Energy and QoS-Aware Functional Split Selection in 5G and Beyond O-RAN Networks

The next generation radio access network (RAN), open RAN (O-RAN), has been introduced as an industry-level standard, supporting interoperability between different vendors' equipment and offering flexibility by including efficient network slicing with different functional split options in 5 G and beyond mobile networks. Nevertheless, strictly satisfying quality-ofservice (QoS) requirements while taking into account the energy consumption when placing network functions within the RAN and allocating resources for each network slice remains a key research problem. In this paper, we propose an O-RAN UserCentric Split Selection (O-RAN-UCSS) that aims at minimizing the deployment cost and power consumption, while considering infrastructure computation cost, link capacities as well as QoS requirements in a three-layer O-RAN architecture. The problem is formulated as an Integer Linear Problem (ILP), then solved using a Branch-and-Cut (B&C) algorithm in a realistic RAN scenario including eMBB and URLLC services. Simulation results show that our proposal outperforms the baseline approaches in terms of deployment cost, power consumption, and latency penalty at the expense of a reasonable increase of the computation time.