On 8/15/07, Jouni Malinen <j@xxxxx> wrote: > On Tue, Aug 14, 2007 at 11:32:58AM +0200, Johannes Berg wrote: > > 802.11 A is easily distinguishable based on frequency, and the difference > > between 802.11B/G isn't really done well in mac80211 with most 802.11G > > drivers supporting only 802.11G channels and no B channels > > Agreed on 802.11a vs. b/g as long as frequency is used for configuration > (as is the case here; channel numbers would not have been unique). > Dropping the b vs. g is somewhat unfortunate, though. > > > What reason is there anyway for distinguishing between an 802.11G and an > > 802.11B channel? Regulatory? In that case, well, needs lots of work. > > The original reason for adding that was that some hardware designs have > separate modes for 802.11b and 802.11g and there may be cases where the > 802.11b mode would be preferred. I'm not sure about all the differences > in hardware, but I would assume this could include power use (save power > by being able to use slower internal frequency since there is less > things to do and by disabling some functionality) and maybe in some > cases just the fact of disabling all non-802.11b extensions. > > Furthermore, frequency may not be unique in future with additional PHY > changes. Having option of setting both a "mode" and frequency is a pair > is a good way of making sure the design is more future proof in this > area. > Just a small example as everybody knows the major distinction is in modulation schema i.e. CCK vs. OFDM. 11b only devices are deaf to OFDM traffic so we use CTS/RTS to overcome it which in turn slows the traffic. Sometime B-only or even G-only (no CCK rates) environments are required. I've used to have laptops with 11b only cards so I've configured the AP to B only not slowing even more the traffic. > -- > Jouni Malinen PGP id EFC895FA > - > To unsubscribe from this list: send the line "unsubscribe linux-wireless" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > - To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
