Years-Long Binary Image Broadcast Using Bluetooth Low Energy Beacons

This paper describes the first 'image beacon' system that is capable of broadcasting binary images over a very long period (years, as opposed to days or weeks) using a set of cheap, low-power, memory-constrained Bluetooth Low Energy (BLE) beacon devices. We design a patch-based image encoding algorithm to produce encoded images of reasonably high quality, having sizes of as low as 16 bytes -- without any prior knowledge of the test images. We test our system with different types of images that contain hand-written alphanumeric characters, geometric shapes, and arbitrary binary images having complex shapes and curves. We empirically determine the tradeoffs between the system lifetime and the quality of broadcasted images, and determine an optimal set of parameters for our system, under user-specified constraints such as the number of available beacon devices, maximum latency, and life expectancy. We develop a smartphone application that takes an image and user-requirements as inputs, shows previews of different quality output images, writes the encoded image into a set of beacons, and reads the broadcasted image back. Our evaluation shows that a set of 2 -- 3 beacons is capable of broadcasting high-quality images (75% -- 90% structurally similar to original images) for a year-long continuous broadcasting, and both the lifetime and the image quality improve when more beacons are used.