Friendly Jammer Research Articles

UAV-enabled friendly jamming scheme to secure industrial Internet of Things

Eavesdropping is a critical threat to the security of industrial Internet of things (IIoT) since many malicious attacks often follow eavesdropping activities. In this paper, we present an anti-eavesdropping scheme based on multiple unmanned aerial vehicles (UAVs) who emit jamming signals to disturb eavesdropping activities. We name such friendly UAV-enabled jamming scheme as Fri-UJ scheme. In particular, UAV-enabled jammers (UJs) emit artificial noise to mitigate the signal to interference plus noise ratio (SINR) at eavesdroppers consequently reducing the eavesdropping probability. In order to evaluate the performance of the proposed Fri-UJ scheme, we establish a theoretical framework to analyze both the local eavesdropping probability and the overall eavesdropping probability. Our analytical results show that the Fri-UJ scheme can significantly reduce the eavesdropping risk while having nearly no impact on legitimate communications. Meanwhile, the simulation results also agree with the analytical results, verifying the accuracy of the proposed model. The merits of Fri-UJ scheme include the deployment flexibility and no impact on legitimate communications.

Secrecy outage analysis of energy harvesting two‐way relaying networks with friendly jammer

This study investigates two-way relaying where an energy harvesting capable relay exchanges information between two sources. Legitimate information is wire-tapped by an eavesdropper. To intercept wire-tapping, this study exploits a friendly jammer. Secrecy outage analysis of the energy harvesting two-way relaying network with the friendly jammer over Rayleigh fading channels is first proposed in terms of individual secrecy outage probabilities and then validated by computer simulations. Various results demonstrate the efficacy of the jammer in preventing the eavesdropper from stealing the source information and significant impacts of relay location, jammer location, jammer's transmit power, energy conversion efficiency, time switching ratio on the security performance.

Leakage rate‐based untrustworthy relay selection with imperfect channel state information: the outage and security trade‐off analysis

This study investigates the effects of the imperfect channel state information on the leakage rate-based untrustworthy relay selection strategies. The investigation considers that the channel state information is imperfect because of the channel estimation errors and also the feedback delay with time-variant channels. The investigation also considers three different types of leakage rate-based selection strategies, which are half-duplex, full-duplex, and hybrid. The investigation also considers a dual-hop one/two-way amplify-and-forward-based half-/full-duplex wireless relaying network in the system model. In addition, in order to mitigate the information leakage, a finite number of friendly jammers are affecting the untrustworthy relay terminals. According to analytical, asymptotic, and Monte–Carlo simulation results, the leakage rate-based selection strategies achieve cooperative diversity order in high signal-to-noise ratio regimes. The channel estimation error causes system coding gain losses in low signal-to-noise ratio regimes. The feedback delay degrades the achievable diversity order from M to 0 and also causes system coding gain losses in high signal-to-noise ratio regimes. In addition, the friendly jammers and loop-interference also degrade the achievable diversity order and also cause system coding gain losses in high signal-to-noise ratio regimes.

Secure Beamforming for Cooperative Wireless-Powered Networks With Partial CSI

In this paper, we investigate the physical layer security (PLS) of cooperative wireless-powered networks where a source transmits confidential information to a destination with the aid of wireless-powered intermediate nodes equipped with multiple antennas in the presence of a passive eavesdropper. We consider two generalized joint relay and jammer selection (GJRJS) frameworks based on the power splitting (PS) and time switching (TS) techniques, respectively. Specifically, the intermediate nodes which cannot decode the source signal successfully are selected to act as friendly jammers to transmit artificial noise, and the remaining nodes are exploited as relays to simultaneously forward the source signal through cooperative beamforming. We further propose two cooperative secure beamforming (CSB) schemes for the PS-based GJRJS (PS-GJRJS) and TS-based GJRJS (TS-GJRJS) frameworks, respectively. To be specific, we investigate the optimization of the beamforming vector of our selected relays for maximizing the secrecy rate of the source–destination transmission. A closed-form solution is derived under the assumption of available instantaneous channel state information (CSI) of the main link and statistical CSI of the wiretap link. In addition, we also illustrate that the pure relay selection (PRS) scheme is a special case of our GJRJS framework at high signal-to-noise ratios (SNRs). The numerical results show that the proposed CSB scheme achieves a higher secrecy rate than the traditional maximal ratio transmission (MRT) method for both the PS-GJRJS and TS-GJRJS frameworks. Additionally, the GJRJS framework outperforms the PRS as well as the joint best relay and jammer selection (JBRJS) methods in terms of secrecy rate.

