Relaying Mechanisms in BLE Mesh Networks: A Method for Improving Latency and Reliability

Bluetooth low energy (BLE) Mesh networks are a promising solution for Internet of Things applications, offering scalability, low power consumption, and resilience to node loss. Different factors in BLE Mesh networks may severely affect performance, from network topology, to the position of relay nodes, to the setting of advertising and scanning parameters that regulate message relaying. The relaying process is the backbone of BLE Mesh networks, enabling many-to-many communication where devices can communicate with any other device in the network, including those outside their coverage range. This article investigates the effects on communication performance of relaying implementations with and without preemption of the scanning process. Two possible methods of preemption are implemented, compared, and analyzed: 1) stateless preemption, which starts a new scanning after the previous event has been interrupted to initiate advertising, and 2) stateful preemption, which maintains information on the current scanning across interrupts. The implementation with stateful preemption displayed better latency than the implementation without any form of preemption, while also achieving a good packet delivery ratio and counterbalancing reliability issues of the stateless preemption approach. Based on these results, stateful implementation proved to be an excellent solution for scenarios where it is essential to ensure low latencies, both in low and high traffic topologies.