A runtime admission control for industrial IoT over bluetooth low energy mesh networks

Bluetooth Low Energy (BLE) is widely used in several industrial IoT applications to save on costs and power consumption. In this context, to widen the coverage area while meeting the constraints of real-time messages, some applications require multi-hop communications with bounded delays. A few approaches in the literature support real-time traffic on BLE mesh networks, but they use offline configurations, which offer a limited flexibility when new connections are dynamically added based on the application requirements. This paper, instead, proposes a Runtime Connection Admission Control for BLE (RAC-BLE) that allows the BLE devices to accept at runtime new connection requests, provided that the relevant transmissions do not overlap with communications from other BLE devices. This way, RAC-BLE by design provides bounded delays on single-hop transmissions, thus enabling BLE-based real-time mesh networks. The paper provides a detailed description of the RAC-BLE approach, an analytical calculation of the worst case end-to-end delays and experimental performance evaluations. The results show that RAC-BLE significantly reduces the maximum end-to-end delays compared with those obtained by another approach in the literature. For instance, a delay reduction of 70% and 92% is measured in the case of one hop and five hops, respectively.