RT-BLE: Real-time Multi-Connection Scheduling for Bluetooth Low Energy.

Bluetooth Low Energy (BLE) is one of the popular wireless protocols to build IoT applications. However, the BLE suffers from three major issues that make it unable to provide reliable service to time-critical IoT applications. First, the BLE operates in the crowded 2.4GHz frequency band, which can lead to a high packet loss rate. Second, it is common for one device to connect with multiple BLE Peripherals, which can lead to severe collision issue. Third, there is a long delay to re-allocate time resource. In this paper, we propose RT-BLE: a real-time multi-connection scheduling scheme for BLE. We first formulate the BLE transmission latency in noisy RF environments considering the BLE retransmission mechanism. With this, RT-BLE can get a set of initial connection parameters. Then, RT-BLE uses collision tree based time resource scheduling technology to efficiently manage time resource. Finally, we propose a subrating-based fast connection re-scheduling method to update the connection parameters and the position of anchor points. The result shows RT-BLE can provide reliable service and the error of our model is less than 0.69%. Compare with existing works, the re-scheduling delay is reduced by up to 86.25% and the capacity is up to 4.33× higher.