To win at 5G, signalling must be a top priority

To win at 5G, signalling must be a top priority
Bryan supports Nokia’s 4G and 5G core portfolio marketing programs. Over his 35-year career in the telecom industry, he has held a variety of roles helping to design the first soft switch systems, architect IMS networks, lead international technical sales teams, and now helps to envision and explain the industry’s 5G future.

We are a few years into the 5G era, and all eyes are on the immense benefits and new service opportunities 5G will bring to Communication Service Providers (CSPs). These are the direct result of standards organizations evolving the role of mobile networks beyond just voice, text and data.

5G represents a new way of designing communication networks and opens the door to completely new services that include location services, low latency, ultra-reliability and high bandwidth for consumer applications. Through network slicing, it includes a novel way of creating highly customized “mini-networks” tuned for the specific needs of individual enterprises. This has all been achieved through significant changes to the network architecture over several decades, including the network core.

Originally, communication networks relied on a single, monolithic switching system that managed all aspects of making voice calls. Over many iterations of technology, the trend has been to decompose the network into well-defined, standardized network functions that communicate with each other via data messages using standardized protocols. As the number of network functions and network function types increases, the communication between them becomes more important and is critical to the correct operation of the network. This system of messaging connections and protocols is called signalling, and it is effectively the nervous system of the 5G core.

It’s hard to overstate how important signalling is to the CSP’s business. With the right signalling framework deployed with their network functions, a CSP can reap the benefits of superior performance, high network reliability, and business agility. But get the approach wrong, and CSPs could be hindered with the inability to capitalize on new opportunities, low performance, or worse, a network-wide outage.

Signalling shouldn’t be an ‘add on’ in your 5G deployment

The key 5G network function that provides a robust signalling architecture in the network is called the Service Communication Proxy (SCP). Much like an ethernet switch connects multiple computers together, the SCP allows the CSP to create a hub and spoke topology to all the network functions, with the SCP acting as the hub. It further helps to enable the Service Based Architecture, by managing the interaction of network elements with the Network Resource Function (NRF), so that a new network function can be easily added and ‘discover’ its environment rather than having to manually provision it in.

It is easy to deploy a 5G network without an SCP. CSPs can do this by manually provisioning connections between each network function and every other function it needs to talk to. However, that creates a complicated mesh of connections. This may be fine for small networks – such as when 5G is first deployed – but as the network grows in size, it becomes unmanageable and results in high operational costs. Most CSPs know that they will need an SCP at some point to address this.

The real question is whether to deploy the SCP right at the start of the 5G standalone core deployment at some higher initial cost or to avoid that cost and wait until later when it becomes necessary. There are several reasons why the latter results in a lower total cost of deployment.

Integration costs: Each time a signalling connection is made from any network function to any other network function, the two need to be integrated by the services team deploying the network. Slight variations in protocol implementation can occur between the two that must be found and fixed – especially if they come from different vendors. In a connected mesh, the number of integrations needed is exponentially related to the number of different types of network functions, and so requires hundreds of integration efforts. In a hub and spoke topology that includes the SCP, each network function must be integrated only with the SCP – resulting in a dramatic reduction of deployment effort and therefore lower deployment cost.

Debugging effort: When the CSP discovers during deployment that something is not working quite correctly, it is important to gain visibility of the signalling messages to find out why. But signalling links are always encrypted, so a probe must be placed at one of the endpoints to expose the messages. Without an SCP,  many probes are required. But if the SCP is in place during the deployment it forms a hub where a single probe can expose all the messages in the core – making debugging far easier.

Message mediation: Sometimes one network function doesn’t use a protocol precisely the way another one does, even when that protocol is standardized. An SCP with a built-in capability to modify messages on the fly can provide a quick and easy remedy by adapting the protocol as it passes through. This again dramatically reduces integration costs and shortens the deployment interval. In a mesh network, the only solution available would be to tweak the network functions directly, or request a software patch from the vendor of one of the network functions.

These aspects continue to be beneficial well into network operation. Integration costs continue to be minimized when new network functions are introduced, or when software updates are applied. Network problems can continue to be identified fast with full visibility of the network through a probe at the SCP. And message mediation can aid the operator in fine-tuning network performance.

Thus, if CSPs separate the signalling issue from their 5G core deployment, they do so at their peril as eventually, it will need to be fixed. It is much cheaper to deal with the issue up-front from a TCO perspective, despite having to invest more to implement an SCP at the start.

Three fundamental signalling characteristics

Given that it is important to include the SCP from the start, what makes for a good one? Network design choices are a series of tradeoffs, so it’s critical to know what requirements are most important. When planning their 5G signalling architecture, CSPs will want to bear these three ‘must haves’ in mind – flexibility, performance and cloud-native design.

A solid signalling architecture must have the flexibility to observe and control all parts of a 5G core network, while also adapting core network functions in a vendor-agnostic way. For CSPs, having the capability to fine-tune operations and address any problems that arise is mission-critical. But since the problems an individual CSP will experience cannot be predicted in advance, the SCP must have a highly flexible message filtering system so that CSPs can adapt when needed.

For performance, an essential quality is low latency combined with high throughput across a diverse landscape of widely disparate service scenarios. Scalability is also a must – whether up or down – to overcome changes in traffic and network elasticity in cloud deployments. Furthermore, the message filtering system must not impact performance but instead work at line rates.

Lastly, being cloud-native is a vital characteristic, especially amid the rapidly-growing cloud era. Signalling must be software-based, cloud-native, and be able to use web-scale IT infrastructure – no matter the underlying cloud implementation (i.e., private, public, or hybrid cloud deployments). A big part of 5G benefits comes from web-scale design patterns like service-based architecture. Thus, a signalling system that lacks a cloud-native design will struggle to realize the benefits of 5G’s intended design.

Start your 5G strategy the right way

Regardless of what network strategy a CSP is following, deploying a signalling strategy at the very start of their 5G project provides numerous benefits. These include the ability to fine-tune the signalling to meet the needs of each service, faster core integration, lower risk of network outages, simplified network operations, and an overall lower TCO.

Kicking off a 5G project the right way – that is, including an up-front signalling strategy – cannot be understated so that CSPs reap the benefits of 5G-enabled services without “surprises” or unintended higher costs. In doing so, CSPs will be able to achieve the bottom line and deliver new 5G services to market faster, and with higher quality.

(Photo by Tobias Cornille on Unsplash)

Want to learn more about 5G and the opportunities it presents from industry leaders? Check out 5G Expo. The next events in the series will be held in Santa Clara on 11-12 May 2022, Amsterdam on 20-21 September 2022, and London on 1-2 December 2022.

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