171 research outputs found
Secrecy Sum-Rates for Multi-User MIMO Regularized Channel Inversion Precoding
In this paper, we propose a linear precoder for the downlink of a multi-user
MIMO system with multiple users that potentially act as eavesdroppers. The
proposed precoder is based on regularized channel inversion (RCI) with a
regularization parameter and power allocation vector chosen in such a
way that the achievable secrecy sum-rate is maximized. We consider the
worst-case scenario for the multi-user MIMO system, where the transmitter
assumes users cooperate to eavesdrop on other users. We derive the achievable
secrecy sum-rate and obtain the closed-form expression for the optimal
regularization parameter of the precoder using
large-system analysis. We show that the RCI precoder with
outperforms several other linear precoding schemes, and
it achieves a secrecy sum-rate that has same scaling factor as the sum-rate
achieved by the optimum RCI precoder without secrecy requirements. We propose a
power allocation algorithm to maximize the secrecy sum-rate for fixed .
We then extend our algorithm to maximize the secrecy sum-rate by jointly
optimizing and the power allocation vector. The jointly optimized
precoder outperforms RCI with and equal power allocation
by up to 20 percent at practical values of the signal-to-noise ratio and for 4
users and 4 transmit antennas.Comment: IEEE Transactions on Communications, accepted for publicatio
Linear Precoding for Broadcast Channels with Confidential Messages under Transmit-Side Channel Correlation
In this paper, we analyze the performance of regularized channel inversion
(RCI) precoding in multiple-input single-output (MISO) broadcast channels with
confidential messages under transmit-side channel correlation. We derive a
deterministic equivalent for the achievable per-user secrecy rate which is
almost surely exact as the number of transmit antennas and the number of users
grow to infinity in a fixed ratio, and we determine the optimal regularization
parameter that maximizes the secrecy rate. Furthermore, we obtain deterministic
equivalents for the secrecy rates achievable by: (i) zero forcing precoding and
(ii) single user beamforming. The accuracy of our analysis is validated by
simulations of finite-size systems.Comment: to appear IEEE Communications Letter
Knowledge Distillation-aided End-to-End Learning for Linear Precoding in Multiuser MIMO Downlink Systems with Finite-Rate Feedback
We propose a deep learning-based channel estimation, quantization, feedback,
and precoding method for downlink multiuser multiple-input and multiple-output
systems. In the proposed system, channel estimation and quantization for
limited feedback are handled by a receiver deep neural network (DNN). Precoder
selection is handled by a transmitter DNN. To emulate the traditional channel
quantization, a binarization layer is adopted at each receiver DNN, and the
binarization layer is also used to enable end-to-end learning. However, this
can lead to inaccurate gradients, which can trap the receiver DNNs at a poor
local minimum during training. To address this, we consider knowledge
distillation, in which the existing DNNs are jointly trained with an auxiliary
transmitter DNN. The use of an auxiliary DNN as a teacher network allows the
receiver DNNs to additionally exploit lossless gradients, which is useful in
avoiding a poor local minimum. For the same number of feedback bits, our
DNN-based precoding scheme can achieve a higher downlink rate compared to
conventional linear precoding with codebook-based limited feedback.Comment: 6 pages, 4 figures, submitted to IEEE Transactions on Vehicular
Technolog
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