Research On MIMO Technology Of High Rate WLAN

Wireless Local Area Network (WLAN) is a very popular topic at present. It is developing rapidly, and the technology of low-rate in WLAN has been very mature. There are many products available at the rate of IMbps, 2Mbps, 5.5mbps, 11Mbps using the IEEE802.1l and IEEE802.11b standard. But with the continuous increase of social demand, it is necessary to develop a WLAN technology that can support higher rate and more services. The IEEE802.11a standard can supply the transmit rate up to 54Mbps. the most important reason is the use of OFDM technology. And the most advantage of OFDM is that it can convert high-rate data stream into the low-rate and reduce data bandwidth so that multi-path-fading can be transformed into flat fading in wireless circumstance. But it is not enough for a simple OFDM system to resist multi-path-fading. The multi-path-fading can be resisted efficiently and system's error bit rate performance can be improved if we combine OFDM, a high-rate modulation technology, with MIMO.The MIMO-OFDM system has three styles such as STBC-OFDM, SFBC-OFDM and VLBAST-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 code designing and the algorithm of the signal detection of three MIMO-OFDM systems. At the same time, their performances were analyzed and simulated. The useful results were got. All of these will play a great guiding role in the development and application in the field of WLAN.