Understanding the Performance of Bluetooth Mesh: Reliability, Delay, and Scalability Analysis

This article evaluates the quality-of-service performance and scalability of the recently released Bluetooth mesh protocol and provides general guidelines on its use and configuration. Through extensive simulations, we analyze the impact of the configuration of all the different protocol's parameters on the end-to-end reliability, delay, and scalability. In particular, we focus on the structure of the packet broadcast process, which takes place in time intervals known as Advertising Events and Scanning Events. Results indicate a high degree of interdependence among all the different timing parameters involved in both the scanning and the advertising processes and show that the correct operation of the protocol greatly depends on the compatibility between their configurations. We also demonstrate that introducing randomization in these timing parameters, as well as varying the duration of the Advertising Events, reduces the drawbacks of the flooding propagation mechanism implemented by the protocol. Using data collected from a real office environment, we also study the behavior of the protocol in the presence of WLAN interference. It is shown that Bluetooth mesh is vulnerable to external interference, even when implementing the standardized limitation of using only 3 out of the 40 Bluetooth low-energy frequency channels. We observe that the achievable average delay is relatively low, of around 250 ms for over 10 hops under the worst simulated network conditions. However, results prove that scalability is especially challenging for Bluetooth mesh since it is prone to broadcast storm, hindering the communication reliability for denser deployments.