A Small Step for Fixed, A Big Leap for Mobile

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Preparing Fixed Network Operators for the 5G Era —

With every new generation of mobile technology, the question of whether this is the end for fixed networks is posed. As the industry continues to work on 5G, this is no doubt preying on operators’ minds — but, as with 3G and 4G, the answer to the question is a resounding No! In fact, in particular for 5G, the opposite is true, and fixed networks will be needed more than ever.

Fixed network operators must echo this need by addressing how they can make their role in 5G more prominent, and how they must adapt their networks within this shift. Delivering flawless 5G mobile services demands nothing less than a world-class fixed network that can support massive connectivity, super-high data rates, and ultra-low latency. 

Introducing new architectures and new interfaces, 5G networks brings a new set of requirements that challenge transport networks to deliver more capacity with lower delays. To meet this demand, high-capacity, high-density fiber broadband networks, which are already being deployed and used for residential services, are proving to be an effective solution for carrying mobile traffic.

Fiber-to-the-home (FTTH) networks tick the box for the key requirements of efficient mobile transport: economics, scale, and performance. They deliver 50% transport cost savings, perfectly matching the footprint of mobile cells, and have the high performance needed for the 5G world. 

Transport networks that interconnect mobile sites are referred to as mobile anyhaul. By using broadband networks for anyhaul, operators can gain the greatest benefit from converging fixed and mobile transport networks. The enhanced bandwidth of next-generation fiber technologies, based on Passive Optical Network (PON) technologies, and network slicing enabled by SDAN, make converged residential broadband, business broadband, and mobile anyhaul, even more attractive to operators.

 The need for flexible backhaul/fronthaul/midhaul/fronthaul has been apparent across previous generations of mobile technologies, such as 3G and 4G — and the technology continues to advance to support the 5G world. 

Matching Footprints

As mobile networks evolve to deliver higher speeds, the number of small cells continues to increase. Fixed networks are progressing alongside this to provide small cells with the backhaul connectivity that will scale in line with mobile network growth.

FTTx networks are, by design, ten times denser than the number of radio cells — even in a 5G mmWave deployment — and can offer a strategic, long-term solution for any bandwidth-intensive service. This density supports mobile operators in efficiently covering new cell sites and keeping up with the demands of their network as it expands. 

If this is to be achieved, mobile traffic must be prioritized — meaning scheduling and shaping of traffic must become flexible to deliver enhanced Quality of Service (QoS). Advanced mechanisms also play a part in enabling this, ensuring the protection, availability, and resilience, of mission-critical services. 

One example of how a strategy such as this can facilitate mobile network upgrades was highlighted in a project we carried out with a North American Tier 1 converged operator, that required a solution to increase capacity and coverage of its mobile network to cope with user requirements and competition. The approach the operator took enabled it to reduce the time of deploying and provisioning mobile cells backhaul from several weeks to 1 day, and reduce operational cost by factor 10. 

Its strategy was to connect small cells to the existing GPON network, and configure each site as a VIP customer with very strict service levels agreement and prioritization of small cell traffic. As fixed networks are generally built for massive and easy provisioning, the operator could pre-provision both small cells and fiber modems to connect those cells, in plug-and-play mode with fewer experts on site.

For operators that have previously experienced long completion times when deploying and provisioning individual macro sites, a solution such as this is gold — drastically cutting the time to market. In this instance, it now takes the operator just a single day, and a single technician, to deploy each small cell site. 

Cloudification Strategies Help

By increasing the synergies between fixed and mobile networks, a responsive network will be created that can adapt to the bandwidth and latency needs of different services as they arise and change over time. And with advances in next-generation fiber technologies, this is not restricted to mobile backhaul and midhaul — latency and synchronization-sensitive fronthaul can also be supported. 

One of the main areas of synergy will be in the cloudification of fixed and mobile access networks. This innovation is opening doors for operators, enabling them to get network assets up and running to monetize them, quicker than ever before — which are crucial factors to the 5G business case. 

And with a little help from virtualization technologies, mobile cells can be provisioned so that they can become automated, allowing easier and faster deployments. 

Cloudification of the network layers means non-real-time applications and management functionality can be hosted in the data center, while more time-critical functions can be hosted in a Cloud facility closer to end users, known as the Edge Cloud. This requires a new way of working, where vendors and service providers collaborate in open software frameworks and optimize end-to-end behavior across the network via programmable interfaces. This is where one of the key advantages of Software Defined Networking (SDN) comes in. 

The introduction of virtualized functions, centralized intelligence in the Cloud, and SDN-programmable interfaces enables the rapid creation, optimization, and termination, of services needed in the 5G era. The Edge Cloud uniquely allows software applications to tap into local content and real-time information about access network conditions. 

With centralized intelligence, the fixed access network can be provisioned and optimized for mobile transport by coordinating with mobile network elements. The central units of the fixed access domain run virtualized OLT (vOLT) functions and the central units of the mobile access domain run virtualized BBU (vBBU) functions, are all hosted in the same multi-level Cloud infrastructure. The Cloud infrastructure can eventually be shared, which improves the business case for both fixed and mobile operations. 

Similar principles apply to both fixed and mobile access network technologies. An example is bandwidth management. In a mobile access network, the central BBU functions are responsible for the scheduling of the RAN. They allocate physical resource blocks (frequency and time) to determine communication channels for the end terminals. Similarly, in a fixed network, the OLT manages the bandwidth usage on the optical distribution network by employing dynamic time-slot and wavelength assignments. There is a clear advantage to coordinating this throughput scheduling between the air interface and the passive optical transport.

Thanks to the programmable interfaces and centralized intelligence of Cloud-based Software Defined Access Networks (SDANs), fixed access networks can coordinate with the mobile network to be provisioned and optimized for mobile transport. For example, the cloudification of networks enables operators to slice the fixed network infrastructure, partitioning it for different services or traffic types. This allows 5G traffic to be managed independently and served with ultra-low latency and high throughput. This level of centralized intelligence will empower seamless, flexible, and efficient operation of the transport network, allowing access to resources as and when they are needed. 

The anyhaul concept supports advances in next-generation PON technologies and prepares networks for the density and capacity 5G will require. Therefore, fixed network operators can be assured their role in 5G is secured — and that they can deliver the infrastructure that is required reliably, cost-effectively, and flexibly.

This article is adapted from the Nokia whitepaper Sharing PON networks for mobile anyhaul. For more information, and to download the complete whitepaper, please visit https://pages.nokia.com/T00273.5G.BB.white.paper.html.


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About Author

Ana Pesovic leads Fixed Network Fiber Marketing at Nokia. She has more than 20 years of experience in telecom, and is a board member of the Fiber to the Home Council Europe. For more information, please email: ana.pesovic@nokia.com, follow Ana on Twitter: @AnaPesovic, or visit: https://networks.nokia.com/solutions/passive-optical-lan.

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