[MLB-WIRELESS] building a mesh

Ryan Abbenhuys sneeze at alphalink.com.au
Fri Apr 23 15:26:50 EST 2004


Yep I think you've got the gist of it.

If you were going to trying using for example WDS, and you had 10 AP's in
an area.  They would all need to be on the same channel and all overlapping
eachother.  The problem is that this means you've got an extremely high
number of devices all fighting for the same RF space.

Ideally, what you want to do is avoid using Omni-directional antennas and
try and use 180 degree antennas.  Then you can control your signal
somewhat.
You then need to organise your Access Points in such a way that they
overlap as little as possible with ajoining access points and try use
channels 1, 6 or 11, in such a way that you keep devices using the same
channels clear of eachother.
You can get away with "some" devices using the same channels near eachother
by switching between vertical and horizontal polarization.  This won't help
with devices on the same mast however.

You might get away with using WDS to do "some" AP to AP links, however your
best bet is a separate directional link between each AP on an unused
channel, or at a stretch, a directional link from a node, associating with
another AP, in sort of a daisy chain way.

>Thanks Ryan,
>
>Does this just mean that it's impossible to have two many access nodes 
>overlapping? Perhaps I'm using the term mesh incorrectly as well. My
specific 
>goal is to have multiple access points so that they cover most of the area
of 
>the town (with respect to clients being able to connect). Also, the AP's
need 
>to be networked together wirelessly, but ideally I'd like this to be in an

>omnidirectional way, rather than point to point transmissions. It sounds
like 
>you're saying that this is quite possible, but has scalability issues. Is 
>that right?
>
>So specifically I'm asking what sort of equipment I would need for the
AP's. 
>Ideally, I'm looking for the simplest solution possible, because I think
that 
>many of these AP's might be operated by very non-technical people, and I'd

>want to be able to just set them up and let them run.
>
>Craig
>
>On Friday 23 April 2004 2:42 pm, Ryan Abbenhuys wrote:
>> Unfortunatelly a mesh on current wireless technology has a few problems.

>> The main one being that in an actual true mesh the noise floor would be
>> extremely high.  So you might have a "mesh" network, however it would be
>> extremely slow.
>> 
>> The only mesh that will truly work is a sectored mesh similar to the way
>> mobile phone towers work and use separate channels for each sector of
>> coverage, and separate channels for tower to tower links. Due to the
>> limitations of current wireless gear you'd be limited to only 3
interfaces
>> per base station making coverage and linking awkward to organise.
>> 
>> (anyone mobile network guru's please correct me if i'm wrong.)
>
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