Network Slicing

Almost every PowerPoint I’ve seen about 5G cellular networks talks about network slicing. This is a new networking term unique to 5G. This is the second article looking at new features of 5G, with the first being a blog on Massive MIMO.

Cellular networks are now expected to make multiple simultaneous connections with different characteristics. The examples used in most presentations explain how a cellular network should be able serve traditional cellular voice, more robust cellular data, IoT monitoring and connecting to self-driving cars. Each of these applications requires connections with different bandwidth, latency, security etc. The cellular network will be expected to immediately recognize the required need and respond appropriately.

It’s a challenge because of the diverse nature of each kind of network demand. For example, an IoT network will be comprised of huge numbers of devices mostly in fixed locations and requiring small bandwidth. Contrast this with cellular data, where as we increase data speeds we’ll expect the network to deliver large amounts of bursty bandwidth to mobile devices by combining multiple channels of frequency and even signals from multiple cell sites. Demands for self-driving cars or gaming will expect large and steady bandwidth with extremely low latency. These examples are some of the primary uses for a future cell site, but there are dozens of other kinds of connections that will be needed.

The ability to design a quick response to diverse network needs is made more difficult by the fact that every market for every cellular carrier uses a different combination of spectrum blocks and different channels within the blocks. This makes it impossible to design a ‘standard’ network strategy that will work everywhere. To be effective a cellular network must combine the spectrum components available in a given network to create a homogeneous network.

Landline networks are able to handle diverse types of demands using a combination of quality of service (QoS) and techniques like virtual private networks (VPNs). QoS uses a feature called differentiated services to classify and manage different types of IP traffic like streaming video, VoIP, web surfing, etc. Many networks also then use VPN functions like IP tunneling to isolate data paths aimed at specific customers.

These same techniques are hard to apply on a cellular network. Cellular systems need a sophisticated networking solution because the network is limited at any given time by the number of channels of frequency that are not being used. We don’t worry about this on landline networks because we can flood the network with enough bandwidth to accommodate every request. To most effectively use the available bandwidth a cellular network must quickly recognize the exact nature of the bandwidth being demanded and then cobble together the most efficient use of available spectrum. Current QoS solutions can’t adequately distinguish between different types of traffic to the degree needed to make this determination.

Network slicing provides a new way to partition the spectrum on a network. In layman’s terms it performs several functions that differ from QoS. Network slicing can quickly determine the nature of a bandwidth demand. It can then create a wide range of network responses.

One of the features of network slicing is that the network can be pre-configured for different uses. For example, a portion of the network can be isolated and assigned to a single function like IoT. Even more important, new revenues can be generated by partitioning and isolating a part of the network for a single customer – a business within range of a small cell site can be sold a share of the capacity of the cell site to guarantee better service. Slicing could also segregate traffic better – for instance, a cellular carrier could isolate traffic from one of it’s MVNO partners from other traffic on the cell site.

Network slicing can also subdivide spectrum. It allows the cell site to use a portion of a channel for a given connection rather than the whole channel. Slicing off small amounts of spectrum for small bandwidth needs if far more efficient than how cell sites operate today.

Finally, network slicing introduces a lot of new data features not available with QoS. The network can customize the way it handles any particular data stream in terms of data priority, encryption, data storage, etc. The network can more easily give priority to things like law enforcement connections, or IoT signals from critical devices.

2 thoughts on “Network Slicing

  1. Doug,
    Network slicing has some newer attributes in 5G, but it is not a new term or new concept. Slicing is a primary attribute of all properly designed Software Defined Networks (SDN) and associated “service chains” that utilize that type of pathing through various virtual network functions in NFV structures. What you highlight is, however, critical in communication networks going forward. That is the highly dynamic and instantly modifiable nature of networks today. We have moved beyond the static, configure once, with some limited group characteristics like QoS marking and the like. It is so nice to see those old rigid architectures go away.
    Thanks for all your good articles.
    eric

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    • You are absolutely right. Most of the technical basis for new features being touted for 5G are already in existence. Most of the 5G improvements come from enhancing capabilities of 4G – 5G is not a revolutionary breakthrough, but an evolution.

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