10 research outputs found
Alternating Beamforming with Intelligent Reflecting Surface Element Allocation
Intelligent reflecting surface (IRS) has become a promising technology to aid
next generation wireless communication systems. In this paper, we develop an
alternating beamforming technique with a novel concept of IRS element
allocation for multiple-input multiple-output systems when a base station
supports multiple single antenna users aided with a single IRS. Specifically,
we allocate each IRS element separately to each user, thus, in the beamforming
stage allowing the IRS element only consider a single user at a time. In result
to this separation, the complexity is vastly decreased. The proposed
beamforming technique tries to maximize the minimum rate of all users with
minimal complexity. In the numerical results, we show that the proposed
technique is comparable to the convex optimization-based benchmark with
sufficiently less complexity.Comment: 5 pages, 3 figures, submitted to Wireless Communications Letters
(WCL
Intelligent Reflecting Surfaces: Sum-Rate Optimization Based on Statistical CSI
In this paper, we consider a multi-user multiple-input multiple-output (MIMO)
system aided by multiple intelligent reflecting surfaces (IRSs) that are
deployed to increase the coverage and, possibly, the rank of the channel. We
propose an optimization algorithm to configure the IRSs, which is aimed at
maximizing the network sum-rate by exploiting only the statistical
characterization of the environment, such as the distribution of the locations
of the users and the distribution of the multipath channels. As a consequence,
the proposed approach does not require the estimation of the instantaneous
channel state information (CSI) for system optimization, thus significantly
relaxing (or even avoiding) the need of frequently reconfiguring the IRSs,
which constitutes one of the most critical issues in IRS-assisted systems.
Numerical results confirm the validity of the proposed approach. It is shown,
in particular, that IRS-assisted wireless systems that are optimized based on
statistical CSI still provide large performance gains as compared to the
baseline scenarios in which no IRSs are deployed.Comment: submitted for journal publicatio