Multi-Input, Multi-Output (MIMO) techniques are seeing widespread usage in wireless communication systems due to their large capacity gains. On the other hand, security is a concern of any wireless system, which can make schemes that implement physical layer security key in assuring secure communications. In this paper, we study the physical layer security issues of MIMO with Singular Value Decomposition (SVD) schemes, employed along with Single-Carrier with Frequency-Domain Equalization (SC-FDE) techniques. More concretely. the security potential against an unintended eavesdropper is analysed, and it is shown that the higher the distance between the eavesdropper and the transmitter or receiver, the higher the secrecy rate. In addition, in a scenario where there is Line of Sight (LOS) between all users, it is shown that the secrecy rate can be even higher than in the previous scenario. Therefore, MIMO-SVD schemes combined with SC-FDE can be an efficient option for highly secure MIMO communications.
Multi-Input, Multi-Output (MIMO) techniques are seeing widespread usage in wireless communication systems due to their large capacity gains. On the other hand, security is a concern of any wireless system, which can make schemes that implement physical layer security key in assuring secure communications. In this paper, we study the physical layer security issues of MIMO with Singular Value Decomposition (SVD) schemes, employed along with Single-Carrier with Frequency-Domain Equalization (SC-FDE) techniques. More concretely. the security potential against an unintended eavesdropper is analysed, and it is shown that the higher the distance between the eavesdropper and the transmitter or receiver, the higher the secrecy rate. In addition, in a scenario where there is Line of Sight (LOS) between all users, it is shown that the secrecy rate can be even higher than in the previous scenario. Therefore, MIMO-SVD schemes combined with SC-FDE can be an efficient option for highly secure MIMO communications.
Physical layer security (PLS) provides strong and lightweight secure communications for vehicle networks, which has attracted great attention. However, current schemes cannot defend against the passive eavesdroppers with any number of antennas. To fill this gap, we propose a physical layer secure MIMO-SVD (singular value decomposition) communication scheme (SSVD) to defend against such an eavesdropper with any number of antennas. In the SSVD scheme, the confidential information first goes through a special data frames secure process at the transmitter. After that, by integrating with SSVD precoding, the key information is attached and delivered in the combination of activated/non-activated MIMO parallel sub-channels of the legitimate receiver through the wireless channel. Due to the uniqueness and independence of wireless channel, only the legitimate receiver can observe the key information and use it to “decrypt” (XOR) the confidential information step by step with an arbitrary low BER (bit error rate). However, for any other eavesdropper who suffers an independent channel from legitimate users, the eavesdropper cannot obtain any key information from the received signals, regardless of how many antennas he/she has. Consequently, the eavesdropper cannot “decrypt” any information about the confidential information. The SSVD security and reliability are theoretically analyzed, and the simulation and numerical results fully verified its validity and effectiveness.
The use of multiple antennas at both the transmitter and receiver aims to improve performance or to increase symbol rate of systems, but it usually requires higher implementation complexity. Multiple Input Multiple Output (MIMO) architectures can be used for combined transmit and receive diversity, for the parallel transmission of data or spatial multiplexing. When used for spatial multiplexing, MIMO technology promises high bit rates in a narrow bandwidth. Therefore, it is of high significance to spectrum users. In this case, MIMO system considers the transmission of different signals from each transmit element so that the receiving antenna array receives a superposition of all transmitted signals. Mobile communication systems must support multiple users achieving at the same time privacy of users contents. Security common solutions are based on encrypted algorithms from higher layers, such as private and public encrypted keys. Other possibility is to implement physical layer security schemes. One advantage of physical layer security relies on their ability to be combined with other security schemes from higher layers. Due to the broadcast nature of MIMO systems, security is a critical issue. However, the constellation shaping on the desired direction introduced by a new proposed transmitter means that we have directivity at the transmitted constellation that can be employed to assure security at physical layer. Privacy is achieved since each user must know the set of coefficients associated to each BPSK component as well as the array configuration; otherwise receives useless data. Therefore, the inherent security lies on the constellation directivity, i.e., the direction in which the constellation is optimized, which can be improved by changes on coefficients’ phases or using constellations that are decomposed with a higher number of BPSK components. The several cases analyzed in this speech show effectiveness of the proposed approach to implement a security scheme at physical layer level.
