NEW ANALYSIS: The promise of 5G varies, from high bandwidth for some users, ultra-low latency for others and ultra-reliable services for mission critical applications.

The technology achieves this network agility using key elements including NFV, SDN and network slicing.

NFV segments network resources into modular building blocks by disaggregating software from the underlying hardware, and SDN provides the necessary management and orchestration requirements for infrastructure virtualisation. Network slicing tailors virtualised network resources to address specific service demands, such as bandwidth, latency and reliability. This seems analogous to a designer crafting innovative creations with Lego building blocks, but unfortunately it is not quite that simple.

Most not virtualised
Today, 5G core networks generally operate on virtualised infrastructure. However, this is not the case for 5G radio networks (RAN), which represent the largest proportion of 5G network deployments. Virtualised radio, or so-called cloud-RAN, has not been embraced by mainstream 5G operators and is only being used for private and indoor public networks and by handful of disruptive network operators, like Rakuten in Japan.

While network slicing can theoretically be implemented in networks with physical as opposed to virtualised radio infrastructure, the agility of the slices is significantly impaired. Without cloud-RAN, network slicing cannot be implemented end-to-end. Instead, dedicated radio resources are required for each of the various sliced network service classes. For the radio network, this is somewhat akin to the static quality of service (QoS) capabilities that were developed for 3G. These capabilities proved too expensive because of the excessive reserve resources needed to ensure the QoS capabilities could be met.

Until tier-1 network operators embrace cloud-RAN for their wide-area networks, we believe network slicing will best be targeted towards specific applications with localised cloud-RAN deployments. Notable examples include digital entertainment applications in sports stadiums, digital retail solutions, smart-city and -building applications, and applications to support Industry 4.0 initiatives in manufacturing plants.

Virtualisation is hard
Network slicing adds complexity to network virtualisation, which itself is already complex and operationally disruptive. NFV and SDN frameworks were originally proposed by several tier-1 operators in 2012, but adoption has been slow. Both NFV and SDN require significant operational transformation and have been hindered by management and orchestration challenges, particularly for the large-scale deployments involved.

Until NFV, SDN and their associated operational regimes mature, network slicing will be best suited for targeted services that are geographically localised and don’t have onerous orchestration and automation requirements. However, these targeted services will challenge the business models for most mobile network operators, whose retail offerings are driven primarily by mass-market consumer demands. To address this, we believe mobile operators must cooperate with ecosystem partners with specialist capabilities and market channels for the network sliced services that are targeted.

Getting the blocks in place
Network virtualisation and slicing depend on enough infrastructure resources being deployed where needed. This is particularly the case for ultra-low latency services, which require networking and edge compute infrastructure near end-users. First order considerations tend to focus on average latency requirements. However, for emerging applications such as AR and VR, the average latency and its variance are both important. To perform effectively, these applications require that the ultra-low latency conditions are achieved in excess of 99.9 per cent of the time. This creates greater demands for networking and edge compute infrastructure near end-users, with adequate capacity and responsiveness. Only then will the network slicing functionality perform as is intended.

As the mobile industry deploys 5G, there will be a natural tension between technology innovation and the practicalities for commercialising these innovations in the marketplace. Network slicing offers tremendous potential, particularly as 5G is adopted for a broad range of services and applications. However, network slicing is complicated to implement and depends on the maturity of virtualisation technologies and their operations. Slicing also depends on ecosystem partnerships that allow for its progressive market adoption.

Without these key ingredients, network slicing runs the risk of technology overreach and being deemed a failure before it has the opportunity to succeed.

By Phil Marshall, chief research officer, Tolaga Research

The editorial views expressed in this article are solely those of the author and will not necessarily reflect the views of the GSMA, its Members or Associate Members.