Research On Channel Estimation And Adaptation In Mimo-ofdm System

As a combination of OFDM with MIMO technique, MIMO-OFDM has recently received considerable atentions, which can not only effectively enhance the transmission rate and capacity of the wireless communication system, but also effectively combat multi-path fading. Recently, industry activities suggest that the use of MIMO-OFDM is particularly promising for new generation wireless communications.Channel estimation is one of the most important problems in the wireless mobile communication engineering. To develop a MIMO system, exact channel estimation is necessary. And if the channel state information is known through channel estimation, adaptive bit and power allocation techniques can be applied to optimize the performance of the systems.In this paper, we discuss the principle of MIMO technique, OFDM technique, and MIMO-OFDM system, based on the introduction of wireless fading channel. We introduce several channel estimation schemes, and focuses on LS criterion based channel estimation and MMSE criterion based channel estimation. Furthermore, the analysis and comparison of these algorithms is made by computer simulation. Finally, after introduce three criterions and Classic water-filling algorithm, Hughes-Hartog algorithm, Chow algorithm, Fischer algorithm, a low-complexity adaptive bit and power allocation algorithm is proposed, based on grouped subcarrier. Computer simulation is also made to analyze the algorithm.