Application Reseach On Cooperative Space-time Coding In MIMO System

MIMO technology can greatly improve capacity of wireless communication systems, and the spectrum efficiency can be improved without increasing the bandwidth and transmit power. At the same time, MIMO can provide diversity gain to combat channel fading and enhance the reliability of wireless links. MIMO can obtain space and time diversity simultaneously through space-time coding of increasing redundant information. However, capacity gain is achieved when the MIMO channels are sufficiently independent, which requires distance larger than 1/4 wavelength among antennas, thus it is not suitable for portable terminals working below 1GHz. While Virtual MIMO technologies can utilize several mobile terminals with independent antennas to form virtual antenna arrays to improve system capacity, it involves cooperation among the terminals. However, the VMIMO depends on the cooperation between the terminals. This thesis will focus on the application of cooperative space-time coding in virtual MIMO system, including:1) Investigate the cooperative relay selection in the virtual MIMO in flat fading channel, propose a serial Multi-Relay Selection(MRS) in the virtual MIMO2) Propose a Space-Time Cooperative Coding scheme based on Mulit-Relay Selection(MRS-STBC).Simulation results show that the proposed MRS-STBC in virtual MIMO can get the better performance compared with the all-selection cooperative space-time coding(ALL-STBC). But the former just only utilize the relay terminals the coding matrix needed, so it can reduce power consumption.