Research On Combined Space-Time Block Code With Spatial Multiplexing In MIMO System

In this paper, we mainly discuss spatial diversity-oriented STBC and spatial multiplexing-oriented V-BLAST. Simulation results show that STBC can achieve large diversity gain but low spectral efficiency, while V-BLAST can get high spectral efficiency but bad resistibility toward fading.After considering the advantages of STBC and V-BLAST, we research two combined schemes in this thesis. The first one is an adaptive MIMO scheme which switching between STBC and VBLAST based on the instantaneous channel state. In this scheme, the receiver estimates the performance of STBC and V-BLAST, and chooses the optimal one based on the proposed switching criterion, and feedbacks this decision to the transmitter. The transmitter then switches to the corresponding mode according to the indication. We mainly study the selection criterion based on error probability. Simulation results show that this scheme performs better than STBC or V-BLAST. The second combined scheme is layered space-time block code (LSTBC). We chiefly study the group interference suppressing based on QR decomposition is used at the receiver, also discuss the performance of LSTBC through simulations, the simulation results demonstrate that LSTBC can get diversity gain and multiplexing gain. Finally, the geometric mean decomposition pre-coding technique is used in LSTBC scheme to pursuit better performance.