[MLB-WIRELESS] DLink 900+ speed problems in bridge mode (and link up!)

[Simon Butcher]

Hi Vak, David, and Pascal (if you're reading :),

Firstly well done David & Pascal, the use of a 'stink stick' to get the
job done was a brilliant idea! ;)

According to
http://melbourne.wireless.org.au/nodes/compare.php?id_1=FKY&id_2=GIS it
says you two have an SOM of 25.42 dB. I thought this was a little high,
so I recalculated it using specs out of the DWL-900AP+ spec sheet from
dlink.com.au. I couldn't find the RX sensitivity, so I guessed it was
around average (-80dBm). I came up with an SOM of 16.5 dB, with
worst-case cable (3dB). You may want to update your locfinder details..
I can forward you my excel calc sheet if you like.

Regardless of that, surely there can't be so much noise in your area to
cause 5.5 Mbps to be the highest rate, unless I'm missing something? If
you can't get 22 Mbps with the stock antennas, and the access points
sitting a few metres apart (with nothing in between), there must be
something wrong with one (or both) of the devices?

Cheers,

 - Simon


> -----Original Message-----
> From: owner-melbwireless at wireless.org.au 
> [mailto:owner-melbwireless at wireless.org.au] On Behalf Of vak
> Sent: Tuesday, 11 March 2003 8:04 PM
> To: melbwireless
> Subject: Re: [MLB-WIRELESS] DLink 900+ speed problems in 
> bridge mode (and link up!)
> 
> 
> Good stuff. Congrats on getting your link up.
> 
> Your problem with 5.5 Megabits at 2.5km is explainable 
> (sitting next to each other is not so easy to explain).
> 
> At 2.5mk, you probably don't have a high enough signal to 
> noise ratio to allow the units to work at the higher speeds.
> 
> In short, the signal to noise ratio is low enough that the 
> modulation techniques
> 
> at 11 and 22mbps don't function properly (they may allow a 
> few spurious packets to get through).
> 
> You are better fixinging the speed to 5.5mbps (instead of 
> auto) so that the DLink won't try and renegotiate the higher speeds.
> 
> Vaskos
> -------
> 
> David Ng wrote:
> 
> > Me, my twin brother nuge (allan) and a mate (pascal/bugger) finally 
> > got our wireless network going!
> >
> > The link is across 2.5Km of air between me+nuges (we're twins 
> > remember!) house and pascals house. Its only in testing mode at the 
> > moment, we got some stuff we need to iron out.
> >
> > Cost of parts required:
> > DLink DWL-900AP+ 802.11b Wireless Access Point $265 (CPL) 18.8dBi 
> > Hills 2.4GHz Parabolic Grid Antenna $110 (thanks simon @
> > melbwireless)
> > 5m LMR-400 cable $free (from my mate marty, thanks man!) 
> N-connector 
> > $4.50 (dick smith) RP-SMA to N pigtail $37 (kudos vak @ 
> melbwireless)
> >
> > So thats a total of $416.50 each side.
> > The 2 APs are running in bridge mode, with 64-bit WEP enabled.
> >
> > small page here (with pictures):
> > wifi.nudgeee.net
> >
> > The problem is, we initially tested the DLink DWL-900AP+ AP's (fw 
> > v2.5) with them sitting about 5 meters apart (with thier inbuilt 
> > antennas), and the max they could talk to each other was at 
> 5.5mbit. 
> > We tried changing modes (AP, client, bridge), disabling 
> WEP, changing 
> > channels, etc, but they don't seem to connect at 22, let 
> alone 11mbit. 
> > We connected them to our antennas anyway, but they still 
> only connect 
> > at 5.5mbits. We have clear LoS and a pretty good fresnel 
> zone. Its at 
> > 5.5mbits rock solid, but as soon as we switch up to 22, 
> theres alot of 
> > packet loss and dropouts (seems like theyre having troubles 
> > negotiating at 11 and 22 and are dropping back to 5.5).
> >
> > We put the link up regardless becuse we wanted to get it up and 
> > running, and we've dragged it out pretty long already (and besides, 
> > uni's started!).
> >
> > I've posted this issue on a forum, and it was mentioned 
> that someone 
> > on melbourne wireless had come across the 5.5mbit/s problem 
> before.  
> > Can anyone explain?
> >
> > Thanks,
> > David Ng (nudge).
> 


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