Chapter 25 HCDSR: A Hierarchical Clustered Fault Tolerant Routing Technique for IoT-Based Smart Societies Thaha Muhammed, Rashid Mehmood, Aiiad Albeshri, and Ahmed Alzahrani 25.1 Introduction Urban population has increased vastly in the recent years. The United Nations Human Settlements Program (UN-Habitat) [41] has foreseen it to be 10 billion by 2050, which is two-thirds of the current population on earth. The cities will have to deal with pressing issues such as public safety, efficient transportation, energy consumption, environmental sustainability, and expense reduction. These pressing issues have led to smart city paradigm which aims to plan and develop efficient urban cities in future. The past decade has witnessed the advancement of Internet of Things (IoT) [37, 40] especially the sensing technology [25]. In addition to the widespread development of sensors, improvement in big data computing infrastructure has enabled the collection of huge amount of heterogeneous data produced daily by urban spaces [11]. Urban spaces produce data related to temperature, weather, pol- lution, traffic control, the mobility of people, and resource consumption (water and electricity) which can be analyzed to improve the services provided and make the environment greener. Smart cities rely on sensors, webcams, IoT systems, wireless sensor networks, databases, ubiquitous devices, and many other frameworks that collect, process, and take informed decisions based on the data [5]. A survey on data fusion and IoT for smart ubiquitous environments can be seen in [6]. T. Muhammed () · A. Albeshri · A. Alzahrani Department of Computer Science, FCIT, King Abdulaziz University, Jeddah, Saudi Arabia e-mail: m.thaha.h@ieee.org; aaalbeshri@kau.edu.sa; asalzahrani@kau.edu.sa R. Mehmood High Performance Computing Center, King Abdulaziz University, Jeddah, Saudi Arabia e-mail: RMehmood@kau.edu.sa © Springer Nature Switzerland AG 2020 R. Mehmood et al. (eds.), Smart Infrastructure and Applications, EAI/Springer Innovations in Communication and Computing, https://doi.org/10.1007/978-3-030-13705-2_25 609 m.thaha.h@ieee.org