Internet of Things for Smart Cities: Technologies, Applications and Challenges

The increasing urbanization and complexity of modern cities necessitate advanced technological solutions to ensure efficient resource utilization, sustainability, and improved quality of life. The Internet of Things (IoT) has become a foundational paradigm for smart cities by enabling large-scale sensing, real-time data acquisition, and intelligent decision-making across heterogeneous urban systems. This paper presents a detailed analysis of core IoT technologies for smart city deployments, including sensor and actuator networks, low-power wide-area networks (LPWANs), 5G-enabled communication infrastructures, edge and cloud computing architectures, and data analytics driven by machine learning techniques. Key smart city use cases—such as intelligent transportation systems, smart grids, environmental monitoring, waste management, and public safety—are systematically reviewed with emphasis on system architectures and performance requirements. Furthermore, the paper critically examines major technical and operational challenges, including scalability, interoperability among heterogeneous devices, latency constraints, energy efficiency, data security and privacy, and compliance with regulatory frameworks. Finally, emerging research directions such as AI-enabled IoT, digital twins, and blockchain-based trust mechanisms are discussed as potential enablers for resilient, secure, and scalable smart city ecosystems.