With over 90 participants on its mailing list, the Critical Broadband Communications Group is both the youngest and most active of the TCCA’s interest groups. Formed in March at a meeting in Barcelona, Spain, it returned to the city in September alongside the PMR Summit and LTE Summit conferences for a day which began with intensive discussions within its three working groups.

Opening the plenary session which followed, chairman Tony Gray summarized a number of meetings he had attended around the world to gather recognition of the broadband needs of critical communications users, and to press the case for accommodating these in the 3GPP’s LTE standards as soon as possible.

In negotiations with 3GPP, he said, a question that urgently needed clarifying was whether functions such as group calls – essential for teamwork among professional radio users – should be embedded within the core LTE standards or should be added as some kind of overlay application. “We, I believe, are strongly of the opinion that it should be in the core standard”, Mr Gray declared. And 3GPP already seemed supportive. “They have been prepared to set aside two additional days before their next week-long meeting in Edinburgh and allowing us and the other contributors the opportunity to argue the case.”

Spectrum requirements

Updates on activities within the CCBG were supplied by the chairmen of various working groups. Risto Toikanen, focusing on spectrum requirements on behalf of the TCCA, ran rapidly through broadband developments in European organs such as CEPT, the 48-nation European Conference of Postal and Telecommunications Administrations. A CEPT project team known as FM49 is currently studying broadband needs for PPDR (public protection and disaster relief) and seeking solutions. Its analysis of frequency band options is due at the end of 2013, laying the ground for a PPDR spectrum decision by or around mid-2014.

But such work was a slow business. “CEPT is producing European common position documents and those are the basis that Europe is using when negotiating with other regions in the conference”, Mr Toikanen said. “In the conference, a single member state cannot do much. If a member state wants to achieve something, it has to be baked in the regional common position for a couple of years before the conference.”

On the bright side, proposals were emerging through various fora for harmonizing LTE bands for PPDR use, bringing the promise of a larger market for PPDR equipment and thus lower manufacturing costs. One of these proposals, relating to a section of the 700 MHz region, would enable the same device to be used on three continents – in fact, everywhere outside North America.

What users need

Hans Borgonjen, of the CCBG working group on user requirements (WG UR), described progress in formulating the needs which the new technology will be required to satisfy. This task has involved collating inputs from a wide variety of user organizations. “We are not going to make new documents”, Mr Borgonjen explained. “We are going to reuse all the existing user requirement specification documents. We will try to make out of those documents an overview document and we call that an umbrella document.” From this data will emerge the requirement for radio bandwidth.

Speaking from the floor, David Chater-Lea, of Motorola Solutions, explained how CEPT’s FM 49 group had been evaluating future spectrum requirements by examining specific scenarios, such as the UK royal wedding of 2011, taking account of the number of police officers who were active during that event, and extrapolating their communications needs into the multimedia era.

“Second thing”, Mr Chater-Lea went on, “and this is very important, this is data. This is not voice. We do not have voice in this spectrum requirement at all. So if you want to think forward beyond data, multimedia and so on, if you want to start saying the spectrum allocation we are asking for will one day absorb our voice, you need to add something on to it. And however clever LTE is in the group environment, it’s not going to be very different from what you have today at 400 MHz for Tetra or Tetrapol.”

Mr Borgonjen replied: “That is, by the way, the reason why we now say in PT 49 not that we need 2 × 10 MHz but that we need at least 2 × 10 MHz – and in PT 49 themselves, they have already said yes. But we should also include voice.... And then we need more!”

Malcolm Quelch, a board member of the TCCA, pointed out that if group communication could not be implemented in LTE, the consequence would be a great increase in spectrum usage. “If you can’t use group communications, you need a massive amount of spectrum”, he said. “Therefore it underlines the importance of getting group communications into Release 12 of 3GPP. It’s quite dramatic.”
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