Intelligent Reflecting Surface-Assisted Proactive Eavesdropping Over Suspicious Broadcasting Communication With Statistical CSI
Guojie Hu, Jiangbo Si, Yunlong Cai, Naofal Al‐Dhahir
Abstract
This paper studies a novel wireless surveillance scenario, where a half-duplex legitimate monitor (E), aided by an intelligent reflecting surface (IRS), aims to eavesdrop the frequency division multiple access based suspicious broadcasting communication from a suspicious transmitter (ST) to multiple suspicious receivers (SRs). Under this setup, instead of eavesdropping the ST over all frequency bands (FBs), E proactively jams over certain <i>undesirable</i> FBs, i.e., jams certain SRs via E-SRs and E-IRS-SRs links, to deliberately force the ST reallocating more transmit power over the unjammed (eavesdroppable) <i>desirable</i> FBs. Then as a reward, E itself can achieve better eavesdropping over those FBs accordingly. Our objective is to maximize the <i>sum ergodic eavesdropping rate</i> of E, by jointly optimizing the set of jammed FBs, the jamming power allocation of E and the reflection coefficients at the IRS. A two-stage optimization procedure is proposed: i) given each possible jammed set, the jamming power allocation and the reflection coefficients are optimized via successive convex approximation and alternative iterations; ii) the optimal and sub-optimal jammed sets are further determined using the exhaustive search and the designed heuristic scheme. Results show the effectiveness of the proposed scheme compared to competitive benchmarks.