Sharing gNB components in RAN slicing: A perspective from 3GPP/NFV standards

To implement the next Generation NodeBs (gNBs) that are present in every Radio Access Network (RAN) slice subnet, Network Function Virtualization (NFV) enables the deployment of some of the gNB components as Virtual Networks Functions (VNFs). Deploying individual VNF instances for these components could guarantee the customization of each RAN slice subnet. However, due to the multiplicity of VNFs, the required amount of virtual resources will be greater compared to the case where a single VNF instance carries the aggregated traffic of all the RAN slice subnets. Sharing gNB components between RAN slice subnets could optimize the trade-off between customization, isolation and resource utilization. In this article, we shed light on the key aspects in the Third Generation Partnership Project (3GPP)/NFV standards for sharing gNB components. First, we identify four possible scenarios for sharing gNB components. Then, we analyze the impact of sharing on the customization level of each RAN slice subnet. Later, we determine the main factors that enable isolation between RAN slice subnets. Finally, we propose a 3GPP/NFV-based description model to define the lifecycle management of shared gNB componentsComment: Article accepted for publication in IEEE Conference on Standards and Networking (CSCN) 201

Automated Network Service Scaling in NFV: Concepts, Mechanisms and Scaling Workflow

Next-generation systems are anticipated to be digital platforms supporting innovative services with rapidly changing traffic patterns. To cope with this dynamicity in a cost-efficient manner, operators need advanced service management capabilities such as those provided by NFV. NFV enables operators to scale network services with higher granularity and agility than today. For this end, automation is key. In search of this automation, the European Telecommunications Standards Institute (ETSI) has defined a reference NFV framework that make use of model-driven templates called Network Service Descriptors (NSDs) to operate network services through their lifecycle. For the scaling operation, an NSD defines a discrete set of instantiation levels among which a network service instance can be resized throughout its lifecycle. Thus, the design of these levels is key for ensuring an effective scaling. In this article, we provide an overview of the automation of the network service scaling operation in NFV, addressing the options and boundaries introduced by ETSI normative specifications. We start by providing a description of the NSD structure, focusing on how instantiation levels are constructed. For illustrative purposes, we propose an NSD for a representative NS. This NSD includes different instantiation levels that enable different ways to automatically scale this NS. Then, we show the different scaling procedures the NFV framework has available, and how it may automate their triggering. Finally, we propose an ETSI-compliant workflow to describe in detail a representative scaling procedure. This workflow clarifies the interactions and information exchanges between the functional blocks in the NFV framework when performing the scaling operation.Comment: This work has been accepted for publication in the IEEE Communications Magazin

Sharing gNB components in RAN slicing: A perspective from 3GPP/NFV standards

To implement the next Generation NodeBs (gNBs) that are present in every Radio Access Network (RAN) slice subnet, Network Function Virtualization (NFV) enables the deployment of some of the gNB components as Virtual Networks Functions (VNFs). Deploying individual VNF instances for these components could guarantee the customization of each RAN slice subnet. However, due to the multiplicity of VNFs, the required amount of virtual resources will be greater compared to the case where a single VNF instance carries the aggregated traffic of all the RAN slice subnets. Sharing gNB components between RAN slice subnets could optimize the trade-off between customization, isolation and resource utilization. In this article, we shed light on the key aspects in the Third Generation Partnership Project (3GPP)/NFV standards for sharing gNB components. First, we identify four possible scenarios for sharing gNB components. Then, we analyze the impact of sharing on the customization level of each RAN slice subnet. Later, we determine the main factors that enable isolation between RAN slice subnets. Finally, we propose a 3GPP/NFV-based description model to define the lifecycle management of shared gNB componentsThis work is partially supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (Project TEC2016-76795-C6-4-R)Spanish Ministry of Education, Culture and Sport (FPU Grant 17/01844)Andalusian Knowledge Agency (project ATIC-241-UGR18)

Analytical Model for the UE Blocking Probability in an OFDMA Cell providing GBR Slices

