The promise of 5G networks portends major shifts in backhaul technology. With the advent of new applications, Internet of Things (IoT) and other factors, the transport network will need to support a variety of applications with different needs and enable more automated deployments. And it needs to be free of hardware constraints.

When considering the evolution to 5G, operators need to ensure that transport is ready. There are a number of key factors that are expected to influence the direction of transport networks to support 5G including:

Fixed Wireless Access (FWA) and Mobility Use Cases
Most large service providers have talked about using FWA to diversify their offerings and compete with fixed line providers. FWA represents the initial use case for 5G at least in the near term and mobility use cases will undoubtedly emerge shortly thereafter. In the developing world, fixed broadband access for enterprises is now starting to take off using wireless access links. 5G could meet the bandwidth demand and provide more economical solutions. FWA drives the need for both capacity and multi-service capabilities in the transport network.

Machine Type Communications (MTC)
MTC are predicted to play a large role in 5G networks. With the increasing demand for connectivity of industrial IoT devices, transportation-related equipment like self-driving and autonomous vehicles, and health and medical devices, MTC is expected to put new demands on the 5G transport network. MTC will increase the numbers of connections and place new security and latency requirements on the transport networks.

RAN Architecture Evolution
With the continued evolution of the radio access network (RAN) to support high density, high capacity, low latency, and more peer to peer communications, 5G is likely to transform the RAN architectures to a denser, street-level network with distributed intelligence and evolved fronthaul/backhaul interfaces. The densification of the network will lead to more advanced topologies (such as ring and mesh) in the access part of the transport networks. Based on the RAN evolution, new demands on the microwave transport network will emerge so products can seamlessly fit into deployment scenarios, be rolled out at scale, and support advanced topologies.

Transport Requirements
Different 5G applications will drive unique requirements on the transport network. In the diagram below, we have depicted target performance, as stated in different 5G related white papers and publications, in four different dimensions – capacity, latency, cost, reliability – and have made an attempt to map different 5G applications to these requirements.

A substantial improvement in capacity is expected to be delivered by 5G which translates into more capacity demands on the backhaul. Main drivers include 3D and 4k video, security and surveillance, and big data applications. The good news is wireless transport well meets the capacity need for 4G networks and is expected to scale to support 5G applications as well.

To meet the transport capacity demands, transport networks will evolve to be more meshed to avoid bottlenecks and dynamic to achieve network-wide optimization of resources. In addition, wireless transport networks will continue to become more spectrally efficient to support the increasing demand.

Critical IoT communications, augmented reality, self-driving cars, gaming applications combined with RAN architecture evolution and peer to peer communications, creates requirement for tighter control over latency in 5G networks – some applications require latency in the order of 3-5ms end-end which is a large departure from the ways networks are built and maintained today.

Beyond the sheer capacity and latency numbers, the ability with which the network can control these performance variables will be key to the future network. Transport networks will need to adapt and dynamically manage latency in ways not possible today – such as optimized routes with a minimum of signal processing and queuing, moving content closer to the network edge, and using network element with a high level of features and integration to remove switching and routing interfaces.

Any rollout of new innovation will need to build on and leverage current network infrastructure. Large networks cannot be ripped out and replaced overnight so new technologies that can cost effectively migrate from today’s installations will be required.

Rising OPEX is choking operators’ ability to grow today. And it’s not just management and service delivery – it’s the OPEX associated with a complex microwave and fiber lifecycle including designing, purchasing, deploying, managing, optimizing transport networks. Increasing energy consumption costs also need to be addressed and will likely grow with 5G. Increasing site density, traffic and subscriber growth, combined with higher requirements on network performance, makes these challenges considerably worse.

With the densification of the mobile RAN, emergence of FWA, and rollout of MTC use cases, 5G will surely bring a higher level of density to the access network – with a potential to drive up costs. This evolution cannot be met in a cost-effective manner without lower cost wireless transport options that are designed to be deployed at street level. Simplification of wireless transport solutions via automation will be essential if 5G networks are to be successfully deployed in the volume levels required.

