1 Resource Sharing for a 5G Multi-tenant and Multi-service Architecture Marcos Rates Crippa ∗ , Paul Arnold † , Vasilis Friderikos ‡ , Borislava Gajic § , Carmen Guerrero ¶ , Oliver Holland ‡ , Ignacio Labrador ‖ , Vincenzo Sciancalepore ∗∗ , Dirk von Hugo † , Stan Wong ‡ , Faqir Zarrar Yousaf ∗∗ , Bessem Sayadi § ∗ University of Kaiserslautern † Deutsche Telekom Technology Innovation ¶ Universidad Carlos III de Madrid § Nokia Bell–Labs ‡ King’s College London ‖ Atos Research and Innovation ∗∗ NEC Europe Ltd. Abstract—As the next generation networks (5G) move into a direction of virtualization and softwarization, using technologies like Software-Defined Networking (SDN) and Network Function Virtualization (NFV), one of the main benefits is the possibility of network resource sharing among different tenants and service providers. This paper focuses on how the architecture of the 5G NORMA project will tackle the issue of resource sharing. Two main areas will be explored: how to achieve efficient resource sharing among network slices, and specific solutions used by the architecture to allow for resource sharing. Index Terms—NFV; SDN; Orchestration; 5G networks; Re- source Sharing; MANO; Network Slicing I. I NTRODUCTION T HE future 5G networks are expected to rely on soft- warization and virtualization of network elements and functions to support flexible and heterogeneous deployment of different services. This deployment could be on the same infrastructure, with services as diverse as Internet of Things (IoT) and Vehicular Networking expected to efficiently share the network resources. A re-engineering of the current 3GPP architecture is necessary, in order to add the flexibility to support diverse services with diverge requirements. One aspect of this re-engineering is to design efficient resource sharing among different tenants, operators and network slices. Network slicing [1] is one innovation 5G NORMA [2] uses to enable the future 5G networks. A network slice can be broadly defined as an end-to-end logically isolated virtual network that includes access, transport and core network functions. In general, these network functions can also be shared between different slices based on pre-defined policies and business criteria. An abstraction of different hardware in- frastructures into a logical virtual network is necessary to allow for this sharing. Various virtual network functions (VNFs), created by the decomposition of network elements, will op- erate in this logical network. Deploying separate hardware infrastructures for each service would not be a cost effective way for efficient resource sharing among multiple tenants. On the other hand, network slices can be instantiated as a mix of dedicated and shared resources (such as transmission points, radio resources, transport and fronthaul capacity, potentially IT This research work has been performed in the framework of H2020-ICT- 2014-2 project 5G NORMA. The authors would like to acknowledge the contributions of their colleagues, although the views expressed are those of the authors and do not necessarily represent the project. resources, for instance), allowing for multi-service and multi- tenant networks. This paper focuses on the 5G NORMA approach to shared resource management between network slices in its 5G ar- chitecture, as well as technical solutions aiming at providing the architecture with tools for resource sharing. Initially, an overview of the 5G NORMA architecture is given. Follow- ing that, the challenges of sharing resources across network slices are described. The different proposed technical solutions addressing this issue in 5G NORMA are listed and detailed next. Finally, a brief discussion of the relationship between the SDM-C and SDM-X components of the 5G NORMA architecture concludes the paper. II. THE 5G NORMA ARCHITECTURE To build a flexible and adaptable mobile network archi- tecture capable of supporting a wide variety of services and their respective requirements, 5G NORMA has introduced a novel paradigm: a network-of-functions-based architecture. This novel paradigm breaks the design principle followed by current network architectures, which are built around enti- ties rather than functions. Our revolutionary approach builds on new technologies, such as Software-Defined Networking (SDN) and Network Function Virtualization (NFV), in con- junction with novel concepts such as the network slicing and multi-tenancy. More details on the relationship between slices and tenants can be found in [13]. This section presents a brief description of the architectural concepts of 5G NORMA related to its various controllers’ design and specification, mobility management, and network slice management. Three different controllers are considered in the architecture, namely the Software Defined Mobile Network Controller (SDM-C), the Software Defined Mobile Network Coordinator (SDM- X), and the Software Defined Mobile Network Orchestrator (SDM-O) as a part of the MANO framework. We refer the interested reader to [2] for further details. Figure 1 presents a functional overview of the 5G NORMA architecture. These functional blocks will be referred in the subsequent sections. A. SDM-C The SDM-C applies the same principles of the current Software-Defined Networking (SDN) to wireless functionality beyond routing. Indeed, the benefits of this technology when