Battle of the bands

Battle of the bands

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The dispute in the US over 5G’s potential effects on aviation and recent reports on future spectrum availability have brought issues around spectrum to light. so, What will it take to ensure spectrum use is maximised in the long term? Gareth Willmer investigates

As 2022 dawned in the United States, new 5G roll outs were struggling to get off the runway. In the culmination of a dispute between the aviation and telecoms industries, airlines warned that 5G in the C-band could have a “catastrophic” impact by interfering with altimeters in aircraft, affecting their ability to safely fly and land.

Having already delayed their C-band roll outs from late 2021, in January AT&T and Verizon agreed to further postponements with the US Federal Aviation Administration (FAA). The operators and FAA then came to an agreement that saw the service’s roll out continue, but with steps to ensure careful deployment and temporary buffer zones around airports.

While the story made big headlines, industry experts do not necessarily believe it has far-reaching implications for potential issues in 5G roll outs, nor a cascading effect in heightening spectrum disputes – or at least, not considerably beyond the norm.

“I think the situation in the US became quite extreme at the beginning of the year, but much more in a political sense than a technical sense,” says Luciana Camargos, GSMA’s head of spectrum.

“I think there will be potential disputes in the future for spectrum, as there always are. Bands between 470MHz to 7GHz are currently being used, either by mobile or by another service. When there is a new band licensed for mobile, there is the potential for there to be a current user, as well as neighbours.” Camargos also points out dozens of countries have already deployed spectrum in the same band without issues.

An EU official does, however, highlight how there are bigger challenges to ensuring efficient spectrum use as it intensifies with new technologies and applications – bringing a need to evaluate coexistence between 5G and devices such as altimeters on an ongoing basis, and take long-term measures if necessary.

Spectrum demand

What the situation has also done is brought to light the issue of spectrum and its presence as a limited resource. As 5G grows, spectrum demand is rising amid booming wireless use across a wide array of industry sectors, and for different technologies and uses, such as satellite, internet-of-things (IoT), smart cities and connected vehicles.

The GSMA recently warned that up to US$360 billion of GDP growth could be lost worldwide unless sufficient spectrum is made available. It estimated that governments and regulators need to release an average of 2GHz of mid-band spectrum for licensed 5G use by 2030 to meet the data speed requirements of the International Telecoms Union (ITU), the United Nations’ specialised agency for ICT.

The mid-band, comprising spectrum in the ranges from 1GHz to 6GHz and including the C-band, is seen as key because it offers a good mix of coverage and capacity for 5G.

“There is no emergency or alarm, but it’s very important to do your roadmap properly,” says Camargos. “It’s important to understand that if you don’t make 2GHz available, then you won’t have the full benefits of 5G in your country.”

One debated mid-band spectrum range has been the 6GHz band. Some in the Wifi community have called for the band to be fully opened up to unlicensed use to help new generations of the technology, such as Wifi 6E and 7, thrive alongside 5G and fibre, whereas others want at least some of it given over for licensed 5G spectrum.

Different countries and regions are at different places in making decisions on this, but the GSMA has called for governments to make at least the upper part of the 6GHz band available for licensed 5G – with countries needing to align to maximise the technology’s potential.

“It is very important to create a balanced solution in the 6GHz band,” says Camargos.

6GHz state of play

So far, the European Union has only allocated the lower part of the 6GHz band for unlicensed use, but some countries have already done that for the whole 1,200MHz of the band’s spectrum, including the United States, Canada, Brazil and South Korea.

When the US Federal Communications Commission (FCC) did this in early 2020, US trade association CTIA, which counts mobile operators as key members, questioned the move given the country’s need for 5G spectrum, and AT&T challenged it on the grounds that it would cause interference issues with existing technologies. The decision was, nonetheless, upheld.

While Nick Ludlum, senior vice president and chief communications

officer at CTIA, highlights a desire to maximise limited opportunities, he says it is now time to look forward: “From our perspective, that 6GHz issue is sort of done and we’ve moved on. The point I’d make is that licensed spectrum continues to be important for fuelling the expansion of 5G networks and we work closely with policymakers here in the US to make sure that we have the pipeline of spectrum we need for that.”

Ludlum says things are going in the right direction in the US, with other mid-band spectrum, such as the C-band and 3.45GHz, being released, and 5G rolling out faster than 4G. “We did have a deficit in the mid-band,” he says. “But that is in the process of being narrowed significantly.”

Yet he adds that it will be important to keep pace as other leading economies, such as Japan and South Korea, continue to free up mid-band spectrum for 5G.

Meanwhile, with Europe still looking into the 6GHz band, the Dynamic Spectrum Alliance (DSA), a cross-industry not-for-profit organisation, has urged countries worldwide to adopt licence-exempt access to the whole 6GHz band – promoting alternative technologies in addition to 5G to deal with some of the new demands of the digital transformation. The DSA believes this will help citizens and businesses choose the technologies that are suited to their needs.

“It’s important to make sure that all the technologies are taken into account,” says Martha Suárez, president of the DSA. “We think that there should be a neutral approach that includes Wifi and satellite as part of those technologies that can provide gigabit connectivity.”

Suárez adds that some of the latest technologies require a variety of options rather than working solely on 5G and fibre – with the DSA giving the example of augmented reality glasses connecting to 5G via a Wifi link. “Some of the new requirements can be covered by a mix,” she says. “We cannot say that augmented and virtual reality are just a 5G use case.”