Secrecy Analysis of Multi-user Half/Full-Duplex Wireless Bi-directional Relaying Network

This paper investigates the physical layer security of orthogonal frequency division multiplexing technique. The investigation considers a multi-user untrustworthy half/full-duplex based two-way wireless relay with a finite number of friendly jammers in the system model. According to Monte-Carlo simulation results, the system model that operates in full-duplex mode achieves slightly better secrecy outage performance than the system model that operates in half-duplex mode. The results also show that friendly jammers, besides minimizing the information leakage, degrade the system performance severely and cause system coding gain losses in high signal-to-noise ratios.

Joint Relay Selection and Destination Assisted Cooperative Jamming with Power Allocation for Secure DF Relay Network

To enhance the physical-layer security of a decode-and-forward (DF) cooperative relay network in the presence of a potential eavesdropper, a joint relay selection and destination assisted cooperative jamming (CJ) scheme is proposed. In phase I, the source transmits its confidential signal, and concurrently, it cooperates with the friendly jammers and the destination to send jamming signals to confuse the eavesdropper without affecting the forwarding relay which is preselected. In phase II, the forwarding relay retransmits the decoded signal, and simultaneously, the particular relay cooperates with the friendly jammers to send jamming signal to confuse the eavesdropper without affecting the destination. The achievable secrecy rate maximization (SRM) problem is investigated by optimally allocating the power between the data signal and jamming signals. Although SRM problem is non-convex, the power allocation problem can be solved by a bisection method together with a one-dimensional search. Optimal relay selection and suboptimal relay selection schemes are also proposed to further improve the secrecy rate. Simulation results are presented to show that the joint scheme can attain higher achievable secrecy rates than some existing works.

Secrecy Outage Probability Analysis of Friendly Jammer Selection Aided Multiuser Scheduling for Wireless Networks

In this paper, we study a multiuser uplink network consisting of one base station (BS), multiple users and one eavesdropper (E), where the users are intended to transmit their confidential messages to BS, while the eavesdropper attempts to tap their transmissions. To improve the transmission secrecy, we propose two friendly jammer selection-aided multiuser scheduling schemes, namely, the random jammer selection-aided multiuser scheduling (RJS-MUS) without knowing the eavesdropper's channel state information (CSI) and the optimal jammer selection-aided multiuser scheduling (OJS-MUS), where the CSIs of eavesdropper are available. For comparison purposes, the conventional non-jammer selection-aided multiuser scheduling (NJS-MUS) scheme is considered as a benchmark. We derive exact and asymptotic closed-form secrecy outage probability expressions for the conventional NJS-MUS as well as proposed RJS-MUS and OJS-MUS schemes. The numerical results show that the proposed RJS-MUS and OJS-MUS schemes with equal power allocation between the selected friendly jammer and scheduled user perform worse than the conventional NJS-MUS approach in terms of the secrecy outage probability in the low signal-to-noise ratio (SNR) region. As the SNR increases, the secrecy outage performance of RJS-MUS and OJS-MUS schemes substantially improves, which is, in turn, better than that of conventional NJS-MUS approach. Moreover, the secrecy advantage of RJS-MUS and OJS-MUS over NJS-MUS becomes more significant with an increasing SNR. Also, it is shown that for both the RJS-MUS and OJS-MUS schemes, a better secrecy performance can be achieved through an optimal power allocation (OPA) between the scheduled user and friendly jammer. In addition, the proposed RJS-MUS and OJS-MUS schemes with OPA strictly outperform the conventional NJS-MUS approach in terms of the secrecy outage probability.

A Scheme for Trustworthy Friendly Jammer Selection in Cooperative Cognitive Radio Networks

In this paper, we consider a centralized cooperative cognitive radio network (CCRN), where a primary base station sends a message to a primary user. Meanwhile, a secondary user transmitter (SU-Tx) acts as a friendly jammer that sends jamming signals (artificial noise) to protect the transmitted message from a potential eavesdropper (Eve). However, the SU-Tx may not be completely honest in sending jamming signals for selfish reasons, i.e., it may be untrusted. To select a trustworthy SU-Tx as a friendly jammer, we adopt the concept of trust degree as a selection criterion. We investigate the trust degree's influence on the secrecy performance of a CCRN in cases of perfect channel state information (CSI) and statistical CSI, respectively. In the case of perfect CSI, the accurate expected secrecy rate is derived to evaluate the secrecy performance. In the case of statistical CSI, we calculate the probabilities of the transmission and secrecy outage events, and the secrecy performance is evaluated in terms of effective secrecy throughput. In both cases, we obtain the target trust degree thresholds based on the target secrecy performance thresholds, respectively. Next, we investigate how to calculate the trust degree of each SU-Tx and establish a trust degree list of all SU-Txs. Finally, according to the trust degree list and the target trust degree thresholds, we can select a trustworthy SU-Tx as a friendly jammer in both two cases. A comprehensive simulation study is carried out to validate our secrecy performance analyses and the trust degree management.

