Reservoir Computing Assisted Ultrafast User Localization in Beam Steering Optical Wireless System

A novel approach to achieving ultrafast real-time user localization in optically controlled beam-steering wireless communications (OWC) is proposed and demonstrated in this letter. Ultrafast wavelength encoded user localization at 50 MHz rate is achieved based on photonic time stretch concept and a passive beam scanner using a 45° tilted fibre grating (TFG). Not only the angular separation but also the linear distance from the access point can be determined simultaneously. More importantly, challenging instantaneous optical wavelength identification within nanosecond range is successfully achieved through chirped microwave frequency encoding and reservoir computing (RC) based frequency identification. A proof-of-concept experiment was carried out to verify the proposed approach. The results show that RC is more efficient in frequency chirp identification than the conventional short-time Fourier transform approach.