Conference Paper

FlexVRAN: A Flexible Controller for Virtualized RAN Over Heterogeneous Deployments

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... Inter-Slice Scheduler Intra- [15,16]. (b) QoS Isolation used in [17][18][19]. ...
... Another approach is the QoS-level isolation [17][18][19] schematically presented in Figure 1b. Here, the tenant creates or modifies the slice with an intra-slice resource allocator, describes the clients' QoS requirements, and distributes its channel resources between them. ...
Article
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Network slicing is considered a key feature of 5G and beyond cellular systems. It opens the door for new business models of mobile operators, enables new services, reduces costs with advanced infrastructure-sharing techniques, and improves heterogeneous traffic service. With slicing, the operators can tailor the network resources to the requirements of specific verticals, applications, and corresponding traffic types. To satisfy the heterogeneous quality of service (QoS) requirements of various slices, efficient virtualization and resource allocation algorithms are required. Such algorithms are especially crucial for the radio access network (RAN) because of the spectrum scarcity. This article develops DeSlice, a novel architecture for RAN slicing. DeSlice enables efficient real-time slicing algorithms that satisfy heterogeneous QoS requirements of the slices and improve the quality of experience for their end users. The article illustrates the advantages of DeSlice by considering the problem of the joint service of cloud VR, video, and web traffic. It develops the algorithms using DeSlice architecture and application-to-network communication. With simulations, it shows that, together, the architecture and the algorithms allow greatly improving the QoE for these traffics significantly.
... Moreover, an interesting dynamic end-to-end slicing testbed has been proposed in [15]. In such a testbed, efficient multiservice RAN slice management and orchestration is enabled by automatically adding core networks according to the slice owner's requirements, while a flexible slicing controller for virtualized RAN over heterogeneous deployments has been proposed in [16]. ...
... Moreover, differently from [14], [15], [16], we mainly focus on evaluating the impact of slicing for enabling a more flexible RAN sharing approach from an operator perspective. Our goal is to evaluate if slicing could be employed to add more flexibility in MOCN scenarios, while guaranteeing the same level of isolation provided by MORAN approaches. ...
Conference Paper
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In this paper, we present an open source Radio Access Network (RAN) sharing prototype, based on Open Air Interface (OAI) platform, which employs slicing features provided by an open source RAN controller, known as FlexRAN. Accordingly, this paper analyzes the benefits of employing network slicing in the RAN to introduce more flexibility in the configuration of RAN sharing architectures. The contribution of this paper is twofold. Firstly, we propose a flexible RAN sharing architecture where a specific radio slice is allocated to each operator that shares the same RAN, while considering specific Service Level Agreement (SLA) constraints. Secondly, we validate the proposed architecture via a simple radio resource allocation algorithm, which enables dynamic creation and configuration of radio slices, making it possible to transform on-the-fly a “Multi-Operator Core Network” (MOCN) sharing scenario, wherein the spectrum is shared by multiple operators, into a “Multi-Operator RAN” (MORAN) scenario, wherein the spectrum is isolated among the operators that share the same RAN. Emulation results show that the employment of the proposed algorithm enables a more flexible allocation of the radio resources among the sharing operators, providing better performance in terms of end-to-end latency and throughput compared to a static RAN sharing approach.
... Virtualized controller LB using the slices technique is based on SDN network virtualization [48]. ...
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The development of the Internet and smart end systems, such as smartphones and portable laptops, along with the emergence of cloud computing, social networks, and the Internet of Things, has brought about new network requirements. To meet these requirements, a new architecture called software-defined network (SDN) has been introduced. However, traffic distribution in SDN has raised challenges, especially in terms of uneven load distribution impacting network performance. To address this issue, several SDN load balancing (LB) techniques have been developed to improve efficiency. This article provides an overview of SDN and its effect on load balancing, highlighting key elements and discussing various load-balancing schemes based on existing solutions and research challenges. Additionally, the article outlines performance metrics used to evaluate these algorithms and suggests possible future research directions.
... Controllers for virtualized RANs and abstractions among the physical and virtual infrastructure are discussed by Schmidt et al. [36]. Moorthy et al. study the virtualization of control-plane functionalities [37]. ...
