Optimal Functional Splitting, Placement and Routing for Isolation-Aware Network Slicing in NG-RAN

In the rapidly evolving landscape of 5G and its successor technologies, the Next Generation Radio Access Network (NG-RAN) stands out as a transformative pillar. Functional splitting, a core concept in NG-RAN, splits the traditional base station into distinct functional entities, notably the Distributed Unit (DU), Centralized Unit (CU) and Radio Unit (RU). With flexible functional splitting, Infrastructure Providers (InPs) can dynamically allocate RAN resources to cater to each network slice's distinct throughput and latency demand. However, the problem of optimally selecting functional splits, placement of RAN functions in DU/CU with constrained computational capacities and determining routing paths present an NP-hard challenge. The coexistence of multiple slices on shared infrastructure may necessitate slice isolation for security, performance, and operational reasons, adding another layer of complexity. To address this multifaceted problem, we formulate an Integer Linear Programming (ILP) model that seeks to maximize the InP profit considering computation, virtual machine instantiation and routing costs. Using Gurobi optimizer, we show that optimal slice admission solutions directly impact InP profit and that enhanced computational capacities can increase the number of slices admitted.