5G mobile networks are highly flexible, and they use a range of different technologies to adapt to the customers’ changing needs. One key technology within 5G New Radio (NR) networks is network slicing which allows them to use the same 5G network infrastructure to serve a wide range of use cases.
Network slicing is a capability in 5G networks that allows a mobile operator to create multiple virtual portions (slices) within the physical network to serve various use cases. Network slicing requires a software-based architecture (SBA) provided by the 5G core network in standalone 5G.
What is 5G network slicing?
Network slicing is a technology that allows mobile operators to create multiple virtual networks within the existing physical network so that each virtual network can serve a different business need or use case. Network slicing is based on network virtualisation principles, and it belongs to the same league as software-defined networks (SDN) and network function virtualisation (NFV).
Depending on the use case in question, the mobile operator can define a virtual network (or slice) that can utilise all the network capabilities to cater to that particular use case in the best way possible. For example, if a mobile network serves a self-driving car and a mobile broadband user, one network slice can focus on generating high throughput for the broadband user while the other slice can focus on offering locally available edge services to reduce latency for self-driving cars.
How does 5G network slicing work in standalone 5G (SA)?
5G network slicing requires end-to-end support from the entire mobile network to function. In 5G network slicing, the 5G core network (5GCN), 5G radio network (NG-RAN), and 5G transport network work together to allocate appropriate network resources to user devices to offer specific service types.
5G networks can support a wide range of use cases by fulfilling different types of network requirements, including varying levels of latencies, throughput, capacity, and reliability of the network. Network slicing is the technique that allows 5G to address all kinds of use cases by utilising the same network infrastructure to serve different service types through virtual network slices within the overall mobile network.
Network slicing requires support from the entire mobile network, including the radio network, core network and transport network, to create slices for various service types. The core network deals with network functions to define the slices, the radio network provides appropriate radio resources for each slice, and the transport network carries data between the radio network and the core network.
In transport networks, there is a concept of hard slicing vs soft slicing. Hard slicing is when the transport network resources (i.e. bandwidth) have a hard isolation through circuit-switched separation for each slice. Soft isolation, on the other hand, is enabled through statistical multiplexing, where the isolation is not dedicated, but resources are shared and allocated based on priority.
The critical network requirement for network slicing is a 5G cloud-native core network that employs a service-based architecture. Service-based architecture means a flexible network architecture that can allocate appropriate network resources to all cellular devices (e.g. mobile phones, 5G IoT devices etc.) depending on the service the customer is trying to access. For example, if a user is trying to access high-speed mobile broadband service, a separate part of the network gets engaged compared to an IoT device attempting to access the network.
As a result, the 5G core network can have several different slices to cater to a wide range of service types and use cases with varying degrees of network and QoS (Quality of Service) needs. Different use cases, for example, healthcare, mobile broadband, connected cars, smart cities etc., have different mobility, throughput, latency and reliability needs. At a high level, the service types network slicing enables fall in the use case classes enabled by 5G NR networks. Have a look at the example below to see how a mobile network can create multiple network slices for offering services of different types. In this example, we have a network with five slices, where each network slice represents a separate service type.
Now, this doesn’t mean that one User Equipment (UE – mobile phone or a cellular device) must only be connected to one network slice at a time. A single UE can be connected to multiple network slices; however, the signalling and control information only flows through one slice. When a user device registers on the 5G mobile network, the information on the available slices is established for the connection, and the UE is configured accordingly for multiple slices.
The 5G core network has a number of nodes that specialise in the network slicing area. The primary node containing network slicing information is the Network Slice Selection Function (NSSF). In addition, the Access and Mobility Management Function (AMF) in the 5G core network works with NSSF to obtain subscription-related information to determine which network slices are applicable to which subscriptions.
The key benefit of 5G network slicing is treating different network slices as various networks so that individual slices can be provided with the right network resources to facilitate specific use cases. For example, if the mobile network is serving low latency use cases, like connected cars, the user plane function (UPF) within the edge network gets engaged to facilitate connectivity. On the other hand, if a regular service like mobile broadband is required, the user plane function (UPF) within the central core network gets engaged.
The role of 5G Radio Access Network (RAN) in network slicing
5G radio network, also known as Next Generation Radio Access Network (NG-RAN), plays a supporting role in network slicing, while the 5G cloud-native core network plays the leading role. 5G RAN supports the 5G core network by ensuring each slice has the required radio resources.
The two essential components of a 5G mobile network are the radio network and the mobile core network. As described in our post on standalone and non-standalone 5G networks, the deployment model that uses the 5G core and 5G radio networks, is called standalone 5G (SA). An end-to-end 5G network is required to benefit from the futuristic technologies and use cases that it supports. The non-standalone version of 5G (NSA) is not an end-to-end 5G network as it relies on a 4G core network (Evolved Packet Core – EPC) to work with the 5G radio network. 5G NSA is the most common 5G deployment type for general use cases, like Enhanced Mobile Broadband (EMBB). Network slicing requires the 5G cloud-native (5GCN) core network, which contains specialised nodes like NSSF and AMF. So even though NSA can help facilitate high-speed broadband services, it is not a suitable deployment model for network slicing. The cloud-native core network in standalone 5G takes advantage of the software-based architecture to define logical functions for facilitating different use case types easily. The role of the 5G radio network (NG-RAN) is to allocate the required radio resources, e.g. spectrum, modulation schemes, antenna configurations etc., to fulfil the network needs of different use cases.
Why do mobile operators need network slicing?
5G caters to a vast range of use case types with different technology needs. For example, if a customer wants to use 5G as a home broadband service, home broadband service, the priority will be the number of Mbps even if the latency is slightly higher. If, however, communication is required for a self-driving car, the requirement on latency is expected to be very strict. The problem network slicing solves is that it allows a mobile operator to utilise the same network to deliver extremely different types of services without deploying different physical networks.
Network slicing allows mobile operators to offer dedicated network capabilities to their customers based on various use case types. It creates new revenue opportunities by enabling innovative business models and maximises the return on network investments by efficiently using network resources.
A mobile network is a massive investment for a mobile operator. By utilising the network resources efficiently, they are better positioned to increase their revenues (ARPU – Average Revenue Per User) from Consumers and Enterprise customers. Using a software-based architecture, the network resources can be adjusted as and when needed, giving a mobile operator a lot of flexibility. Network slicing allows a mobile operator to create slices for different customer or market segments. As a result, they can plan resources and offer a better quality of service to their customers. Furthermore, network slicing allows a mobile operator to have a number of virtual networks within the same physical network infrastructure, allowing them to achieve their business goals whilst maximising network utilisation by making software-based changes to the existing network.
With network slicing, everything is based on the service being offered to the customer through the end-user application. Depending on the end-user application’s business needs, necessary network resources and computing power from the physical network can be assigned to the applications to address that need. For the end-user application, the network slices are just like independent networks.
Here are some helpful downloads
Thank you for reading this post. I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need extra support, especially when preparing for a new job, studying a new topic, or buying a new phone. Whatever you are trying to do, here are some downloads that can help you:
Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.
Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.