Power and Time Slot Allocation Method for Secured Satellite Transmission Based on Weighted Fractional Data Carrying Artificial Noise

In this paper, a power and time slot allocation method is proposed for the weighted fractional data carrying artificial noise (DCAN) to secure satellite transmission. We first introduce a data carrying artificial noise based on weighted fractional Fourier transform (WFRFT) to achieve physical layer security in satellite transmission which outperforms the traditional artificial noise method when the channel state information (CSI) is not precise at the transmitter. Then, we formulate an optimization problem to optimize the power allocation among the main signal and the weighted fractional DCANs in three steps by adopting the fractional programming, the alternative research, and difference of convex functions (DC) programming, respectively. We further divide the transmission time into different time slots and assign them to the main signals by solving a maximum weighted sum problem to ensure the transmission security with limited transmission power. Simulation results show that the proposed power and time allocation method outperforms the DCAN based on WFRFT with average power allocation when the number of the transmitted signals increases. Meanwhile, the proposed power allocation method is superior to the method based on perfect CSI or the assumption of massive transmission antennas, which may be not possible at the satellite.