An IoT Group-Based Protocol for Smart City Interconnection Jaime Lloret 1 , Sandra Sendra 1,2(&) , Pedro Luis González 3 , and Lorena Parra 1 1 Instituto de Investigación para la Gestión Integrada de zonas Costeras, Universitat Politècnica de València, Carretera Nazaret-Oliva s/n, 46730 Valencia, Grao de Gandia, Spain jlloret@dcom.upv.es, loparbo@doctor.upv.es 2 Departamento de Teoría de la Señal, Telemática y Comunicaciones (TSTC), Universidad de Granada, Calle Periodista Daniel Saucedo Aranda s/n, 18071 Granada, Spain ssendra@ugr.es 3 Departamento de electrónica, Universidad Central, Cra 5 No. 21-38, Bogotá, Colombia pgonzalezr1@ucentral.edu.co Abstract. The evolution of the information and communication technologies (ICT) and the need to solve and improve some services in large cities such as environmental monitoring, health, traf fic, etc., day by day, new sensors capable of taking parameters of the environment are developed. These sensors must be integrated into larger networks and, in turn, these networks must be integrated into a bigger network so that these sensors together can improve the ef ficiency and sustainability of cities. These cities equipped with sensors are known as Smart cities. This paper presents an architecture and communication protocol for interconnecting all these sensors and networks. The proposal is group-based architecture able to connect the different infrastructures that provide services to the smart cities. The proposed system is scalable and fault-tolerant. The paper also provides the mathematical model for this interconnection system. Finally, the system is simulated in different topologies to see its operation and perfor- mance. The results show that although the size of network increases the amount of generated traf fic remains quite stable. Keywords: Smart City  Internet of Things (IoT)  Protocols  Group-based topology  Sustainability  Wireless Sensor Networks (WSNs) 1 Introduction The paradigm of the Internet of Things (IoT) is a new concept based on the inter- connection of objects of everyday life which surround us. These devices are composed by digital systems, microcontrollers, sensors and a communications interface that will allow them to communicate with each other and with the users, being integral elements of the Internet [1]. Therefore, IoT tries to extend the networks and the Internet to give access to devices such as appliances, surveillance cameras, monitoring sensors, © Springer Nature Switzerland AG 2019 S. Nesmachnow and L. Hernández Callejo (Eds.): ICSC-CITIES 2018, CCIS 978, pp. 164–178, 2019. https://doi.org/10.1007/978-3-030-12804-3_13