## 4 Smart City Service and the CEI Continuum
### Key Benefits of CEI Continuum in Support of Smart City Applications  
We can identify several key benefits of the CEI continuum when considering its use in Smart Cities. Improved Performance and Responsiveness: The CEI continuum enables real-time data processing and analysis closer to the data sources, reducing latency for time-sensitive applications. This is important for many of the categories of Smart City applications outlined in Section 2. Low latency is particularly beneficial for Smart City applications that exhibit classic real-time behaviours such as Smart Mobility where traffic management and autonomous vehicles require rapid response times or Smart Living, for example, elderly care where issues such as fall monitoring require real-time responsiveness [19; 34]. Enhanced Scalability and Resource Optimization: The continuum allows for the dynamic allocation of computing resources across edge devices and cloud infrastructure, optimising performance and resource utilisation and facilitating scalability. Scalability is an issue that touches most of our Smart City application categories ranging from processing scalability which is crucial for managing the vast amounts of data generated by IoT devices in smart cities [35] to deployment scalability when we consider the massive number of far-edge devices embedded in the fabric of the city [33; 34]. Equally, the issue of effective orchestration of resources and tasks across the CEI continuum is particularly relevant to all categories of Smart City applications, as efficient resource allocation is crucial for optimising performance across the continuum. For example, in smart mobility applications, proper orchestration can ensure that time-sensitive traffic management tasks are processed at the edge while long-term planning tasks utilise cloud resources. Similarly, when considering Smart Environment and Smart Economy applications that often involve large-scale sensor networks and data-intensive operations, the ability to scale operations and dynamically assign resources is critical to their effective use [36]. Improved Reliability and Operation Continuity: Edge computing capabilities ensure that critical Smart City services can continue functioning even during network interruptions or cloud connectivity issues [37]. This is essential for maintaining the efficiency and reliability of urban services and infrastructure [35] and critical for example in the Emergency Management context where critical city services need to remain running even in the face of natural disasters. Energy Efficiency and Cost Reduction: Processing data closer to the source, often at the edge, can reduce energy consumption and bandwidth usage compared to sending all data to centralised cloud servers [38]. Obviously, this can lead to cost savings in data transmission and storage for Smart City applications [33]. This issue is particularly relevant to Smart Environment applications, but it affects all categories as energy efficiency is a key concern in Smart City initiatives. For instance, in smart lighting systems or environmental monitoring networks, energy-efficient operation of edge devices, especially those running on batteries, is crucial for long-term sustainability. Enhanced Security and Privacy: The edge-cloud continuum allows for initial data filtering and anonymization, at the edge, before sensitive information reaches the cloud. Enhancing overall security and privacy protection for citizens [39]. Security and privacy are particularly relevant to Smart Governance and Smart Living applications, where personal and sensitive data is often processed. Implementing robust security measures across the continuum is crucial for maintaining citizen trust and compliance with data protection regulations. Ultimately, the benefits listed above offer a Flexible and Adaptive Computing Model that can adapt to the specific needs of different Smart City applications.