Low-Cost Covert Wireless Communication Assisted by Optical Frequency Comb for Deep Denoising

Abstract

Covert wireless communication assisted by optical frequency comb (OFC) has already been presented, but its denoise capacity is restricted by the OFC properties. A novel, low-cost covert wireless communication system is proposed and demonstrated. In the proposed approach, original data are spread and buried by the noise to ensure high covertness, and then are effectively recovered by analog frequency convolution using the OFC and the cloned OFC generated by an optical frequency shifter. A same signal to noise ratio (SNR) enhancement can be achieved by employing half of the optical comb lines, which alleviates the requirement of OFC generator. 400 comb lines provide 800 comb channels, so that 29 dB SNR rise is achieved for the microwave signal with a 16 GHz bandwidth and a 20 Mbit/s data rate, which is hidden below the in-band noises by 20 dB or even 29 dB in both the frequency and time domains.