Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Joint Hardware Design and Capacity Analysis for Intelligent Reflecting
  Surface Enabled Terahertz MIMO Communications   Terahertz (THz) communications have been envisioned as a promising enabler to
provide ultra-high data transmission for sixth generation (6G) wireless
networks. To tackle the blockage vulnerability brought by severe path
attenuation and poor diffraction of THz waves, an intelligent reflecting
surface (IRS) is put forward to smartly control the incident THz waves by
adjusting the phase shifts. In this paper, we firstly design an efficient
hardware structure of graphene-based IRS with phase response up to 306.82
degrees. Subsequently, to characterize the capacity of the IRS-enabled THz
multiple-input multiple-output (MIMO) system, an adaptive gradient descent
(A-GD) algorithm is developed by dynamically updating the step size during the
iterative process, which is determined by the second-order Taylor expansion
formulation. In contrast with conventional gradient descent (C-GD) algorithm
with fixed step size, the A-GD algorithm evidently improves the achievable rate
performance. However, both A-GD algorithm and C-GD algorithm inherit the
unacceptable complexity. Then a low complexity alternating optimization (AO)
algorithm is proposed by alternately optimizing the precoding matrix by a
column-by-column (CBC) algorithm and the phase shift matrix of the IRS by a
linear search algorithm. Ultimately, the numerical results demonstrate the
effectiveness of the designed hardware structure and the considered algorithms.

36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th