168 research outputs found
Limits of Reliable Communication with Low Probability of Detection on AWGN Channels
We present a square root limit on the amount of information transmitted
reliably and with low probability of detection (LPD) over additive white
Gaussian noise (AWGN) channels. Specifically, if the transmitter has AWGN
channels to an intended receiver and a warden, both with non-zero noise power,
we prove that bits can be sent from the transmitter to the
receiver in channel uses while lower-bounding
for any , where and respectively denote the
warden's probabilities of a false alarm when the sender is not transmitting and
a missed detection when the sender is transmitting. Moreover, in most practical
scenarios, a lower bound on the noise power on the channel between the
transmitter and the warden is known and bits can be sent in
LPD channel uses. Conversely, attempting to transmit more than
bits either results in detection by the warden with probability one or a
non-zero probability of decoding error at the receiver as .Comment: Major revision in v2. Context, esp. the relationship to steganography
updated. Also, added discussion on secret key length. Results are unchanged
from previous version. Minor revision in v3. Major revision in v4, Clarified
derivations (adding appendix), also context, esp. relationship to previous
work in communication updated. Results are unchanged from previous revision
Covert Communications with a Full-Duplex Receiver over Wireless Fading Channels
In this work, we propose a covert communication
scheme where the transmitter attempts to hide its transmission to
a full-duplex receiver, from a warden that is to detect this covert
transmission using a radiometer. Specifically, we first derive the
detection error rate at the warden, based on which the optimal
detection threshold for its radiometer is analytically determined
and its expected detection error rate over wireless fading channels
is achieved in a closed-form expression. Our analysis indicates
that the artificial noise deliberately produced by the receiver
with a random transmit power, although causes self-interference,
offers the capability of achieving a positive effective covert rate
for any transmit power (can be infinity) subject to any given
covertness requirement on the expected detection error rate. This
work is the first study on the use of the full-duplex receiver with
controlled artificial noise for achieving covert communications
and invites further investigation in this regard.ARC Discovery Projects Grant DP15010390
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