On the performance of multiuser MIMO systems relying on full-duplex CSI acquisition

IEEE In this paper, we propose a combined full duplex (FD) and half duplex (HD) based transmission and channel acquisition model for open-loop multiuser multiple-input multipleoutput (MIMO) systems. Assuming residual self interference (SI) at the BS, the idea is to utilize the FD mode during the uplink (UL) training phase in order to achieve simultaneous downlink (DL) data transmission and UL CSI acquisition. More specifically, the BS begins serving a user when its CSI becomes available, while at the same time, it also receives UL pilots from the next scheduled user. We investigate both zero-forcing (ZF) and maximum ratio transmission (MRT) MIMO beamforming techniques for the DL data transmission in the FD mode. The BS switches to the HD mode once it receives the CSI of all users and it employs ZF beamforming for the DL data transmission until the end of the transmission frame. Furthermore, we derive closedform approximations for the lower bounded ergodic achievable rate relying on the proposed model. Our numerical results show that the proposed FD-HD transmission and channel acquisition approach outperforms its conventional HD counterpart and achieves higher data rates

The estimated five global PDMs for the T7–P7 (left panels) and Fp1–F3 (right panels) inputs in connection with P3–O1 (as an output) in the time- (top panels) and frequency-domain (bottom panels).

<p>PDMs, principal dynamic modes.</p

The estimated five global PDMs for the T7–P7 (left panels) and Fp1–F3 (right panels) inputs in connection with P3–O1 (as an output) in the time- (top panels) and frequency-domain (bottom panels).

<p>PDMs, principal dynamic modes.</p

The ensemble averages of estimated cubic ANFs along with their standard deviation bounds for the T7–P7 (top panels) and Fp1–F3 (bottom panels) for the interictal states of the training data set.

<p>The solid lines represent means and dotted lines represent standard deviation bounds. Coefficients of cubic ANFs were utilized to determine the mean and standard deviation bounds. ANFs, associated nonlinear functions.</p

The block diagram of a dual-input global PDM model with five global PDMs.

<p>In the present study, the T7–P7 and Fp1–F3 channels are taken as input 1 and input 2, respectively, and the P3–O1 channel is considered as a model output. The ANFs are cubic polynomials. Only significant cross-terms are included in the final model. PDM, principal dynamic mode.</p

The estimated cubic ANFs for the interictal state of one representative subject of the training data set corresponding to the five global PDMs (shown in Fig 2) for the T7–P7 (upper panels) and Fp1–F3 (bottom panels), along with their best linear fits (red line).

<p>ANFs, associated nonlinear functions; PDMs, principal dynamic modes.</p

The ensemble averages of estimated linear gain coefficients (i.e., slopes of best linear lines fitted to cubic ANFs) for the T7–P7 (upper panel) and Fp1–F3 (bottom panel) for interictal and ictal states of the training data set.

<p>No significant changes were found across any ANF of either input for ictal versus interictal states of the training data set (<i>p</i> > 0.05, paired <i>t</i>-test). The error bars represent standard deviation. ANFs, associated nonlinear functions.</p

The ensemble averages of estimated linear gain coefficients (i.e., slopes of best linear lines fitted to cubic ANFs) for the T7–P7 (upper panel) and Fp1–F3 (bottom panel) for interictal and ictal states of the test data set.

<p>No significant changes were found across any ANF of either input for ictal versus interictal states of the test data set (<i>p</i> > 0.05, paired <i>t</i>-test). The error bars represent standard deviation. ANFs, associated nonlinear functions.</p

The estimated cubic ANFs for the ictal state of one representative subject of the training data set corresponding to the five global PDMs (shown in Fig 2) for the T7–P7 (upper panels) and Fp1–F3 (bottom panels), along with their best linear fits (red line).

<p>ANFs, associated nonlinear functions; PDMs, principal dynamic modes.</p

Scatter-plot of estimated linear gains coefficients of ANFs corresponding to the 2nd and 4th global PDMs for the Fp1–F3 for interictal and ictal states of the training data set.

<p>The classification line has been obtained using a linear discriminator, and shows no false-negatives and no false-positives. ANFs, associated nonlinear functions; PDMs, principal dynamic modes.</p