Covert Communication With Gaussian Noise: From Random Access Channel to Point-to-Point Channel

We propose a covert communication protocol for the spread-spectrum multiple random access with additive white Gaussian noise (AWGN) channel. No existing paper has studied covert communication for the random access channel. Our protocol assumes binary discrete phase-shift keying (BPSK)modulation, and it works well under imperfect channel state information (I-CSI) for both the legitimate and adversary receivers, which is a realistic assumption in the low power regime.Also, our method assumes that the legitimate users share secret variables in a similar way as the preceding studies. Although several studies investigated the covert communication for the point-to-point communication, no existing paper considers the covert communication under the above uncertainty assumption even for point-to-point communication. Our protocol under the above uncertainty assumption allows O(n)legitimate senders andO(n/logn)active legitimate senders. Furthermore, our protocol can be converted to a protocol for point-to-point communication that works under the above uncertainty assumption