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Delivering Next-Generation Connectivity with Evolved Wireless Backhaul

As we have already started talking about the post-5G world, we need to keep in mind that 5G still has a lot of enhancements and new features in pipeline. Many of these new features will require support of an enhanced backhaul, be it terrestrial or in the sky. 

Earlier this year, GSMA released a report on backhaul, titled, "Wireless Backhaul Evolution: Delivering next-generation connectivity" that outlines the evolution of this important area. It has been written by ABI Research and details wireless backhaul for 5G era and the role played by new backhaul and existing bands, as well as technologies that improve spectrum efficiency.

The summary of the report says:

The transition to 5G will need a sizable backhaul evolution to accommodate growing traffic and new network capabilities. Despite the growing importance of fibre, wireless backhaul is set to play a central role in these developments. This means regulators have a vital role as their decisions moving forward will impactfully help or hinder the fledgling 5G market. This report aims to assess the evolution of wireless backhaul over the 5G era and, particularly, the role played by new backhaul bands and technologies. A major focus is on the cost of the network infrastructure and spectrum fees on which this evolution relies.

It concludes that higher capacity backhaul bands will be vital in meeting 5G traffic demands and that high backhaul spectrum costs can present a significant burden to mobile operators, and even deter technology upgrades. The report recommends regulators carefully consider future backhaul spectrum needs so the right bands can be made available at the right time. It also encourages regulators to carefully consider backhaul spectrum pricing and ensure the formulas used to set fees are reasonable and do not disincentivize the use of wider channels and encourage the use of advanced technologies.

GSMA says:

The report finds that higher capacity backhaul bands (both mmWave and microwave) will be vital in meeting 5G traffic demands. Without access to new spectrum there is an imminent risk that network become congested. Also, terrestrial wireless backhaul is the most technology now and in the future.

Also, high backhaul spectrum costs can present a significant burden to mobile operators, and even deter technology upgrades. The report highlights large variances in different parts of the world. For example, the highest spectrum prices in some markets were found to be 22X higher than the global median and 59X higher than the lowest priced markets.

The position paper spectrum for wireless backhaul, on the other hand, highlights how governments and regulators can help set the stage for best-in-class mobile networks. Its recommendations include:

  • New backhaul bands are needed to support evolving network requirements and growing traffic;
  • Current backhaul bands will still play an important role but need support to maintain relevance in the 5G era – especially through wider channel sizes; and
  • Regulators need to carefully consider the most effective backhaul licensing terms approaches, terms and conditions.

Laurent Bodusseau, Senior Director – Spectrum / Government & Regulatory Affairs at GSMA in his blog post on this topic says:

5G will have significant impact on backhaul networks. For the top 30 markets, traffic is estimated to increase to 6,268 exabytes (1 EB equals 1 billion GB) annually by 2027, with 5G accounting for 83% of total traffic by the end of the period. The growth means that most networks in urban areas will be congested within 3 years without access to new wireless backhaul bands (with channel sizes of up to 2 GHz) such as:

  • E-band (70/80 GHz): needed as soon as possible
  • W-band (92 GHz to 114 GHz): needed by 2024/2025
  • D-band (130 GHz to 175 GHz): also needed by 2024/2025

But making the spectrum available is only the first step, getting the licensing process right is equally important. The highest spectrum prices in some markets were found to be 22X higher than the global median and 59X higher than the lowest priced markets. This places a significant burden on operators in some markets, making it more difficult to quickly roll out faster broadband services with better coverage.

An important part of this equation is fees. High backhaul spectrum fees have a significant impact on the total cost of networks in the 5G era. The report describes what the impact of applying high representative maximum spectrum fees across all the microwave and millimetre wave bands for a network in a developed market is. The result a yearly aggregate network TCO of US$1.68 billion, which is 266 per cent higher than the minimum spectrum fee scenario.

Another unfortunate habit is placing fees on operators that adopt innovative backhaul technologies that increase spectrum efficiency. For example, some countries charged operators double the price of a single radio channel link when the operator employed secondary polarisation technology, which doubles spectrum efficiency.

As part of a success terrestrial wireless backhaul strategy, governments and regulators also need to adapt and in some cases protect existing backhaul bands. Existing bands between 6-42 GHz are still important. They depend on some flexibility to accommodate wider channels.

One of the hottest bands at the moment is 6 GHz. This is an important band for mobile fixed links – the lowest frequency that is widely used for backhaul and thus one of the most affordable. Where there is less fibre, mobile base stations need more backhaul spectrum and the relationship between existing fixed links and the new access connectivity will need to be managed.

So what should happen next? What should governments and regulators do to ensure that 4G and 5G networks can connect more people and things, offer faster speeds, and better coverage without congestion. To help navigate this topic, the GSMA’s spectrum team has developed five recommendations. They are:

  1. New backhaul bands are needed to support evolving network requirements and growing traffic;
  2. Current backhaul bands will still play an important role but need support to maintain relevance in the 5G era – especially through wider channel sizes;
  3. Regulators need to carefully consider the most effective backhaul licensing terms approaches, terms and conditions;
  4. High backhaul spectrum prices present a barrier to mobile network evolution, improved coverage and more spectrum efficient backhaul technologies; and
  5. Regulators should, in consultation with the industry, ensure the timely availability of a sufficient amount of affordable backhaul spectrum under reasonable licensing approaches, terms and conditions.

You can view and download the report from here.

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