## 3 Related Works  
What is a Smart City? The concept of Smart City is quite broad. Several definitions exist: [PERSON] _et al._ (2016) studied several definitions and provided a more comprehensive formulation defining a Smart City as: \"A space for coexistence among people who, based on the available technologies, can thrive and develop, while taking into account economic, social and environmental sustainability\". Figure 3: The iNUIT architecture with the modules developed within the SmartCrowd and OpEC (Optmisation de l’Eclairage public) projects tinted in purple and orange, respectively. The modules in white have been developed during other projects within the iNUIT program. From this definition, it appears that the two essential elements that constitute a Smart City are \"people\" and \"technology\". A city cannot be detached from its citizens. They are the main actors that produce and consume all the services of the city and they are also part of the institutional factors (e.g., governance, policy, _etc._) that should guarantee the smart growth of the community. While the citizens contribute to make the city \"smart\" providing these institutional and human dimensions, often the forefront role is attributed to the technology dimension and the use of \"Smart Computing technologies\" [34]. In this work, we focused more on this technological aspect. Smart Computing Technologies are defined by Forrester [5] as \"A new generation of integrated hardware, software, and network technologies that provide IT systems with real-time awareness of the real world and advanced analytics to help people make more intelligent decisions about alternatives and actions that will optimize business processes and business balance sheet results.\" In the Internet of Things (IoT) paradigm, many of the objects that we use daily and that surround us are connected to each other and the information and communication systems are invisibly integrated in the environment [6]. In many works, the IoT paradigm has been chosen as the ideal candidate for the implementation of the smart computing technologies needed to take into account, transparently and seamlessly, a large number of heterogeneous systems and, therefore, enabling Smart Cities. For instance, [PERSON] _et al._[7] focused their analysis on Urban IoTs (_i.e._, IoT designed to support the Smart City vision) and presented the technical solutions and best-practice guidelines used in the Padova Smart City project, in which they demonstrated its feasibility in the city of Padova, Italy. Other works have highlighted the open challenges of using IoT for Smart Cities proposing different approach or model such as hub-centric approach to the IoT [8], or a cognitive management framework for IoT (in which \"cognitive\" represents \"the ability to dynamically select behavior through self-management, taking into account information and knowledge on the context of operation as well as policies\") [9]. Similar to what was presented in the previous works, iNUIT proposes an approach based on the IoT to enable Smart Cities. iNUIT has the main goal of establishing the technological backbone for the future Smart Cities tackling concrete problems concerning its implementations: from the heterogeneous nature of the collected data to the protection of citizens' privacy. In order to do that, we attacked the problem from two different directions proposing two proof-of-concepts for two well-defined application scenarios: improving \"physical security and mobility\" during large events and \"resource management\" and, in particular, smart public illumination. The SmartCrowd project concretizes the first direction. The goal of this project is to detect groups and dangerous situations during large events by monitoring the crowd's movement. We focused on the GPS data collected through an application running on the participants' smartphones.