We propose a robust wireless relay scheme in narrow-band communications for IoT access, which matches the typical features of IoT often carrying relatively low data rate with limited bandwidth. This framework is towards offering robustness in QoS guarantees with emphases on security and/or reliability, and we use the security-assured network as the typical scenario. In particular, we consider a dual-hop relay network including a transmitter, a receiver, an amplify-and-forward (AF) untrusted relay, and a jamming node. The jamming node is treated as a helper. Specifically, the jammer broadcasts artificial noise (AN), which in fact pollutes both the untrusted relay and the destination node’s signals. However, we show that such AN can be effectively mitigated after the destination node obtains the forwarded signal from the relay, while the untrusted relay node cannot do so. The core idea for robustness assurance is to exploit higher signal dimensions at the receiver over the untrusted relay node. Simulations and analyses are also conducted to demonstrate that our proposed scheme can make the performance at the untrusted relay an interference-limited manner while completely removing the interferences at the receiver, therefore corroborating our claim in robustness in terms of security and reliability.
We propose a robust wireless relay scheme in narrow-band communications for IoT access, which matches the typical features of IoT often carrying relatively low data rate with limited bandwidth. This framework is towards offering robustness in QoS guarantees with emphases on security and/or reliability, and we use the security-assured network as the typical scenario. In particular, we consider a dual-hop relay network including a transmitter, a receiver, an amplify-and-forward (AF) untrusted relay, and a jamming node. The jamming node is treated as a helper. Specifically, the jammer broadcasts artificial noise (AN), which in fact pollutes both the untrusted relay and the destination node’s signals. However, we show that such AN can be effectively mitigated after the destination node obtains the forwarded signal from the relay, while the untrusted relay node cannot do so. The core idea for robustness assurance is to exploit higher signal dimensions at the receiver over the untrusted relay node. Simulations and analyses are also conducted to demonstrate that our proposed scheme can make the performance at the untrusted relay an interference-limited manner while completely removing the interferences at the receiver, therefore corroborating our claim in robustness in terms of security and reliability.
Cooperative relaying can be introduced as a promising approach for data communication in the Internet of Things (IoT), where the source and the destination may be placed far away. In this paper, by taking a variety of realistic hardware imperfections (HWIs) and channels estimation errors (CEEs) into account, the secrecy performance of a three-hop cooperative network with a source, a destination and two consecutive amplify-and-forward (AF) relays is investigated. The relays are considered to be untrusted, i.e., while they are mandatory helpers for data transmission, they may overhear the received signals. We adopt the artificial noise injection scheme, to keep the source message secret from being captured by the untrusted relays. Given this system model, a novel closed-form expression is obtained in the high signal-to-noise ratio (SNR) regime for the ergodic secrecy rate (ESR) performance over Nakagami-m fading. Our simulation results highlight that the secrecy performance of the system is improved when the tolerable HWIs are distributed beneficially across the transmission and reception radio-frequency (RF) front-ends of each node. Our work reveals that unlike the ideal case, the realistic scenario of non-ideal hardware with CEEs faces with the secrecy rate ceiling. Finally, under a constraint on the total energy consumption which is applicable for battery-limited IoT equipment, we maximize the achievable secrecy rate. Our results highlight the importance of the destination's jamming cooperation and the first relay's role on the secrecy performance.
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 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 noninformation 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 (CR) approach, as well as our proposed benchmarks, the two-way WoJ and GNJ scenarios.
The Internet-of-Things (IoT) spans various applications in healthcare filed, from smart wearable or implantable sensors to remote monitoring of elderly, and medical device networking. In this paper, a jamming-resistant scheme for the healthcare IoT is proposed to provide secure and reliable data transmission in a two-hop cooperative network, where a source communicates with a destination in the presence of an untrusted relay and an active adversary. The untrusted relay is an authorized necessary helper who may wiretap the confidential information, e.g., the secret measured data of a patient, while the jammer is an external attacker who tries to interrupt the communication. Different from traditional frequency hopping spread spectrum (FHSS) techniques that require a pre-determined pattern between communicating nodes, in our proposed scheme, the source an destination enjoy the local observations of the two-hop channel exploited as the source of common randomness to generate shared secret keys, which facilitates secure communication. To obtain the shared FHSS sequence, a three-phase key generation scheme with minimum mean square error (MMSE) channel estimators is implemented. For the proposed FHSS-based scheme, we derive new closed-form expressions for characterizing the achievable secret key rate (SKR) to highlight the efficiency of our proposed scheme compared to the state-of-the-arts. Finally, several numerical examples and discussions are presented to gain engineering insights behind the studied communication scenario.
