Linear Precoding of Data and Artificial Noise in Secure Massive MIMO Systems

Abstract

In this paper, we consider secure downlink transmission in a multi-cell massive multiple-input multiple-output (MIMO) system where the numbers of base station (BS) antennas, mobile terminals, and eavesdropper antennas are asymptotically large. The channel state information of the eavesdropper is assumed to be unavailable at the BS and hence, linear precoding of data and artificial noise (AN) are employed for secrecy enhancement. Four different data precoders (i.e., selfish zero-forcing (ZF)/regularized channel inversion (RCI) and collaborative ZF/RCI precoders) and three different AN precoders (i.e., random, selfish/collaborative null-space based precoders) are investigated and the corresponding achievable ergodic secrecy rates are analyzed. Our analysis includes the effects of uplink channel estimation, pilot contamination, multi-cell interference, and path-loss. Furthermore, to strike a balance between complexity and performance, linear precoders that are based on matrix polynomials are proposed for both data and AN precoding. The polynomial coefficients of the data and AN precoders are optimized respectively for minimization of the sum mean squared error of and the AN leakage to the mobile terminals in the cell of interest using tools from free probability and random matrix theory. Our analytical and simulation results provide interesting insights for the design of secure multi-cell massive MIMO systems and reveal that the proposed polynomial data and AN precoders closely approach the performance of selfish RCI data and null-space based AN precoders, respectively.

Full-Duplex Cyber-Weapon With Massive Arrays

“…Power control schemes for training and data transmission to enhance the security of massive MIMO systems with the help of artificial noise were studied in [11]. In [12], the authors proposed various data precoders and artificial noise precoder to secure downlink transmission of a multi-cell massive MIMO system with large numbers of terminal users and antennas at the eavesdropper. The aforementioned works focused on designing the protecting schemes for the legitimate side and considered the passive eavesdroppers.…”

Secure Communications for Dual-Polarized MIMO Systems

“…Expanding the work of [20], a Gaussian degraded wiretap channel was investigated in [21]. Based on these theoretical fundamentals, a large amount of literature were produced focusing on the physical layer security of various multiple-antenna systems [22]- [28]. Specifically, a security beamforming strategy was designed for the multiple-input single-output (MISO) system in [22], [23], the single-input multiple-output (SIMO) system in [24], and the MIMO system in [25]- [28].…”

“…Based on these theoretical fundamentals, a large amount of literature were produced focusing on the physical layer security of various multiple-antenna systems [22]- [28]. Specifically, a security beamforming strategy was designed for the multiple-input single-output (MISO) system in [22], [23], the single-input multiple-output (SIMO) system in [24], and the MIMO system in [25]- [28]. In particular, to effectively balance the security performance among different links of an MIMO network, the work [25] proposed a game theory based collaborative transmission scheme, while an artificial noise scheme was proposed in [26] for secure communications of the two-way relaying MIMO network under a realistic scenario that the CSI of eavesdropper is unavailable.…”

“…In particular, to effectively balance the security performance among different links of an MIMO network, the work [25] proposed a game theory based collaborative transmission scheme, while an artificial noise scheme was proposed in [26] for secure communications of the two-way relaying MIMO network under a realistic scenario that the CSI of eavesdropper is unavailable. Further extending these research, the work [27] jointly designed a matched-filter data precoding and a null-space or random artificial noise scheme for secure communications of the multi-cell massive MIMO system, while in [28], several data precoding schemes were considered to investigate the achievable ergodic secrecy capacity region of massive MIMO.…”

“…Thus, in addition to providing more compact antenna array which is beneficial for practical implementation as well as imposing lower computational complexity in designing the dualstructured precoding, the dual-polarized MIMO offers the performance advantage, compared to the single-polarized MIMO. Additionally, we apply the standard MIMO precoding schemes [26], [28], [31] to the dual-polarized MIMO system and use their achievable security performance as the benchmarks for the three respective CSI scenarios. Although outperforming the proposed dual-structured precoding scheme, these standard MIMO designs require the full instantaneous CSI which is difficult to acquire in practice and they impose huge channel feedback overhead.…”