Secure Energy-Efficient Transmission for SWIPT Intelligent Connected Vehicles With Imperfect CSI

In this paper, the secure energy-efficient transmission problem for an artificial-noise (AN)-aided simultaneous wireless information and power transfer (SWIPT) and vehicle-to-infrastructure (V2I) communication system with the imperfect channel state information (CSI) is studied. The secure energy efficiency problem is formulated with the imperfect CSI, where the constraints contain the minimum secrecy rate request of the legitimate vehicle (LV), the minimum energy harvesting (EH) request, the maximum transmit power, and the power splitting (PS) value. By exploiting the maximum ratio transmission (MRT) scheme and the norm-bounded matrix theory, we convert the original intractable problem to a fractional optimization one with three variables. Then, a two-level optimization algorithm is presented for the nonconvex fractional optimization problem. By introducing an auxiliary slack variable, the first level problem can be solved via one-dimensional optimization algorithm. The second level fractional optimization problem was furhther converted into an integer optimization one by the Dinkelbach method, and the closed-form solutions of the transmit power and the AN power are provided. Simulation results are given to verify the performance of our presented algorithm.