A slice of life

Network slicing overlays multiple virtual networks on top of a shared network. Each slice of the network can have its own logical topology, security rules and performance characteristics – within the limits imposed by the underlying physical networks. Different slices can be dedicated to different purposes, such as making sure a specific application or service gets priority access to capacity and delivery or isolating traffic for specific users.

Network slicing is a key feature of 5G, applying the principles of virtualization to the radio access networks and the supporting backhaul and carrier core networks that underlie 5G. Software-defined networking and network function virtualization allow the implementation of flexible and scalable network slices on top of a common network infrastructure.

A 5G network operator can physically segregate traffic on different radio networks, slice a single network, or combine the capacity of multiple networks and slice the pooled resources. This enables 5G network operators to choose the characteristics needed to support their target levels of spectrum efficiency, traffic capacity and connection density.

Network slicing allows a mobile operator to create specific virtual networks that cater to particular clients and use cases. Certain applications – such as mobile broadband, machine-to-machine communications, or smart cars – will benefit from leveraging different aspects of 5G technology. One might require higher speeds, another low latency, and yet another access to edge computing resources.

A company depending on a 5G network for autonomous vehicle management might contract for a mobile network slice with latencies under 5 milliseconds on a guaranteed minimum throughput per vehicle to guarantee responsive control. The provider would provision the slice on the lowest-latency equipment and paths between vehicles and cloud or edge resources and reserve enough capacity to meet the throughput target.

For a security monitoring system in a large auditorium, latency may not matter. But the security company may want to buy guaranteed delivery of the camera data. The company would want its traffic to get 1.5 megabits per second of throughput per camera with no packets dropped, ever. The provider might aggregate multiple connectivity and processing device options to meet the needs of this slice.

The basic idea of network slicing is to ‘slice’ the original network architecture into multiple logical and independent networks that are configured to effectively meet the various services requirements. To quantitatively realize such a concept, several techniques are employed: network functions, virtualization and orchestration.

Slicing can also enhance service continuity via improved roaming across networks, by creating a virtual network running on physical infrastructure that spans multiple local or national networks; or by allowing a host network to create an optimised virtual network which replicates the one offered by a roaming device’s home network.

Network slicing architecture can be considered as composed by two mains blocks, one dedicated to the actual slice implementation and the other dedicated to the slice management and configuration. The first block is designed as a multi-tier architecture composed by three layers (service layer, network function layer, infrastructure layer), where each one contributes to the slice definition and deployment with distinct tasks. The second block is designed as a centralized network entity, generically denoted as network slice controller, that monitors and manages the functionalities between the three layers in order to efficiently coordinate the coexistence of multiple slices.

Operators can have the capability of hosting applications as well as collecting relevant data within a network slice. Data collected in the slice together with external sources can be used by machine learning algorithms to predict future patterns or to improve analytics, and to improve the performance and efficiency of the enterprise application.

Operators can offer a business customer the capability to manage their own services or slices by means of Application Programming Interfaces offered by the operators according to a contract or SLA. These APIs will also provide access to network-specific information allowing each business customer to derive insights, for instance, into the perceived service quality, current network condition or the environment.

The salient feature of network slicing is the ability to customise the capabilities and functionality that a mobile network offers to business customers. Such customised service can be logically separated into two components: network connection service or network resources service.

The network connection service comprises a set of technical attributes that determine the behaviour of the slice, as well as the topology and geographical spread of a slice. Business customers may be granted access to the operator network resources for running proprietary applications. The operator will commit to provide a lifecycle management service to the business customer.

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