This work is partially supported by the H2020 research and innovation project 5G-CLARITY (Grant No. 871428); the Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund (Project PID2019-108713RB-C53); and the Spanish Ministry of Education, Culture and Sport (FPU Grant 17/01844).When a network operator designs strategies for planning and operating Guaranteed Bit Rate (GBR) slices, there are inherent issues such as the under(over)-provisioning of radio resources. To avoid them, modeling the User Equipment (UE) blocking probability in each cell is key. This task is challenging due to the total required bandwidth depends on the channel quality of each UE and the spatio-temporal variations in the number of UE sessions. Under this context, we propose an analytical model to evaluate the UE blocking probability in an Orthogonal Frequency Division Multiple Access (OFDMA) cell. The main novelty of our model is the adoption of a multi-dimensional Erlang-B system which meets the reversibility property. This means our model is insensitive to the holding time distribution for the UE session. In addition, this property reduces the computational complexity of our model due to the solution for the state transition probabilities has product form. The provided results show that our model exhibits an estimation error for the UE blocking probability below 3.5%.This work is partially supported by the H2020 research and innovation project 5G-CLARITY (Grant No. 871428)Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund (Project PID2019-108713RB-C53)Spanish Ministry of Education, Culture and Sport (FPU Grant 17/01844

Automated Network Service Scaling in NFV: Concepts, Mechanisms and Scaling Workflow

This work is partially supported by the Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund (Project TEC2016-76795-C6-4-R), the Spanish Ministry of Education, Culture and Sport (FPU Grant 16/03354), and the University of Granada, Andalusian Regional Government and European Social Fund under Youth Employment Program.Next-generation systems are anticipated to be digital platforms supporting innovative services with rapidly changing traffic patterns. To cope with this dynamicity in a cost-efficient manner, operators need advanced service management capabilities such as those provided by NFV. NFV enables operators to scale network services with higher granularity and agility than today. For this end, automation is key. In search of this automation, the European Telecommunications Standards Institute (ETSI) has defined a reference NFV framework that make use of model-driven templates called Network Service Descriptors (NSDs) to operate network services through their lifecycle. For the scaling operation, an NSD defines a discrete set of instantiation levels among which a network service instance can be resized throughout its lifecycle. Thus, the design of these levels is key for ensuring an effective scaling. In this article, we provide an overview of the automation of the network service scaling operation in NFV, addressing the options and boundaries introduced by ETSI normative specifications. We start by providing a description of the NSD structure, focusing on how instantiation levels are constructed. For illustrative purposes, we propose an NSD for a representative NS. This NSD includes different instantiation levels that enable different ways to automatically scale this NS. Then, we show the different scaling procedures the NFV framework has available, and how it may automate their triggering. Finally, we propose an ETSI-compliant workflow to describe in detail a representative scaling procedure. This workflow clarifies the interactions and information exchanges between the functional blocks in the NFV framework when performing the scaling operation.This work is partially supported by the Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund (Project TEC2016-76795-C6-4-R)Spanish Ministry of Education, Culture and Sport (FPU Grant 16/03354)University of Granada, Andalusian Regional Government and European Social Fund under Youth Employment Program

Handover Implementation in a 5G SDN-based Mobile Network Architecture

This work is partially supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (project TIN2013-46223-P), and the Spanish Ministry of Education, Culture and Sport (FPU grant 13/04833).Requirements for 5G mobile networks includes a higher flexibility, scalability, cost effectiveness and energy efficiency. Towards these goals, Software Defined Networking (SDN) and Network Functions Virtualization have been adopted in recent proposals for future mobile networks architectures because they are considered critical technologies for 5G. In this paper, we propose an X2-based handover implementation in an SDNbased and partially virtualized LTE architecture. Moreover, the architecture considered operates at link level, which provides lower latency and higher scalability. In our implementation, we use MPLS tunnels for user plane instead of GTP-U protocol, which introduces a significant overhead. To verify the correct operation of our system, we developed a simulator. It implements the messages exchange and processing of the primary network entities. Using this tool we measured the handover preparation and completion times, whose estimated values were roughly 6.94 ms and 8.31 ms, respectively, according to our experimental setup. These latencies meet the expected requirements concerning control plane delay budgets for 5G networks.This work is partially supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (project TIN2013-46223-P)Spanish Ministry of Education, Culture and Sport (FPU grant 13/04833

