LAUSR

A direction-range-time dependent vortex wave directional modulation (DM) scheme based on the frequency diverse array (FDA) is proposed for secure transmission. We design the random frequency offset for the array element in a circular arc FDA, which generates the quasi-helical phase front and the irregular phase front at the specific range. In order that the time-variance phase front can maintain the helical phase characteristics at the desired range, according to the designed frequency offset function, we design a DM excitation signal with the specific time-variance phase offset for each array element. The direction-range-time dependent phase pattern is modulated into the vortex signal constellation for the desired transmission. Theoretical analyses and numerical simulations validate the effectiveness of our proposed approach with no artificial noise.