Better use

For spectrum as a whole, there are calls for increased availability, harmonisation and more efficient use of bands. In January, a report by the European Court of Auditors (ECA) – the EU’s independent external auditor – highlighted that some EU member states have experienced significant delays in 5G roll outs. This includes hold-ups in assigning spectrum for reasons including Covid-related delays, weak demand among mobile operators, and issues relating to cross-border coordination and security.

“Member states are taking different approaches to deploying 5G services,” adds Annemie Turtelboom, the ECA member responsible for the report. “That brings with it the risk that inequalities may arise in access to and quality of 5G services in the EU, thereby creating a ‘digital divide’ between different member states and regions… many EU countries have fallen behind in their deployment of 5G.”

Turtelboom says that at the current pace of implementation, there is a real risk of member states missing EU deadlines for progress in 2025 and 2030. In line with this, says Turtelboom, the European Commission has accepted the ECA’s recommendation to work with member states to develop common service standards for 5G networks, adding that “harmonised spectrum management is crucial”.

Indeed, this February, the Commission adopted decisions to aid harmonisation of spectrum for technologies including 5G for mobile broadband, Wifi 6 and IoT.

“To ensure effective spectrum harmonisation, member states should provide timely and investment-friendly access to spectrum for users,” says Johannes Bahrke, coordinating spokesperson for digital economy, research and innovation at the European Commission. “The growing need for more and better wireless connectivity, and the ever-increasing number of use cases, call for a paradigm shift towards making shared spectrum use a mainstream mode in spectrum policy and regulation.”

Spectral efficiency

Advances in mobile technology, such as moves towards 5G, enable better spectral efficiency among operators, enabling them to look for new ways of optimising its use. Ludlum points to estimates from a 2019 CTIA paper that US wireless providers had increased their spectrum efficiency by 42 times compared to 2010.

Jennifer Alvarez, CEO at US spectrum analysis and technology firm Aurora Insight, suggests that to further maximise efficiency, the industry can look towards methods and technologies that allow dynamic geographical- and time-based use of spectrum. She points out that specific bands are not in use continuously, with certain types of new technologies, such as IoT, being very time-intermittent – opening up the possibility of allocating use, for example, on a daily or weekly basis.

“More complicated techniques for sharing spectrum must be considered, in which multiple users have access to spectrum,” says Alvarez. “There’s a driving need for that now or in the next few years.”

This would benefit from some kind of spectrum management system, she says, given that many different providers and technologies will be battling it out for limited spectrum resources in the coming years, including telecoms providers, IoT players, satellite mega-constellations and others. “Therefore, there’ll have to be some method of measuring and monitoring the spectrum, and reporting that back to some coordination system.”

Aurora Insight has developed ways to do this which it is looking to expand, with radiofrequency sensors on the ground, on aircraft and in space to analyse how spectrum is being used and how networks are deployed across the globe.

Charles Murray, a partner at consultancy firm Analysys Mason, points to improvements in efficiency enabled by technologies such as massive MIMO and agrees that flexible approaches to spectrum use are needed. Rather than operators continuing to view their mobile network as standalone infrastructure, he says, they should seek to optimise capacity use by leveraging 5G in its guise as a converged technology that gives access to multiple access technologies, including seamless handoff with neutral-host and Wifi networks.

“I think there’s got to be a fundamental shift in the way that operators think about the network,” he says. “Ultimately, a mobile communications provider is going to be an aggregator of networks in which the macro network is part of a wider set of solutions.”

But for Europe, Christian Leon, VP and head of networks and managed services for Europe and Latin America at Ericsson, believes that one of the most important things for now is ensuring the spectrum that is already available is used.

Leon points out that the EU is lagging behind some other regions in rolling out 5G, estimating that less than 20% of people in the region were covered with mid-band 5G at the end of 2021. “Between now and 2025, for me, the urgency is to go and deploy what we have, especially when it comes to 5G mid-band,” he says.

Leon adds that scaling up would be aided by greater harmonisation, while refarming can help provide more spectrum. “If there is a global alignment of what type of spectrum is in which band, frequencies will be released at the global scale and then the industry can build the right technology. That’s how, as a whole, the cellular industry has been successful – by building global scale.”

Harmonised outlook

Industry observers point to the ITU World Radiocommunication Conference (WRC-23), which is to be held in November 2023, as a moment for enabling further harmonisation of key mid-band spectrum, such as the 3.5GHz and 6GHz bands. “That’s a key harmonisation opportunity to create scale globally,” says Leon.

For its part, the ITU agrees that harmonisation is crucial. “Harmonised spectrum sets the scene for investment, industrial planning and the present and future of ecosystems,” says Uwe Löwenstein of the ITU’s Radiocommunication Bureau. He adds technical advances can provide many solutions for more effective harmonisation, “allowing more flexibility for equipment manufacturers and vendors to serve global markets with the same products”.

Löwenstein agrees that there are challenges in finding spectrum resources to meet many different needs.

“Spectrum is a unique resource in that different frequencies and frequency ranges have different characteristics that may or may not be suitable for specific applications,” he explains. “Hence, finding available spectrum that is suitable for the required service capabilities can be rather difficult.”

But the industry is forging ahead to address this and also developing a vision for 2030 and beyond, with the ITU and the market already setting the stage for future technologies such as 6G.

“We are seeing more and more WRC agenda items seeking access to additional spectrum for new mobile applications to be introduced alongside the existing incumbent services,” says Löwenstein.

“The ITU membership is continuing its long-standing contribution to mobile communications, facilitating its mission to be ‘committed to connecting the world’.”

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