Intelligent Reflecting Surface-Assisted Proactive Eavesdropping Over Suspicious Broadcasting Communication With Statistical CSI

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
undesirable
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)
desirable
FBs. Then as a reward, E itself can achieve better eavesdropping over those FBs accordingly. Our objective is to maximize the
sum ergodic eavesdropping rate
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.