Good point Cortland. Cognitive radio offers national regulators the opportunity to adopt a much lighter touch to regulation. They could do away with rigid frequency allocations - the users radio will just look for an "unused" frequency and use it.
As you say the problem lies in what is considered an occupied frequency. We may well find that a signal 10 db above the prevailing noise floor would be considered noise and thus available for use. On 2.4 GHz technologies such as Bluetooth and Wifi adapt to interference. I'm sure as cogitive techniques develop we'll see large chunks of the spectrum operated in a similar manner to 2.4 GHz, eg license exempt with the Equipment (users won't necessarily realize it's a radio) choosing the lowest interference frequencies to carry out the required task. European Union RSPG report on Cognitive Technologies http://www.southgatearc.org/news/november2009/rspg_report_on_cognitive_technologies.htm 73 Trevor M5AKA --- On Wed, 16/12/09, Cortland Richmond <k...@earthlink.net> wrote: > I do hope cognitive radio designs > will be done responsibly for the spectrum > they occupy, and I cite RMS Express as an example of a > responsible approach > to mitigating interference. And (military) ALE as I've > experienced it as > the opposite. > > However, I fear device manufacturers wanting to use > spectrum everywhere > will not produce radios able to detect weak emissions when > their receiver > bandwidth is so wide as not to see it above the > noise. Among the BPL > comments and replies is one manufacturer's assertion that > there were no > signals to be interfered with -- when his spectrum analyzer > noise floor was > higher than the level those signals would normally > reach. By using only > measurement technology to required for Part 15 > certification, that > manufacturer was able to ignore signals I believe he "knew > or should have > known" (as the lawyers say) were or could be present. > > We must listen first. So should any responsible user of > shared spectrum. He > must be able to hear *any users authorized* in the spectrum > shared, at > levels and in bandwidths they are authorized to use. > This is not so easy, > considering that we often carry on Olivia or Contestia QSOs > below the > background noise level. It could be made > easier by restricting automatic > (cognitive) radio to spectrum where weak signal modes will > not be > encountered. > > Cortland > KA5S > > > > > [Original Message] > > From: Bob McGwier <rwmcgw...@gmail.com> > > To: <digitalradio@yahoogroups.com> > > Date: 12/16/2009 12:54:35 AM > > Subject: Re: [digitalradio] cognitive radio systems;? > > > > Cortland Richmond wrote: > > > > > > > > > One problem with "cognitive radio" is that it > seems it will be designed > > > to detect only emissions similar to those it is > meant to receive. > > > Therefore, it is best used in spectrum > particularly allotted to > > > just those kinds of > emissions. This rather defeats the purpose > of > > > "white space." > > > > > > RMS Express by way of contrast has a busy > detector that will prevent > > > transmitting over many kinds of modulation > different than it uses. > > > Compare this with (say) ALE, whose polling > (encountered on MARS > > > frequencies) takes no account of voice or even > Olivia on channels it > > > happens to select. > > > > > > > > > Cortland > > > KA5S > > > > > > > > > > This is not correct in my experience. In all serious > systems under > > development, the CR is looking to characterize all > energy to some degree > > or another, irrespective of whether it is a "matched > filter" to a > > particular waveform. > > > > The purpose is to find a channel that works. > Energy on the channel is > > an indicator it would not as the source would be > cochannel interference > > and with some high degree of probability, the > interference would be > mutual. > > > > Dislike for any particular system which automates > channel usage but does > > not behave responsibly is not to be used to condemn > responsible digital > > system developers. The enforcement of this > responsibility is done by > > pressure (peer) and performance (being interfered with > by those not > > detected). > > > > Bob > > N4HY > > > > > ------------------------------------ > > Suggested frequencies for calling CQ with experimental > digital modes = > 3584,10147, 14074 USB on your dial plus 1000Hz on > waterfall. > > Announce your digital presence via our Interactive Sked > Pages at > http://www.obriensweb.com/sked > Yahoo! Groups Links > > > digitalradio-fullfeatu...@yahoogroups.com > > >
