Energy-Efficient Scheduling for Multiple Latency-Sensitive Bluetooth Low Energy Nodes

Energy-efficient scheduling in wireless embedded devices is a critical consideration due to limited energy supplies and the latency constraint of sensory data processing. Bluetooth low energy (BLE) is a low power solution that provides a user-defined connection interval parameter for extending the sleep time of BLE nodes. Instead of minimizing the values for this connection parameter to minimize latency, which can lead to excessive energy consumption, this paper presents a practical energy-efficient scheduling framework for multiple BLE devices having applications with latency constraints. First, we determine the required connection interval for a single BLE node with multi-rate sensing applications. Then, considering the scheduling issues caused by non-preemptive data transmission, we present an energy-efficient connection interval assignment for a sensor network with multiple BLE nodes to meet the latency constraints of sensing applications. Finally, based on the proposed connection interval determination, we propose a priority inversion awareness scheduler for the BLE master node to schedule all slave node transmissions in the network. Extensive experiments show that the proposed algorithms prolonged network lifetime by 235% compared with a simple pessimistic setting.