Joint Beamforming Design and Power Minimization for Friendly Jamming Relaying Hybrid RF/VLC Systems

In this paper, we study physical layer security (PLS) aspects of a hybrid radio frequency (RF)/visible light communication (VLC) system with multiple decode-and-forward relaying nodes equipped with friendly jamming capabilities. We first propose a novel joint relay–jammer selection algorithm to enhance the secrecy performance of the network. Next, we obtain beamforming vectors and the minimal power values, which satisfy the required secrecy threshold. Our simulation results show that the proposed hybrid RF/VLC scheme obtains higher secrecy capacity compared to the standalone VLC and RF technologies. Finally, we proved the proposed technique to be an eavesdropping-resilient PLS solution.

Security and reliability performance analysis for two‐way wireless energy harvesting based untrusted relaying with cooperative jamming

In this study, the authors investigate the security and the reliability performance of a two-way relay-based network, where a source-destination pair establishes secured communication through a wireless-powered untrusted amplify-and-forward relay while employing a friendly jammer. The relay utilises the harvested energy from radio-frequency signals sent by the sources to forward the received data; however, the friendly jammer employs that to generate and transmit noise-like signals to confuse the curious relay. Two power transmission protocols, namely variable power transmission (VPT) and constant power transmission (CPT) at the jammer and relay are adopted. As a benchmark to highlight the performance advantages of employing a jammer, they also considered the case of zero power transmission (ZPT), where there is no jammer in the network. For the three scenarios, the intercept probability (IP) and the connection outage probability (COP), as well-known secrecy criteria associated with the successful transmission are mathematically examined. Finally, the derived expressions are confirmed by comparison with Monte-Carlo simulations and furthermore, numerical examples are provided to demonstrate the effects of system parameters on the IP and the COP metrics. Specifically, they find that jammer's artificial noise distribution plays a paramount role in the secrecy performance of the considered system.

A Game of One/Two Strategic Friendly Jammers Versus a Malicious Strategic Node

We present a game-theoretic analysis of the interaction between a malicious node, attempting to perform unauthorized radio transmission, and friendly jammers trying to disrupt the malicious communications. We investigate the strategic behavior of the jammers against a rational malicious node and highlight counterintuitive results for this conflict. We also analyze the impact of multiple friendly jammers sharing the same goal but acting without coordination; we find out that this scenario offers a better payoff for the jammers, which has some strong implications on how to implement friendly jamming.

Optimisation of secrecy rate in cooperative device to device communications underlaying cellular networks

In this study, the optimisation of cooperation level and uplink spectrum sharing are analysed by employing physical layer security concept in the device to device communications underlaying cellular networks. It is assumed that two transmitting devices communicate with the same receiving device in the presence of a passive eavesdropper. Also, it is assumed that one of the two transmitting devices aids the other one as a relay node. The optimum cooperation level and channel assignment schemes are obtained through maximizing the secrecy rate under constraints of satisfying the quality of services for cellular users (CUs) and the receiving device. In this sense, the selected CU which shares its resource block acts as a friendly jammer to interfere the eavesdropper. Although the proposed approach initially leads to a non-convex optimization problem, it can be solved efficiently by using GloptiPloy (global optimum polynomial) and SeDuMi software packages. Simulation results are provided to evaluate the performance of the proposed optimum cooperation level scheme and demonstrate the superiority of the proposed approach compared to the conventional fixed cooperation level schemes.

Wireless-Powered Full-Duplex Relay and Friendly Jamming for Secure Cooperative Communications

Wireless energy harvesting, physical-layer security, and full-duplex wireless are important, emerging fifth generation (5G) technologies. In this paper, we thus investigate a source–destination link with an energy-harvesting full-duplex relay and a jammer (to degrade the eavesdropper channel) in the presence of an eavesdropper. Thus, to exploit energy harvesting and to improve security, we propose a full-duplex jammer (FDJ) protocol and its half-duplex version (HDJ). Two cases for availability of the eavesdropper channel state information (ECSI) are considered: complete ECSI and incomplete ECSI. For both FDJ and HDJ protocols and for complete ECSI, we derive the instantaneous and average secrecy rates and compute optimal time split for energy harvesting. To gain more insights, we consider a practical interference-limited scenario and derive closed-form cumulative distribution function of the signal-to-interference plus noise ratio at the destination and eavesdropper nodes. Comparatively, we show that FDJ improves instantaneous secrecy rate over HDJ. However, the degree of improvement is highly dependent on time split for energy harvesting, amount of self-interference, the channel gains, and locations of the nodes. Our findings reveal that FDJ increases the average secrecy rate 150% over HDJ and 260% over HD relaying without jammer. For incomplete ECSI scenario, we derive asymptotic secrecy outage and show that FDJ performs better for small-to-medium values of source powers; otherwise, HDJ yields a higher gain.

