Spatial division multiplexing of LED strips for optical camera communication

Abstract

Rolling shutter based optical camera communication (RS-OCC), a promising candidate of optical wireless communication (OWC), has the advantage of unlicensed spectrum and no electromagnetic interference. Since RS-OCC can use the built-in camera of a smartphone as a receiver, it can provide flexible, low-cost, and timely private information exchange between mobile users. However, the enhancement of data throughput for the RS-OCC is challenging. Light emitting diode (LED) strips can be designed as both a smartphone accessory and a transmitter of RS-OCC. Here, we propose and experimentally demonstrate the LED strip based spatial division multiplexing (SDM) technique. In order to enhance the aggregated data throughput, we investigate and optimize the operation parameters of LED strips and a smartphone camera. Consequently, when the least mean square-based feedforward equalizer (LMS-FFE) with 5 taps is employed, eight LED strips modulated with 8-level pulse amplitude modulation (PAM-8) signals can realize a record data throughput of 201.96 kbit/s, indicating of an alternative flexible data transfer scheme between two smartphones.