Wireless communication is vulnerable to eavesdropping attack due to the broadcast nature of radio propagation. In recent years, physical-layer security is emerging as a promising paradigm to prevent an eavesdropper from interception. In this paper, we consider a wireless network consisting of one source, one destination and one eavesdropper, and exploit multiple antennas at all the network nodes to improve wireless security against eavesdropping attack. Considering multiple transmit antennas at source node, we propose the optimal antenna selection (OAS) scheme to enhance the physical-layer security. We also examine the conventional single-input single-output (SISO) and space-time-coded transmission (STT) for the comparison purpose. We analyze the intercept probability performance of SISO, STT and OAS schemes in Rayleigh fading channels and theoretically prove that the proposed OAS scheme strictly outperforms conventional STT scheme in terms of the intercept probability. In addition, numerical results illustrate that with an increasing number of antennas at source and destination, the intercept probabilities of both OAS and STT schemes significantly decrease, implying the advantage of exploiting multiple antennas for wireless security against eavesdropping attack.
Wireless communication is vulnerable to eavesdropping attack due to the broadcast nature of radio propagation. In recent years, physical-layer security is emerging as a promising paradigm to prevent an eavesdropper from interception. In this paper, we consider a wireless network consisting of one source, one destination and one eavesdropper, and exploit multiple antennas at all the network nodes to improve wireless security against eavesdropping attack. Considering multiple transmit antennas at source node, we propose the optimal antenna selection (OAS) scheme to enhance the physical-layer security. We also examine the conventional single-input single-output (SISO) and space-time-coded transmission (STT) for the comparison purpose. We analyze the intercept probability performance of SISO, STT and OAS schemes in Rayleigh fading channels and theoretically prove that the proposed OAS scheme strictly outperforms conventional STT scheme in terms of the intercept probability. In addition, numerical results illustrate that with an increasing number of antennas at source and destination, the intercept probabilities of both OAS and STT schemes significantly decrease, implying the advantage of exploiting multiple antennas for wireless security against eavesdropping attack.
Abstract—In this paper, we consider a multiple-input multiple-output (MIMO) system consisting of one source, one destination and one eavesdropper, where each node is equipped with an arbitrary number of antennas. To improve the security of source-destination transmissions, we investigate the antenna selection at the source and propose the optimal antenna selection (OAS) and suboptimal antenna selection (SAS) schemes, depending on whether the source node has the global channel state information (CSI) of both the main link (from source to destination) and wiretap link (from source to eavesdropper). Also, the traditional space-time transmission (STT) is studied as a benchmark. We evaluate the secrecy performance of STT, SAS, and OAS schemes in terms of the probability of zero secrecy capacity. Furthermore, we examine the generalized secrecy diversity of STT, SAS, and OAS schemes through an asymptotic analysis of the probability of zero secrecy capacity, as the ratio between the average gains of the main and wiretap channels tends to infinity. This is different from the conventional secrecy diversity which assumes an infinite signal-to-noise ratio (SNR) received at the destination under the condition that the eavesdropper has a finite received SNR. It is shown that the generalized secrecy diversity orders of STT, SAS, and OAS schemes are the product of the number of antennas at source and destination. Additionally, numerical results show that the proposed OAS scheme strictly outperforms both the STT and SAS schemes in terms of the probability of zero secrecy capacity. Index Terms—MIMO, antenna selection, space-time code, eavesdropping attack, secrecy diversity.
In this paper, we consider a multiple-input-multiple-output (MIMO) system consisting of one source, one destination, and one eavesdropper, where each node is equipped with an arbitrary number of antennas. To improve the security of source-destination transmissions, we investigate the antenna selection at the source and propose the optimal antenna selection (OAS) and suboptimal antenna selection (SAS) schemes, depending on whether the source node has the global channel state information (CSI) of both the main link (from source to destination) and the wiretap link (from source to eavesdropper). Moreover, the traditional space-time transmission (STT) is studied as a benchmark. We evaluate the secrecy performance of STT, SAS, and OAS schemes in terms of the probability of zero secrecy capacity. Furthermore, we examine the generalized secrecy diversity of the STT, SAS, and OAS schemes through an asymptotic analysis of the probability of zero secrecy capacity as the ratio between the average gains of the main and wiretap channels tends to infinity. This is different from the conventional secrecy diversity that assumes an infinite signal-to-noise ratio (SNR) received at the destination under the condition that the eavesdropper has a finite received SNR. It is shown that the generalized secrecy diversity orders of the STT, SAS, and OAS schemes are the product of the number of antennas at source and destination. Additionally, numerical results show that the proposed OAS scheme strictly outperforms both the STT and the SAS schemes in terms of the probability of zero secrecy capacity.
