Throughput Scaling of Covert Communication over Wireless Adhoc Networks

Abstract

We consider the problem of covert communication over wireless adhoc networks in which (roughly) n legitimate nodes (LNs) and n κ for 0 < κ < 1 non-communicating warden nodes (WNs) are randomly distributed in a square of unit area. Each legitimate source wants to communicate with its intended destination node while ensuring that every WN is unable to detect the presence of the communication. In this scenario, we study the throughput scaling law. Due the covert communication constraint, the transmit powers are necessarily limited. Under this condition, we introduce a preservation region around each WN. This region serves to prevent transmission from the LNs and to increase the transmit power of the LNs outside the preservation regions. For the achievability results, multi-hop (MH), hierarchical cooperation (HC), and hybrid HC-MH schemes are utilized with some appropriate modifications. In the proposed MH and hybrid schemes, because the preservation regions may impede communication along direct data paths, the data paths are suitably modified by taking a detour around each preservation region. To avoid the concentration of detours resulting extra relaying burdens, we distribute the detours evenly over a wide region. In the proposed HC scheme, we control the symbol power and the scheduling of distributed multiple-input multiple-output transmission. We also present matching upper bounds on the throughput scaling under the assumption that every active LN consumes the same average transmit power over the time period in which the WNs observe the channel outputs.Index Terms-Covert communication, low probability of detection, wireless adhoc networks, capacity scaling law.

Covert Communication With Mismatched Decoders

“…multiuser channels [18]- [22], channel with states [23], [24], channel with jammers [25]- [28], Rayleigh-fading channels [29]- [31], continuous-time channels [32]- [34], quantum channels [35]- [37], MIMO channels [38], adhoc networks [39], [40], etc. In addition to characterizing the information-theoretic limits, researchers have also studied covert communication from a coding perspective, and have investigated various coding techniques such as concatenated codes [41], PPM [8], multilevel coding with PPM [42]- [44], and polar codes [45].…”

Treating Interference as Noise is Optimal for Covert Communication over Interference Channels

“…The fundamental limits of covert communications have been actively studied mainly for pointto-point (p-to-p) channels such as additive white Gaussian noise (AWGN) channels [2], [3], discrete memoryless channels (DMCs) [3], [4], low-complexity coding scheme based on the pulse-position modulation [5], [6], channels using multiple antennas [7], and channels with some uncertainty of statistics [8], [9]. In most interesting cases, the covertness constraint restricts the number of no "off" input symbols (for discrete channel cases [4]) or the transmit power (for continuous channel cases [2], [3]) that leads the so-called square-root law, i.e., the maximum number of bits that can be communicated reliably and covertly over n channel uses scales proportionally to √ n. Recently, this line of research has been extended to various network scenarios such as multiple access channels (MACs) [10], broadcast channels (BCs) [11], relay channels (RCs) [12]- [14], and wireless adhoc networks [15]. It turns out that in some canonical models, the covertness constraint affects This paper was submitted to IEEE Transactions on Information Forensics and Security, and a shorter version of this paper was submitted to IEEE ISIT 2020 [1].…”