Date: Wed, 19 May 1999 15:56:03 -0400 (EDT) From: Brad Karp <karp@eecs.harvard.edu> To: freebsd-mobile@freebsd.org Cc: wpaul@ctr.columbia.edu Subject: wi driver and WaveLAN IEEE 802.11 Turbo cards Message-ID: <199905191956.PAA02729@dominator.eecs.harvard.edu>
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I've just verified that the wi driver (for Lucent WaveLAN IEEE 802.11 cards)
works fine with the WaveLAN Turbo cards, which offer (according to Lucent)
three times the throughput of the non-Turbo cards.
The Hermes interface (CPU side of the card) appears identical, so no driver
changes are necessary. What a pleasant surprise that a card manufacturer
has improved performance without requiring a single line of new code from
driver authors.
A wider range of transmit rate values make sense for the Turbo cards. The
values for Turbo cards are:
1 - Fixed Low
2 - Fixed Standard
3 - Auto Rate Select (High)
4 - Fixed Medium
5 - Fixed High
6 - Auto Rate Select (Standard)
7 - Auto Rate Select (Medium)
The old cards did "Low" (1 Mbps link) and "Standard" (2 Mbps link). The
newer cards add "Medium" and "High", where "High" is purported to be three
times faster than Standard. I'm not sure if that means the _link_ bitrate
is 6 Mbps, or if Lucent's statement pertains to an end-to-end (application-
level) measurement, taking into account MAC behavior, &c.
Note that the choice of 3 for auto rate select, with a maximum of High, means
that drivers for older, 2 Mbps cards will get the higher bitrate behavior
when the link is good enough, if they defaulted to auto rate selection (also
3) between Low and Standard with the non-Turbo cards.
(These values are supplied to wicontrol's -t option.)
Bill Paul: you might want to add values 4-7 to the wicontrol man page
when you've time.
-Brad, karp@eecs.harvard.edu
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