Alternating Minimization for Wideband Multiuser IRS-aided MIMO Systems under Imperfect CSI
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Date
2023-11
Journal Title
Journal ISSN
Volume Title
Publisher
IEEE
Abstract
This work focuses on wideband intelligent reflecting
surface (IRS)-aided multiuser MIMO systems. One of the major
challenges of this scenario is the joint design of the frequency dependent base station (BS) precoder and user filters, and the IRS
phase-shift matrix which is frequency flat and common to all the
users. In addition, we consider that the channel state information
(CSI) is imperfect at both the transmitter and the receivers. A
statistical model for the imperfect CSI is developed and exploited
for the system design. A minimum mean square error (MMSE)
approach is followed to determine the IRS phase-shift matrix,
the transmit precoders, and the receiving filters. The broadcast
(BC)-multiple access channel (MAC) duality is used to solve
the optimization problem following an alternating minimization
approach. Numerical results show that the proposed approach
leads to substantial performance gains with respect to baseline
strategies that neglect the inter-user interference and do not
optimize the IRS phase-shift matrix. Further performance gains
are obtained when incorporating into the system design the
statistical information of the channel estimation errors.