Covert Communications with a Full-Duplex Receiver over Wireless Fading Channels

Abstract

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.

Covert Wireless Communications With Channel Inversion Power Control in Rayleigh Fading

“…This is due to the following two facts. The first fact is that in [29] it is assumed that Willie knows the channel from Alice to Willie (i.e., h aw ), while in this section we assume that h aw is unknown to Willie (since Alice did not transmit any signal before the covert transmission). The second fact is that in this work we adopt the CIPC at Alice, while in [29] a fixed power is adopted at Alice.…”

“…The first fact is that in [29] it is assumed that Willie knows the channel from Alice to Willie (i.e., h aw ), while in this section we assume that h aw is unknown to Willie (since Alice did not transmit any signal before the covert transmission). The second fact is that in this work we adopt the CIPC at Alice, while in [29] a fixed power is adopted at Alice. It should be noted that the proposed CIPC scheme is to achieve covert communications in wireless fading channels without the need for Alice to transmit training signals for Bob to perform channel estimation.…”

“…As a practical technique, the full-duplex radio has been widely explored in wireless communications (e.g., [30], [31]). For example, using a full-duplex receiver to generate AN for security enhancement has been widely examined the context of physical layer security (e.g., [29], [32], [33]). Similarly to [29], we consider a full-duplex receiver Bob who simultaneously receives covert information signal from Alice and transmits AN with a random power to confuse the warden Willie on detecting the covert transmission.…”

“…For example, using a full-duplex receiver to generate AN for security enhancement has been widely examined the context of physical layer security (e.g., [29], [32], [33]). Similarly to [29], we consider a full-duplex receiver Bob who simultaneously receives covert information signal from Alice and transmits AN with a random power to confuse the warden Willie on detecting the covert transmission. Generating AN by the full-duplex Bob enables varying the presence and amount of uncertainty at Willie on demand, which leads to that the covert communication between Alice and Bob is fully under the control of Alice and Bob.…”

Covert Transmission With a Self-Sustained Relay

“…A covert communication system under block fading channels was examined in [20], where transceivers have uncertainty on the related channel state information (CSI). In [21], [22], the authors utilized a full-duplex receiver to achieve covert communications in wireless fading channels and analyzed the covert communication limits. The covert communication with interference uncertainty from non-cooperative transmitters is studied in [23].…”