A Joint Beamforming Design in Heterogeneous SWIPT Network with Imperfect CSI

In a heterogeneous simultaneous wireless information and energy transfer (SWIPT) network, the beamforming scheme for multi-users is significantly influenced by the imperfect channel state information (CSI). A joint beamforming scheme for multiple eavesdroppers in two-layer SWIPT network is proposed, jointly design the information and energy beam in the presence of imperfect CSI to serve the several users in the cell. In the meantime, using the signals between macro and pico base stations as the equivalent artificial noise to protect the security and improve the energy efficiency. To this end, an optimization algorithm is designed to approximate the optimal beamforming matrix for maximizing the overall minimum secure energy efficiency. the successive convex approximation (SCA) and semi-positive definite relaxation (SDR) techniques are used to simplify and solve this non-convex optimization problem. The simulation results verifies the security and effectiveness of the scheme.