"Theodore Y. Ts'o" wrote:
>
> Date: Thu, 29 Jun 2000 13:22:32 -0400
> From: RJ Atkinson <[EMAIL PROTECTED]>
>
> Actually, IETF has made IEEE 802.11-DSSS the convention for wireless
> LANs at all IETF meetings for some time now. This has been supported
> at least at Oslo, DC, Adelaide, (and will be at Pittsburgh). It probably
> has been supported for some significant time before Oslo, though I
> don't have first-hand remembrance of that. In DC, Nortel was pushing
> their 802.11-FH system, but a full 802.11-DS system was up and running
> in parallel.
>
> I'm not sure that it's been officially decided as the convention, but
> it's certainly been the practice most of the time (although the Nortel
> use of frequency hoppers was a certainly an exception to this rule).
>
> I think there was one other time that frequency hoppers were used in the
> past; I seem to recall dispairing that we would *ever* settle on a
> standard 802.11 type when I broke down and purchased a 802.11-FH PCMCIA
> card. That way, I'd be ready no matter what a particular IETF meeting
> site decided to use.
>
> It would be good if we could standardize on one particular type, but as
> I recall the last time the issue was raised, it was explained to me that
> different systems worked better in different RF environments, so we
> should get used to switching back and forth between DS and FH cards.
> If we we could depend on it always being 802.11-DS, that might make a
> number of people's lives easier.
DS appears to be better for large, flat spaces (largely 2-dimensional,
under 3 stories tall, since transcievers on the middle floor largely
cover the upper and lower).
FH is better for more spherical spaces (largely 3-dimensional).
And DS and FH do not play well together, i.e., it's much better to stay
away from concurrent overlapping installations. I had earlier measured a
BW penalty of between 1/2 to 3/4 (transferring data over only one of the
two technologies at a time, in a concurrent deployment).
The decision of what to use may depend on the local environment.
Joe
