[Prism54-users] Field report - performance at a distance

[Rob Gipman]

Into Jeff's request,

I'm going to do a connection to a neigbour house about 700 meters away 
down the hill here. For this i have build my own omni 13dBi antenna out 
of coax pieces and pvc pipe. This antenna is connected to a Sitecom 54Mb 
802.11G pci card. The machine runs both win2k and Redhat linux 9. The 
machine reboots often for my work here so connection has to be through 
win2k and linux.

Under linux the prism54 module runs as fine a the official sitecom 
driver under win2k as tested so far within a range of 50 meters in and 
out of the house. Still have to do the 700 meter test. (waiting for the 
second sitecom pci card to get to Uganda.)

At the neigbours location the sitecom pci will connect to a home made 
point (prinqles type) antenna. And then we will test.

Rob

Jeff Bobzin wrote:

>--10 Second Drops Revisited--
>
>I know some people probably thought I was crazy when I did a post here that reported seeing bursts of dropped packets at exactly 10 second intervals. Well the performance diagrams in this article from SmallNetBuilder shows this same behavior.
>
> (article is http://www.smallnetbuilder.com/Sections-article43-page1.php )
> (diagram is http://www.smallnetbuilder.com/myimages/NTK/11gntk_intersil_newfw_vs_wrt54g.jpg )
>
>Apparently this is characteristic of Intersil  firmware but does not show up in Broadcom-based devices. I wonder what the firmware is doing every 10 seconds - maybe housekeeping?
>
>--Client Performance at Distance--
>
>I was reviewing this great article for tips on my broader concern - performance at a distance.  I get great bandwidth at line-of-sight distances but it falls off dramatically through a single wall.  I have been able to compare prism54-based units with windows-based units connecting to  a standard SMC "G" wireless router at the other end of the building.  The windows driver reported 40% signal, the prism54 reported  minus 60db.
>
>It is difficult to get consistent test results as the signal fades unpredictably,  but I don't see any consistent difference between the drivers.  It does seem as if the prism-based unit is more prone to drop connection and has problems reconnecting.
>
>Control of connection is in the hands of the firmware which is the same between units. But there may be private configuration IOCTLs that the windows driver authors had access to configure draft-G performance variables. Its possible private variables may influence decisions to drop connection on errors. This is pure speculation though.
>
>--AP Performance-
>
>Comparing a Prism54-based AP vs SMC gives the same signal strength to clients located at distance. Clients have a lot of trouble connecting though. It is difficult to directly compare performance because the SMC Router has the diversity dual antenna. Doing 'ping -A' reveals similar transmission times with periodic jumps in time (performance drops) for both.  The periodic performance loss seems a little worse connected to a prism54 AP. Updating the SMC router to the latest firmware (nitro!) seemed to make it more prone to connection drop and more similar to prism-ap.
>
>--Hawking Antennas-- 
>
>I am also testing the Hawking Omni and Directional High Gain antennas.  Iwconfig does report a numerically stronger signal but the connection drops continue. Of course better antennas collect more noise too.   I can give a more complete report at a later date if desired.
>
>--Conclusions--
>
>The only suggestion I can give the developers is to investigate adding more private IOCTLs - if we can get the current owners of Intersil to reveal them. Certainly there must be several additional firmware controls for master mode.  The g-only or g+b control for example.
>
>Also - I am open to a suggestion to move this discussion to a forum,  perhaps called "Performance & Tips",  if the mailing list manager desires.
>
>--Jeff
>
>
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>

-- 
Rob Gipman 
IP Consultant 
MTN Uganda, Kampala 
?   E-Mail:  Gipmanr@mtn.co.ug 
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