Research On Channel Estimation In MIMO-OFDM System

Channel estimation is one of the most important and most difficult problems in the wireless mobile communication engineering. The contents of this dissertation are concentrated on the channel estimation technologies in new generation wireless communication systems.Wireless mobile communication has undergone surprising development recently. The second generation mobile communication is developing at a never appeared speed. The third generation mobile communication, which can provide voice, data, video as well as other multimedia services, is at the beginning phase of commercialization. And the research on new generation mobile communication, i.e. the fourth generation or the beyond third generation mobile communication, has also been started.The main characteristics of new generation wireless communication lie on the ability to support high data rate and large system capacity services. Demands for high data rate based mobile wireless communication services are rapidly increasing. The main driver of this development is the booming mobile Internet and multimedia market. However, physical limitations on wireless channel present a fundamental technical challenge for high data rate mobile wireless communications. So some new powerful technologies are needed to support high spectral efficiency in new generation wireless mobile communication. MIMO-OFDM is one of the most promising scheme for achieving high data rate and large system capacity over wireless mobile links.As a combination of OFDM with space time coding technique, MIMO-OFDM has recently received considerable attentions, which can not only effectivelyenhance the transmission rate and capacity of the wireless communication system but also effectively combat multi-path fading and interfere. In this paper, we discuss the principle of MIMO-OFDM system based on the introduction of fading channels. Furthermore, the channel estimation technique in MIMO-OFDM system is investigated, describes several channel estimation schemes for multiple input multiple output(MIMO) orthogonal frequency division multiplexing(OFDM) systems, and focuses on time domain and frequency domain least square(LS) criterion based channel estimation schemes, and also introduce several improved algorithms based on time domain least square(LS) criterion. Furthermore the analysis and comparison of these algorithms is made by computer simulation. Then, a new channel estimation method, based on the frequency domain least square algorithm, is proposed to improve the performance of channel estimation method named block least square algorithm.