Experimental Time and Frequency Domain MIMO Channel Matrix Characterization versus Distance for 6×28Gbaud QPSK Transmission over 40×25km Few Mode Fiber

BACKGROUND Transcranial magnetic stimulation (TMS), when applied over the primary motor cortex (M1) elicits a motor evoked potential (MEP) in electromyograms measured from peripheral muscles. MEP amplitude has often been observed to fluctuate trial by trial, even with a constant stimulus. Many factors cause MEP fluctuations in TMS. One of the primary factors is the weak stationarity and instability of cortical activity in the brain, from which we assumed MEP fluctuations originated. We hypothesized that MEP fluctuations must be suppressed if TMS is delivered to M1 at the time when several electroencephalogram (EEG) channels measured on the scalp have high similarity in the frequency domain. OBJECTIVE We developed a TMS triggering system for suppressing MEP fluctuations using EEG coherence analysis, which was performed to detect the EEG signal similarity between the two channels in the frequency domain. METHODS Seven healthy adults participated in the experiment to confirm whether the TMS trigger system works adequately, and the mean amplitude and coefficient of variation of the MEP were recorded and compared with the values in the control task. We also determined the experimental time under each condition and verified whether it was within the predicted time. RESULTS The coefficient of variation (CV) of MEP amplitude decreased in five out of seven subjects, and significant differences (P=.02) were confirmed in two of the subjects by performing an F-test. The CV of the experimental time required for each stimulus with threshold modification was less than that without threshold modification, and a significant difference (P<.001) was confirmed by performing an F-test. CONCLUSIONS We consequently found that MEP could be suppressed using the system developed in this study and that the TMS trigger system could also stabilize the experimental time by changing the triggering threshold automatically.

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A semi-blind technique for MIMO channel matrix estimation

2003 4th IEEE Workshop on Signal Processing Advances in Wireless Communications - SPAWC 2003 (IEEE Cat. No.03EX689) ◽

10.1109/spawc.2003.1318971 ◽

2004 ◽

Cited By ~ 7

Author(s):

A. Jagannatham ◽

B.D. Rao

Keyword(s):

Mimo Channel ◽

Channel Matrix ◽

Matrix Estimation

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Relay Selection Scheme for Multi-Hop Transmission of MU-MIMO System

Applied Sciences ◽

10.3390/app8101747 ◽

2018 ◽

Vol 8 (10) ◽

pp. 1747 ◽

Cited By ~ 2

Author(s):

Won-Chang Kim ◽

Min-Jae Paek ◽

Hyoung-Kyu Song

Keyword(s):

Communication Systems ◽

Relay Selection ◽

Mimo System ◽

Singular Values ◽

Mimo Channel ◽

Wireless Communication Systems ◽

Transmission Scheme ◽

Selection Scheme ◽

Channel Matrix ◽

Cell Coverage

Recently, wireless communication systems use a multi-hop transmission scheme using a relay to expand the cell coverage of the system. The multi-hop transmission scheme can expand the cell coverage of wireless communication systems. However, if an appropriate relay is not selected, errors generated during signal processing in the relay are transmitted to the receiver. Therefore, a relay selection scheme is essential for reliable multi-hop transmission. This paper proposes a relay selection scheme for reliable multi-hop transmission in a multi user-multiple input multiple output (MU-MIMO) system. The proposed relay selection scheme uses a MIMO channel matrix between the transmitter and relays to select an appropriate relay. The proposed relay selection scheme obtains the singular values of the MIMO channel matrix using the singular value decomposition (SVD). Then, the sum of the singular values is calculated, and the relay having the largest value is selected. Therefore, in the proposed relay selection scheme, although the transmitter only knows the channel information between the transmitter and relays, the transmitter can select an appropriate relay for reliable multi-hop transmission.

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Codebook based Direct Vector Quantization of MIMO Channel Matrix with Channel Normalization

The Journal of Korean Institute of Communications and Information Sciences ◽

10.7840/kics.2014.39a.3.155 ◽

2014 ◽

Vol 39A (3) ◽

pp. 155-157

Author(s):

Bing Hui ◽

KyungHi Chang

Keyword(s):

Vector Quantization ◽

Mimo Channel ◽

Channel Matrix

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Gram-Schmidt Combined LLL Lattice-Reduction Aided Detection in MIMO Systems

REV Journal on Electronics and Communications ◽

10.21553/rev-jec.17 ◽

2011 ◽

Vol 1 (2) ◽

Cited By ~ 2

Author(s):

Tadashi Fujino

Keyword(s):

Mimo Systems ◽

Mimo System ◽

Lattice Reduction ◽

Mimo Channel ◽

Lll Algorithm ◽

Detection Scheme ◽

Channel Matrix ◽

Mmse Detector ◽

The Cost ◽

Ber Performance

This paper proposes an improved lattice-reduction aided (LRA) MMSE detection scheme, based on the Gram-Schmidt (GS) procedure. The proposed scheme reduces the column vectors of the MIMO channel matrix, by using the LLL algorithm followed by the GS procedure in order to transform the channel matrix into a new one which has mutually purely orthogonal column vectors. Compared to the conventional LRA MMSE detector, the proposed detector achieves a very good BER performance, almost equivalent to those using the ML detector in the 4 × 4 MIMO system at the cost of a slightly larger computational complexity.

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