Archived from groups: alt.internet.wireless (
More info?)
"Richard Perkin" <f000nurdle@hotmail.com> wrote in message
news:2m0ollFhf68oU1@uni-berlin.de...
> "gary" <pleasenospam@sbcglobal.net> wrote in
> news:auFKc.14989$Di6.11575@newssvr23.news.prodigy.com:
>
> >
> > "Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
> > news:fc5mf0lcfpbfq0ur168catgm6sv6k8ne78@4ax.com...
> >> On Sun, 18 Jul 2004 11:43:41 -0700, Jeff Liebermann
> >> <jeffl@comix.santa-cruz.ca.us> wrote:
> >>
> >> >On Sun, 18 Jul 2004 18:02:25 GMT, "gary"
> >> ><pleasenospam@sbcglobal.net> wrote:
> >> >
> >> >>And if the DI-614+ is using 22Mbps PBCC, I wouldn't
> >> >>necessarily assume
> > it
> >> >>will interoperate with all the other adapters. The DWL-G650+
> > documentation
> >> >>claims back-compatibility with "802.11b+", but I'm not sure how
> > inclusive
> >> >>that is. If there's a way to disable 22 Mbps, I suggest trying
> >> >>that.
>
> >> The plot thickens. I logged into my office DI-614+ remotely and
> >> noticed that there was this box on the bottom of the wireless
> >> page
> >>
http://support.dlink.com/techtool/di614+/emulator/adv_perform.ht
> >> m
> >> inscribed:
> >> 4x mode [ ]enable [ ]disable
> >> I'd never noticed that. So, I dig into the support pile and
> >> find:
> >>
http://support.dlink.com/faq/view.asp?prod_id=1245
> >> which declares:
> >> "If you are using non-4X adapters in your wireless network,
> >> performance will degrade if 4X is enabled."
> >> Ummmm... perhaps we should turn it off?
> >
> > Good question. My guess would be that this is akin to saying that
> > if you mix 802.11b and 802.11g devices, performance will degrade
> > (but not significantly below 802.11b highest bitrates). My
> > uneducated guess would be that a mix of D-Link 4x and non-4x
> > adapters is expected (by D-Link) to downgrade to standard 802.11b
> > bitrates. D-Link has said that it only recommends using 4x mode if
> > all of the network elements are Airplus, so they expect it might
> > break if you have other vendors in the mix.
>
> As I understand it, the so-called "4x" mode is not a higher bitrate
> (which remains at 22 Mbit/s) - but uses higher frame packing rates to
> reduce overheads.
This agrees with what I have read. From what I understand, the claim is not
that the max bitrate is 4x the 802.11b max bitrate, but that max real-world
throughput is 4x. The underlying encoding method is 22 Mbps PBCC.
>
> 22 Mbit/s using PBCC modulation is fine IMO, since it's now part
> (albeit optional) of 802.11g.
I've read that one of the reasons TI started shipping 22 Mbps was that early
drafts of 802.11g did not support PBCC. It was a way of forcing the issue.
Don't know if this is true, but it sounds plausible.
>
> But I'm none too keen on proprietary extensions of whatever kind,
> whether they're called marketingspeak things like SuperG, Nitro,
> Turbo or 2x or 4x or whatever. It all affects interoperability - the
> very reason for standardisation in the first place...
Yes, I completely agree. But my guess is that these tweaks are relatively
inexpensive for both chipmaker and vendor, and the temptation to gain a
product differentiator is almost irresistible.
>
> Hope this helps
>
> --
>
> Richard Perkin
> To email me, change the AT in the address below
> richard.perkinATmyrealbox.com
>
> It's is not, it isn't ain't, and it's it's, not its, if you mean it
> is. If you don't, it's its. Then too, it's hers. It isn't her's.
> It isn't our's either. It's ours, and likewise yours and theirs.
> -- Oxford University Press, Edpress News
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