Half-duplex visible light communication using an LED as both a transmitter and a receiver

In typical visible light communication (VLC) systems, light-emitting diodes (LEDs) are used as optical transmitters and photodiodes are used as optical receivers. Currently, many communication devices such as smart phones have a built-in LED lamp whereas they usually do not have a built-in photodiode. If we find a way to receive VLC signals without the need to add an additional photodiode on the communication devices, it will contribute to the spread of VLC. Therefore, we propose and demonstrate a VLC scheme without the need for a photodiode. As the first step, we investigate the characteristics of an LED as a VLC receiver and find out that an LED can also be used as a VLC receiver in certain conditions. Then, we demonstrate a half-duplex VLC system using an LED as both an optical transmitter and an optical receiver, without the need for a photodiode. This technique could be used in various applications such as the VLC between smart phones with a built-in LED lamp and the VLC between LED traffic lights. Copyright (C) 2015 John Wiley & Sons, Ltd.