Expanding Frontiers Through Digitalisation

January 28, 2021 3:51 pm

Cellnex successfully clears the 700 MHz band in Spain

The radio spectrum is like a motorway along which radio, television and telephone signals travel. Use of this space – which is regulated by governments – has evolved in tandem with needs and innovations, with extra lanes being added and traffic being rerouted to facilitate circulation.

With 5G technology now poised to become a driver of business competitiveness and a facilitator of new products and services for the public, the European Union called on member countries to free up one of the lanes – the 700 megahertz (MHz) band – to provide a place for higher-speed “data” to travel.

This so-called “second digital dividend” entailed freeing up this space and preparing it for the circulation of the long-awaited 5G technology, safety and emergency networks, and other telecommunication uses.

This lane – between 694 and 790 MHz – used to be occupied by digital terrestrial television (DTT) signals (including UHF channels 48 to 60) managed by Cellnex, one of the organisations responsible for the complex mission of diverting traffic without affecting users – a commendable example of public-private collaboration.

The engineers and technicians at Cellnex – the company that spearheaded the implementation of DTT in Spain and has a network of broadcasting facilities consisting of more than 3,200 sites with remote control and monitoring systems – took up the mandate in 2019 and completed the task in October after a three-month extension prompted by difficulties associated with COVID-19 lockdown measures.

The task, which the Spanish government described as “highly complex”, was carried out in stages, without provoking any interruptions of service or the obsolescence of television receivers. However, it did require the coordination of thousands of transmission centres throughout Spain. This was done by splitting up the country into 75 geographical areas with varying degrees of affectation and different adaptation solutions.

Cellnex was well acquainted with the task of reorganising traffic. In 2015, it implemented the first “dividend” – a concept that combines the two meanings of the word, in the sense of division and distribution – by freeing up the 790-862 MHz frequency band from television services for the deployment of the 4G network.

The second “reassignment”, led by the Spanish Secretary of State for Telecommunications and Digital Infrastructure, involved the participation of operators, broadcasters, antenna installers, property managers, equipment suppliers and even the media, which helped to inform the public about a service change that, in most cases, required nothing more than retuning their set.

“We were able to achieve success thanks to a large-scale joint effort involving practically the entire Cellnex Spain team in a project led by Engineering and executed by Network Operations and our International Service Operation Centre,” commented Albert Cuatrecasas, General Manager of Cellnex Spain.

Optimizing resources

Cellnex modified 2,800 sites, some in remote locations and others requiring multiple actions due to the technical complexity, with the aim of minimising the impact on 37.5 million users. The modifications required temporary simultaneous broadcasts on different frequencies, the adaptation of shared aerials on more than 1.1 million buildings and the retuning of television receivers in 20 million homes.

These two “dividends” have compressed the band on which television signals are transmitted and forced Cellnex to play a complex game of “Tetris” to reassign channels without affecting service. In fact, far from congesting the services, this rerouting of traffic made it possible to optimise a series of motorways that, until very recently, were practically country roads.

“Now DTT takes up less space. It is more spectrum-efficient because channels have been grouped together and geographical areas have been joined together according to orography and the locations of the antennas. Therefore, the same frequencies are used for more areas,” explained Cuatrecasas. “Ten years ago, we had seven analogue channels. Now, the DTT offering is much richer in terms of channels and content.”

“The reassignment of traffic has allowed us to optimize highways that, in the end, are practically local roads”

With a third “digital dividend” having been ruled out, television channels – a strategic vehicle that not only entertains but also plays a key role in informing and educating the public – will remain in the current frequency range at least until 2030, although the challenges associated with broadcasting are not yet a thing of the past.

“The immediate challenge is the migration of all content to HD, which is scheduled for late 2022,” explained Cuatrecasas. “This will be a transparent transition for the public and will require no significant adaptations, since the stock of receivers is practically ready. Then we will witness the arrival of ultra-high-definition (UHD) content, which is already being tested, and an explosion of hybrid services combining the best of the broadcast world, DTT, with the broadband world, Internet.”

Now that the 700 MHz frequency band has been freed up, the Spanish government will auction off the spectrum for ultra-fast networks to telecommunications operators, probably during the first quarter of the year. This is a “toll motorway”, since the 2021 budget forecasts an income of just over €2 billion, nearly five times the amount entered in the July 2018 bid for 4G space.

“Now is the time for imagination. The frequencies are available and the infrastructure is ready. Now is the time for creators to invent the services of the future,” declared the head of Cellnex, a company involved in several use cases of the new technology that, for the time being, use other frequencies.