# PISIoT: A Machine Learning and IoT-Based Smart Health Platform for Overweight and Obesity Control
## Materials and Methods
### PISIoT: Architecture and Functionality
#### 3.2.1 Monitoring Network Layer  
The availability of a reliable platform, the particular device characteristics (brand, model, and battery life) and data access permissions by suppliers must all be considered in order to guarantee optimal monitoring of patients' biomedical variables. On the other hand, data acquisition by smart devices depends on various factors such as compatibility between the devices used, the wearable device's portability during the day, the correct positioning of the wearable device at night, continual reporting of weight, and patients' honesty in reporting food and water ingested. For this reason, a monitoring network is required that allows PISIoT to monitor and collect patients' biomedical variables and identify daily eating habits and physical activity with the purpose of motivating patients  
Figure 1: General architecture of PISIoT.  
to maintain or reduce their weight, thus contributing to reducing the prevalence of overweight and obesity. Therefore, PISIoT uses an IoT-based monitoring network that allows smart devices to link up and communicate. The main purpose of the monitoring network is to collect patients' biomedical and other variables from wearable devices. In particular, the monitoring network is made up of IoT-based smart devices that are divided into three categories:  
* Wearable devices. Wearable devices are responsible for monitoring and collecting most of the biomedical variables, as well as other variables generated from the patient's actions. The wearable devices in the IoT provide a high-tech infrastructure that enables communication and links between portable sensors to monitor a person's activities, including but not limited to the person's biomedical variables, behavior, and welfare, with the purpose of improving quality of life [15]. Wearable devices are classified according to their appearance, functionality, portability on the body, characteristics, and functional capacity in order to provide a better description of different sectors. For this reason, the authors of [47] classified wearable devices into smartwatch, smart eyewear, fitness tracker, smart clothing, wearable camera, and wearable biomedical device. PISIoT works with devices from some suppliers, but its scalability makes it possible to consider wearable devices from other suppliers.
* Smart devices. These devices are responsible for the smart collection of weight or other variables not identified by wearable devices (e.g., smart scale, temperature sensor, motion sensor). Smart devices are the driving force of the IoT because they provide fast and accurate information in real time and identify various patterns. In this sense, PISIoT includes some smart device suppliers but ensures that other smart device providers can be incorporated.
* Smartphones. Smartphones are in charge of maintaining communication between the devices, the providers, and PISIoT. The wearable devices used in the IoT lack an operating system as such; therefore, they must be linked to a smartphone or a computer with Internet access because the information collected by the devices must be safeguarded by the storage and support scheme of PISIoT and of its suppliers. PISIoT is multiplatform; however, depending on the model and provider of the wearable device that you wish to use, there are specific compatible smartphone models.