Hybrid Analog-Digital Precoder Design for Securing Cognitive Millimeter Wave Networks

Abstract

Millimeter wave (mmWave) communications and cognitive radio technologies constitute key technologies of improving the spectral efficiency of communications. Hence, we conceive a hybrid secure precoder for enhancing the physical layer security of a cognitive mmWave wiretap channel, where a secondary transmitter broadcasts confidential information signals to multiple secondary users under the interference temperature constraint of the primary user (PU). The optimization problem is formulated as jointly optimizing the analog and digital precoder for maximizing the minimum secrecy rate of all the secondary users under practical constraints. In particular, our design satisfies the constraint on the maximum interference power received by multiple PUs, as well as the secondary users' minimum quality-of-service (Qos), and the unit-modulus constraint on the analog precoder. Due to the non-convexity of the resultant objective function and owing to the coupling between the analog and digital precoder, the optimization problem formulated is nonconvex and nonlinear, hence it is very challenging to solve directly. Hence, we first transform it into a tractable form, and develop a penalty dual decomposition (PDD) based iterative algorithm to locate its Karush-Kuhn-Tucker (KKT) solution. Finally, we generalize the proposed PDD algorithm to a secure hybrid precoder design relying on practical finite-resolution phase shifters and show that the proposed PDD algorithm can be straightforwardly adapted to handle the scenario, where each PU is equipped with multiple antennas and the CSI of multiple eavesdroppers (Eves) is imperfectly known. Our simulation results validate the efficiency of the proposed iterative algorithm.

On the Physical Layer Security of Untrusted Millimeter Wave Relaying Networks: A Stochastic Geometry Approach

“…As a remedy, highly directional beamforming techniques have been proposed for mitigating the path loss of mmWave systems [4]. The authors of [5] have designed a hybrid secure precoder for boosting the physical layer security (PLS) of a cognitive mmWave wiretap channel, where the channel-state-information (CSI) of multiple eavesdroppers (Eves) is imperfectly known. A range of popular spatial statistical models of the mmWave channel were presented in [6] and [7].…”

Opportunistic Wiretapping/Jamming: A New Attack Model in Millimeter-Wave Wireless Networks

“…MIMO has been regarded as an appealing technology to reap the benefits of mmWave communication, motivating a plethora of work investigating the security performance of mmWave MIMO systems [11]- [15]. For instance, the joint design of the analog and digital precoders of the secondary transmitter (ST) was investigated to maximize the secrecy rates of the secondary users (SRs) in a mmWave cognitive network with one ST broadcasting information to multiple SRs in the presence of multiple primary users and eavesdroppers [11]. A sparse mmWave massive MIMO network was considered in [12], where a security scheme was proposed to send information signals through dominant angles of the sparse channel and broadcast AN over the remaining non-dominant angles to interfere only with the eavesdropper.…”

“…Physical layer security techniques have been considered as an important approach to ensuring secure mmWave communication [6]- [10], since they reveal the fundamental capability of achieving informationtheoretic and quantifiable security at the physical layer regardless of the computation capabilities of eavesdroppers. Current research on the physical layer security of mmWave communication mainly focuses on combating the conventional wiretapping attack in various mmWave systems, such as mmWave multiple-input and multiple-output (MIMO) systems [11]- [15], mmWave non-orthogonal multiple access (NOMA) systems [16]- [19], intelligent reflecting surface (IRS)-aided mmWave systems [20]- [22], hybrid mmWave-free space optical (FSO) systems [23]- [26] and mmWave ad hoc networks [27]- [29], etc (See Section II for related works).…”

On the Physical Layer Security of the Cooperative Rate-Splitting-Aided Downlink in UAV Networks

“…decade as a promising technique of enhancing the secrecy of wireless communications [1]- [10]. A pair of proposed PLS solutions, namely beamforming and jamming techniques have been particularly extensively exploited [3], [4], [6]- [9]. However, the performance of these PLS schemes critically relies on the availability of near-perfect Channel State Information at the Tx (CSIT), particularly in multi-user systems 1 [10], [11].…”

“…We have also included an interference management constraint to protect the communications of over-sailing macro-cell against small UAV-cell transmissions. • To solve the resultant non-convex optimization problem, we resort to the Sequential Parametric Convex Approximation (SPCA) methodology of [34], leading to a trade-off between approaching optimality and the computational complexity 3 . Moreover, to avoid any failure due to a potential infeasibiity, a beneficial initialization algorithm is proposed for finding a feasible initial point of the original problem.…”