  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 frequency-division 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.
