# An Overview of Indoor Localization System for Human Activity Recognition (HAR) in Healthcare
## 6 Systems for HAR  
Human activity recognition (HAR) is an application area aimed at determining people's activities and the context in which they are addressed. In HAR systems, different technologies based on visual, nonvisual, and multimodal sensors are used to analyze and process data and images necessary to understand people's behavior. Some analyses of the activities performed are carried out by human operators with the help of camera networks. This solution is currently used in security and surveillance services to visualize people's behavior and detect anomalies to activate intervention services [70]. With the progress made by the new generations of cameras and intelligent classification systems, the contribution of operators is being reduced or even replaced with automatic systems, improving the efficiency and effectiveness of observation and the analysis process. The availability of these systems has found wide application in the home care field, making up for the shortage and expensive availability of caregivers. The use of visual sensors in the field of the healthcare system has been very effective in fall detection, especially for the elderly who suffer from cognitive loss. The results based on this technology stand at accuracy values of 99%. Nonvisual systems are predominantly used in ambient assisted living (AAL) applications. Sensors are used that can collect a lot of information. They can be environmental detectors, microphones, or wearable devices. The collected data are sent to intelligent systems for classification. The solution based on multimodal sensors uses different sensory devices distributed in different parts of the body to collect real-time data to be analyzed for monitoring the health conditions of the elderly. The availability of smartphones equipped with multiple sensors: inertial, environmental, heart rate, and respiration rate has made these devices a suitable platform for collecting real-time data for innovative HAR solutions. These sensors offer a guarantee of privacy, are more efficient, and provide accurate physiological data but are not easily accepted by the elderly for wearability problems. Their misuse can lead to erroneous assessments and trigger signs of false emergencies. Table 4 shows a comparison between the three different types. HAR systems represent the most suitable technology to monitor and assist the elderly and disabled people in ensuring their safety and wellbeing. They aim to identify the activities the elderly carries out daily regarding domestic work, personal hygiene, and free time. These activities implicitly identify where the older person is, as they are closely related to specific rooms within the house. Continuous real-time monitoring of activities and physiological data allows the identification of potentially dangerous situations. The precise identification of the patient's whereabouts facilitates the interventions of health assistants in case of emergency or urgency. Therefore, by combining an IPS system, we have additional information to estimate a more accurate positioning and improve the recognition of activities. Combining these two themes requires an intelligent environment to deduce