BLEach: Exploiting the Full Potential of IPv6 over BLE in Constrained Embedded IoT Devices

The ability to fine-tune communication performance is key to meeting the requirements of Internet of Things applications. While years of low-power wireless research now allow developers to fully optimize the performance of applications built on top of IEEE 802.15.4, this has not yet happened with Bluetooth Low Energy (BLE), whose networking performance is still largely unexplored and whose potential is not yet fully exploited. Indeed, BLE radios are often treated as a black box, because they are meant to only execute data transfer commands and because manufacturers build BLE soft devices with closed-source network stacks. As a result, developers working with BLE cannot modify the radio driver or the link layer, and have no direct control of the duty cycling and re-transmission logic. To tackle these challenges, we analyze and model how specific BLE features can be used to fine-tune communication performance at run-time. We further present the design and implementation of BLEach, an IPv6-over-BLE stack architecture that exposes tuning knobs for controlling the energy usage and timeliness of BLE transmissions and allows to enforce a variety of quality of service (QoS) metrics. We design three exemplary modules for BLEach providing novel BLE functionality: adaptive duty cycling, IPv6-over-BLE traffic prioritization and multiplexing, and indirect link-quality monitoring. We integrate BLEach into the Contiki operating system and release its code, addressing the lack of a full-fledged open-source IPv6-over-BLE stack. Experiments demonstrate that BLEach is lightweight, interoperable with other standard-compliant devices, and quickly adapts to changes in interference, traffic priority, and load, reducing energy costs by up to 50 % while giving QoS guarantees