We present two attacks on two different versions of physical layer cryptography schemes based on massive multiple-input multiple-output (MIMO). Both cryptosystems employ a singular value decomposition (SVD) precoding technique. For the first one, we show that the eavesdropper (who knows its own channel and the channel between legitimate users) can decrypt the information data under the same condition as the legitimate receiver. We study the signal-to-noise advantage ratio for decoding by the legitimate user over the eavesdropper in a more generalized scheme when an arbitrary precoder at the transmitter is employed. On the negative side, we show that if the eavesdropper uses a number of receive antennas much larger than the number of legitimate user antennas, then there is no advantage, independent of the precoding scheme employed at the transmitter. On the positive side, for the case where the adversary is limited to have the same number of antennas as legitimate users, we give an O(n2) upper bound on the advantage and show that this bound can be approached using an inverse precoder. For the second cryptosystem, we show that the required security conditions prevent the legitimate user from decoding the plaintext uniquely.
In this paper, a secure multiple-input multiple-output (MIMO) communication technique based on the singular value decomposition (SVD) is investigated. In a previous work, it has been shown that a secure MIMO communication based on the SVD, where interference signal and confidential signal are assigned to two different streams, can achieve positive secrecy rate. In this investigation, it was assumed that the stream assignment information is available at both the legitimate receiver and the eavesdropper. In fact, random stream assignment has a potential to increase the secrecy rate. Specifically, pilot signal is inserted into the pilot time frame and this is used to inform the stream assignment. If either the legitimate receiver or the eavesdropper decodes the pilot signal incorrectly, the receiver attempts to decode the interference signal in the following data time frame even if there is no information about the confidential signal. Therefore, we propose a signaling technique to expand the difference in mutual information between the legitimate receiver and the eavesdropper which leads to enhanced secrecy. In the proposed signaling technique, correlation between pilot signals in successive pilot time frames is provided. Due to this correlation, correct pilot signal decoding in the current pilot time frame requires the correct pilot signal decoding in the previous pilot time frame. Numerical result shows that the propose method can significantly decrease the mutual information between the transmitter and the eavesdropper which leads to increased the secrecy rate.
One of the most important issues for secure communication in the physical layer is developing physical layer security techniques to provide confidentiality and data integrity in wireless communication systems. The properties of the physical channel are used in these methodologies to safeguard communication from eavesdropping and some other security threats. This article presents physical layer security methods that can be implemented in wireless communication systems. Artificial Noise (AN) is one of the most popular techniques. The original signal is combined with a generated by the transmitter in such a way that eavesdroppers cannot easily decode the data. Cooperative Anti-jamming: Yet another strategy for jammer localization is to employ cooperative jamming, where multiple friendly users can add noise signals over the signal in an effort to confuse potential eavesdroppers. In addition, additional technologies such as multi-input multi-output beamforming and transmit power control can further improve the security of wireless communication systems. In this regard, strategies based on game theory have been proposed as a viable alternative to enhancing physical layer security. Viewing the interaction between the transmitter, receiver, and eavesdropper as a game allows us to reveal their optimal strategies and security levels.
The use of physical layer methods for improving the security of wireless links has recently become the focus of a considerable research effort. Such methods can be used in combination with cryptography to enhance the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers, or they can be used to enable secrecy in the absence of shared secret keys through the use of coding strategies, jamming or beamforming. Indeed, one of the driving forces behind the recent emergence of physical layer techniques for security is the push toward adding extra degrees of freedom in the form of multiple antennas at the transmitter and receiver of the link. Multiple-input multiple-output (MIMO) wireless systems have been extensively studied during the past two decades, and their potential gains in throughput, diversity, and range have been well quantified. MIMO approaches are now an integral part of the WiFi and 4G standards in use today. It is not surprising that MIMO architectures are useful in improving wireless security as well, since they can provide focused transmit selectivity of both information and noise toward desired and undesired receivers. In this chapter, we discuss a number of different ways that physical layer security can be achieved in wireless networks with MIMO links. We will focus primarily on signal processing related issues (e.g., beamforming, power control, resource allocation) that enable reliable reception at intended recipients and minimize data leakage to eavesdroppers, and we will consider a variety of different MIMO settings including point-to-point, broadcast, interference, and multi-hop networks. We cannot offer an exhaustive survey of such methods in just a single chapter; instead, we present a few representative approaches that illustrate ✐ ✐ — — ✐ ✐ ✐ ✐ ✐ ✐ Physical Layer Security in Wireless the gains that multiple antennas provide. Additional and more complete treatments of the physical layer security problem can be found in [1-4] as well as other chapters in this book.