Preprint
Obtaining access to exclusive spectrum, cell sites, Radio Access Network (RAN) equipment, and edge infrastructure requires major capital expenses for mobile network operators. A neutral host infrastructure, where a third-party company provides RAN services to mobile operators through network virtualization and slicing techniques, is seen as a promising solution to decrease these costs. Currently, however, neutral host providers lack automated and virtualized pipelines for onboarding new tenants and to provide elastic and on-demand allocation of resources matching operator's demands. To address this gap, this paper presents NeutRAN, a zero-touch framework based on the O-RAN architecture to support applications on neutral hosts and automatic operator onboarding, that enables multiple tenants to access a shared RAN infrastructure. The NeutRAN architecture builds upon two key components: (i) an optimization engine to guarantee coverage and meet quality of service requirements while accounting for the limited amount of shared spectrum and RAN nodes, and (ii) a fully virtualized and automated infrastructure that converts the output of the optimization engine into deployable micro-services to be executed at RAN nodes and cell sites. NeutRAN was prototyped on an OpenShift cluster and on a programmable testbed with 4 base stations and 10 users from 3 different tenants. We evaluated the benefits of NeutRAN compared to a traditional license-based RAN where each tenant has dedicated physical and spectrum resources. Experimental results show that NeutRAN can deploy a fully operational neutral host-based cellular network in around 10 seconds, and it increases the cumulative network throughput by 2.18x and the per-user average throughput by 1.73x with shared spectrum blocks of 30 MHz.
... A number of prototypes have been proposed in the literature to address the challenges imposed by sliced 5G networks. In view of this, authors in [1] described how to use FlexRAN [2] and OpenAirInterface (OAI) [3] to deploy a Cloud Radio Access Network (C-RAN) architecture in an automated and virtualized way. Authors in [4] described their experience building a 5G prototype that uses dynamic network slicing for Internet of Things (IoT) and Enhanced Mobile Broadband (eMBB) services. ...
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Network slicing, where a single physical network is partitioned into several fit-for-purpose virtual networks with different degrees of isolation and quality of service (QoS), is a key enabler of 5G and beyond mobile networks. However, it is prone to security threats such as Distributed Denial-of-Service (DDoS) attacks. In this paper, we propose a solution based on Deep Learning (DL) that detects such attacks, and then creates a sinkhole-type slice with a small portion of physical resources to isolate and mitigate the attackers' action. Using our 5G prototype based on OpenAirInterface, we evaluate our approach by comparing several DL models in terms of detection accuracy, false positive rate, execution time, among other Machine Learning-related metrics. We also assess the performance of created 5G network slices in terms of benign/malicious users' throughput, as well as the processing time during the slicing operations. Results show that our approach is able to detect DDoS attacks in a timely manner with an accuracy of almost 97% and a false positive rate of less than 4%. We also show that our approach decreases the network throughput for the malicious users by a factor of 15, while maintaining a high network throughput for benign users.
... Following a similar approach, Papa et al. study the combination of functional split and network slicing in [51]. From a more generic perspective, the authors of [52] propose a framework to handle heterogeneous RAN, functional split selection, and network slicing for multiple services. Finally, the authors of [53] consider split selection together with task offloading, analyzing the interplay of functional split and fog/cloud services. ...
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We study the delay over virtual RAN (vRAN) topologies, entailing base stations that are divided into centralized and distributed units, as well as the packet-switched fronthaul network that connects them. We consider the use of flexible functional split, where the functions that are executed at each of these two entities can be dynamically shifted. We propose a queuing-based model, which is able to precisely mimic the behavior of such nodes, and we validate it by means of extensive simulations. We also exploit Jackson Networks theory to establish the end-to-end delay over the fronthaul network, allowing us to assess the impact of having different networking policies and conditions (for instance, background traffic or heterogeneous technologies). Thanks to the simulator we can also broaden the analysis, by studying the delay variability. In addition, we conduct an in-depth analysis of the performance exhibited by a realistic network setup, whose particular characteristics might hinder the services performance, due to the longer dwell times at each split configuration. The results evince the validity of the proposed model, even under realistic conditions. We show that it might not be enough to guarantee an average stable operation of the centralized/distributed units, but the traffic load should remain below the slowest service rate, to avoid reaching unacceptable delays. An increase of > 100× is observed in the delay, using the realistic network setup, when these conditions do not hold.
