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PCAST: Re-casting the Future

July 27, 2012

I am one of those people people who tends to get either over-enthusiastic about or dead-against things in general. I have to say I am on the side of ‘wildly enthusiastic about’ the PCAST REPORT TO THE PRESIDENT REALIZING THE FULL POTENTIAL OF GOVERNMENT-HELD SPECTRUM TO SPUR ECONOMIC GROWTH.  I am not well versed enough in American politics to be able to comment on whether this report will get anywhere and actually be implemented. Some of the random comments I read online suggesting it smacks of communism makes me feel there might be a few issues! But  I have no real feeling for how it might pan out. That aside, I think there is much worth noting. What follows are a few of the many points that could be made.

  • While not a new point the report underscores the fact that it is our spectrum management practices that ‘mange spectrum into scarcity‘. I think this can never be emphasised enough. A phrase we use here in CTVR is ‘managing into abundance’ and I think the proposals here head in this direction.
  • The report comes up with a set of behaviours that will govern how spectrum is accessed over the entire 1000 MHz of interest rather than thinking about individual services or bands. A whole swathe of spectrum is therefore  considered in a completely systematic way rather than the typical piece-meal fashion we tend to do things around the world. This is very important and long overdue.
  • Three tiers of access to spectrum are suggested. The report talks about Federal Primary Access, Secondary Access and General Authorized Access. One of my favourite sentences is, ‘ Federal Primary Access should be an exclusive right to actual use, but not an exclusive right to preclude use by other Federal or private sector users‘.  Hence when the Federal users are not availing of the spectrum, other users get access in different ways and with different priorities.  I find it helpful to broadly think of  the three tiers as exclusive use, exclusive sharing and non-exclusive sharing.  I think this is a very effective way of organizing access. And from what I read they seem to have thought through the different tiers in quite a comprehensive way.
  • There is an explicit acknowledgement that spectrum access can be authorised on multiple time scales from decades to on-the-fly access.  It is extremely important to see this kind of thinking embedded into manage processes.
  • There is a major acknowledgement that the receiver is a key part of the picture. The report speaks about defining interference limits which as far as I can see akin to the Ofcom  Spectrum Usage Rights  (SUR) approach. Interference  limits would be defined in cases where receivers can expect protection (Federal Primary Access users and Secondary Access users but NOT for General Authorised Access users for example).  The use of interference limits or SURs or some kind of receiver-centric licensing approach, should in my opinion be the licensing approach for all systems in the future so I was particularly happy to see this. The importance of knowing receiver characteristics in spectrum management is also stressed. I think there are many interesting self-profile/self-awareness/cognitive radio opportunities here.
  • The idea of a Test City is suggested.  This sounds exciting.

It is of course true to say the the devil may be in the detail and of course all of this could be implemented in a highly conservative and restrictive way. For example TV white space databases can use highly conservative propagation models which make spectrum appear less empty and pander to the incumbents. However I think the principles are heading in the right direction.

For me there are  number of key conclusions.

The first is that I think this framework is suitable for ALL SPECTRUM  MANAGEMENT.  Federal Users are a defined group of users over which there is an entity that has authority. Commercial incumbents across the globe or actually even in individual countries do not fall into this category.  Hence there is not an easy way to change the current licenses and order commercial users to behave in new ways. However there are ways to begin to make this happen. I am going to do a blog post on one way of doing this rather than go in to details here.

My second key conclusion is Europe-centric. I feel a crisis coming on … ok what is new here? We are all in constant crisis in this part of the world.  What I am alluding to here is the fact we are long past the glory days of GSM and not world leaders in mobile communications any more. Should the USA truly embrace what is in the PCAST report and not in a limited and conservative way, we might as well turn out the lights unless we adopt bold new ideas here too. There are moves to look at new spectrum regimes and embrace sharing but they are not fast enough.

Finally – all of this is music to the ears of those interested in adaptive, reconfigurable wireless systems, proper dynamic spectrum access, self-aware radios, cognitive techniques, collaborative systems etc. etc etc.


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