Engenius / Senao AP Bridge Problem

Dear All,

I have a remote office (2 KM) away from my headquarter. They have both Senao Long Range Multi Client Bridge/Ap, with 24Grid Antenna. They both used to work really well for months at ~80 Quality and 11Mbps transmission rate! One day the internet speed at my office dropped from 3 Mbps to 256kbps, I tried to play with it and change some configuration bu that didn't help. I order my blacksmith to create a 6m tower to have better line of site (which is by default good), but that didn't help! The transmission rate varies between 11Mbps and 1Mbps and keep changing! I made sure that the antenna are pointing each other! but still no luck. Today I change my other end with a flat Antenna, but that didn't help as well! I am not sure what is going on, and what should I get to return that link as good as it used to be! Now I discovered that if the link is at 11Mbps (no activity on the line), but once I do any activity the transmission rate drops! What does that mean!!! what the Antenna/AP is trying to tell me? How I can fix this?


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On Fri, 8 Feb 2008 12:20:31 -0500, rami.qutub wrote in :

This probably means radio interference in the path. Try different channels (1, 6, 11).

Reply to
John Navas


Interference. Probably someone along the line of sight has discovered wireless networking. Such are the dangers of unlicensed wireless links.

Did you try changing channels? Try 1, 6, and 11 and see if that helps. If all of those are occupied, try some of the intermediate channels and you might get partial relief or make it worse depending on the source of the interference.

I don't see how you could get a stable antenna position with a 24dBi dish and what I assume is an un-guyed tower. The -3dB beamwidth of a

24dBi dish is about 5 degrees and must the aimed within about +/- 2 degrees to be usable. Even boresight alignment (remove feed and sight along the feed mount pipe), is not quite perfect. Are you using some sort of signal strength indicator to aim the antenna, or are you just using the "quality" indicator? If you're doing this by crude pointing or guesswork and/or your antenna tower is mechanically unstable, it's possible that your loss of signal was simply due to something moving in the antenna area.

Sounds like interference. The Senao bridge will always try to go as fast as possible and will attempt an 11mbit/sec connection. However, if it encounters any data errors, caused by a weak signal or interference, then it will slow down the connection until the error rate becomes reasonable. Unfortunately it never really becomes reasonable if interference is the cause. Since the interference appears to be intermittent, the speed will vary. Change channels.

How? I'm still suspicious. Blacksmith?

Luck cannot be engineered.

How much gain? Panel antennas have lower gain and wider patterns than your 24dBi dish. Depending on the location of the intereference along the line of sight, the lower gain might improve the situation, while the wider beamwidth might make it worse. Hard to tell from here.

Well, neigher am I. Have you done any sniffing with Netstumbler, Kismet, or a spectrum analyzer?

See my explanation of how the AP sets it's speed. It tries to go at

11Mbits/sec. With no data, there are no errors so it sits at that speed. As soon as you try to move data, it gets errors from the interference, and slows down in an attempt to improve the BER.

The meaning of life is beyond my limited abilities. Please consult a philosopher.

First, try a different channel. If that doesn't work, do some hunting, find the culprit and negotiate. If you discover that your city has installed a mesh free Wi-Fi network, as is quite common, give up and get either a licensed wireless link, or telco lease line. If you would rather fight than switch, 802.11g is far more resistant to interference than 802.11b.

Reply to
Jeff Liebermann

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