... Such approaches have been enabled through the wide application of softwarization for the different network functions, applied even for the Radio Access Network (RAN), and the disaggregation of previous monolithic components (e.g. the cellular core network and the RAN base stations) to separate functions. Efforts like OpenRAN (O-RAN) [1], Software Defined RAN (SD-RAN) [2] and FlexRAN [3] take advantage of such functionalities, and build on them for providing the network operators with advanced functions for the on-the-fly network re-configuration and slicing. In this manner, the network can be dynamically and even autonomously adjusted [4] in an endto-end manner, based on the actual load that it is experiencing, allowing the transition to self-managed and organized 6G networks. ...
Conference Paper
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Cloud-native approaches for network functions in the 5G context have been embraced by the community, as they allow flexible management, reconfiguration and monitoring of the network in an end-to-end manner. As network softwarization extends to the RAN, empowered through the cellular stack disaggregation, even base station components can be executed as a cloud-native service. As low latency access is needed in the 5G and beyond networks for serving ultra Reliable Low Latency Communications, Multi-Access Edge Computing (MEC) needs to be integrated in the overall architecture. As the user moves among different RANs, the latency of accessing the service needs to be preserved for providing users with a seamless experience. To accomplish such behavior, migrations of the hosted services are needed, though not fully compatible with the cloud-native approach, and placing them closer to the network access point of the user. In this work, we experiment with a cloud-native end-to-end network, enhanced with Follow-me MEC functionalities. Heterogeneous access is provided at the RAN level, using disag-gregated base stations, and MEC is integrated on the fronthaul of the network, ensuring low-latency access to services. The entire network is instantiated in a cloud-native manner, using a widely adopted container orchestration solution. Our results show that the scheme is able to provide low latency access to the hosted services, while the UE remains agnostic of the entire process and without any drops of the already established connections.
... Resource allocation has recently received significant attention as it is one of the pivot ideas around the slicing concept [36] [37] [38]. Unfortunately, most literature about slicing discusses the resource allocation problem without considering 5G's packet-switched network nature (e.g., segmentation problem where the information is not forwarded unless all the fragments are reassembled), or 5G's RB distribution peculiarities (e.g., RBG). ...
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The 3rd Generation Partnership Project (3GPP) is investing a notable effort to mitigate the endogenous stack and protocol delays (e.g., introducing new numerology, through preemptive scheduling or providing uplink granted free transmission) to attain to the heterogeneous Quality of Service (QoS) latency requirements for which the fifth generation technology standard for broadband cellular networks (5G) is envisioned. However, 3GPP’s goals may become futile if exogenous delays generated by the transport layer (e.g., bufferbloat) and the Radio Link Control (RLC) sublayer segmentation/reassembly procedure are not targeted. On the one hand, the bufferbloat specifically occurs at the Radio Access Network (RAN) since the data path bottleneck is located at the radio link, and contemporary RANs are deployed with large buffers to avoid squandering scarce wireless resources. On the other hand, a Resource Block (RB) scheduling that dismisses 5G’s packet-switched network nature, unnecessarily triggers the segmentation procedure at sender’s RLC sublayer, which adds extra delay as receiver’s RLC sublayer cannot forward the packets to higher sublayers until they are reassembled. Consequently, the exogenously generated queuing delays can surpass 5G’s stack and protocol endogenous delays, neutralizing 3GPP’s attempt to reduce the latency. We address RLC’s related buffer delays and present two solutions: (i) we enhance the 3GPP standard and propose a bufferbloat avoidance algorithm, and (ii) we propose a RB scheduler for circumventing the added sojourn time caused by the packet segmentation/reassembly procedure. Both solutions are implemented and extensively evaluated along with other state-of-the-art proposals in a testbed to verify their suitability and effectiveness under realistic conditions of use (i.e., by considering Modulation and Coding Scheme (MCS) variations, slices, different traffic patterns and off-the-shelf equipment). The results reveal current 3GPP deficits in its QoS model to address the bufferbloat and the contribution of the segmentation/reassembly procedure to the total delay.
... • Prototype: We contribute a prototype SDK implementation, namely ElasticSDK v1.0, which cooperates fully with ElasticSearch (ES) distributed search and analytics engine and Mosaic5G FlexRAN platform [8], [9]. Due to the SDK abstraction, ElasticSDK v1.0 remains applicable to other underlying platforms and can be extended to cover the CN, as well. ...
