Covert Communication With Truncated Channel Inversion Power Control in D2D Underlaid Cellular Networks

Abstract

Device-to-device (D2D) underlaid cellular networks are regarded as an emerging network structure in the 5G systems. We study the covert communication of such networks consisting of a base station BS, a cellular user Alice, a D2D pair with a transmitter Dt and a receiver Dr , and a warden W illie. To conduct the covert communication, Alice adopts the truncated channel inversion power control (CIPC) to hide itself from W illie, where the received signal power at BS is fixed avoiding channel estimation for decoding Alice’s signal. Meanwhile, the interference generated by the D2D pair reusing the spectrum of Alice is exploited to confuse W illie. To understand the fundamental covert rate performance in the considered network, we first provide a theoretical model for characterizing the detection error probability of W illie as well as the effective covert rate at BS under the truncated CIPC scheme. Based on the main results, we then explore the effective covert rate maximization under the constraint of the detection error probability to identify the optimal truncated CIPC scheme designing and interference management. Finally, extensive numerical results are presented to illustrate the impacts of the truncated CIPC and interference from Dt on the covert performance.