Research On Blind Channel Estimation Technique For MIMO-OFDM System

Utilizing the spacial diversity obtained by spatially separated antennas in a dense multi-path scattering environment, multiple-input multiple-output communication can increase significantly the channel capacity without the band-width increasing. OFDM is robust against the frequency-selective fading channels. Thus, it is a challenge to research on MIMO-OFDM systems to achieve high data rate and high channel capacity. And recently, increasing interest has concentrate on MIMO-OFDM systems for it can provide high data rates and high channel capacity over broadband wireless channels, it can combat the multi-path fading, and it can also restrain the interference and the noise.In this paper, we discuss the principle of MIMO-OFDM systems, point out that the channel estimation is one of the most important elements for the performance of the systems. Two blind channel estimation methods which are blind channel estimation for MIMO-OFDM systems via nonredundant linear precoding and blind channel estimation algorithm based on second-order-statistics have been introduced in chapter 3. Furthermore, a subspace-based blind channel estimation algorithm and its improved algorithm have been investigated. The improved algorithm obtains accurate channel estimation and fast convergence with insensitivity to overestimates of the true channel order. If virtual carriers (VCs) are available, the proposed method can work with no or insufficient cyclic prefix (CP), thereby potentially increasing channel utilization. Furthermore, the proposed method can also work with MIMO-OFDM systems which have more transmit antennas than receive antennas. Simulation results illustrate the feasibility and the availability of this algorithm.