# IoT-Enabled Smart Cities: Evolution and Outlook
## 5 Conclusions  
As can be seen from the examples described, a plethora of smart city applications and services have been developed. Many of them are at a proof-of-concept level, but more and more have already passed the pilot phase and have developed into production-level deployments. This shows that the minimum set of technology enablers is already available and is being deployed in cities and integrated with real-world public services. However, often such services are being developed and deployed in application silos, limiting the value of the information that is being collected as re-use and sharing of this information is difficult. The use of IoT platforms enables such data accessibility and exchange, but the use of proprietary platforms that have been developed individually and in an isolated manner by large companies results in further restrictions as solutions cannot be replicated across cities relying on a different proprietary platform. As applications cannot be re-used, they have to be built from scratch or be adapted to a different platform, making developments expensive. The cities thus suffer from vendor lock-in, i.e., they cannot easily buy and integrate components or applications from a different vendor, but are stuck to the provider of their IoT platform. The way out is to build on standards that are beginning to emerge. Smart city organizations have started to define standard-based minimum interoperability mechanisms. Another aspect is the use of open-source components that reduce costs and risks for cities while still giving room for standard-compliant commercial components. Building on standard-based minimum interoperability mechanisms is important for creating a real smart city market as applications, information and services can be used in many smart cities instead of having to be custom-made or require costly adaptations for each city. This reduces costs significantly and makes deployments on a larger scale viable. As we have described, there are significant advances on the technical side that make smart cities feasible. Still, there are some technological challenges to overcome, mainly related to guaranteeing the necessary resiliency on data and networks to support mission-critical services (e.g., emergency response, critical infrastructures real-time monitoring and management, etc.). Integration of novel computing paradigms like fog computing and 5G and beyond networks in IoT scenarios unveils a promising path to address such application scenario. However, the biggest challenges may be on the administrative and organizational sides. Smart city deployments often require cooperation between different departments or even different organizations. This may require budgets to be readjusted, as there is the need for initial investments. These may be significantly offset by savings at a later point, but not necessarily where the initial investments have been made. Moreover, technological or public administrations push cannot, on their own, untap the full value of the smart city paradigm. Surely, it can initiate the transition and settle the roots for all the stakeholders and actors involved in urban environments (e.g., citizens, companies, organizations, visitors, etc.) to become actively engaged in the smart city, not only as consumers of services or data that others provide, but also as producers of valuable information that would bring forward new services, thus contributing to a virtuous cycle with unforeseeable benefits. However, for this vision to become a reality, it is necessary to work on challenges of data security and self-sovereignty so that data producers are confident that their data is used for those, and only those purposes for which it was shared, and they are also appropriately and fairly rewarded for the value that their data has generated. Finally, there is often resistance to change, especially if it does not bring immediate benefits to those who have to adapt. Making the city smart will lead to changes in the way the city operates.