Recent information theoretic results have shown that interference can be exploited in wireless relay-assisted networks to secure the information communicated between two legitimate network nodes from the potentially untrusted nodes. In this paper, we consider a two-hop multi-relay network with untrusted relays, where the destination node, aiming at securing the source node's information signal, designs and broadcasts artificial noise (AN) symbols to jam the reception by the multiple relays. By focusing on the case where long-term channel state information is available at the destination, the objective of the considered AN design is to increase the decoding error probability at all the relays. Given an average power constraint at the destination, we propose a unified AN scheme to optimally generate the phase and the power of the AN symbols to maximize the minimum average symbol error rate (ASER) at the relays. The proposed AN generation scheme accounts for practical modulations, such as square quadrature amplitude modulation and M-ary phase-shift-keying. In addition, it is not restricted to specific channel fading model. Numerical and simulation results clearly show that the proposed scheme achieves considerably higher ASER performance than various AN generations, including the frequently used Gaussian distribution.
In the context of Internet-of-Things (IoT) applications, ensuring secure and covert wireless communication remains a critical challenge, especially when using energy harvesting relays. Moreover, the analysis of hardware impairments is a pivotal practical aspect in the evaluation of IoT communication networks. This paper investigates four scenarios to address security and covert communication. In the first scenario, the focus is on guaranteeing the security in the presence of hardware impairments. In this case, the external jammer transmits interference signals toward both the relay and Bob to prevent information leakage from the untrusted relay. However, in this scenario, since the state of the untrusted relay is always superior to that of Bob, security cannot be guaranteed under any network parameters. Accordingly, in the second scenario, to tackle this problem, a receiver equipped with the capability to transmit jamming signals (receiver jammer) is proposed, aiming to protect the communication against potential information leakage from the untrusted relay. In the third and fourth scenarios, the relay is considered a trusted node, and warden (Willie) is introduced into the system. Here, the external jammer plays a crucial role when transmitting interference signals simultaneously toward Bob, relay, and Willie to ensure communication security. This scenario incorporates covert communication designed to counter threats from Willie’s detection. Covert communication in these two scenarios is analyzed under the following two conditions: 1) When Willie has Channel State Information (CSI); 2) When Willie lacks CSI, in which case he equips himself with multiple antennas. Simulation results show that the proposed power allocation can enhance secure and covert communications, even in the presence of hardware impairments and a multi-antenna Willie. Moreover, it is shown that when Willie has CSI, the performance of covert communication is severely reduced.
We apply the concept of artificial and controlled interference in a two-hop relay network with an untrusted relay, aiming at enhancing the wireless communication secrecy between the source and the destination node. In order to shield the square quadrature amplitude-modulated (QAM) signals transmitted from the source node to the relay, the destination node designs and transmits artificial noise (AN) symbols to jam the relay reception. The objective of our considered AN design is to degrade the error probability performance at the untrusted relay, for different types of channel state information (CSI) at the destination. By considering perfect knowledge of the instantaneous CSI of the source-to-relay and relay-to-destination links, we first present an analytical expression for the symbol error rate (SER) performance at the relay. Based on the assumption of an average power constraint at the destination node, we then derive the optimal phase and power distribution of the AN that maximizes the SER at the relay. Furthermore, we obtain the optimal AN design for the case where only statistical CSI is available at the destination node. For both cases, our study reveals that the Gaussian distribution is generally not optimal to generate AN symbols. The presented AN design takes into account practical parameters for the communication links, such as QAM signaling and maximum likelihood decoding.