Efficient method of MMSE Channel Estimation for MIMO-OFDM Using Spatial and Temporal Correlations

Channel has been introduced to achieve high data speed and better bit rate. The system becomes more efficient when OFDM (Orthogonal Frequency Division Multiplexing) is combined with MIMO to obtain high transmission rates, good quality of service and minimize the probability of error. Channel estimation is of great importance in MIMOOFDM system. Channel estimation is used to estimate the transmitted signal using the corresponding receiver signal. This project proposes a parametric sparse multiple input multiple output (MIMO)-OFDM channel estimation scheme based on the finite rate of innovation (FRI) theory, whereby super-resolution estimates of path delays with arbitrary values can be achieved. Meanwhile, both the spatial and temporal correlations of wireless MIMO channels are exploited to improve the accuracy of the channel estimation. For outdoor communication scenarios, where wireless channels are sparse in nature, path delays of different transmit-receive antenna pairs share a common sparse pattern due to the spatial correlation of MIMO channels. Meanwhile, the channel sparse pattern is nearly unchanged during several adjacent OFDM symbols due to the temporal correlation of MIMO channels. By simultaneously exploiting those MIMO channel characteristics, the proposed scheme performs better than existing state-of-the-art schemes. Furthermore, by joint processing of signals associated with different antennas, the pilot overhead can be reduced under the framework of the FRI theory I.INTRODUCTION Multiple Input Multiple Output (MIMO) – OFDM is key technology for future wireless communication due to its highspectral efficiency and superior robustness to multipath fading channels [2]. For MIMO-OFDM systems, better channel estimationis essential for system performance [3]. Generally, there are two categories of channel estimation schemes for MIMOOFDMsystems. The first one is nonparametric approach, which utilizes orthogonal frequency domain pilots or time domain trainingsequence to convert the channel estimation in MIMO-OFDM system to single antenna system[3] . In this paper I proposed Timedomain training based orthogonal pilot (TTOP) for example of this channel estimation approach. However, these sort schemes suffers from high pilot overhead when number of transmit antennas increases. The second approach is parametric channel estimation which utilizes sparsity of wireless channels to reduce the pilot overhead [4],[5] . This ismuch useful for future advancement since it can achieve better higher spectral efficiency.However, path delays of sparse channels are assumed to be located at the integer multiples of sampling period, which isunrealistic in practice. In this paper, a more practical sparse MIMOOFDM channel estimation scheme based on spatial andtemporal correlation of sparse wireless MOMO channels is proposed to deal with arbitrary path delays. The proposed scheme can achieve super-resolution estimates of arbitrary path delays,Which is more suitab le for wireless channels in practice. Due to the small scale of the transmit and receive antenna arrays compared to long signal transmissiondistance in