Industrial and public safety use cases for the 5G networks emerge, transport networks cannot sacrifice reliability to achieve capacity, latency and cost objectives. Network and node level redundancy schemes will need to evolve to improve on today’s reliability in an automated and cost reduced network for 99.999% reliability and close to 100% coverage.

Beyond this however, bringing mission critical reliability to 5G networks will require a new mindset around building networks including backup generators, and elevated sites along with improved node and network level redundancy schemes within the transport networks.

Service Delivery
More recently, operators have moved beyond offering simple data capacity for mobile applications. And in some markets, they have begun to take place of wired networks for real-time rich media like two-way video conferencing and 4K HDTV. In others, wireless carriers have no fixed line competitors and carry these data-intensive applications to subscribers and enterprise customers in a greenfield market. As a result, operators are building more service-delivery intelligence (IP/MPLS today) into their transport networks. With 5G, the need to up the game in terms of service delivery will be paramount.

To do this, operators will need to address standardization in transport networks. Additionally, 5G networks will require open control layer to standardize operations across technology (fiber and microwave), domains (access/metro/core) and across vendors.

SDN will be an essential aspect of simplifying service delivery in complex multi-domain, multi-technology transport networks. Part of a broader solution to automate the microwave lifecycle, SDN concepts can be implemented today – giving time for networks to learn and grow towards 5G. SDN will enable multi-vendor, best of breed networks allowing innovation to flourish in each part of the network.

If we think security is a problem in networks today, wait five years. It’s critical that 5G wireless transport solutions be delivered in a secure environment and solutions must leverage latest security and reliability capabilities to ensure operator networks and data is protected and services are always on.

Solutions must continue to evolve encryption capabilities for 5G and follow industry standard security best practices to provide encrypted connections from infrastructure devices to private or public cloud environments. Data replication and backup are must haves and are inherent with prominent cloud providers today on which some of the most critical networks already depend. With the overwhelming number of security alerts and cybersecurity staffing shortages, new solutions will be needed to identify threats faster and more accurately.

Key Evolutions for 5G Transport Networks
Wireless transport solutions will continue to evolve to support the above transport requirements. To ensure they do, there are a number of key areas of evolution that need to happen.

  1. Unified

Due to latency and capacity requirements, CPRI is not going to be a viable option for 5G transport. Fiber cannot and will not be everywhere and the industry needs a wireless transport option for fronthaul/midhaul applications to support 5G. While evolutions in various standards look promising (eCPRI, IEEE 1914, 802.1cm, TSN, etc), more time is needed to determine how viable these will be in allowing ubiquitous wireless options for 5G transport.

One thing for sure, standards need to evolve so that wireless transport is an option – otherwise deployment scenarios for 5G will be limited. The end goal is a single integrated and common, unified transport solution (likely based on Ethernet) across fronthaul, midhaul, and backhaul portions of the networks.

  1. Independent

Next generation sites will not only be used for 5G but will also house other devices for security and machine related communications. We can also assume that after 5G there will be a new RAN standard defined just as it has been since the days of 2G.

To support a true multi-service network and to ensure that the radio acces network (RAN) can evolve independently from the transport network, it’s important that the transport domain is clearly separated from RAN. To support this, not only do the transport interfaces need to be open and standardized but the transport devices must be kept separate and not integrated with the RAN or 5G system.

  1. Automated

Regardless what happens to the transport protocols, to support 5G, transport networks need to transform – with growth in traffic, subscribers, and network infrastructure we cannot sustain current levels of complexity and cost. Whatever 5G turns out to be, new demands will be placed on virtually every aspect of the wireless transport networks. We believe simplification of wireless transport through automation is not only possible but an absolutely necessary if 5G transport networks are to become reality at the performance, reliability, and latency required.

To build a transport network with enough flexibility to support all 5G use cases and meet all the performance requirements, network operators need to start making the right technology choices now. Using a combination of flexible high-performance hardware, unique software tools and applications, and rich data-centric services portfolio, Aviat will continue its recent innovations to ensure 5G transport networks are Unified, Independent, and Automated to fulfill the 5G promise for our customers.


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