Space-Time Code Technology In Wireless Telecommunications System

People have more and more demands on mobile communications with the development of the society and technology. Except for voice, more and more subscriber want to get other multimedia access services, like data, video and images from everywhere and at anytime by the wireless network. All these call for mobile communication systems with more frequency effective and with more capacity. However, the channels for wireless mobile communications are very random because of the open and mobile property. These will lead to time-selective or frequency-selective fading. In wireless mobile communications, diversity techniques are widely used to reduce the effects of multipath fading and improve the reliability of transmission without increasing the transmitted power or sacrificing the bandwidth. According to the domain where diversity is introduced, diversity techniques are classified into time, frequency and space diversity. Only space diversity can be exploited without data rate loss. We can exploit space diversity by placing multi antennas at the transmitter or the receiver. The systems with multi antennas are called MIMO systems, and MIMO techniques are the most eminent progress in communication fields. It may be one of the prominent way to solve the bottleneck of the service capacity. Space-time coding is a technique to get the maximum coding and diversity advantages in MIMO systems. Researches on space-time coding are mostly based on flat fading channels, which can not met the demanding for wideband applications. Recently, space-frequency coding was emerging to solve the problem on frequency-selective channels. The main researches in this dissertation including: 1. Researches on MIMO system under quasi-static fading channels In the past ten years, although people have achieved great progress on MIMO technology, there are still some problems need to research to reach the increased channel capability in the real communication system. These problems are also current...