# IoT-Enabled Smart Cities: A Review of Concepts, Frameworks and Key Technologies
## 4 Discussion on Recent Trends, Open Challenges and Future Directions
This allows the development of large infrastructures that can support multiple organizations, enhance scalability and reduce the infrastructures' costs since they are shared between multiple operators [36]. This aspect is closely connected with the reuse of components in smart city frameworks and tries to harmonize and overcome the efforts needed in building custom-made platforms for each city or each specific context, which is economically inefficient [3]. Other potential future directions include the introduction and dissemination of novel network technologies, such as 5G [28; 59; 72; 102]. Technological advances in networks and device solutions are important. In fact, the adoption of the most recent network technologies, such as 5G, combined with higher efficiency in building techniques and technologies following the paradigm of net zero energy infrastructure can lead to building solutions that are aiming for net zero carbon emissions [102]. Furthermore, the introduction of innovative computing paradigms, such as the introduction and integration of deep learning and AI solutions [109; 115], semantic technologies and natural language processing (NLP) would improve the interaction level between smart devices and all smart city actors, as well as enabling the production of smarter services for a better quality of life. Finally, in order to also discuss the societal challenges addressed by IoT and smart city technologies, we focused on assessing each application area and domain, as discussed in Section 3, in terms of their contribution to the SDGs. To this end, we will briefly introduce the 17 indicators representing the SDGs: (1) no poverty; (2) zero hunger; (3) good health and well-being; (4) quality education; (5) gender equality; (6) clean water and sanitation; (7) affordable and clean energy; (8) decent work and economic growth; (9) industry, innovation and infrastructure; (10) reduced inequalities; (11) sustainable cities and communities; (12) responsible consumption and production; (13) climate action; (14) life below water; (15) life on land; (16) peace, justice and strong institutions; and (17) partnerships for the goals. On the basis of our findings while reviewing the literature, relevant contributions and relations among the presented IoT-smart city application areas and the following SDGs were retrieved:  
* Zero Hunger: Smart agriculture [7] solutions contribute to improving efficiency in accessing fundamental resources, such as food, and also allow precision agriculture [89];
* Good Health and Well-being: Smart healthcare solutions [106; 108] contribute to improving efficiency in healthcare services that are provided in hospitals and medical structures, as well as at home. Big data collection and analysis in healthcare contextscan be useful for monitoring critical cases, conditions and events [109], especially in the period of COVID-19 pandemic;
* Quality Education: Smart education solutions contribute to creating innovative education services, as well as to enhancing the interaction between remote and real-world learning activities [66];
* Clean Water and Sanitation: Smart water solutions [100] are employed to monitor the quantity and quality of water distribution and aim to minimize consumption and manage wastewater treatments [101]. This represents an important step in the proper design and maintenance of quality water systems;
* Affordable and Clean Energy: Smart energy solutions and energy grids [3; 58; 93; 97; 96] contribute to a more efficient energy distribution and usage [92], helping to minimize power consumption and consider innovative sustainable energy sources [91];
* Decent Work and Economic Growth: Smart governance solutions [3; 38; 39; 46; 47; 48; 49; 50; 51; 52; 53; 54] contribute to economic growth [38] since they are expected to provoke a strong push in the direction of smart and digital public administrations [39].