Improving the Timeliness of Bluetooth Low Energy in Noisy RF Environments
Michael Spörk, Carlo Alberto Boano, Kay Römer · International Conference on Embedded Wireless Systems and Networks · 2019
The ability to communicate within given delay bounds in noisy RF environments is crucial for Bluetooth Low Energy (BLE) applications used in safety-critical application domains. In this work, we experimentally study the latency of BLE communications in the presence of radio interference, and show that applications may incur long and unpredictable transmission delays. To mitigate this problem, we devise a model capturing the timeliness of connection-based BLE communications in noisy RF channels by expressing the impact of radio interference in terms of the number of connection events necessary to complete a successful data transmission (nCE ). We show that this quantity can be estimated using the timing information of commands sent over the host controller interface of common BLE devices, hence without additional communication overhead or energy expenditure. We finally show that a BLE application can make use of our model and recent nCE measurements to adapt its connection interval at runtime, improving its performance in the presence of radio interference. Experiments on the popular nRF52840 platform running Zephyr show that a BLE application can effectively increase the timeliness of its communications in noisy RF environments, reducing the number of delayed packets by up to a factor of 40.