On Sun, 2009-03-22 at 10:02 +0100, Johannes Berg wrote: > Ok, so I'm thinking about the interpretation rules for the regulatory > information. I even dreamt about this tonight, unfortunately... [...] > Now how should you interpret this? I'll propose the following > interpretation rules (and show how you arrive at the required > interpretation from above): > > 1) MIN values are really something like MIN+, i.e. approaching the MIN > from above, that means that the value "2452 MHz" falls into the > first of the ranges, not the second [3] > > 2) The entire band a channel occupies needs to be covered by (any > number of) contiguous rules. > > 3) The MAXBW value specifies what maximum bandwidth a channel can use > which has its center frequency (!) falling into the given range. > > 4) The FLAGS specify restrictions that any channel _overlapping_ the > given range has to operate under. > > That is all. Now let me show how to interpret this. Let me rewrite those rules, more formally. Let's take an example regdomain with "n" rules: country EX: (MIN_1 - MAX_1 @ BW_1), (MAXAG_1, TXPWR_1), FLAGS_1 ... (MIN_n - MAX_n @ BW_n), (MAXAG_n, TXPWR_n), FLAGS_n And let's say we need to determine whether a channel, which (disregarding modulation for a moment) is determined by its center frequency and bandwidth: CHANNEL = (CENTER, BW) Then the rules are as follows, now using the notation outlined here: http://en.wikipedia.org/wiki/Interval_(mathematics)#Notations_for_intervals (I'd use latex notation if I knew everybody was familiar with it, you have to do with some words instead) 0) (stated outside rules before) for all 1 <= k < n : MAX_k <= MIN_{k+1} [1] 1) each rule in the regdomain covers the frequency range (MIN_1, MAX_1] [2] 2) given C = union (over all k = 1 .. n) of (MIN_k, MAX_k] it must be true that (CENTER - BW/2, CENTER + BW/2) is a subset of C 3) it must be true for all 1 <= k <= n: if CENTER in (MIN_k, MAX_k] : BW <= BW_k [3] 4) This is easier to formulate algorithmically: USE_FLAGS = 0 for k = 1 .. n if CENTER in (MIN_k, MAX_k]: USE_FLAGS |= FLAGS_k johannes [1] this says "no overlap" but also "must be sorted" which can be beneficial [2] this is a useless rule given the way I formulated rules 3 and 4, but it helps think about how it works [3] given rule 0) the if only matches (at most) once
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