Legitimate Eavesdropping with Multiple Wireless Powered Eavesdroppers

This paper considers a suspicious communication network with multiple suspicious source-destination nodes and multiple wireless powered legitimate eavesdroppers, where the legitimate eavesdroppers are assumed to be collusive or non-collusive. A minimum harvested energy constraint is applied at each eavesdropper such that each eavesdropper must harvest a minimum required energy. The legitimate eavesdropping in such a scenario is investigated and our aim is to maximize the average successful eavesdropping probability by optimizing the power splitting ratio at each eavesdropper under the minimum harvested energy constraint. The optimal algorithm is proposed to solve the optimization problem for both collusive eavesdroppers and non-collusive eavesdroppers. Simulation results show that the proposed algorithm achieves the upper bound of the successful eavesdropping probability when the energy harvesting efficiency is large, the required minimum harvested energy is small, or the transmit power of the suspicious source node is high.