Throughput Scaling of Covert Communication over Wireless Adhoc Networks

Abstract

e study the throughput scaling law of covert communication over wireless adhoc networks where (roughly) n legitimate nodes (LNs) and nκ for 0 < κ < 1 warden nodes (WNs) are randomly distributed in a unit area. Each legitimate source wants to communicate with its destination while ensuring that each WN is unable to detect the presence of communication. A preservation region, where the transmission of the LNs is not permitted, is introduced around each WN to increase the transmit power of the LNs outside the preservation regions. For achievability, multi-hop (MH), hierarchical cooperation (HC), and hybrid HC-MH schemes in the literature are utilized with some modifications. In the MH and the hybrid schemes, because the preservation regions may block the direct data paths, a detouring method that distributes the detours evenly over a wide region is proposed to avoid the concentration of relaying burdens. In the HC scheme, we properly control the symbol power and the MIMO transmission scheduling. We also present matching upper bounds on the throughput scaling under an assumption that every active LN consumes a same average transmit power over the time period that the WNs observe.