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2D Discrete Cosine Transform Based Channel Estimation for Single User Millimeter Wave Communication System

S. Merlin Gilbert Raj 1, G. Josemin Bala 2, and M. L. Merlin Sajin
1. Karunya Institute of Technology and Sciences, Dept of ECE, Coimbatore-641 114, India
2. Coimbatore Institute of Technology, Dept of EEE, Coimbatore-641 114, India
Abstract—Channel estimation is a very challenging problem in millimeter wave communication system. With its sparse nature, millimeter wave channel has strong path loss and severe scattering effects. The higher operating frequency and larger bandwidth enables large number of antenna elements packed in single antenna array for hybrid beamforming architecture. The channel degradation and RF chains less than propagation path to estimate the channel parameters is an open problem. Previously, channel estimation approach like 2D-Discrete Fourier transform results with complex valued, even for real data. A related transform, the 2D discrete cosine transform (DCT), does not have this problem. It is also possible to use 2D- DCT for filtering using a slightly different form of convolution called symmetric convolution. In this paper, we propose a 2D DCT based channel estimation method for millimeter wave systems with the transmitter and receiver equipped with less number of RF chains than the number of antenna elements. A training sequence is used to setup the analog and digital beamformers to probe the channel. A prefilter technique using 2D-DCT is applied to the received training samples. This exploits the sparse nature of the millimeter wave channel and improves the effective SNR at the receiver using the energy compaction property. Proposed channel estimation method is justified using the estimation of angle of arrival (AOA), angle of departure (AOD), path gain, spectral efficiency and bit error rate. Numerical results show that the proposed 2D-DCT based channel estimation method improves effective SNR than the 2D-DFT method at the receiver chain.
 
Index Terms—Millimeterwave, Channel estimation, angle of arrival (AOA), angle of departure (AOD), Discrete Cosine Transform, Average SNR, Spectral Efficiency and BER

Cite: S. Merlin Gilbert Raj, G. Josemin Bala, and M. L. Merlin Sajin, “2D Discrete Cosine Transform Based Channel Estimation for Single User Millimeter Wave Communication System,”Journal of Communications vol. 15, no. 2, pp. 205-213, February 2020. Doi: 10.12720/jcm.15.2.205-213
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