TC-RAN: A programmable traffic control service model for 5G/6G SD-RAN

Irazabal, Mikel; Nikaein, Navid
IEEE Journal on Selected Areas in Communications, Vol.42, N°2, February 2024

Driven by the key principles of open interfaces, virtualization and programmability, Open RAN has emerged as a new paradigm to evolve contemporary Radio Access Networks (RANs) into a more vendor-agnostic, softwarized, and intelligent ecosystem. To this end, Software Defined RAN (SD-RAN) initiatives (e.g., O-RAN) are drafting specifications to provide the means to embrace it. However, even though O-RAN following the Open RAN paradigm specifies Service Models (SMs) to monitor
and control the RAN, it does not go beyond the Quality of Service (QoS) mechanisms provided by 3GPP. Therefore, the QoS degradation that occurs mostly due to data flow’s nature at the slowest data path link (e.g., high L2 sublayers), is not addressed
by contemporary O-RAN SMs. In this paper, we present a traffic control system for SDRAN, denoted as TC-RAN, that consists of an E2 service Model (E2SM) and a RAN Function (RF) that adheres to the Open RAN principles and promotes data flows to first-class citizens in cellular networks, upgrading contemporary 5G QoS mechanism. TC-RAN introduces a 6 programmable, extendable, and customizable
pipeline composed of a classifier, a policer, a queue, a scheduler, a shaper and a pacer. Additionally, TC-RAN addresses QoS degradation scenarios unsolvable through Resource Block (RB) allocation or 3GPP slicing mechanisms, unleashing the true
potential for deploying extremely demanding applications and creating a green field for AI/ML cross-optimization algorithms on the road to 6G. We prototype and validate TC-RAN in a real 5G Stand Alone (SA) RAN stack using an O-RAN compatible near
Real-Time Radio Intelligent Controller (nearRT-RIC), xApps, and Commercial off-the-shelf (COTS) User Equipments (UEs). The results show that intelligently composing a TC-RAN pipeline in cellular networks can considerably reduce the latency, notably
enhancing the Quality of Experience (QoE) in a real multiplayer online game.

Systèmes de Communication
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