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On Wednesday 07 July 2004 09:31, Margit Schubert-While wrote:
> Note that AFAIK, the 5GHz WLAN channels start at 34 (5.17 GHz)
> (but I am not sure) and I don't know the top limit (except that
> it is <= 6GHz). Maybe somebody can shed light on this.
> If there is a clear definition, that should be reflected int the code.
> And something similar for channel_to_freq.
> Apparently Japan is doing something in the 10GHz band -
> will have to look for details.
It is not 10 GHz band. They use the same 5 GHz band, exactly same frequencies,
but channel is twice narrower - 10Mhz instead of 20Mhz as usual 802.11.
In 10Mhz channels, they use 1/2 data rates as well. I.e.
(6,9,12,18,24,36,48,54) rates replaced by (3,4.5,6,9,12,18,24,27)
For frequencies, there are several documents. I'll try to summarize:
2.4Ghz band (as in code):
in 802.11b standard, 14 channels defined:
freq=channel*5 + 2407, channel=1..13
Those "unofficial" frequencies are not defined. BTW, do anyone know document
5Ghz band (as in code):
freq=channel*5 + 5000, channel=0..200 (from standard)
For valid channels, 802.11a standard says there are 3 bands (all in US):
TGh (regulation in Europe) adds channels
100..140 with interval 4
Tgj (japan) spec adds new rules: 10Mhz channels I mentioned above, and channel
dot11ChannelStartingFrequency may be 4000 or 5000 (as for .11a)
For channels 183 and above, it is 4000, for others - 5000
Valid channels for Japan (note some channels may have both 10 and 20 Mhz
width, some - only one of them):
20Mhz channels: 184,188,192,196;8,12,16,34,38,42,46
10Mhz channels: 183,184,185,187,188,189;7,8,11
For TGn (high throughput) standard expected to finalize around 2006, wide
40Mhz channels expected, with maybe some additional attributes.
After describing this whole mess, some points to pay attention:
- - channel number is not enough to determine frequency - there are same
in 2.4 and 5Ghz bands.
- - to properly init hardware, channel witdh should be provided as well.
Thus, we probable need to use (channel,band,width) triples or (channel,domain)
tuples, where (band,width) mapped into domain.
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