Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hiding Communications in AWGN Channels and THz Band with Interference
  Uncertainty   Covert communication can prevent an adversary from knowing that a wireless
transmission has occurred. In additive white Gaussian noise (AWGN) channels, a
square root law is found that Alice can reliably and covertly transmit
$\mathcal{O}(\sqrt{n})$ bits to Bob in $n$ channel uses. In this paper, we
consider covert communications in noisy wireless networks, where the receivers
not only experience the background noise, but also the aggregate interference
from other transmitters. Our results show that uncertainty in interference
experienced by the adversary Willie is beneficial to Alice. In AWGN channels,
when the distance between Alice and Willie $d_{a,w}=\omega(n^{1/(2\alpha)})$
($\alpha$ is the path loss exponent), Alice can reliably and covertly transmit
$\mathcal{O}(\log_2\sqrt{n})$ bits to Bob in $n$ channel uses. Although the
covert throughput is lower than the square root law, the spatial throughput is
higher. In THz (Terahertz) Band networks,covert communication is more difficult
because Willie can simply place a receiver in the narrow beam between Alice and
Bob to detect or block their LOS (Line-of-Sight) communications. We then
present a covert communication scheme that utilizes the reflection or diffuse
scattering from a rough surface to prevent being detected by Willie. From the
network perspective, the communications are hidden in the interference of noisy
wireless networks, and what Willie sees is merely a "shadow" wireless network.

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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: physics
6
The categories of this paper are: astro-ph