Towards Energy Efficient Functional Split and Baseband Function Placement for 5G RAN

The energy efficiency of 5G and beyond 5G(B5G) networks is critical for reducing the high operational expenditure (OPEX) of mobile network operators. In 5G RAN, functional split enables the disaggregation of baseband functions, which significantly increases energy efficiency but induces various challenges in the placement of baseband functions. Various recent works have focused on addressing these challenges; however, most of the solutions do not consider the delay and data rate requirements of different slices as well as different functional splits. In this work, we aim to develop an energy-efficient baseband function placement strategy that jointly considers different functional splits and network slice-specific requirements. We formulate an Integer Linear Program (ILP) based optimization model to minimize the energy consumption in the network by selecting appropriate functional split and baseband function placement options for RAN slices. We show that our proposed model outperforms the baseline strategies in providing energy efficient baseband function placement solution. To tackle the computational complexity of ILP, we also design a polynomial time heuristic algorithm that can be applied in large-scale scenarios.