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Pseudo Eigenbeam-Space Division Multiplexing (PE-SDM) in Frequency-Selective MIMO Channels
Hiroshi NISHIMOTO Toshihiko NISHIMURA Takeo OHGANE Yasutaka OGAWA
IEICE TRANSACTIONS on Communications
Publication Date: 2007/11/01
Online ISSN: 1745-1345
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
MIMO system, frequency-selective fading, transmit beamforming, effective channel, frequency continuity, singular value decomposition (SVD), pseudo eigenvector, pseudo eigenbeam-space division multiplexing (PE-SDM), channel estimation,
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In a frequency-selective multiple-input multiple-output (MIMO) channel, the optimum transmission is achieved by beamforming with eigenvectors obtained at each discrete frequency point, i.e., an extension of eigenbeam-space division multiplexing (E-SDM). However, the calculation load of eigenvalue decomposition at the transmitter increases in proportion to the number of frequency points. In addition, frequency-independent eigenvectors increase the delay spread of the effective channel observed at the receiver. In this paper, we propose a pseudo eigenvector scheme for the purpose of mitigating the calculation load and maintaining frequency continuity (or decreasing the delay spread). First, we demonstrate that pseudo eigenvectors reduce the delay spread of the effective channels with low computational complexity. Next, the practical performance of the pseudo E-SDM (PE-SDM) transmission is evaluated. The simulation results show that PE-SDM provides almost the same or better performance compared with E-SDM when the receiver employs a time-windowing-based channel estimation available in the low delay spread cases.