ABSTRACT We study a wireless communication system consisting of a transmitter, a legitimate receiver, multi‐antenna eavesdroppers and randomly distributed friendly jammers. A secrecy guard zone surrounds the transmitter, within which eavesdroppers can be detected or denied entry. To counter the multi‐antenna eavesdroppers' ability to mitigate jamming, we propose a randomised activation strategy where jammers independently transmit artificial noise with a probability. We derive closed‐form expressions for the transmission probability and secrecy outage probability, and develop an optimisation framework to adjust the rates of transmitted codewords and confidential messages. Simulation results validate our analytical derivations and demonstrate that the proposed strategy effectively maximises secrecy throughput while maintaining the secrecy outage probability below a specified threshold.
ABSTRACT We study a wireless communication system consisting of a transmitter, a legitimate receiver, multi‐antenna eavesdroppers and randomly distributed friendly jammers. A secrecy guard zone surrounds the transmitter, within which eavesdroppers can be detected or denied entry. To counter the multi‐antenna eavesdroppers' ability to mitigate jamming, we propose a randomised activation strategy where jammers independently transmit artificial noise with a probability. We derive closed‐form expressions for the transmission probability and secrecy outage probability, and develop an optimisation framework to adjust the rates of transmitted codewords and confidential messages. Simulation results validate our analytical derivations and demonstrate that the proposed strategy effectively maximises secrecy throughput while maintaining the secrecy outage probability below a specified threshold.
The issues of the physical layer security are studied, where one transmitter (Alice), one full‐duplex (FD) legitimate receiver (Bob) and one multi‐antenna jammer (Charlie) are considered to defend against multiple passive and non‐colluding eavesdroppers (Eves), for multiple‐input multiple‐output wiretap channels. With the assumption that the complete channel state information (CSI) for main channels and the statistical CSI for Eves' channels are available, an improved secrecy transmission design is proposed to minimise the secrecy outage probability (SOP), under the minimum secrecy rate requirement. In addition to integrating artificial noise aided transmit beamforming and multi‐antenna cooperative jammer to impair Eves' channels, which is widely used in many existing works, a FD legitimate receiver is applied together to further enhance physical layer security. Based on the basic probability theory and convex optimisation, the accurate closed‐form expression of the SOP is derived, and the impacts on secrecy performance are described, including the qualities of main channels, the Alice's transmit power and the number of Eves. Numerical results show that the proposed scheme using the FD Bob can significantly enhance the system security, as compared with that employing the half‐duplex Bob.
This paper investigates the physical layer security for a distributed antenna system, where a base station (BS) equipped with multiple distributed antennas transmits signals to a legitimate user (U) through an opportunistic antenna. Meanwhile, multiple non-colluding eavesdroppers (Es) attempt to tap the information transmission between the BS and U. To enhance the physical layer security, a friendly jammer (J) is employed to create a potential interference to Es by emitting artificial noise. However, since U is not aware of the information sent by J, it can be affected by the interference. In this context, this paper proposes adaptive jamming (AJ) scheme and interference cancellation (IC) scheme to mitigate the interference’s impact on U and consequently improve secrecy performance. Specifically, the AJ scheme avoids interference from having a negative effect on the system security by setting an interference threshold, activating the jammer only when the interference to U is below the threshold value. By contrast, the IC scheme designs an advanced special signal to eliminate the interference from J to U. For comparison, we present conventional non-jammer (NJ) scheme as a benchmark. Exact and asymptotic secrecy outage probability expressions for NJ, AJ, and IC schemes are derived over Nakagami-mfading channels. Numerical results show that the proposed AJ and IC schemes perform better than NJ scheme in terms of secrecy outage probability. Additionally, the physical layer security of all schemes can be improved by increasing the number of distributed antennas.
In this article, we investigate the physical layer security for a wireless communication system consisting of a base station (BS) and a user (U) in the face of an eavesdropper (E). A friendly jammer is opportunistically selected from multiple jammers to create intentional interference upon E. However, the legitimate user U is not aware of the information transmitted by the jammer and thus cannot remove the interfering signal. In this context, we propose interference-limited opportunistic jammer selection (IL-OJS) scheme and interference-canceled opportunistic jammer selection (IC-OJS) scheme to reduce the damage of interference to U for improving physical layer security. Specifically, in the IL-OJS scheme, the selected jammer sets an interference threshold. When the interference to U is less than the threshold value, the selected jammer will work (i.e., emit artificial noise), and vice versa, it will stop jamming. By contrast, IC-OJS scheme utilizes a specially designed signal to eliminate interference received by U from the selected jammer. For comparison, we also present the conventional non-jammer (NJ) scheme as a benchmark. Exact and asymptotic closed-form secrecy outage probability expressions for NJ, IL-OJS, and IC-OJS schemes are derived over Nakagami-mfading channels. Numerical results show that the secrecy performance of proposed IL-OJS and IC-OJS schemes is better than that of NJ scheme. Additionally, the secrecy outage probability performance of IL-OJS and IC-OJS schemes can be improved by increasing the number of jammers.
We analyze the physical layer security of a communication scheme with a multiple antenna legitimate transmitter, employing transmit antenna selection (TAS), and a single antenna legitimate receiver in the presence of a single antenna eavesdropper. We developed closed-form expressions for the analysis of the secrecy outage probability supposing independent and quasi-static Rayleigh fading channels. Our results show that the secrecy outage probability is considerably increased when multiple antennas are available at the legitimate transmitter. Moreover, due to the use of the TAS technique, the eavesdropper is not able to exploit the additional spatial diversity offered by the legitimate transmitter.
Jamming emits white Gaussian noise that causes interference to both the legitimate receiver and eavesdropper. It has been an effective method for improving physical-layer security in wireless communication. In this paper, cautious jamming strategy based on optimal jammer selection method is proposed. More specifically, by using perfect channel state information, cautious jamming strategy selects an optimal jammer to improve the secrecy performance. For the purpose of comparison, we consider the direct jamming strategy and the adaptive jamming strategy as benchmark schemes. Closed-form expressions of the exact intercept probability for three jamming strategies are derived over Rayleigh fading channels and the theoretical analysis is validated by Monte-Carlo simulation. Both the analytical and the simulation results show that: 1) increasing the power of jammer is an effective approach to mitigate the intercept probability; 2) the intercept probability can be decreased and the wiretapped range of eavesdropper can be reduced by increasing the number of jammer; 3) by using perfect CSI and selecting optimal jammer, cautious jamming strategy outperforms direct jamming strategy and adaptive jamming strategy.
In this paper, we investigate wireless networks consisting of a legitimate transmitter (Alice), a legitimate receiver (Bob), eavesdroppers (Eves), and friendly jammers. Two network scenarios are considered depending on whether Alice and the jammers have the ability to detect the existence of Eves in their vicinity. If they do not have the ability, as a means to enhance the secrecy, Alice transmits artificial noise and each jammer selectively radiates a jamming signal based on the channel gain between the jammer and Bob. On the other hand, when they have the ability, Alice sends a confidential message to Bob if no Eve is detected within its guard zone, and the jammers transmit jamming signals when there exists at least one Eve in their vicinity. We model the spatial distributions of Eves and jammers as $\beta $ -Ginibre point processes, which can characterize repulsion among the nodes and include the Poisson point process (PPP) as a special case. Then, we analyze both the probability that Bob successfully decodes the confidential message and the probability that the message is secure against eavesdropping. Also, we show that our analysis is a generalization of previous works on the networks with PPPs by recovering them from our analytical results.