# IoT-Enabled Smart Cities: A Review of Concepts, Frameworks and Key Technologies
## 3 Review of IoT-Enabled Smart City Components and Solutions
### Smart Living and Infrastructures  
The smart living domain includes all components related to developing smarter city infrastructures (e.g., smart homes, smart buildings, etc.) as well the management and improvement of public services, such as cultural activities, tourism and education, which are involved in enhancing the general quality of life of citizens:  
* Smart Buildings: IoT allows the rapidly growing implementation of many kinds of facilities for smart buildings, for instance, air conditioning management, rainwater drainage, security systems for managing authenticated access to buildings, video surveillance and human activity monitoring [55], alerts for events such as fires and gas leaks, tools for monitoring the structural integrity of buildings [56], etc. Many different IoT technologies are involved in the living and infrastructures domain, depending on the specific use case or scenario. As for smart buildings, IoT integration with Building Information Modeling (BIM) tools provides a high-fidelity representation of buildings and spatial properties as a set of virtual assets [57], i.e., a digital twin of the building;
* Smart Homes: In these environments, different kinds of sensors, actuators and personal devices are connected through wireless networks and are often powered by human-machine interfaces that are based on artificial intelligence to provide smart and automated services for the users, with the goal of assisting them in daily tasks, such as lighting control, surveillance, managing home appliances and home resources, energy consumption, etc. [58]. In addition, smart home applications can be useful to detect and track the actions of the house's residents in order to monitor their health conditions [12], thereby especially helping the elderly and disabled people. Several kinds of sensors are applied to smart home and indoor sensing contexts. For instance, microelectromechanical systems (MEMS) are employed for the detection of gas leaks [59]. Devices based on triboelectric nanogenerators (TENG) are used for smart windows [60] and smart indoor lighting systems [61]. Video cameras and Closed-circuit television (CCTV) systems are used for smart surveillance. Digital humidity and temperature (DHT) sensors are largely adopted in fire alerting systems [62]. The most recent generation of domestic appliances and entertainment devices is often powered by AI and assistive services, so that they can interact while interconnected through wireless networks (the most used network communication protocols are Bluetooth, Zigbee, infrared and Wi-Fi [63]), thus providing users with a better, more efficient and enjoyable home life and experience;
* Smart Living Services: IoT devices have a large application in a variety of areas and activities that contribute toward improving the general quality of life for smart citizens. Cultural activities, for instance, smart tourism management, are taking advantage of exploiting mobile applications, GIS-aware and location-based services, multimedia streams, virtual and augmented reality and social media to manage and offer a better experience for tourism stakeholders [64]. Examples of these applications include tourist experience enhancement, destination competitiveness and sustainability improvement by tracking users' flows and behaviors [65]. Education is experiencing an increasing decentralization process with the inclusion of ICT and IoT elements, and this allows the production of new education services that can enhance interaction in remote and real-world learning activities [66]. Numerous smart living and infrastructures applications can be found in real-world cases. In [67], it is reported that 840 million units of smart home products were supplied in China in 2019. Los Angeles has implemented smart strategies for tourism management. Tourist traffic is measured through sensors embedded in the pavements and this information is used to adjust site visitor lights [68].