[MLB-WIRELESS] Channel management

Simon Butcher pickle at alien.net.au
Fri Dec 13 23:04:43 EST 2002


Hi,

Has any consideration been put into managing the 802.11 channels in the
2.4GHz band? The reason I ask is for five issues seem to stand out, in
my mind:


1. Channels 1 through 10 have a maximum power output of 4 watts EIRP,
however channels 11 through 13 have a maximum of 200 milliwatts EIRP.
Obviously, a link which only spans a short distance should use the
latter segment.

(Perhaps LocFinder should incorporate the different EIRP allowances
depending on the channel set on each interface?)


2. The more networks on the same channel, the more packet dropping (from
mismatching SSID's) must be done. This is counter-productive.
Unfortunately outside sources will also undoubtedly effect this too,
such as commercial hot-spots and so forth.


3. Using channels sequentially in an area is also counter-productive due
to noise generated by channel cross-talk. I believe it's recommended
that only 3 or 4 channels being used in one area at a time (i.e. you use
channels 1, 4, 7, and 10, and don't touch the ones in between). In the
real world, it's more difficult than that, but it's not helpful to have
two nodes in close proximity using, for example, channels 1 and 2 for
different network segments respectively.

(I expect that point will cause some controversy! :)


4. There needs to be one single channel network-wide if roaming is ever
to be achieved. Julian Featherston reminded me of this recently (thanks
Julian :) and has suggested Channel 1. I concur, as it's both easy to
remember and falls under the 4 watt EIRP license.


5. The ACA's "public playground" concept needs to be adhered to, and
it's not fair on other 2.4GHz users to stomp all over the entire band
available. Nor is it legal to unreasonably interfere with existing
users, such as cordless telephones, bluetooth, and so forth.


Thoughts, anyone?

Cheers

 - Simon

P.S.
  I don't claim to be a wireless expert, just an enthusiast :)


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