Due to the broadcast nature of radio propagation, wireless transmission can be readily overheard by unauthorized users for interception purposes and is thus highly vulnerable to eavesdropping attacks. To this end, physical-layer security is emerging as a promising paradigm to protect the wireless communications against eavesdropping attacks by exploiting the physical characteristics of wireless channels. This article is focused on the investigation of diversity techniques to improve physical-layer security differently from the conventional artificial noise generation and beamforming techniques, which typically consume additional power for generating artificial noise and exhibit high implementation complexity for beamformer design. We present several diversity approaches to improve wireless physical-layer security, including multiple-input multiple-output (MIMO), multiuser diversity, and cooperative diversity. To illustrate the security improvement through diversity, we propose a case study of exploiting cooperative relays to assist the signal transmission from source to destination while defending against eavesdropping attacks. We evaluate the security performance of cooperative relay transmission in Rayleigh fading environments in terms of secrecy capacity and intercept probability. It is shown that as the number of relays increases, both the secrecy capacity and intercept probability of cooperative relay transmission improve significantly, implying there is an advantage in exploiting cooperative diversity to improve physical-layer security against eavesdropping attacks.
In this paper, we investigate the physical layer security technique of a cooperative communication network with a source node having multiple transmitting antennas, in which these antennas provide the most optimal antenna to increase security performance to a destination node via a relay node in the presence of an eavesdropper node. Here, we propose and analyze a transmission antenna selection (TAS) solution to enhance security performance in the eavesdropping channel, the cooperative communication model between the source node including multiple transmitting antennas and a destination node through a relay node and the influence of the eavesdropping node. The secrecy performance is exactly evaluated based on the secrecy outage probability (SOP) of the main channel compared to the eavesdropping channel in the Rayleigh fading channels. Monte-Carlo simulation method is applied to verify simulations and theoretical analysis results in the proposed model. The results show that when using such multiple transmit antennas significantly enhanced the system's security performance.
Wireless communications offer data transmission services anywhere and anytime, but with the inevitable cost of introducing major security vulnerabilities. Indeed, an eavesdropper can overhear a message conveyed over the open insecure wireless media putting at risk the confidentiality of the wireless users. Currently, the way to partially prevent eavesdropping attacks is by ciphering the information between the authorised parties through complex cryptographic algorithms. Cryptography operates in the upper layers of the communication model, bit it does not address the security problem where the attack is suffered: at the transmission level. In this context, physical layer security has emerged as a promising framework to prevent eavesdropping attacks at the transmission level. Physical layer security is based on information-theoretic concepts and exploits the randomness and the uniqueness of the wireless channel. In this context, this thesis presents signal processing techniques to secure wireless networks at the physical layer by optimising the use of multiple-antennas. A masked transmission strategy is used to steer the confidential information towards the intended receiver, and, at the same time, broadcast an interfering signal to confuse unknown eavesdroppers. This thesis considers practical issues in multiple-antenna networks such as limited transmission resources and the lack of accurate information between the authorised transmission parties. The worst-case for the security, that occurs when a powerful eavesdropper takes advantage of any opportunity to put at risk the transmission confidentiality, is addressed. The techniques introduced improve the security by offering efficient and innovative transmission solutions to lock the communication at the physical layer. Notably, these transmission mechanisms strike a balance between confidentiality and quality to satisfy the practical requirements of modern wireless networks.
In this paper, we investigate security issues in a collaborative wireless network in the presence of eavesdropping attacks, where multiple amplify-and-forward (AF) relays are exploited to secure the message transmission between legitimate users. We first consider the multiple AF relays all participating in assisting the transmission from source to destination, which is called all-relay based collaborative transmission scheme as denoted by all-relay scheme for notational convenience. We also propose the best-relay transmission scheme in which only the single “best” relay is selected to help the source transmit messages to destination. We then analyze the intercept behavior in wireless networks and evaluate intercept probabilities of the proposed all-relay and best-relay schemes as well as the conventional direct transmission without relay in a Rayleigh fading environment. Numerical results show that the best-relay transmission scheme always outperforms the all-relay and direct transmission schemes in terms of intercept probability. It is also shown that as the number of eavesdroppers increases, the intercept probabilities of both all-relay and best-relay schemes increase. Moreover, the intercept probability performance of all-relay and best-relay schemes significantly improves with an increasing number of relays, implying the advantage of exploiting multiple relays against eavesdropping attacks.