물리계층 보안 성능 향상을 위한 재밍 조건

물리계층 보안기법은 무선 채널의 통계적 특성에 의존하지 않는 인공노이즈 기법과 결합되어 MIMO 시스템, 멀티유저, 릴레이 시나리오 등 다양한 모델에서 연구되고 있다. 하지만 정교하게 수립되지 않는 무분별한 재밍 전략은 오히려 보안성능을 감소시키기 때문에 성능에 영향을 주는 요소들을 이론적으로 분석해야 한다. 따라서, 본 논문에서는 도청자가 존재하는 MIMO 채널에서 재밍파워와 노드배치의 관점에서 보안성능의 변화를 살펴보았다.

Energy Efficiency of Secure Cognitive Radio Networks with Cooperative Spectrum Sharing

Energy-efficient and secure wireless communications have recently earned tremendous interests due to economic, environmental, and military concerns. This paper investigates the tradeoff between the secrecy throughput and the energy efficiency in cognitive radio networks (CRNs), where primary and secondary users with different priorities of spectrum access can either interfere or cooperate with each other. To gain an understanding of the intricate effects that system parameters have on underlay network's performance, we exclusively focus on characterizing several key aspects that may have potential impacts on secure underlay CRNs, including the transmission power, the number of interfering users, and the designed interference resistance coefficient. Based on the obtained analytical results, we further propose a cooperative spectrum sharing paradigm to improve both the secrecy throughput and the energy efficiency of primary users. The main idea is that primary users allow secondary users to simultaneously access the licensed spectrum and in return, the secondary transmitter acts as both a relay for primary transmissions and a friendly jammer against eavesdropping, in case the primary transmission fails. Both theoretical and numerical results reveal that: (i) When the interference from secondary transmitters is small, there is an optimal transmission power that maximizes the secrecy throughput for primary users compared to CRNs without the security issue. (ii) When the interference from secondary transmitters is large, the secrecy throughput increases with the transmission power for primary users. (iii) The transmission power that maximizes the energy efficiency is smaller than that maximizes the secrecy throughput for primary users. (iv) The number of interfering users has a slight impact on the secrecy throughput and the energy efficiency of primary users due to the secondary power control. (v) The proposed cooperative paradigm is an efficient approach to boost both the secrecy throughput and the energy efficiency of primary users compared with the traditional non-cooperative spectrum sharing, and provides an alternative method to compensate for the interference caused by secondary users.

Distributed Power Control in Single-Stream MIMO Wiretap Interference Networks With Full-Duplex Jamming Receivers

We consider a multi-link interference network that is tapped by an external eavesdropper. To conceal information from the eavesdropper, legitimate links are equipped with transmitter-based friendly jamming (TxFJ) and receiver-based friendly jamming (RxFJ). Each link seeks to maximize its secrecy rate by determining the best power assignment (PA) for the information, TxFJ, and RxFJ signals. Joint optimization of these parameters is a non-convex problem. Hence, we seek sub-optimal solutions. Specifically, we find a lower bound on the allocated power to TxFJ above which positive secrecy is achievable for a given link. Once positive secrecy is achieved, the secrecy rate becomes monotonically increasing in the power at the transmitter (Alice). Therefore, the rest of Alice's power is allocated to the information signal. Despite its sub-optimality, such an approach precludes the possibility of employing successive interference cancellation by the eavesdropper. The RxFJ PA of a link is adjusted using an on-off PA that depends only on the link's local channel state information (CSI). With every link following such a strategy, we model this interaction as a non-cooperative game. We derive sufficient conditions for the uniqueness of the resulting Nash equilibrium. We then propose an algorithm to implement the PA game. Lastly, we relax knowledge of eavesdropper's CSI (E-CSI) and propose a framework that is robust to unknown E-CSI. Our results indicate that this robust framework performs close to when E-CSI is fully known to legitimate links. Moreover, empirically it is shown that the secrecy sum-rate scales with the power budget of transmitters.

