Mimo-ofdm System, Synchronization, Channel Estimation And Adaptive Algorithm

The need for wireless data and multimedia services enhances during the development and applications of broadband wireless communication techniques. Thus in the last a few years , Multiple Input and Multiple Output (MIMO) techniques and Orthogonal Frequency Division Multiplexing (OFDM) techniques have gained more and more interest. The great merit of MIMO is high usage of frequency spectrum and the MIMO technique gives high speed data transmit in multi-path fading channel. Meanwhile, OFDM is an effective modulation mode which can can combat ISI in multi-path fading channel. Nowadays, there are more and more applications choosing OFDM as their physical layer technique, including DVB (Digital Video Broadcast), HDTV (High Density Television) and WLAN (Wireless Local Area Network). Because of these, how to combine advantages of the MIMO and OFDM in a wideband wireless communication system has been a pop research.Basing on many researches about MIMO and OFDM, the article mainly does research on the key technologies for the wideband wireless system (MIMO-OFDM system). The main technologies contain channel estimation, system synchronization and adaptive modulation. By analyzing and simulating the corresponding arithmetic, detailed algorithms are researched for different channel environments.The article is organized as follows:In the chapter one, the phylogenies of MIMO and OFDM are succinctly introduced. The relative merits of the two technologies are researched too.Chapter two gives study on the synchronization algorithms for different channel environments. Groups are divided based on usage of different inputs and detailed characteristics of these groups are analyzed. Then by analyzing and simulating based on those characteristics, the performances in different channel environments are compared.Chapter three gives study on the channel estimation algorithms for different channelenvironments and discusses the key problem of MIMO-OFDM------doubly selective channel.Theoretical analysis is made based on the variant channel and calculation burden. Then the optimum design is studied and the corresponding simulations are made in different channels.The last chapter gives discussion for other key techniques in MIMO-OFDM system, Space-Time Codes are researched based on an real simple system, at the same time adaptive modulation arithmetic are introduced.Finally, according to the limitation of the MIMO-OFDM system designed in the article, some ideas are discussed to improve the system performance.