A Study on Packet Error Rate in Bluetooth Mesh Networks With Relay Redundancy

The Bluetooth Mesh protocol (BMP) has become an excellent solution for sensor networks and Internet of Things (IoT) deployments due to its low power consumption, self-organizing capabilities, and security mechanisms. In this article, we focus on analyzing reliability in Bluetooth low-energy (BLE) mesh networks. Our investigation reveals an anomaly inherent to the standard, where the addition of extra relays may lead to a reliability degradation instead of improvement due to new packet collisions, particularly in scenarios with low error probabilities. This anomaly may appear undesirably even in small networks. This work demonstrates the influence of the number of relays in a two-hop section and how the packet error ratio (PER) may be degraded by more than two orders of magnitude. This article also provides a mathematical model validated through simulations and real measurements using a hardware network emulator based on nRF52840 development kits. We discuss the network reliability under standard parameters and offer insights into optimal relay configurations, proposing adjustments to mitigate this anomaly.