Positional Modulation Design with Discrete Phase Values for Metasurface Elements

Positional modulation (PM) as a special form of Directional modulation (DM) technology can transmit information to the desired position or positions with known constellation mappings, but with scrambled ones in other areas. To achieve PM, metasurface can be used as a reflecting surface. However, in previous designs, continuous phase shifts are assumed, which is difficult and also unrealistic to achieve. To solve the problem, a metasurface with discrete phase values is considered for positional modulation in this work with a novel design method developed, and design examples are provided to show the effectiveness of the proposed solution.