Closed-Loop Transmission Power Control for Reliable and Low-Power BLE Communication in Dynamic IoT Settings

Ziyao Zhou, Hen-Wei Huang

Abstract: Reliable and energy-efficient Bluetooth low energy (BLE) communication is crucial for the Internet of Things (IoT) applications in dynamic environments. However, the received signal strength indicator (RSSI) and data throughput in BLE are highly susceptible to environmental variability, affecting communication performance. In this work, we systematically analyze the interdependence between RSSI, throughput, transmission power (TXP), and the peripheral device’s system power consumption under various real-world conditions, observing that adjusting the TXP effectively influences both the RSSI and throughput. We propose a robust closed-loop TXP control framework based on proportional–integral–derivative (PID) controllers. Two initial control strategies were implemented: an RSSI-based approach and a throughput-based approach, each with distinct advantages and limitations. The RSSI-based method offers rapid responsiveness to signal fluctuations but lacks direct correlation with data throughput, while the throughput-based method provides more accurate feedback on transmitting throughput at the cost of slower response. To address these limitations, a hybrid RSSI–throughput control strategy was developed, combining the responsiveness of RSSI feedback with the accuracy of throughput measurements. This hybrid approach effectively maintains data throughput near the target level with minimal variance, even under rapidly changing environmental conditions.