Power Consumption and Maximum Number of Supported Nodes for BLE Biosensor Applications

There has been significant growth in wearable wireless patient physiological monitoring over the last decade. Many applications require a real-time, low-latency, small profile, and low-power-battery system. In this work, various Bluetooth low energy (BLE) configurations were tested in a multi-channel, wireless system to determine the lowest peripheral power configuration and the number of supported peripherals for each BLE configuration. Using nodes that continuously sampled at 1 kHz, connection intervals from 10-100 ms and event lengths of 2500, 5000 and 7500 mu s were tested. The lowest current consumption, 2.39 mA, was measured for a connection interval of 100 ms, event length of 2500 mu s, and maximum transmission unit (MTU) of 247 bytes. The maximum number of supported peripheral connections was observed to be 11 for a connection interval of 100 ms, event lengths of 5000 and 7500 mu s, and MTU size of 247 bytes. We found that using longer connection intervals led to decreases in power consumption and shorter event lengths allowed for support of more peripheral sensors nodes for a given connection interval, assuming the event length is long enough to transmit the desired amount of data. Future work should investigate techniques to optimize power consumption further and to extend the number of supported peripheral nodes.