Physical Layer Security for Pinching-Antenna Systems via Index and Directional Modulation

The pinching-antenna system (PASS) has recently emerged as a promising architecture for enhancing wireless communications through flexible beamforming along dielectric waveguides. In this contribution, we propose a pinching-antenna-enabled index and directional modulation (PA-IDM) scheme that integrates the concepts of index modulation (IM) and directional modulation (DM) towards enhanced physical layer security (PLS). Specifically, to avoid eavesdropping, confidential information is simultaneously embedded in both the baseband symbols and the receiver indices. Furthermore, analog beamforming is performed by repositioning the pinching antennas to steer the beam toward the intended user, while injecting artificial noise (AN) into undesired directions to disrupt potential eavesdroppers. Finally, simulation results demonstrate that the proposed PA-IDM scheme provides reliable communication for legitimate users while significantly degrading the decoding performance of eavesdroppers, thereby highlighting the effectiveness of PASS in secure wireless transmission scenarios.