Physical Layer Security in Frequency-Domain Time-Reversal SISO OFDM Communication

Abstract

A frequency domain (FD) time-reversal (TR) precoder is proposed to perform physical layer security (PLS) in single-input single-output (SISO) system using orthogonal frequencydivision multiplexing (OFDM). To maximize the secrecy of the communication, the design of an artificial noise (AN) signal well-suited to the proposed FD TR-based OFDM SISO system is derived. This new scheme guarantees the secrecy of a communication toward a legitimate user when the channel state information (CSI) of a potential eavesdropper is not known. In particular, we derive an AN signal that does not corrupt the data transmission to the legitimate receiver but degrades the decoding performance of the eavesdropper. A closed-form approximation of the AN energy to inject is defined in order to maximize the secrecy rate (SR) of the communication. Simulation results are presented to demonstrate the security performance of the proposed secure FD TR SISO OFDM system.

Physical Layer Security in a SISO Communication using Frequency-Domain Time-Reversal OFDM Precoding and Artificial Noise Injection

“…To circumvent the aforementionned issues, physical layer security (PLS) has emerged as an effective way to enhance security of wireless communications, [5]- [8]. PLS classically takes benefit from unpredictable wireless channel characteristics (e.g., multipath fading, noise, dispersion, diversity) to improve security of communications against potential eavesdroppers without relying on computational complexity, i.e., the security is not affected if Eve has unlimited computing capabilities, [9], [10].…”

“…While many works implement these schemes with multiple antennas at the transmitter, using for instance frequency diverse array beamforming [23], [24], directional modulation (DM) [25], antenna subset modulation (ASM) [26], nearfield direct antenna modulation (NFDAM) [27], [28], spatial diversity [29]- [32], or waveform design [33], only few works perfom PLS using single-input single-output (SISO) systems [9], [34]- [42]. SISO systems are indeed more suitable to resource-limited devices such as in IoT-type applications.…”

“…TR is achieved by up/downsampling the signal in the TD. While the impact of the back-off rate (BOR), defined as the up/downsampling rate [44], was studied in [9], [35], limited non-optimal decoding capabilities were attributed to Eve. Another approach to provide security at the physical layer is the use of orthogonal frequency-division multiplexing (OFDM) scheme which can be implemented in time or frequency domain (FD).…”

“…To further enhance the secrecy, few works combine TD or FD precoding with AN injection, [9], [38]- [42]. In [38]- [40], TD TR precoders are presented.…”

“…While the condition for AN generation is given, its derivation is however not detailed. In [9], [41], [42], FD precoders using OFDM and AN injection are presented. In [9], the AN is injected in the null space of Bob but only limited decoding capacilities were attributed to Eve.…”