Subject: Re: tinkering with wi interfaces (Prism 2.5)
To: Jeff Rizzo <firstname.lastname@example.org>
From: Wojciech Puchar <email@example.com>
Date: 01/22/2004 10:52:23
> > of time, turn off speed autonegotiation and set maximum speed that works
> > reliably.
> There's the rub; I haven't figured out how to stop autonegotiation from
> happening at some level; I thought that setting it with "ifconfig wi0
> media DS11" would do it, but it would appear that some (if not all)
> frames are sent at lower speeds anyway.
broadcast, ACK, RTS etc. frames are sent by default at lowest possible
speed - at least with atheros driver (in which i looked into source). it's
a matter of changing source code to send this frames at same speed as data
if it is set to be constant, not auto.
> > 2) all antennas have to see each other, or "hidden node" problem produces
> > lots of collision and retransmition
> Yup, I'm aware of that. Only two nodes, anyway.
if distance is many miles, you will actually experience hidden node
problem with 2 stations... (because waves needs time to travel, may be
> > 3) ad-hoc mode is generally fastest.
> > i'm working on my own PtP and PtMP mode program that bypasses part of the
> > 802.11 protocol sending everything as broadcasts (no ACKing this case with
> > adhoc mode) and doing all air access control and retranmitions by myself.
> > mostly deciding exactly when each node transmits data, instead of "try and
> > maybe you are lucky" method in standard WiFi.
> > it's mostly for long distance outdoor network, but could be usable indoors
> > too. of course unix only.
> Which is exactly what I'm doing. :) The nodes are about 3 or 4 km apart.
> > lots of connections and full speed transmisions. this case "try end error"
> > algorithm of transmission have low chance of sending data without making
> > collisions.
> I'd certainly be interested in looking at anything you're doing in this
> Jeff Rizzo http://boogers.sf.ca.us/~riz