From 2G to 5G: a complex evolution for operators

Mobile operators are moving to all-IP networking and correspondingly delivering LTE communication services, such as Voice and Video over LTE (VoLTE and ViLTE). The benefits of this transformation are clear – for the consumer they promise faster, cheaper and better quality voice and video services; for operators, they deliver spectrum and network cost efficiencies.

However, the introduction of LTE means that operators have to run multiple networks in parallel: the circuit-switch network for 2G, 3G and the IP Multimedia Subsystem (IMS) to support voice, video and messaging on the LTE network. This also involves the operation of multiple service layers simultaneously, which control the real-time communication services, such as voice and video calls, on each network.

With every additional generation of network technology, operation costs have and will continue to increase significantly. Operators need to find a way to manage the transition of their pre-existing services and networks to all-IP cost-effectively and to do so without incurring the costs of running four different service environments concurrently, which will happen when 5G arrives.

The requirement for legacy networks

Whilst LTE is currently the preferred radio access network in the USA and many other developed countries for data services, operators must continue to run their 2G and 3G circuit-switch networks for the next few years. This is because voice services have not yet migrated in any significant volumes to the LTE IP network. Even when there are large numbers of active VoLTE users, 2G and/or 3G will be needed where there is inadequate LTE coverage, and to support in-bound international roamers, who may still actively use 2G and 3G services. Unless operators are willing to forego the revenues that these services afford their bottom lines, a complete transition to LTE cannot take place until all revenue generating customers have moved over to 4G/LTE. Most industry observers believe 2/3G networks will remain for up to ten more years.

A complex combination of networks

In the 2 and 3G networks, operators will typically have multiple service control points and service layers. When new services were created for business and consumers over the years, the extra services were added to the service control points (SCPs). Often, a separate service-layer was implemented for prepaid subscribers in parallel with those for post-paid subscribers; likewise, service control points were added for enterprise customers in addition to those serving consumers.

Mergers and acquisitions also play their part in adding to the complexity. When mergers take place, separate service layers must co-exist effectively, all the while serving their own access network independently. A good example is the merger in the UK between T-Mobile and Orange to create EE. The two networks had their own SCPs for the various services they offered their customers, which had to coexist and be available to all customers on the new EE network. As operators move to all-IP they must run their circuit switched networks alongside the IMS networks for VoLTE and WiFi Calling. With 5G due to be introduced some time before the end of the decade with specific support for the Internet of Things (IoT), this complexity is set to continue and probably, get worse.

How can operators help themselves?

One option operators should manage the transition of their network services, is to re-architect their service layers with a single, converged service layer (CSL). This positive step forward replaces the multiplicity of access specific (and pre/post-paid-specific) service-layers with a converged service-layer that delivers services across multiple types of access network.

Not only will this reduce operational expenditure (OPEX), making a far more attractive bottom line for operators, but this converged service layer also provides more network agility. The ability to counter innovation from competition from web communication providers will be greatly improved. This layer will also make the transition to IMS networking and services more affordable in time and in money, providing a consistent customer experience as well as facilitating faster customer migration to all IP.

With LTE access becoming ubiquitous across the globe, the broadband access network is in place to deliver the IP-based, real-time, multi-media person-to-person communication services long promised by IMS. But the necessary and continued existence of the legacy networks and services hosted in service layer silos rather than in a CSL is a direct impediment to subscriber migration to IMS-based communication services. CSLs provide the means to short-circuit this problem. It makes network-based services available to all network users regardless of the access network being used. For the subscriber, this means they can move to LTE and IMS without waiting for key network services to be ported or re-implemented in the IMS. Operators are freed-up to re-factor services to IMS or retire them as appropriate at their own pace without impacting subscriber migration.

This network transition will still be ongoing when the first 5G networks are deployed. Although many IoT uses of 5G do not require the services in the older generations of network, others such as security and monitoring using video, voice control of machines, in-vehicle concierge and emergency services and healthcare, undoubtedly will. The CSL will have a part to play here too. One service layer will dramatically simplify the inevitable signalling challenges that will arise with 5G implementation.

Some tier-one, and smaller, independent and agile operators, have already implemented CSL solutions within their networks. Consequently, they’re reaping the rewards of lower OPEX and increased customer satisfaction due to their drive to develop and launch new services. The time has come for others to play catch up to those out in front if they want to remain profitable, keep their subscriber base, and ultimately survive in what is going to become an even more competitive market.