 healthcare, smart governance, public safety, environmental protection, etc.). Overall, SSC architecture is integrating many emerging ICT technologies based on IoT services including massive and critical ones. The main target is to provide a sustainable quality living environment for the citizens based on use of the ICTs for provision of "digitalized" city services. Smart sustainable city (SSC) architecture Application layer Smart water Smart Smart home E-business supply energy Intelligent Smart Smart E-government transportation education healthcare Data and support layer (clouds) Network layer (fixed and mobile networks) Sensing layer (sensors, cameras, various loT devices) loT - Internet of Things Figure 7.8 Smart sustainable cities (SSC) architecture. 7.6 KPIs for Smart Sustainable Cities Regarding the scope of KPIs for the SSC [17], they can be categorized in six dimensions: ICT, environmental sustainability, productivity, quality of life, equity and social inclusion, and physical infrastructure. Then, each dimension has its subdi- mensions. For example, subdimensions of ICT are network and access, services and information platform, information privacy and security, and electromagnetic field. For the dimension quality of life, the subdimensions are education, health, safety/security, and convenience and comfort. If we look (as an example) into the subdimension access and networks (from the dimension ICT) [18], the KPIs are as follows: Availability of computers or similar devices. Refers to proportion of households with at least one computer or similar device (e.g. smartphones). Availability of Internet access in households. Refer to proportion of households with Internet access via a fixed or mobile network. Availability of fixed broadband subscriptions. Refers to fixed broadband subscriptions penetration (number of broadband subscriptions per 100 inhabitants). Availability of wireless broadband subscriptions. Refers to wireless-broadband penetration including mobile and wireless terrestrial networks and sate