Applied Research Of MIMO Technology In The OFDM System

OFDM technology converted high-rate data stream into the low-rate through serial-paralell transformation, and distributed it to many orthogonal subcarriers to transform so that the data bandwidth was reduced and frequency selective fading channel can be transformed into flat fading channel and the multi-path-fading can be resisted efficiently. But it will increase complexity and bandwith of the system for a simple OFDM system to increase capacity and transformation rate. And MIMO technology can produce many mutually independently paralell transformation channel in woreless circumstance and then use it to transform paralell data information simultaneously, Which can improve transformation rate without extra bandwidth and gain the aim of increasing frequency utilization. So we not only reach the requirement of high rate and large capacity but also inhance the capability of resisting noise and multi-path, improve system performance, if we combine OFDM with MIMO.The MIMO-OFDM system contains a few basic forms such as STBC-OFDM, STTC-OFDM, VBLAST-OFDM, SFBC-OFDM. Firstly the basic principle of OFDM and its anti-multi-path-fading are briefly introduced in this paper. Then basing on this point, we researched the basic principle, the coding designing and the algorithm of the signal detection of these MIMO-OFDM systems. At the same time, the performances of STBC-OFDM and SFBC-OFDM were analyzed and simulated under short wave circumstance, and got some useful conclusions, they have certain reference value for more research of short wave communication in future.