The need for physical layer security techniques is increasing with the deployments of machine to machine (M2M), internet of things (IoT), and device to device (D2D) communications. An important aspect of physical layer security is to perform covert communications of a possibly unencrypted signal without allowing an eavesdropper to detect the signal. In this paper, cylindrical antenna arrays with a large number of elements are proposed in order to reach this objective. These arrays allow the transmission of both the useful signal to the destination and the jamming signal to the eavesdropper without resorting to the help of other nodes for relaying the signal and/or jamming the eavesdropper. In addition, these arrays can be used at the destination for enhancing the received signal level and/or jamming the eavesdropper simultaneously with the transmitter. Monte Carlo simulation results show that high levels of secrecy capacity can be achieved with the proposed approach.
The need for physical layer security techniques is increasing with the deployments of machine to machine (M2M), internet of things (IoT), and device to device (D2D) communications. An important aspect of physical layer security is to perform covert communications of a possibly unencrypted signal without allowing an eavesdropper to detect the signal. In this paper, cylindrical antenna arrays with a large number of elements are proposed in order to reach this objective. These arrays allow the transmission of both the useful signal to the destination and the jamming signal to the eavesdropper without resorting to the help of other nodes for relaying the signal and/or jamming the eavesdropper. In addition, these arrays can be used at the destination for enhancing the received signal level and/or jamming the eavesdropper simultaneously with the transmitter. Monte Carlo simulation results show that high levels of secrecy capacity can be achieved with the proposed approach.
Physical layer security allows secure communications between a source and destination without the need to resort to key-based encryption techniques. Its increasing importance stems from the difficulty of implementing advanced encryption techniques in certain networks, such as the internet of things (IoT). In this paper, physical layer security is implemented by using massive multiple input multiple output (MIMO) techniques. Specifically, beamforming with large cylindrical antenna arrays is investigated. These arrays allow the transmission of both the useful signal to the destination and the jamming signal to the eavesdropper without resorting to the help of other nodes for relaying the signal and/or jamming the eavesdropper. Simulation results show that high levels of secrecy capacity can be achieved with the proposed approach.
In this letter, a novel approach for physical layer security is implemented using massive cylindrical antenna arrays. A part of the arrays is used for transmitting a signal reliably from source to destination using highly directive beams. At the same time, the remaining part can be used to mitigate eavesdropping by transmitting a jamming signal through another directive beam toward the eavesdropper. In addition, the cylindrical arrays can mitigate the impact of malicious jamming by placing a null in the array pattern at the destination in the direction of the jammer. The results show that the proposed approach can lead to good jamming mitigation and high secrecy capacity in both 2D and 3D, even when there are errors in determining the location of the eavesdropper.
The need for physical layer security techniques is increasing rapidly with the significant rise in the number of devices connected to the internet. In this paper, physical layer security using massive planar antenna arrays is investigated to secure the communication between two parties in the presence of an eavesdropper. Different scenarios are studied assuming the presence of a passive eavesdropper at a known location. Some of the subarrays of the massive planar antenna arrays at both the transmitter and receiver are used to send jamming signals towards the eavesdropper to improve security. To measure the system secrecy, the secrecy capacity between the transmitter and receiver is derived and different schemes are studied considering their effect on the secrecy capacity. The simulation results show that when jamming signals are sent to the eavesdropper, the secrecy capacity improves significantly, and the eavesdropper is unable to obtain considerable useful information. Therefore, the use of massive MIMO for joint transmission and jamming is an important physical layer security technique to combat a passive eavesdropper.
The Internet of Things (IoT) is one of the most promising technological revolutions. However, the IoT is inherently vulnerable to attacks. In this paper, we propose to enhance the physical layer security of the IoT by using a technique called information passing and interference addition. In the physical layer security analysis, the achieved secrecy rate has an inverse relationship with the intruder's distance to the legitimate transmitter. Our work is, first, to increase the achievable secrecy rate by letting the legitimate transmitter find an alternative route to the fusion center that could achieve a higher secrecy rate than the direct route. Hence, the legitimate transmitter must not disclose the actual information to the fusion center if there is an eavesdropper located between them, and rather must pass its information to another node via a directional antenna to concentrate the power towards the intended receiving node. Passing the information to the nearest node must happen under the condition that there is no intruder in between. Second, we use simultaneous multi-stream beamforming transmission to strengthen the legitimate receiver's signal-to-noise ratios and at the same time poison the eavesdropper channel with interference. Third, we disclose false information to the intruder. We created the system design and investigated the secrecy analysis of that system. Also, we discussed the use of directional antennas on the legitimate nodes. The result showed that using directional antennas would increase the probability of having at least one secure connection coming out of the node to the other legitimate nodes. Moreover, the results showed that using the simultaneous multi-stream beamforming improved the legitimate channel's achievable secrecy rate and that it has superiority over the directional antenna effect.
With the great-leap-forward development of Internet of Things (IoT), it is extremely important to study secure wireless transmission for IoT systems. A cooperative jamming (CJ) strategy has been extensively studied to enhance physical layer security in IoT systems. However, CJ's secrecy performance has not been well studied in the scenario of collusive eavesdroppers. In this paper, we propose a CJ scheme for IoT systems to fight against multiple passive and collusive eavesdroppers of unknown channel state information. Considering nodes with multi-antenna in an IoT system, we design beamforming vectors to maximize signal-to- interference-plus-noise ratio (SINR) of the wireless link from a controller (transmitter) to an actuator (receiver). Under the worst-case assumption that eavesdroppers can aggregate all signals to enhance their eavesdropping abilities, we derive the closed- form expressions of the secrecy outage probability (SOP) with and without CJ. In addition, we employ a strict mathematical asymptotic analysis to provide insights into the effects of various system parameters on the SOP. Numerical results verify that the CJ scheme can effectively prevent eavesdropping and the effects of system parameters on SOP is consistent with theoretical analytical results.
Cooperative communications is obviously an evolution in wireless networks due to its noticeable advantages such as increasing the coverage as well as combating fading and shadowing effects. However, the broadcast characteristic of a wireless medium which is exploited in cooperative communications leads to a variety of security vulnerabilities. As cooperative communication networks are globally expanded, they expose to security attacks and threats more than ever. Primarily, researchers have focused on upper layers of network architectures to meet the requirements for secure cooperative transmission while the upper-layer security solutions are incapable of combating a number of security threats, e.g., jamming attacks. To address this issue, physical-layer security has been recommended as a complementary solution in the literature. In this thesis, physical layer attacks of the cooperative communication systems are studied, and corresponding security techniques including cooperative jamming, beamforming and diversity approaches are investigated. In addition, a novel security solution for a two-hop decode-and-forward relaying system is presented where the transmitters insert a random phase shift to the modulated data of each hop. The random phase shift is created based on a shared secret among communicating entities. Thus, the injected phase shift confuses the eavesdropper and secrecy capacity improves. Furthermore, a cooperative jamming strategy for multi-hop decode-and-forward relaying systems is presented where multiple non-colluding illegitimate nodes can overhear the communication. The jamming signal is created by the transmitter of each hop while being sent with the primary signal. The jamming signal is known at the intended receiver as it is according to a secret common knowledge between the communicating entities. Hence, artificial noise misleads the eavesdroppers, and decreases their signal-to-noise-ratio. As a result, secrecy capacity of the system is improved. Finally, power allocation among friendly jamming and main signal is proposed to ensure that suggested scheme enhances secrecy.