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Unfinished Histories …

May 8, 2011

Usage Rights for Spectrum – the Unfinished History was the title of Martin Cave and William Webb‘s paper at IEEE DySPAN 2011. I am very interested in everything to do with this topic and think that this is a great title. And I do feel that the whole situation re usage rights seems to have stalled. So I am very glad they are taking up the topic again.

William Webb who gave the presentation spoke about the extending of usage rights to more scenarios.   In the paper the authors advocate thinking about the usage rights of the whole band as well of the usage rights of users within the band which may be licensed, unlicensed or a mix thereof. The paper considers UWB (underlay) and Cognitive Radio (overlay) scenarios and teases out some of the implications for allowing these kinds of technologies to be used to share bands.

I am all for usage rights. Usage rights is the way in which we can take a technology neutral approach to spectrum management. I am all for technology neutrality. I spoke about technology neutrality in a previous blog for those who seek a definition. I say forget harmonisation. Think usage rights. This is liberalisation which ultimately leads to harmonisation of USAGE rather than harmonisation of USES. This nuance is very important.

This point also relates to one of my main interests in TV White Space. As I said before, one of the key advances that has been made because of TV White Space, is the fact that technology neutrality is very much on the agenda, whether it is acknowledged or not. In the case of TV White Spaces, none of the rules applying to the use of white spaces stipulate what kind of technology should be used. Devices will have to access a database and not cause harmful interference to the incumbents but as long as they do that they can use any transmission techniques they see fit. We have been looking at the concept of Dynamic BEMs as means of managing TV White Space usage. A BEM is a block edge mask. It has it pros and cons. It is defined at the transmitter and thus easy to apply but receiver centric usage rights such as the SURs suggested by Ofcom are actually a more accurate means of controlling interference.  [Cave and Webb discuss SURs in their paper as well – read it for a quick intro. ] We are interested in how networks of cognitive  radios can conform to any Block Edge Masks they are given through controlling their emission profile. We envisage scenarios in which some bands may become dynamically available with strict Block Edge Masks and other bands with more lenient ones. It is feasible that a network would retrieve a Block Edge Mask (or in fact a set of SURs) from a database that would be associated with a certain band of spectrum. As mentioned already, our work to date has focused on the dynamic BEM and not on SURs but the point is not that. The point is that thinking in terms of usage rights lays a foundation for approaching all spectrum management in the future in my opinion. And of course there is plenty of opportunity to stretch the use of the database.

William Webb did mention that one auction in the UK auction spectrum with a SUR-based license but that unfortunately for other reasons the band was not used by the successful bidder. It is a pity as I am dead curious to see how the SURs are put into action.

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