“…Directional mod- ✩ The work was supported by The Science & Technology Development Fund of Tianjin Education Commission for Higher Education 2019KJ087. ulation (DM) [3] as a beamforming based technique, which aims to transmit the information to the desired direction or directions with known constellation mappings, but with scrambled ones in other directions, has been studied extensively based on various antenna array configurations [4,5,6,7,8,9,10,11,12,13]. To overcome the inherent limitation of DM, where eavesdroppers and the desired users share the same received signal when they lie in the same direction of the antenna array, positional modulation (PM) designs were proposed as a further extension of DM, with the aid of either a reflecting surface [14] or multiple antenna arrays [15].…”