Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Joint IRS Location and Size Optimization in Multi-IRS Aided Two-Way
  Full-Duplex Communication Systems   Intelligent reflecting surfaces (IRSs) have emerged as a promising wireless
technology for the dynamic configuration and control of electromagnetic waves,
thus creating a smart (programmable) radio environment. In this context, we
study a multi-IRS assisted two-way communication system consisting of two users
that employ full-duplex (FD) technology. More specifically, we deal with the
joint IRS location and size (i.e., the number of reflecting elements)
optimization in order to minimize an upper bound of system outage probability
under various constraints, namely, minimum and maximum number of reflecting
elements per IRS, maximum number of installed IRSs, maximum total number of
reflecting elements (implicit bound on the signaling overhead) as well as
maximum total IRS installation cost. First, the problem is formulated as a
discrete optimization problem and, then, a theoretical proof of its NP-hardness
is given. Moreover, we provide a lower bound on the optimum value by solving a
linear-programming relaxation (LPR) problem. Subsequently, we design two
polynomial-time algorithms, a deterministic greedy algorithm and a randomized
approximation algorithm, based on the LPR solution. The former is a heuristic
method that always computes a feasible solution for which (a posteriori)
performance guarantee can be provided. The latter achieves an approximate
solution, using randomized rounding, with provable (a priori) probabilistic
guarantees on the performance. Furthermore, extensive numerical simulations
demonstrate the superiority of the proposed algorithms compared to the baseline
schemes. Finally, useful conclusions regarding the comparison between FD and
conventional half-duplex (HD) systems are also drawn.

3
The categories of this paper are: physics
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci