  The rapid proliferation of smart cities has transformed urban landscapes into
dynamic ecosystems teeming with interconnected computational nodes and sensors.
During this evolution, the search for seamless communication in time-critical
scenarios has become evident. With the escalating complexity of urban
environments, envisioning a future with a blend of autonomous and conventional
systems, each demanding distinct quality-of-service considerations, services in
smart cities vary criticality levels and necessitate differentiated traffic
handling, prioritizing critical flows without compromising the network's
reliability or failing on hard real-time requirements.
  To tackle these challenges, in this article we propose a Time-Sensitive
Networking (TSN) approach which, at the scale of a smart city network, presents
multifaceted challenges, notably interoperability among diverse technologies
and standards. Nonetheless, TSN emerges as a promising toolkit, encompassing
synchronization, latency management, redundancy, and configuration
functionalities crucial for addressing smart city challenges. Moreover, the
article scrutinizes how TSN, predominantly utilized in domains like automotive
and industry, can be tailored to suit the intricate needs of smart cities,
emphasizing the necessity for adaptability and scalability in network design.
  This survey consolidates current research on TSN, outlining its potential in
fortifying critical machine-to-machine communications within smart cities while
highlighting future challenges, potential solutions, and a roadmap for
integrating TSN effectively into the fabric of urban connectivity.
