Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Physics-based Modeling and Scalable Optimization of Large Intelligent
  Reflecting Surfaces   Intelligent reflecting surfaces (IRSs) have the potential to transform
wireless communication channels into smart reconfigurable propagation
environments. To realize this new paradigm, the passive IRSs have to be large,
especially for communication in far-field scenarios, so that they can
compensate for the large end-to-end path-loss, which is caused by the
multiplication of the individual path-losses of the transmitter-to-IRS and
IRS-to-receiver channels. However, optimizing a large number of sub-wavelength
IRS elements imposes a significant challenge for online transmission. To
address this issue, in this paper, we develop a physics-based model and a
scalable optimization framework for large IRSs. The basic idea is to partition
the IRS unit cells into several subsets, referred to as tiles, model the impact
of each tile on the wireless channel, and then optimize each tile in two
stages, namely an offline design stage and an online optimization stage. For
physics-based modeling, we borrow concepts from the radar literature, model
each tile as an anomalous reflector, and derive its impact on the wireless
channel for a given phase shift by solving the corresponding integral equations
for the electric and magnetic vector fields. In the offline design stage, the
IRS unit cells of each tile are jointly designed for the support of different
transmission modes, where each transmission mode effectively corresponds to a
given configuration of the phase shifts that the unit cells of the tile apply
to an impinging electromagnetic wave. In the online optimization stage, the
best transmission mode of each tile is selected such that a desired
quality-of-service (QoS) criterion is maximized. We show that the proposed
modeling and optimization framework can be used to efficiently optimize large
IRSs comprising thousands of unit cells.

27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg