Abstract
The multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) technology is the combination of the OFDM and MIMO technologies, which could improve the system capacity and make efficient utilization of the frequency spectrum. This paper utilizes space-time block coding (STBC) to achieve diversity gains and combat the channel fading. However, channel estimation is an essential block for space-time block decoding (STBD). Many channel estimation methods are utilized for the single antenna OFDM system, but they cannot be directly applied to the multiple antennas system due to the interference from other antennas. In this paper, orthogonal pilot sequences are designed to suppress the interference of pilot symbols from other transmit antennas. This paper also derives a minimum mean square error (MMSE) channel estimation method in MIMO-OFDM systems. The MMSE method involves the inverse operation of the channel autocorrelation matrix, which has a large calculation complexity. To further reduce the complexity of the MMSE method, the singular value decomposition (SVD) is used to decompose the channel autocorrelation matrix, which avoids the inverse operation. Simulation results verify that the SVD channel estimation method with comb-type pilots and STBC can be effectively adapted to multipath propagation conditions.
Highlights
Orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-out (MIMO)technologies have been widely used in wireless communication systems [1,2]
This paper focuses on the analysis of the channel transformed into the single antenna channel estimation problem, which reduces the complexity of the estimation methodThis to paper improve system further reduce the calculation channel estimation
The bit error rate (BER) performance of the proposed singular value decomposition (SVD) channel estimation method is shown
Summary
Orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-out (MIMO). An iterative scatter-based channel estimation method for the OFDM/offset quadrature amplitude modulation (OQAM), which reduces the real and imaginary interferences at the receiver to improve the channel estimation, was proposed in [12]. Inserting pilot sequences into the transmitted data would reduce the spectral efficiency To solve this problem, the blind channel estimation method is proposed for OFDM systems [13,14]. A fast blind subspace channel estimation method for STBC-OFDM systems based on the circular property of the channel matrix was proposed in [17]. A joint maximum likelihood and MMSE estimation based signal detection is proposed for the combination system of radio over fiber link and MIMO-OFDM wireless channel.
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