| OFDM has been considered as one of the key techniques in 4G mobile communication systems due to its high rate data transmission with high bandwidth efficiency and its robustness to multipath delay. MIMO can greatly increase the capacity of wireless communication systems,as well as improve wireless communication systems performance, which highly meet the requirements for high data rate in next generation mobile communication network. Therefore, it's natural to consider combining the two kinds of techniques to improve the performance of mobile communication systems further.Channel estimation is one of the key considerations in MIMO-OFDM systems. The precision of channel estimation will directly influence the system performance. So, providing a fast, accurate and reliable channel estimation algorithm is an important research subject, which is discussed in detail.This paper gives a brief introduction about the basic principle of OFDM systems and MIMO channel firstly, based on which the system construction and system model of MIMO-OFDM are given. Secondly, the issue of the selection of one important parameter, pilot, is proposed. Then, a kind of channel estimation and an optimum training sequences designing method is introduced. In the following, we focus on estimation of maximum Doppler frequency in MIMO-OFDM system. Also in this part, one special estimation algorithm is presented that the estimation of maximum Doppler frequency can be achievedby setting up its statistical amount. Finally, we further discuss the issue of channel estimation. And a channel estimation algorithm is provided here. By some extensive simulations we evaluated the influence of different kinds of parameters on the channel estimation of MIMO-OFDM system. |
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