| Being the central technique of the next generation mobile communication, MIMO-OFDM has become the focus of research. MIMO (Multi-Input and Multi-Output) makes use of multi-antennae at transmitting and receiving side to transmit signals, and the multi-paths spreading characters of wireless channel to improve the performance of the system and the capability of the channel. OFDM (Orthogonal Frequency Division Multiplexing) is a multi-carriers transmitting manner. This manner divides the whole channel into some sub-channels, which are orthogonal and independent each other. ISI of system caused by multi-paths delay spread can be reduced through this flow process. In order to show the advantages of MIMO-OFDM system fully, crucial techniques should be studied deeply. In this thesis, channel estimation technique, one of the MIMO-OFDM crucial techniques, is researched, and some results are showed through simulation.At the beginning, this thesis introduces fading characters of wireless channel. Aiming at multi-antennae system, spatial fading trait is discussed with parameters, like interval of antennae, degree of arriving angle and angle spread. A typical method of time and spatial channel constitution is shown and a simulating model is established in second chapter, this method can change spatial fading trait through controlling the setting of parameters. Then construction character of STBC is analyzed, and transmitting traits of MIMO system based on STBC are studied through simulation under the conditions of different antenna numbers and different diversities. Some pilot aided channel estimation methods are theoretically analyzed in OFDM system. Some simulating comparisons among algorithms are carried out toward pilot types, channel response calculation at pilot position and channel response estimation at data position. On the foundation of theories mentioned above, performance curves of MIMO-OFDM system with estimation algorithms are given and good performances are received under... |
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