time coding combines the technique of channel coding and array diversity, and can increase the capacity of wireless communications systems and give diversity gain and coding gain to them. It can also improve the bandwidth efficiency of traditional single-antenna systems. This technique is intended to provide new solutions to the problem of limited bandwidth.This paper introduces the antenna selection technique based on the research on the model of MIMO system and the technique of diversity. It introduces in detail the incremental selection algorithm which selects one receive antenna every step to make the system capacity best. However, the computation is still large in the systems with large scale antenna array. Aim at this disadvantage, this paper proposes an improved algorithm for incremental selection algorithm, which reduces the computation complexity by updating the quantities in real time and decreases computation time by handling two rows every step.This paper researches the quasi-orthogonal STBC (QSTBC) in detail. It analyzes the structure and difference of several types of QSTBC and the character of QSTBC, proposes two novel design methods of QSTBC for four antennas which enlarges the number of QSTBC. This paper proposes Zero Forcing (ZF) decoding algorithm based on the research of the proposed algorithms. Experiment proves that ZF algorithm has good performance and can reduce the computation complexity. There is some theoretic meaning and practicality value in it.