Fronthaul-Aware Scheduling Strategies for Next Generation RANs

Abstract

Next generation Radio Access Networks (RANs) consider virtualized architectures in which base station functions are distributed in different logical nodes, connected through fronthaul (FH) links. To reduce the FH deployment costs and the required FH capacity, operators may install a single FH link shared among multiple cells and exploit key enabling techniques, such as modulation compression, to decrease the data rates over the FH. In shared FH capacity scenarios, it is essential to provide efficient methods to control and optimize the FH resources' utilization with limited impact on the air interface performance. In this paper, we propose and analyze different fronthaul-aware scheduling strategies, leveraging on modulation compression, for multi-cell multi-user scenarios with a shared FH link across multiple cells. We consider holistic approaches based on packet dropping at the PHY layer and postponing of MAC scheduling decisions, combined with the reduction of the modulation order per cell. Additionally, we propose optimization methods for resource allocation and dynamic modulation compression, in which the modulation order and resource block assignment is dynamically optimized per user and slot. We finally evaluate the proposed FH-aware scheduling methods over an end-to-end dynamic 5G NR system-level simulator based on ns-3.