White space devices: will they come?

On 2nd May 2012, I was at BNetzA (German regulator) office in Mainz, Germany to attend the workshop on CR and SDR organized by COST-TERRA and ECC. The workshop was held to discuss efficient use of spectrum in general rather than specific CR technology. It seems that CR is now regarded as the synomym of the efficient spectrum utilization. Original definition of CR by Joe Mitola is gone. Anyhow, this is really a hot topic. Alexandre Kholod, the chairman of ECC SE43, mentioned that the ECC report 159 has recorded 180,000+ downloads in one year since the approval of the document in January 2011. Wow… 180,000+!

The workshop was a gathering of over 100 people including many influential figures in European spectrum policy as well as in industry (for example, representatives of ITU, CEPT, ETSI, EC, Ofcom, BNetzA, NGMN, and so on). It was full of good presentations about recent regulatory activities, findings of European research projects, and lessons from TV white space (TVWS) trials in the USA and the UK. Here, I’m to share some of the reflections that I’ve got from the workshop.

1. Hen and egg problem still exists.
In QUASAR deliverable D1.2, we identified that the hen and egg problem is one of the biggest hurdle to overcome for the commercial use of secondary spectrum. Regulators want industry to provide technical proposals so that they can come up with a regulatory framework, whereas industry is reluctant to invest in the secondary spectrum which has regulatory uncertainties. It looks that this is still the case. However, things are getting better now. While most of regulators and industry players are still stuck with this hen and egg problem, there are some brave regulators (such as Ofcom) and startup companies who took initiatives from each side. Commercial use of TVWS may not be a distant future at least in the UK.

2. Other spectrum bands than TVWS are getting attention.
For last a few years, TVWS has been the only frequency band that the regulators and industry paid serious attention to. Now, people started talking about the need for investigating other spectrum. (three different speaker mentioned this in a day!) My personal guess is that it is because they realized TVWS is not a silver bullet to cope with the spectrum scarcity problem, i.e. the availability of TVWS in urban and dense urbarn area turned out unsatisfactory. I was surprised to hear that a speaker from Ofcom named radar band when she was asked to give examples of other spectrum (note: it was her very personal opinion). Chances are the radar spectrum will get popular among researchers rather soon.

3. QUASAR conclusion is backed by industry.
I was one of the speakers at the workshop. I presented the preliminary conclusion of the QUASAR project. (similar presentation given by Jens can be found here) In short, QUASAR conclusion is that commercial sweetspot of secondary spectrum lies in low-power wireless for indoor and hotspot capacity provision, i.e. white space offloading. My presentation was followed by the speakers from two companies, Spectrum Bridge and InterDigital. They expressed similar views in their talks: permissible power for white space devices in urban area is simply too low to obtain macro coverage, and the white space offloading will obviate the need for complicated heterogeneous networks.

More information about the workshop is available at http://cept.org/ecc/groups/ecc/client/introduction/news/workshop-on-cognitive-radio-and-software-defined-radio

Presentation slides will be available soon.

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