Physical-Layer Security for Coherent Communications System

A transmitter device comprising:

• a digital signal processor (DSP) operative to generate digital drive signals from information bits, the DSP operative to select symbols of a discrete data constellation and to use a digital filter implemented in the DSP to introduce pseudo-random deterministic changes in phase or both phase and amplitude into the digital drive signals such that the discrete data constellation is remapped into a continuous signal without identifiable constellation points;
• digital-to-analog converters operative to convert the digital drive signals to respective analog drive signals;
• and
• one or more modulators operative to modulate a carrier signal or components of the carrier signal with the analog drive signals to produce a modulated carrier signal that conveys the information bits.

A coherent receiver device comprising:

• a mixer and down-conversion module operative to mix a received modulated carrier signal with a local version of an unmodulated carrier signal and operative to output analog received signals;
• analog-to-digital converters operative to convert the analog received signals to respective digital received signals, wherein the digital received signals are indistinguishable from random noise;
• and
• a digital signal processor (DSP) operative to process the digital received signals to yield recovered bits, the DSP operative to use a digital filter implemented in the DSP to remove pseudo-random deterministic changes in phase or both phase and amplitude from the digital received signals.