Adaptive Transmission Power Control in BLE: Unveiling and Overcoming the Limits of Current Solutions

Adapting the transmission (TX) power of Bluetooth Low Energy (BLE) devices at runtime is pivotal to maximize the reliability and efficiency of their communications. Unfortunately, research in this area is scant. Firstly, there is a notable gap in exploring the efficacy of utilizing received signal strength information to adjust the TX power, as mandated by BLE's newly-introduced LEPC feature. Secondly, the performance of existing approaches is constrained by their reliance on connection-wide information. In this work, we fill this gap and investigate in detail the performance of different schemes used to adapt the TX power of BLE devices at runtime. After shedding light on the suitability of different link quality indicators to inform the adaptation, we demonstrate experimentally that adjusting the TX power on a per-channel basis allows to drastically improve the performance of existing solutions. Finally, we propose and implement a novel TX power control mechanism for BLE devices embedding our empirical observations, showcasing its superior reliability and energy efficiency over traditional approaches.