Research On Differential Space-Time Block Coding In MIMO System

In wireless communication environment, High-speed communications is faced with the limited spectrum resources, time-varying complex wireless environment and other issues. It is difficult to resolve these questions by using traditional way. In order to meet the higher data rates, better service quality, and greater damand for network capacity, innovative techniques that improve spectral efficiency and transmission reliability are proposed. Such as the MIMO (Multiple Input Multiple Output) technology which uses multiple antennas at the receiver and transmitter. Without increasing bandwidth or transmit power, MIMO systems can improve channel capacity greatly, which is much larger than single antenna systems. Space-time code is proprosed by combining transmit diversity and coding technology.The thesis focuses on the related technologies of differential space-time code. The main contents are as follows.(1) Firstly, the orthogonal design of space-time code is introduced. The coding and decoding principle of the Differential Space-time Code is investigated, Without channel state information, the receiver can decode correctly by differential decoding. The performance of differential decoding reduces, but it improves spectral efficiency.(2) In flat fading channels, the concatenation of the linear error-correcting code and DSTBC is investigated in order to improve the performance of the DSTBC. The simulation result indicates the concatenated code can improve the performance.(3) In frequency selective fading channel, frequency selective fading channel is transformed into flat fading sub-channels by adopting OFDM (Orthogonal Frequency Division Multiplexing) technology. Usually, estimating channel state information is very difficult in OFDM system, so the thesis adopted DSTBC. At the same time, error-correcting code is used for Compensating the performance loss of DSTBC. The simulation result indicates the concatenated code can improve the performance. Finally, the program is simulated in frequency selective fading channel and performance is analysed.