Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Adaptive Coding and Channel Shaping Through Reconfigurable Intelligent
  Surfaces: An Information-Theoretic Analysis   A communication link aided by a reconfigurable intelligent surface (RIS) is
studied in which the transmitter can control the state of the RIS via a
finite-rate control link. Channel state information (CSI) is acquired at the
receiver based on pilot-assisted channel estimation, and it may or may not be
shared with the transmitter. Considering quasi-static fading channels with
imperfect CSI, capacity-achieving signalling is shown to implement joint
encoding of the transmitted signal and of the response of the RIS. This
demonstrates the information-theoretic optimality of RIS-based modulation, or
"single-RF MIMO" systems. In addition, a novel signalling strategy based on
separate layered encoding that enables practical successive cancellation-type
decoding at the receiver is proposed. Numerical experiments show that the
conventional scheme that fixes the reflection pattern of the RIS, irrespective
of the transmitted information, as to maximize the achievable rate is strictly
suboptimal, and is outperformed by the proposed adaptive coding strategies at
all practical signal-to-noise ratio (SNR) levels.

31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an