Harmonizing 3GPP and NFV Description Models: Providing Customized RAN Slices in 5G Networks

This work is partially supported by the Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund (Project TEC2016-76795-C6-4-R), the Spanish Ministry of Education, Culture and Sport (FPU Grant 17/01844), and the University of Granada, Andalusian Regional Government and European Social Fund under Youth Employment Program.The standardization of Radio Access Network (RAN) in mobile networks has traditionally been led by 3GPP. However, the emergence of RAN slicing has introduced new aspects that fall outside 3GPP scope. Among them, network virtualization enables the particularization of multiple RAN behaviors over a common physical infrastructure. Using Virtualized Network Functions (VNFs) that comprise customized radio functionalities, each virtualized RAN, denominated RAN slice, could meet its specific requirements. Although 3GPP specifies the description model to manage RAN slices, it can neither particularize the behavior of a RAN slice nor leverage the NFV descriptors to define how its VNFs can accommodate its spatial and temporal traffic demands. In this article, we propose a description model that harmonizes 3GPP and ETSI-NFV viewpoints to manage RAN slices. The proposed model enables the translation of RAN slice requirements into customized virtualized radio functionalities defined through NFV descriptors. To clarify this proposal, we provide an example where three RAN slices with disruptive requirements are described following our solution.This work is partially supported by the Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund (Project TEC2016-76795-C6-4-R)Spanish Ministry of Education, Culture and Sport (FPU Grant 17/01844)University of Granada, Andalusian Regional Government and European Social Fund under Youth Employment Program

5G Non-Public Networks: Standardization, Architectures and Challenges

his work was supported in part by the H2020 Project 5G-CLARITY under Grant 871428, and in part by the Spanish National Project TRUE-5G under Grant PID2019-108713RB-C53.Fifth Generation (5G) is here to accelerate the digitization of economies and society, and open up innovation opportunities for verticals. A myriad of 5G-enabled use cases has been identified across disparate sectors like tourism, retail industry, and manufacturing. Many of the networks of these use cases are expected to be private networks, that is, networks intended for the exclusive use of an enterprise customer. This article provides an overview of the technical aspects in private 5G networks. We first identify the key requirements and enabling solutions for private 5G networks. Then, we review the latest 3rd Generation Partnership Project (3GPP) Release 16 capabilities to support private 5G networks. Next, we provide architecture proposals for single site private networks, including the scenario in which the radio access network (RAN) is shared. Afterwards, we address mobility and multi-site private 5G network scenarios. Finally, we identify key challenges for private 5G networks.H2020 Project 5G-CLARITY 871428Spanish National Project TRUE-5G PID2019-108713RB-C5

The Creation Phase in Network Slicing: From a Service Order to an Operative Network Slice

This work is partially supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (Project TEC2016-76795-C6-4-R), the Spanish Ministry of Education, Culture and Sport (FPU Grant 16/03354), and the University of Granada, Andalusian Regional Government and European Social Fund under Youth Employment Program.—Network slicing is considered a key mechanism to serve the multitude of tenants (e.g. vertical industries) targeted by forthcoming 5G systems in a flexible and cost-efficient manner. In this paper, we present a SDN/NFV architecture with multitenancy support. This architecture enables a network slice provider to deploy network slice instances for multiple tenants on-the-fly, and simultaneously provision them with isolation guarantees. Following the Network Slice as-a-Service delivery model, a tenant may access a Service Catalog, selecting the slice that best fits its needs and ordering its deployment. This work provides a detailed view on the stages that a network slice provider must follow to deploy the ordered network slice instance, accommodating it into a multi-domain infrastructure, and putting it operative for tenant’s consumption. These stages address critical issues identified in the literature, including (i) the mapping from high-level service requirements to network functions and infrastructure requirements, (ii) the admission control, and (iii) the specific information a network slice descriptor should have. With the proposed architecture and the recommended set of stages, network slice providers can deploy (and later operate) slice instances with great agility, flexibility, and full automation.This work is partially supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (Project TEC2016-76795-C6-4-R)Spanish Ministry of Education, Culture and Sport (FPU Grant 16/03354)University of Granada, Andalusian regional Government and European Social Fund under Youth Employment Program