Client nodes are the devices which perform the monitoring. Any Android device can potentially be a client node in our framework. Usually, this node will be a smartphone or a smartwatch. For the remainder of this tutorial, we will assume for conciseness that the client node is a smartphone.
The client nodes library includes a Bluetooth/BLE stack, vital sign estimators from internal sensors, phone state extractors, delivering surveys (and rendering capabilities for surveys) and communication capabilities to the telemonitoring server.