Joint and dynamic optimization of functional split selection and slice configuration in vRAN

We jointly consider network slicing and functional split for 5G/6G Radio Access Network (RAN). Exploiting virtu-alization techniques, virtual Radio Access Network (vRAN) is an architectural shift that moves some of the functions that were traditionally performed by the base station to centralized nodes, deployed at cloud-based resources. By appropriately selecting the location of these nodes, they can effectively coordinate a number of radio access elements, thus bringing potential gains, for instance, in terms of interference reduction. One pivotal decision for vRAN operation is how to split the functions between these central elements and the corresponding distributed units. Deploying more functions at the cloud could potentially bring more benefits, due to the tighter cooperation between access elements. On the other hand, higher centralization poses more requirements, in terms of computational resources at the nodes where these functions are deployed. Along with the virtualization, RAN slicing enables the deployment of independent service verticals over the same physical infrastructure, and this could greatly benefit from the coordination achieved by exploiting the vRAN features. In this paper we propose a vRAN model to jointly consider functional split and RAN slicing, and we establish the corresponding configuration, exploiting Lyapunov's Theory to tackle the underlying problem. The results show that, in highly heterogeneous networks, the dynamic configuration of the functional split can reach the same performance of fully centralized networks, with substantially fewer computation resources.