The Study Of The Signal Detections Of The MIMO OFDM System

High data-rata wireless access is demanded by many applications. Traditionally, more bandwidth is required for higher data-rata transmission. However, due to spectral limitations, it is often impractical or sometimes very expensive to increase bandwidth. In this case, we can use multiple-input multiple-output (MIMO) technology. It is proved that, compared with a single-input single-output (SISO) system with flat Rayleigh fading or narrowband channels, a MIMO system can improve the capacity by a factor of the minimum of the number of transmit and receive antenna. The orthogonal frequency division multiplexing technology divides the entire channel into many narrow parallel subchannels, thereby increasing the symbol duration and reducing or eliminating the intersymbol interference (ISI) caused by the multipath. Multiple transmit and receive antennas can be used with OFDM to further improve system performance. In this paper, we will focus on signal detection for MIMO-OFDM.Before introducing the signal detection, we briefly describe the OFDM technology and MIMO technology, and then the VBLAST signal model is defined and four signal detections are introduced, at last we define the MIMO OFDM signal model and implant four signal detections in MIMO OFMD system. In each section, the performance of the four signal detections is evaluated analytically and numerically and conclusions are also drawn in each section. In the end, we introduce a new signal detection which is based on QR algorithm and the result shows that the performance of the new signal detection is better than the others.