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Nokia has successfully demonstrated a 4G LTE network which can hop aside when someone else wants the frequency, opening up the possibilities for dynamically-shared radio spectrum.

Nokia's test network reached three Finnish cities and was able to switch radio frequencies based on availability by regularly checking back with a database of users. This increased capacity by 18 per cent with no additional infrastructure, simply using existing LTE handsets a little more carefully.

The live test built on May's trials of the database approach, which focused on TD-LTE as it's slightly easier to shuffle about given that it uses a single band for sending and receiving. That test ran in the 2.3GHz band which is available for LTE in some countries, but reserved for wireless camera equipment in others - including Finland.

TV companies planning outside broadcasts logged on to a database to say where and when they'd be using the band, and the network base stations then switched frequencies when they knew interference was possible, filling the airwaves more consistently and efficiently to the benefit of all - in the trial at least.

While Nokia likes to call it Authorised Shared Access this is what we know as White Space, which is already being deployed in America and will be rolling out in the UK early next year. The first deployments are using TV spectrum, partly because it's particularly useful but also because TV transmitters are well mapped and documented.

But the concept can be applied to any frequency: once one has a database on-line then a frequency can be added to those being dished out (or denied) as Nokia's work demonstrates.

It would be better if the radios could decide between themselves what band to use, but that presents technical problems which may prove insurmountable. The database approach also permits governmental control (such as the four-year access Ofcom will provide to 600MHz). Few engineers believe cognitive radios will render the database approach redundant in the foreseeable future, though they might complement it.

Network operators, having paid enormous sums of money for exclusive access to slivers of spectrum, shouldn't be expected to embrace such an approach. For all their public demands for more spectrum, every MHz released decreases the value of their assets - particularly given that the FCC and Ofcom are both making use of White Space licence-free.

Nokia's testing has demonstrated that LTE is perfectly capable of making use of such bandwidth, so it will be up to government regulators to decide whether who should be allowed to do so. ®

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