The heterogeneity of use cases that next-generation wireless systems need to support calls for flexible and programmable networks that can autonomously adapt to the application requirements. Specifically, traffic flows that support critical applications (e.g., vehicular control or safety communications) often come with a requirement in terms of guaranteed performance. At the same time, others are more elastic and can adapt to the resources made available by the network (e.g., video streaming). To this end, the Open Radio Access Network (RAN) paradigm is seen as an enabler of dynamic control and adaptation of the protocol stack of 3rd Generation Partnership Project (3GPP) networks in the 5th Generation (5G) and beyond. Through its embodiment in the O-RAN alliance specifications, it introduces the Ran Intelligent Controllers (RICs), which enable closed-loop control, leveraging a rich set of RAN Key Performance Measurements (KPMs) to build a representation of the network and enforcing dynamic control through the configuration of 3GPP-defined stack parameters. In this paper, we leverage the Open RAN closed-loop control capabilities to design, implement, and evaluate multiple data-driven and dynamic Service Level Agreement (SLA) enforcement policies, capable of adapting the RAN semi-persistent scheduling patterns to match users requirements. To do so, we implement semi-persistent scheduling capabilities in the OpenAirInterface (OAI) 5G stack, as well as an easily extensible and customizable version of the Open RAN E2 interface that connects the OAI base stations to the near-real-time RIC. We deploy and test our framework on Colosseum, a large-scale hardware-in-the-loop channel emulator. Results confirm the effectiveness of the proposed Open RAN-based solution in managing SLA in near-real-time.

翻译：下一代无线系统需支持多样化用例，这要求网络具备灵活性与可编程性，能够自主适应应用需求。具体而言，支撑关键应用（如车辆控制或安全通信）的流量通常对性能保障有明确要求，而另一些弹性业务（如视频流）则可适应网络提供的资源。为此，开放无线接入网（RAN）范式被视为在第五代（5G）及未来网络中实现第三代合作伙伴计划（3GPP）协议栈动态控制与适配的关键技术。通过O-RAN联盟规范的具体实现，该范式引入了RAN智能控制器（RIC），其利用丰富的RAN关键性能测量指标（KPM）构建网络表征，并通过配置3GPP定义的协议栈参数实施闭环控制。本文利用开放RAN的闭环控制能力，设计、实现并评估了多种数据驱动的动态服务等级协议（SLA）执行策略，这些策略能够调整RAN半持续调度模式以匹配用户需求。为此，我们在OpenAirInterface（OAI）5G协议栈中实现了半持续调度功能，并开发了易于扩展与定制的开放RAN E2接口版本，该接口可连接OAI基站与近实时RIC。我们在大规模硬件在环信道仿真器Colosseum上部署并测试了该框架。结果证实，所提出的基于开放RAN的解决方案能够有效实现近实时的SLA管理。