In this paper, we propose a novel secure transmission scheme for multiple-input multiple- output (MIMO) Two-Way relay channels, where multi- pair communication partners exchange information securely with the help of relay. By utilizing the properties of transmission medium in physical layer, our scheme can achieve high transmission efficiency as well as information theoretic security. With the secrecy capacity analysis, we show that our scheme is a secure approach under two different adversarial models: 1) untrusted relay attack model; 2) trusted relay with eavesdropper attack model. Finally, we conduct three simulations of our proposed scheme. The simulation results agree with the theoretical analysis illustrating that our proposed scheme can achieve a better performance than the existing schemes.
In this paper, we propose a novel secure transmission scheme for multiple-input multiple- output (MIMO) Two-Way relay channels, where multi- pair communication partners exchange information securely with the help of relay. By utilizing the properties of transmission medium in physical layer, our scheme can achieve high transmission efficiency as well as information theoretic security. With the secrecy capacity analysis, we show that our scheme is a secure approach under two different adversarial models: 1) untrusted relay attack model; 2) trusted relay with eavesdropper attack model. Finally, we conduct three simulations of our proposed scheme. The simulation results agree with the theoretical analysis illustrating that our proposed scheme can achieve a better performance than the existing schemes.
Security issue has been considered as one of the most pivotal aspects for the fifth-generation mobile network (5G) due to the increasing demands of security service as well as the growing occurrence of security threat. In this paper, instead of focusing on the security architecture in the upper layer, we investigate the secure transmission for a basic channel model in a heterogeneous network, that is, two-way relay channels. By exploiting the properties of the transmission medium in the physical layer, we propose a novel secure scheme for the aforementioned channel mode. With precoding design, the proposed scheme is able to achieve a high transmission efficiency as well as security. Two different approaches have been introduced: information theoretical approach and physical layer encryption approach. We show that our scheme is secure under three different adversarial models: ( 1 ) untrusted relay attack model, ( 2 ) trusted relay with eavesdropper attack model, and ( 3 ) untrusted relay with eavesdroppers attack model. We also derive the secrecy capacity of the two different approaches under the three attacks. Finally, we conduct three simulations of our proposed scheme. The simulation results agree with the theoretical analysis illustrating that our proposed scheme could achieve a better performance than the existing schemes.
From security perspective, a friendly relay may help to keep the confidential messages from being eavesdropped, while an untrusted relay may intentionally eavesdrop the messages when relaying. This paper studies the secure beamforming for multiple-input multiple-output (MIMO) two-way communications, where two source nodes exchange information with the help of an untrusted relay node. The relay adopts amplify-and-forward (AF) strategy and acts as both an essential helper and a potential eavesdropper. Our goal is to maximize the secrecy sum rate of the bidirectional links by jointly optimizing the source and relay beamformers. For the two-phase two-way relay scheme, we first derive the optimal structure of the relay beamformer and then propose an iterative algorithm to jointly optimize the source and relay beamformers. Then, a comprehensive study on the asymptotical performance is conducted by letting the source and relay powers approach zero or infinity. In particular, we show that when all powers approach infinity, the two-way relay scheme achieves the maximum secrecy rate if the transceiver beamformers are designed such that the received signals at the relay can be aligned to be parallel.
This paper focuses on the multiple-input-multiple-output (MIMO) two-way relay system with an untrusted relay and investigates its secure and energy-efficient precoding design issue based on the physical layer security technology. We first provide theoretical modeling for the index of secrecy energy efficiency (SEE) and formulate the optimal precoding design for SEE maximization (SEEM) as a high-dimensional non-convex programming problem. By exploring the techniques like fractional programming, alternate optimization and semi-definite programming, we then develop a hierarchical theoretical framework to solve the SEEM problem and thus to identify the optimal precoding designs for the source and relay. Furthermore, we demonstrate the proposed theoretical framework is also applicable to the problem of precoding design for secrecy sum rate maximization. Finally, with the help of generalized singular value decomposition, we propose a sub-optimal relay precoding design scheme with significantly lower computational complexity. Extensive numerical results provided in the paper indicate that the proposed schemes can remarkably improve the SEE performance in MIMO two-way untrusted relay systems.
In this paper, we propose a secure transmission protocol for two users exchanging their respective information in an n-hop MIMO Ad hoc network. By exploiting the properties of the transmission medium in the physical layer, three channel models are utilized to provide secure transmission, namely one-way relay channel, two-way untrusted relay channel, and multiple access channel. Using these channel models, we design a basic protocol with a minimized time slot cost, i.e. n+1. Based on this basic protocol, we show that the attacker, either untrusted relay or external eavesdropper, can only obtain a summed signal in each time slot, and this summed signal cannot be decomposed to recover the individual information from the users. We then present cryptographic analysis for the first time to identify a weakness which is common for all known security schemes based on the summed signal. Thirdly, we introduce an evolutionary protocol proposed with two rounds of interlaced information exchange, which defeats this weakness. Finally, the simulation is performed to demonstrate the theoretical analysis.
Secure information exchange occurs in many recently emerging cooperative-based networks, such as 5G networks (especially those with a Device to Device architecture), the Internet of Things, and vehicular ad hoc networks. However, the existing information exchange protocols only focus on either pairwise information exchange or group information exchange, and none of these protocols enable private and public information exchange to occur simultaneously. Thus, a general secure information exchange protocol for a multiuser channel is desirable. With this motivation, this paper investigates simultaneous private and public information exchange in a Multiple Inputs Multiple Outputs (MIMO) multiuser relay channel. In an aim to achieve this goal, signal alignment is chosen as the core technique. With the designed precoding matrix for each user, private information is aligned with its exchange partner, and public information forms a coding chain at the relay. With the aligned private signal and public coding chain, neither an untrusted relay nor external eavesdroppers can recover the original individual information. Performance analyses of the proposed protocol are conducted. First, we conduct transmission performance analyses from the perspective of time slot cost. Second, we conduct a security analysis for private information exchange and public information exchange. Third, we conduct secrecy sum-rate analysis for three attack scenarios: an untrusted relay attack only, an eavesdropper attack only, and both an untrusted relay and eavesdropper attack. The simulations are conducted to demonstrate that the proposed protocol can enable simultaneous private and public information exchange while resisting attacks by an undesired receiver, an untrusted relay, and external eavesdroppers.
This work investigates the vulnerability of analog network coding (ANC) to physical layer attacks from adversarial users, when all nodes are equipped with multiple antennas. Specifically, we examine the MIMO two way relay channel (TWRC) with two users trying to communicate with each other via a relay node in the presence of a passive eavesdropper. We propose a new performance metric, namely the secrecy sum rate of the MIMO TWRC, to quantify performance. We then consider secure transmission strategies for the scenarios of no eavesdropper channel state information at the transmitters (ECSIT) and complete ECSIT, respectively. Finally, numerical results are presented to illustrate the improvement in secrecy obtained with the proposed transmission schemes.