PriWhisper+: An Enhanced Acoustic Short-Range Communication System for Smartphones

The recent proliferation of Internet of Things (IoT) device coupled with the demand for an inexpensive way of transmitting data has been the primary factors behind the popularity of the short-range acoustic communication. It enables a seamless transfer of digital information via soundwaves, using device’s loudspeaker and microphone only and the whole interaction takes place without the need for network connection. Due to the limited computational power of the IoT device, the short-range acoustic communication system has adopted the friendly jamming technology to save energy. However, the security of the friendly jamming technology in mobile applications has not been thoroughly studied. When propagating sound in public, the soundwaves are subject to eavesdropping by nature. In particular, the friendly jamming technology is vulnerable to the separation attacks which can separate data signals from mixed signals. In this paper, we propose PriWhisper+—a secure acoustic short-range communication system between IoT devices. We analyze the security of PriWhisper+ via information theory and propose physical security enhancement mechanisms for acoustic communication by combining device mobility with secret sharing scheme. We then design a secure data communication scheme that transmits data in acoustic signals. This scheme can be applied in many security-sensitive situations, such as device pairing, contactless payments, and privacy data sharing. At last, we evaluate the performance of our proposed PriWhisper+ by extensive experiments on Android smartphones. The results of the experiment show that the PriWhisper+ can protect the data confidentiality within thirty centimeters of communication range.

Secure Performance of an Untrusted AF Relay System with a Friendly Wireless Powered Jammer

We propose a jam-then-harvest protocol for dual-hop cooperative networks with an untrusted relay, where an external friendly jammer helps keep information secret from the untrusted relay by transmitting a priori jamming signal for the destination. In particular, the wireless powered jammer scavenges energy from the received forwarded signal and recovers its initial energy to perform jamming in next time slot. We analytically derive an exact expression of the probability of nonzero secrecy rate (PNSR) for the proposed jam-then-harvest protocol. For performance comparison, cooperative jamming with the constant power supply is provided as a lower bound benchmark. Our results show that the proposed protocol not only can achieve the secure communication but also can harvest the enough energy without a loss of performance in the low jamming power region.

Optimal System Performance in Multihop Energy Harvesting WSNs Using Cooperative NOMA and Friendly Jammers

In this paper, we investigate the system performance of multihop energy harvesting (EH) wireless sensor networks (WSNs) with imperfect channel state information (CSI) using cooperative non-orthogonal multiple access (NOMA) and friendly jammers in the presence of multiple passive eavesdroppers (EAVs). Specifically, we propose a two-phase communication protocol consisting of EH and information transmission (IT). In the first phase, relays in all clusters harvest energy from power transfer station (PTS) signals. In the first time slot of the second phase, the gateway simultaneously broadcasts information and interference signals. In the subsequent time slots, a relay acting as a friendly jammer in each cluster uses the harvested energy to send an interference signal. Simultaneously, another EH relay applies the NOMA technique to transmit the information signal according to an optimal scheduling scheme based on the maximum signal-to-interference-plus-noise ratio (SINR) of a far user (MSm) and a near user (MSn). To ensure security performance, we propose an algorithm for determining the EH time constraint for a friendly jammer. Additionally, closed-form expressions for the outage probability and throughput of the considered system are derived. Accordingly, an optimal power allocation coefficient algorithm is proposed to achieve throughput fairness for pairs of users. The results of the mathematical analysis are verified by Monte Carlo simulations. Finally, the numerical results demonstrate that the MSn scheme is recommended for guaranteeing throughput fairness for pairs of users.

A Reassessment on Friendly Jamming Efficiency

With the rapid and continuous growth of various types of wireless devices in IoT, securing the communications among heterogeneous devices becomes an emerging issue. A physical layer security scheme, called “friendly jamming”, has drawn great attention recently owing to its ability to protect the confidentiality of the communication as well as to enable message authentication and access control for those already employed, unencrypted, weakly encrypted, or resource constrained devices. We notice that in a large number of cases in which friendly jamming are preferable, the transmitting signals to be protected have varying spectrum utilization at symbol level. In this paper, we rebuild secrecy capacity models and re-evaluate the jamming efficiency by taking this micro time scale non-stationary characteristic into consideration. Our reassessments reveal that jamming efficiency is greatly overestimated in the existing literature. The second part of our work further proposes a waveform design on jamming signal as a means to enhance the jamming efficiency. The basic idea is to consider both time and frequency domain structure of the transmitting signal when designing the jamming signal, making both time and frequency bandwidth largely match to each other. We discuss the implementation details for jamming common QAM and PSK modulated signals. Both simulations and proof-of-concept experiments validate the theoretical correctness of our reassessment and practical effectiveness of our method.