This paper investigates the wireless surveillance with a legitimate monitor (E) over hybrid automatic repeat request (HARQ) based suspicious communications between a suspicious transmitter (S) and a suspicious destination (D).… Click to show full abstract
This paper investigates the wireless surveillance with a legitimate monitor (E) over hybrid automatic repeat request (HARQ) based suspicious communications between a suspicious transmitter (S) and a suspicious destination (D). Specifically, with the HARQ protocol, S uses at most $L \geq 2$ transmission rounds (TRs) for delivering the same message to D. Under this setup, E deliberately jams D at each TR to decrease its signal receiving quality, so as to induce S to consume more TRs for transmitting its message. Then, as a reward, E at these TRs can overhear the suspicious message from S more clearly. Our purpose is to maximize E's eavesdropping success probability, by allocating its jamming power at these $L$ TRs, subject to its power budget constraint. The problem is highly non-convex. To solve it, we first exploit the general successive convex approximation (SCA) approach to determine the iterative solution. Considering the large complexity of the SCA-based approach, we further develop an easy-to-implement Lagrange multiplier method to find the sub-optimal solution. Numerical results show that the proposed schemes increase the eavesdropping success probability as compared with several benchmarks.
