In line below … speaking strongly in favor of "b"
Gabor, I agree on possible renaming, if we want to specify unavailable channels. Please see comments inline. On Mon, Sep 23, 2013 at 12:56 PM, <[email protected]<mailto:[email protected]>> wrote: Vince, This proposal of yours below could potentially become very confusing. The message itself is named Available Spectrum Request, and you propose the Available Spectrum Response to include a bunch of channels with unspecified power levels, which are btw, not available channels. So far, we have 4 proposed ways to indicate unavailable channels: a) Not listing it, implicit unavailability This has the drawback of not distinguishing between being silent about a channel that is within the database's purview (channel off), and being silent about a channel that is outside the database's purview (out of scope for given ruleset). [DJ – Why should the database care about channels that are outside the scope of the ruleset specified by the radio? For example, if the specified ruleset is FCC-related, then why would I need to include Ofcom-related channels in the response? Am I missing something?] The rules have strict adjacent channel requirements. Meeting the spectral mask for the adjacent channels is one of the hardest parts for fielding real equipment. If the rules allow relative measurement of the adjacent channel energy, you can simply lower your transmit power to the point that you can meet the adjacent requirements. For a general White Spaces solution – it is critical to have knowledge for the full spectrum mask. The full spectrum mask includes adjacent non-allowed channels. RF channel usage are NOT a binary on/off or a simple transmit level. The mask has a specific contour that extends beyond the "allowed" channel. Transmitters will always send energy in more than the allowed channel! Paul b) List unavailable channels and specify the power limit, eg -56dbm Since the protocol should stand on its own, independent of any particular regulatory rule, do we really want to rule this out? In our interpretations of the FCC rules, for example, a Database is not prevented from doing this. [DJ – I’m still in favor of just using the implicit unavailability method described above in a). What value is there in providing a power level for an unavailable channel? If I’m the radio, I can’t use the channel, and I’m not going to intentionally transmit in that channel. This comment also applies to c) and d).] c) List unavailable channels and specify –inf as power limit "-Inf" is not really workable, because JSON does not allow Infinity or NaNs (http://tools.ietf.org/html/rfc4627), hence the d) proposal. d) List unavailable channels and do not specify any power limit So far, we have majority in favour of a), few people who could live or prefer c) and sort of consensus to strike out option b) from the list above. We’ll wait for more input on the list before declaring rough consensus for the question above; then we’ll go back to the original question on whether the encoding of spectrum profile should be option 1 or option 2. p.s. It looks to me, that if we want to specify unavailable channels, we may need to modify the names of the paws messages to ‘Spectrum schedule’ or sg along these lines. - Gabor
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