On The Simulations Of The Space Time Coding And Its Applications In Space Time Cooperative Communications

As one of the key technologies to enable broadband wireless communications, the multiple input multiple output (MIMO) technique can significantly improve the channel capacity without increasing the spectrum resource and transmitting power by using multiple antennas at both transmitter and receiver to make full use of spatial resource. Space-time coding is one of the most important signal processing techniques for MIMO. Previous research has validated that, space-time coding offer a feasible method to combine coding techniques and array antennas to achieve both diversity gain and coding gain by exploiting both space and time diversity.Unfortunately, in practical wireless communication environment, it would be difficult to install multiple antennas on the mobile unit to form the antenna array due to the limited physical size. However, this problem could be well overcome by using the cooperative communication technology. Basically speaking, the principle of cooperative communication is that, it makes use of the broadcasting property in radio communication, where the cooperative nodes will overhear each other, thus could be organized to share their antennas to formulate the virtual antenna array for utilizing the MIMO technique. By means of cooperation, mobile unit is able to achieve the high data throughput and meet the reliable data transmission requirement.In this thesis, after a brief survey of the existing space-time coding and cooperative communication techniques, the emphasis is laid on the three primary space-time coding schemes of orthogonal space-time block coding(OSTBC), space-time trellis coding(STTC) and vertical Bell laboratory layered space-time coding(VBLAST). The simulation system platform is developed to validate the above three space-time coding schemes, and a number of simulation is performed to illustrate the performances for different space-time coding schemes. It is shown that, different schemes have different characteristics and could be utilized in different communication environment. Based on the analysis of the existing space-time coding schemes, the space-time cooperative coding schemes are investigated for some cooperation communication model. More specifically, both the OSTBC-based and the STTC-based cooperation schemes were proposed for multiple relays and multiple hop communication models, wherein both the amplify-and-forward (AF) mode and the decode-and-forward (DF) mode are employed. The simulation platform is developed to validate the performance of the proposed space-time cooperative coding schemes as well. It is shown that, although the performance of OSTBC scheme was not as good as that of the STTC scheme, it could be readily utilized in cooperative communication system due to its simpleness to be implemented, lower complexity, the flexible configuration and the significant improvement achieved.