Conference Paper

SDRBench: A Software-Defined Radio Access Network Controller Benchmark

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Abstract

Software-Defined Networking (SDN) has been identified as a key enabler for 5G networks to enhance the network capabilities by introducing flexibility and programmability. While SDN has been widely exploited in the core network side, it still remains an open research question in the Radio Access Network (RAN). Initial works highlight the benefits of SDN in RAN and investigate the idea of separating the control plane from the data plane of the Base Stations (BS) by means of SDN. The pioneer Software-Defined RAN (SD-RAN) controllers are available, nonetheless there exist no tools which can shed light on their performance and help to understand their limitations. We introduce SDRBench, a novel SD-RAN controller benchmark tool to fill this void. In this work, we evaluate FlexRAN, which is the first open source SD-RAN platform. In our tool, a Python-based instance of a FlexRAN agent is created and it communicates messages with the controller according to the FlexRAN protocol. The benchmark is used to uncover the limits of the SD-RAN controller.

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... First, there is a range of specialized controllers that might be built on top of the SDK. For instance, it has been shown that SD-RAN controllers optimized for real-time operation are not scalable enough for the large number of devices expected for 5G [125], [126]. Distributed controllers have shown to increase scalability for (wired) SDN networks [127], [128]. ...
Thesis
5G networks are envisioned to be a paradigm shift towards service-oriented networks. In this thesis, we investigate how to efficiently combine slicing and SD-RAN to provide the required level of flexibility and programmability in the RAN infrastructure to realize service-oriented multi-tenant networks. First, we devise an abstraction of a base station to represent logical base stations and describe a virtualized network service. Second, we propose a novel standard-compliant SD-RAN platform, named FlexRIC, in the form of a software development kit (SDK). Third, we provide a modular design for a slice-aware MAC scheduling framework to efficiently manage and control the radio resources in a multi-service environment with quality-of-service (QoS) support. Finally, we present a dynamic SD-RAN virtualization layer based on the FlexRIC SDK and MAC scheduling framework to flexibly compose a multi-service SD-RAN infrastructure and provide programmability for multiple SD-RAN controllers.
... To overcome the aforementioned issues, in this paper we address the question of SD-RAN control plane design impact on the UE QoS performance. We develop a 5G simulator that contains the SD-RAN control plane messages and models controllers' behavior, based on measurements conducted with open-source SD-RAN controllers [9], [11], [12]. With the help of our simulator, we provide insights on distributed and centralized SD-RAN control plane effects on UE QoS considering metrics such as throughput, packet loss ratio and average packet delay. ...
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Next generation radio access networks (RANs) envision softwarization and programmability as the main tools to provide the quality of service (QoS) requirements of emerging applications. Consequently, software-defined radio access networks (SD-RANs) have gained increased traction as a technology to foster network management and alleviate orchestration. While there exist SD-RAN architecture concepts both with single and multiple SD-RAN controllers, currently developed prototypes only include a single controller. Such a design may be sufficient for a low number of managed devices, for instance below 50. When the number of devices increases beyond 300, the controller performance deteriorates. A distributed control plane provides a solution, but renders the management in the control plane complex and incurs additional overhead, for instance control handover. In this way, both single controller and distributed control plane approaches may have a negative impact on a user's QoS. Yet, proper evaluations are missing and therefore the performance remains unclear. In order to investigate the effect of SD-RAN control plane on the user performance, in this work, we provide an extensive evaluation based on a 5G simulator, compliant with 3GPP standardization, as well as measurements with open-source SD-RAN controllers. Based on our simulator, we are able to demystify the user QoS depending on the control plane design choices. Our results demonstrate that having a distributed control plane with control handovers improves the user performance by at least 20% in terms of throughput, 5x regarding the packet loss ratio and 140% in terms of delay compared to a single controller approach. This confirms that the benefits of multiple controllers surpass the overhead caused by more complicated management.
... Intuitively, the signaling overhead is affected by the number of slices, users of a slice and gNBs that the RANCF is controlling as well as the size and frequency of control message updates. Initial benchmark of FlexRAN SD-RAN controller is provided in [14], where the impact of controlling multiple gNBs is presented with respect to memory, CPU consumption and slice initiation time. Even though users are not present in the current version of the benchmarking tool, an insight of signaling overhead is provided for the impact of the underlying network on SD-RAN controllers. ...
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