Abstract
Use of blinking LED to convey useful status information to be decoded by smartphone cameras has been shown to be a useful feature for end users of devices in the Internet of Things (IoT). Previous techniques have been limited to decoding of a single LED, which is limited in bandwidth and response time. We propose to overcome these limitations by exploring the use of multiple LEDs in different ways: decoding multiple devices that output using their own single LED in parallel, and decoding a single device that raises bandwidth by using multiple LEDs to encode more information in a given time frame. Experimental results show the practical limits achieved by a modern smartphone-class device.