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Driven by the need to cope with exponentially growing mobile data traffic and to support new traffic types from massive numbers of machine-type devices, academia and industry are thinking beyond the current generation of mobile cellular networks to chalk a path towards fifth generation (5G) mobile networks. Several new approaches and technologies are being considered as potential elements making up such a future mobile network, including cloud RANs, application of SDN principles, exploiting new and unused portions of spectrum, use of massive MIMO and full-duplex communications. Research on these technologies requires realistic and flexible experimentation platforms that offer a wide range of experimentation modes from real-world experimentation to controlled and scalable evaluations while at the same time retaining backward compatibility with current generation systems. Towards this end, we present OpenAirInterface (OAI) as a suitably flexible platform. In addition, we discuss the use of OAI in the context of several widely mentioned 5G research directions.
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Heterogeneous mobile networks, HMNs, with flexible spectrum use, densified cell deployment, and multi-layer multiple types of radio access technologies, are expected to be key to meeting the 1000 times increase of mobile data traffic in 2020 and beyond. The increasing complexity in HMNs renders the control and coordination of networks a challenging task. The control frameworks of current cellular networks, which were previously designed for sparse network deployment, hit the wall for HMNs. HMNs need good separation of control and data planes, and call for novel control methods to handle the highly complex dynamics therein. In this article, we first briefly review the control planes of 2G to 4G cellular networks, and then identify their constraints to support HMNs. We analyze the complexity in HMNs and examine enabling control technologies for HMNs. We believe new thinking is needed for efficient control of HMNs. SDN is a promising technology to solve complex control problems in the Internet. Principle-based control methods applied in SDN are promising to solve control problems in HMNs. Several SDN approaches have been proposed for mobile networks. However, most of them are targeted at mobile core networks. We propose an SDNbased control framework named SoftMobile to coordinate complex radio access in HMNs. The main features of SoftMobile are low-layer abstraction, separation of control and data planes, and network-wide high-layer programmable control. Important research problems in SDN for mobile networks are highlighted. We believe SDN for mobile networks will be the controlling evolution of future HMNs.
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With the rapid growth of the demands for mobile data, wireless network faces several challenges, such as lack of efficient interconnection among heterogeneous wireless networks, and shortage of customized QoS guarantees between services. The fundamental reason for these challenges is that the radio access network (RAN) is closed and ossified. We propose OpenRAN, an architecture for software-defined RAN via virtualization. It achieves complete virtualization and programmability vertically, and benefits the convergence of heterogeneous network horizontally. It provides open, controllable, flexible and evolvable wireless networks.
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An important piece of the cellular network infrastructure is the radio access network (RAN) that provides wide-area wireless connectivity to mobile devices. The fundamental problem the RAN solves is figuring out how best to use and manage limited spectrum to achieve this connectivity. In a dense wireless deployment with mobile nodes and limited spectrum, it becomes a difficult task to allocate radio resources, implement handovers, manage interference, balance load between cells, etc. We argue that LTE's current distributed control plane is suboptimal in achieving the above objective. We propose SoftRAN, a fundamental rethink of the radio access layer. SoftRAN is a software defined centralized control plane for radio access networks that abstracts all base stations in a local geographical area as a virtual big-base station comprised of a central controller and radio elements (individual physical base stations). In defining such an architecture, we create a framework through which a local geographical network can effectively perform load balancing and interference management, as well as maximize throughput, global utility, or any other objective.
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Network virtualization is receiving immense attention in the research community all over the world. There is no doubt that it will play a significant role in shaping the way we do networking in the future. There have been different approaches to virtualize different aspects of the network: some are focusing on resource virtualization like node, server and router virtualization; while others are focusing on building a framework to set up virtual networks on the fly based on different virtual resources. Nevertheless, one very important piece of the puzzle is still missing, that is “Wireless Virtualization”. The virtualization of the wireless medium has not yet received the appropriate attention it is entitled to, and there have only been some early attempts in this field. In this paper a general framework for virtualizing the wireless medium is proposed and investigated. This framework focuses on virtualizing mobile communication systems so that multiple operators can share the same physical resources while being able to stay isolated from each other. We mainly focus on the Long Term Evolution (LTE) but the framework can also be generalized to fit any other wireless system. The goal of the paper is to exploit the advantages that can be obtained from virtualizing the LTE system, more specifically virtualizing the air interface (i.e. spectrum sharing). Two different possible gain areas are explored: spectrum multiplexing and multi-user diversity. KeywordsLTE virtualization–future internet
OpenAirInterface: A flexible platform for 5G research
  • N Nikaein
OpenRAN: A software-defined RAN architecture via virtualization
  • M Yang