Virtualisation brings known technical (capex, opex etc) and commercial benefits (digital services, on-demand services etc) for the CSPs. Virtualisation is being adopted by mobile networks at a rapid rate, with many Tier 1 operators claiming to have most of their networks virtualised by 2020. In the mobile networks, NFV onboarding has already happened in the Core networks and some operators are beginning to virtualise the RAN network as well, starting with C-RAN in LTE networks. But have we figured out what will make this transformation a smooth success? Is it the new telco cloud infrastructure, the reduced infrastructure footprint, the reduced operations through a MANO and/or an orchestrator or a combination of all these? The answer is yes, however we need to consider some critical factors of success that need attention now, as the NFV rollouts gain momentum.
It is important to note that not everything in the network has virtualised. And that network functions have not disappeared, they have only been virtualised, i.e., relocated, centralised, downsized, and run on non-proprietary hardware. The end customer is still connected to the virtualised core network through the mesh of transport network to transfer voice, video and data. This transport network continues to be physical: microwave or fiber. While its IP-isation (IP/MPLS or Carrier ethernet) has made the physical transport infrastructure more efficient, it is still needs the most attention, if virtualisation must deliver.
With C-RAN introduced in LTE networks, and introduction of a fronthaul transport segment, the transport network is now transformed to the new mobile Xhaul (fronthaul and backhaul), which will serve as the backbone for current and new access technologies for several years.
A stable, error-free, highly available and highly reliable transport network will greatly contribute (and guarantee) to the success of the virtualised network and its promised services. To support this need, optical fiber is the transport network of choice. But with low availability of fiber globally, especially in the under-developed/emerging economies, this may not happen so easily, so fast.
Carrier ethernet offers a solution on microwave and optical fiber, making the transport network more reliable. However, there need to be better protocols to make the virtualised network deliver on stringent requirements of 5G. Introduction of new protocols on the fronthaul solves the problem to a large extent. Such protocols establish low BER, low jitter/wander and high availability.
A robust Xhaul transport network, using the new QoS protocols will ensure that the web-scale traffic is efficiently handled, and that ultra-high quality is continuously guaranteed.
However, as all new technologies need to be vetted and policed, QoS assurance and SLAs will come into play. To keep up with the SLAs, the services that are delivered over the NFV networks require a high dependency on the transport network especially when they are dynamically provisioned. It is essential to assure QoS 24*7 over the highly IP-ised transport infrastructure in an integrated way to support current LTE-A traffic, small cell growth, and the upcoming 5G network slices.
