Abstract
In this paper, we propose a two-way secure communication scheme where two transceivers exchange confidential messages via a wireless powered untrusted amplify-and-forward (AF) relay in the presence of an external jammer. We take into account both friendly jamming (FJ) and Gaussian noise jamming (GNJ) scenarios. Based on the time switching (TS) architecture at the relay, the data transmission is done in three phases. In the first phase, both the energy-starved nodes, the untrustworthy relay and the jammer, are charged by non-information radio frequency (RF) signals from the sources. In the second phase, the two sources send their information signals and concurrently, the jammer transmits artificial noise to confuse the curious relay. Finally, the third phase is dedicated to forward a scaled version of the received signal from the relay to the sources. For the proposed secure transmission schemes, we derive new closed-form lower-bound expressions for the ergodic secrecy sum rate (ESSR) in the high signal-to-noise ratio (SNR) regime. We further analyze the asymptotic ESSR to determine the key parameters; the high SNR slope and the high SNR power offset of the jamming based scenarios. To highlight the performance advantage of the proposed FJ, we also examine the scenario of without jamming (WoJ). Finally, numerical examples and discussions are provided to acquire some engineering insights, and to demonstrate the impacts of different system parameters on the secrecy performance of the considered communication scenarios. The numerical results illustrate that the proposed FJ significantly outperforms the traditional one-way communication and the Constellation rotation approach, as well as our proposed benchmarks, the two-way WoJ and GNJ scenarios.
Highlights
We proposed a wireless-powered two-way cooperative network wherein the two sources communicate via a wirelesspowered untrusted relay
To enhance the secrecy performance, we employed an external jammer which is wirelessly charged by the two sources
By adopting the time switching (TS) protocol at the untrusted relay and jammer, we investigated the ergodic secrecy sum rate (ESSR) criterion for the without jamming (WoJ), friendly jamming (FJ), and Gaussian noise jamming (GNJ) scenarios
Summary
C OOPERATIVE relaying improves energy efficiency, extends coverage, and increases the throughput of wireless communication networks. In the area of untrusted relaying, for the first time, the authors in [9] proposed destination-based cooperative jamming (CJ) technique to achieve a positive secrecy rate for a one-way untrusted relay, in which the jammer is co-located with the destination receiver. Several works have considered the more interesting scenario of two-way untrusted relaying [14]–[17], where physical-layer network coding can enhance the security of communication by receiving a superimposed signal from the two sources instead of each individual signal. The authors in [14] proposed a game-theoretic power control scheme between the two sources and multiple jammers, where single user decoding (SUD) is assumed for the untrusted relay to extract the information signal. The authors in [23] proposed employing a wireless-powered jammer to provide secure communication between a source and a destination. Kalamkar et al in [24] studied secure one-way communication in the presence of an untrusted relay based on WIPT technology, where either TS or PS is adopted at the relay
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