5G Architecture Design Verification

Heinz Droste (Deutsche Telekom AG)

The main goal of the 5GPPP project 5G NORMA (Novel Radio Multiservice adaptive network Architecture) is to propose a multi-service mobile network architecture that adapts the use of the mobile network resources to the service requirements, the variations of the traffic demands over time and location, and the network topology. Basics of those novel 5G architectures can be found in [1, chapter 3].

5G NORMA key innovations are

  • Adaptive (de)composition and allocation of mobile network functions to optimize performance on a per-service and per-scenario basis
  • Multi-service and context-aware adaptation of network functions to efficient support of multiple services
  • Mobile network multi-tenancy to reduce deployment and operational costs (CAPEX and OPEX)
  • Software-based mobile network control to allow flexible operation and
  • Pooling of network functions for joint optimization of mobile access and core network functionalities in order to achieve significant performance improvements.

At the beginning of the project, use cases have been defined that, with their related requirements, help on the definition of the 5G NORMA architecture, as well as proposing scenarios combining several uses cases that, all together, challenge the key innovations that 5G NORMA claims. In order to meet all requirements during project runtime, a two-step architecture design iteration is executed.

Verification Methodology

Each architecture design iteration is accompanied by comprehensive verification activities that check fulfillment of different requirements from system point of view based on generic 5G services as defined in METIS [2].

Applied evaluation criteria are depicted in Figure 1.

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Figure 1: 5G NORMA Evaluation criteria.

Arranging the verification of requirements and KPIs, more tangible roll out case studies have been defined that provide a link between evaluations on technical and economic feasibility. In addition, these roll out case studies may reveal potential show stoppers and challenges that become visible when putting the developed system into practice. For a typical urban sample area in London, three so-called evaluation cases have been created. A baseline evaluation case emulates the development of extended mobile broadband (eMBB) radio access networks (RAN) in the sample area for the time span between 2020 and 2030. A multi-tenant evaluation case expands the view from one up to four mobile operators and identifies benefits of 5G NORMA multi-tenant compared to single operator networks. Finally, a multi-service evaluation case adds to the sample RAN network slices for massive machine type communications (mMTC) and vehicular to anything communications (V2X) that includes ultra-reliable low latency services (URLLC). At current design iteration intermediate verification results for eMBB performance, functional, operational and security requirements as well as soft-KPI fulfillment are compiled in [3].

Intermediate results

Performance requirements for eMBB incorporate peak data rates, different kind of transmission latencies, network capacity, and network behavior at increasing device velocity (mobility). Some of these requirements (e.g. peak data rates and mobility) are not in scope of 5G NORMA and respective performance results have to be collected from other research projects. The baseline evaluation case revealed that most of the MBB traffic in future as in the past will be carried by WiFi. Nevertheless future spectrum extensions at macro sites will lead to bottlenecks with antenna panel deployment that could hopefully be mitigated by 5G NORMA multi-tenant bare-metal sharing.

Network capacity is measured as data volume that the network is capable to carry during the busy hour. We could show that under realistic assumptions and an assumed annual increase of traffic densities by 20%, macro cells with their limited spectrum efficiency would not be able to provide sufficient capacity to cope even with this moderate traffic growth. Hence small cell layers at lower and high frequency bands will be needed. Because of limited line-of-sight cell ranges the contribution by small cell layers at high frequency bands will be limited by their capability to offload the macro layer. Hence, it can be concluded that from capacity perspective there is no need for spectrum efficiency improvements for mmW radio nodes.

Many of the functional requirements identified for the generic 5G services are already fulfilled at the current stage of 5G NORMA design iteration [3]. Further, since selected requirements, e.g., functionality for controlling device networks, ability to keep track of devices, and ability to discover the topology of vehicular-to-vehicular (V2V) networks are rather in the scope of other 5G-PPP projects, 5G NORMA will consolidate an overview of possible solutions in the final report.

According to [4], the considered operational requirements up to now are mainly related to deployment of multi-tenant and multi-service networks. Enablers for multi-tenant dynamic resource allocation, service specific and context aware adaptation and placement of network functions as well as dynamic network monitoring are or will be investigated until the end of the project.

Assessing the threats and risks present in a complex system and the compliance with security requirements of the system is a difficult task and can must be done by (partially subjective) expert assessments rather than by formal verification. Regarding tenant isolation, there exist the usual risks that tenant SLAs and data confidentiality, integrity, and availability are violated. In addition, tenants must trust their mobile service providers (MSP), and MSP must trust potential third-party infrastructure providers (InP) that the functions hosted byt external platforms are secured appropriately. Besides, new security concepts described in [3] and novel concepts provided by the research community as a whole may be integrated into 5G NORMA architecture.

Check of ‘Soft-KPIs’ in general shall make sure that results of the architecture design are mature for implementation. In our verification, we could prove that interfaces between service management and management and orchestration are able to carry all information needed for automated processing of service deployment requests according to so called offer types. Offer types distinguish between the degrees of service control that is exposed to a tenant. Verification of scalability of centrally arranged management and control functions builds on methods used to evaluate scalability of SDN controllers. Further, the introduction of several network instances (so-called network slices) increases complexity, e.g., by multiplying many of the existing network operability processes. While this aspect can be tackled by increased levels of automation, the number of feasible network slices is rather going to be limited by the scarce bottleneck resources (e.g. spectrum, backhaul capacity) [5]..

Next steps

Topics to be addressed until the end of the project are listed in the table below.

Topics identified for next architecture design iteration phase.
Topic Check of fulfilment of
Update of performance requirements (mMTC, V2X, e2e latency) Performance requirements
Multi-connectivity Performance requirements
Opportunities for RAN sharing (virtual, bare metal & spectrum resources) Operational requirements
Backhaul aspects Operational requirements
Adaptation and placement of virtual network functions (VNFs) Operational requirements
Investigation of network programmability Functional requirements
Investigation of QoE based routing and network agility Functional requirements
Investigation of Edge function mobility Functional requirements
Assessment of mobility concepts Functional requirements
Protocol overhead analysis Functional requirements
Reliability concepts, reliability prediction Functional requirements
Update of security requirements Security requirements
Internal and external interfaces, comparison 4G/5G interfaces Soft KPI
Demonstrator learnings Soft KPI
Trial runs implementing multi-tenant and multi-service networks Soft KPI
Economic evaluations (WP2 part of verification) Economic feasibility

References

[1] A. Osseiran, J. F. Monserrat and P. Marsch, “5G mobile and wireless communications technology,” Cambridge University Press, 2016.

[2] METIS D6.6 “Final report on the METIS 5G system concept and technology roadmap,” ICT-317669 METIS Deliverable 6.6, Version 1, May 2014

[3] EU H2020 5G NORMA, “D 3.2: 5G NORMA network architecture – Intermediate report”, Jan. 2017

[4] EU H2020 5G NORMA, “D 3.1: Functional Network Architecture and Security Requirements”, Dec. 2015

[5] C. Mannweiler et al., “5G NORMA: System Architecture for Programmable & Multi-Tenant 5G Mobile Networks”, submitted to European Conference on Networks and Communications (EUCnC), March 2017.

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