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Fibre for 5G: Need for compatible backhaul infrastructure

May 23, 2018

Globally, 5G technology is gaining significant traction even as countries are witnessing increasing 4G deployments. Some of the leading telecom operators are exploring the commercial viability of 5G technology. According to industry estimates, early 5G trials should start by end 2018, while commercial deployment is expected to begin in 2020. This requires 5G-ready cellular networks with compatible backhaul. These networks are expected to significantly impact both wireless and the wireline side of backhaul infrastructure.

The transition to 5G technology promises performance benefits like 1,000 times increase in bandwidth per unit area, 100 times more connected devices, up to 10 Gbps connection rates for mobile devices, a perceived network availability of 99.999 per cent, 100 per cent network coverage, low latency of around 1 millisecond, and up to 90 per cent reduction in network energy utilisation. These performance indicators are likely to drive the market for 5G and the most important challenge for telecom operators will be to develop backhaul that can support the technology. To this end, the entire network including transport or backhaul will need to be redesigned. Although the existing mobile backhaul networks may be sufficient to meet technology requirements for 4G, they are likely to get overloaded with 5G, especially in terms of capacity and latency.

5G technology will be used to enable machine-to-machine (M2M) communication, connecting billions of devices like sensors and machines. The introduction of internet of things and M2M services will lead to a multifold increase in the number of connected devices. New services such as autonomous driving will be provided through mission-critical networks, which are vulnerable to risks of failure. A compatible 5G backhaul infrastructure will be crucial for such services to function smoothly.

Backhaul requirements for 5G

While migrating to 5G technology, telecom operators need to make a number of changes to their existing networks, especially in terms of wireless backhaul infrastructure. Although the legacy mobile backhaul architecture has served the industry for long, it is getting obsolete with the launch of 4G and may be of little use for 5G.

5G networks will require a multifold increase in capacity from the existing 100 Mbps to about 10 Gbps. This will change the sizing requirements of backhaul networks. Currently, most networks use the microwave frequency band that operates at a frequency of 300 MHz to 30 GHz. The backhaul for 5G will require support from a millimetre frequency band, which has an operating frequency of 30-300 GHz. This band will facilitate 5G roll-outs owing to its higher bandwidth, higher spatial resolution, reduced probability of interception and interference, and lower power requirement.

The supporting backhaul for 5G will also require ultra high data rates. Further, it is estimated that the accuracy requirements for 5G will be three times higher than those for long term evolution-advanced (LTE-A) technology.

Scope of SDN in wireless backhaul

With the launch of 5G, there will be a need to improve the operational efficiency of networks and bring about a significant reduction in time-to-market for services. In this scenario, software-defined networking (SDN) and cloud-based virtualised radio access network (RAN) technologies could be used to make complex 5G networks easier to handle. These will automatically manage the network by adjusting traffic to one or more links. Wireless backhaul will require integration with SDN and network functions virtualisation architecture to enable multi-vendor and multi-domain network optimisation. Therefore, wireless backhaul upgradation remains crucial for 5G deployments.

Need for wired backhaul

Microwave backhaul has bandwidth issues since it uses traditional bands with 300 Mbps of capacity, whereas fibre-based backhaul can offer unlimited capacity and low latency that are a prerequisite for 5G applications. Fiberisation of small and macro- cell sites is important if these cell sites are to be upgraded to 5G in the coming years, as copper and wireless backhaul options cannot be scaled to cater to the large amount of backhaul traffic that will be generated by a 5G RAN. Further, with large-scale adoption of 3G and 4G technologies, microwave backhaul has already become congested and overloaded. As a result, India has one of the lowest data speeds in the world despite the launch of 4G long term evolution in the country. As 5G is intended as an overlay on the existing 3G/4G mobile networks, it is crucial for operators to upgrade their cell sites with fibre backhaul in order to support future networks.

5G networks will use higher frequencies to deliver higher bandwidth, making highspeed fibre backhaul critical. Further, the forecasted increase in network capacity is 1,000 times more than the existing networks. The high capacity per cell site and move to higher RAN frequencies would require smaller coverage, thus making mobile grids highly dense and overloaded. This grid will be made up of macro-cells and small cells installed on mobile towers, or on streets using smart poles as physical infrastructure. Such infrastructural upgrades will require a large amount of fibre.

Challenges for the Indian market

India is in the process of aligning itself with the global roadmap for 5G deployment. However, the migration from existing networks to 5G will not be easy without a relevant backhaul strategy in place. India is aiming to be 5G-ready, both in terms of technology and spectrum, and there is a strong need to develop a flexible and robust backhaul infrastructure, which should be an optimal mix of both wireless and fibre.

The level of fiberisation is extremely low in India with over 80 per cent of cell sites connected through microwave backhaul and fewer than 20 per cent sites connected through fibre. Operators face a major challenge as they need to complement their existing wireless backhaul with fibre backhaul in a bid to support increased bandwidth capacities. To set up adequate fibre backhaul, several telecom operators have started laying fibre across their backhaul networks.

However, the capex required to set up backhaul infrastructure for 5G deployments is expected to burden telecom operators given that the industry is reeling under financial stress and declining revenues. It is estimated that Indian telecom operators need to invest $60 billion-$70 billion in 5G. On the regulatory front, the government needs to resolve spectrum harmonisation issues in a bid to create a standard spectrum band for the evolution of 5G.

As India prepares itself for a 5G revolution, operators need to rework their backhaul strategies to match the global 5G standards and service delivery.


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