The rapid expansion of megacities and the rise of smart city applications have led to unprecedented growth in data traffic, placing immense demands on urban digital infrastructure. Current networks rely on diverse wireless, optical, and computing technologies owned by various providers, including small-scale operators. As 5G becomes more widespread, expected to serve up to 65% of the population, the challenge lies in integrating edge computing, virtualised Radio Access Network (vRAN), and Open RAN (O-RAN) technologies into a unified, low-latency, secure system. This integration is complicated by the isolated development of these technologies and the need for architectures that scale flexibly across complex urban environments.

The MARSAL project addressed these challenges by introducing a novel paradigm of elastic virtual infrastructures that transparently integrated advanced radio access, networking, management, and security technologies. It focused on three core pillars: network design, virtual infrastructure, and network security. MARSAL advanced cell-free networking and mmWave integration aligned with O-RAN standards, while enhancing Mobile Edge Computing and network slicing through layered analytics. Furthermore, it developed machine learning-based mechanisms to ensure data privacy and security in multi-tenant environments. Overall, MARSAL delivered an end-to-end framework for efficient, secure data transfer, processing, and storage tailored to the needs of future smart megacities.