Position-Aided On/Off States Judgment for 1-Bit RIS Assisted V2V MmWave Communication

The reconfigurable intelligent surface (RIS), com-posed of nearly-passive elements to induce reconfigurable re-flecting replicas of signal, is regarded as one of the promising approaches to support multi-gigabit data about the surrounding environment and recognizing objects in real-time. This makes RIS a potential technology in the autonomous vehicle application. However, the application of RIS and the mobility of vehicles substantially increase the training overhead of channel estimation, without which the RIS cannot optimally operate passive beamforming. To overcome the aforementioned problems, in this paper we aim to leverage the Fresnel zone characteristic and the position information of vehicles to design a position-aided on/off states judgment (POSJ) scheme for practical 1-blt RIS. The proposed scheme does not require instantaneous channel state information at the transmitter (CSIT) and is based on the superposition of the reflected signals from different Fresnel zone boundaries. Simulation results indicate that our developed scheme performs well with the increase in positioning accuracy, thus enabling the practical application of RIS.