Research On Channel Estimation Methods Of MIMO-OFDM Wireless Communication System

The next generation wireless communication systems are expected to provide higher data rate and better quality of service in order to support the multimedia service in the complex mobile environment. MIMO-OFDM system is a combination of orthogonal frequency division multiplexing(OFDM) technology and multiple-input multiple-output (MIMO) technology, which can not only improve the communication capacity and transmission rate greatly but also combat against multi-path fading, inter-symbol interference and noise effectively, so these technologies have been widely considered as the core technologies of the next generation wireless communication systems,These systems based on Long Term Evolution (LTE) and other protocols are the MIMO-OFDM systems.Channel state information in MIMO-OFDM system is the key factor of the detection in the receiver, the channel estimation can estimate a reliable channel state information for the accurate decoding in the receiver, it has a direct impact on the quality of entire wireless communication system transmission. In this thesis we analyse the multi-path fading characteristics with the wireless fading parameters of the mobile communication channel, and study the basic principles of MIMO-OFDM system. Furthermore, the channel estimation technique which is important in MIMO-OFDM system is investigated, the discussion focus on the pilot-based channel estimation method, and on this basis, study the channel estimation method based on the frequency-domain least-square (LS) algorithm in the MIMO-OFDM system.In order to solve the problem that least-squares(LS) channel estimation of MIMO-OFDM system is sensitive to the noise, a channel estimation method based on the wavelet de-nosing is proposed, which reduces the effect of the noise acting on the channel estimation accuracy effectively, on this basis, an improved method based on the wavelet packet de-nosing is proposed, further improves the performance of channel estimator. This thesis implements the analysis and verification about the validity and feasibility of these algorithms by the computer simulation.