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Apology accepted. Thanks :)<br>
<br>
Tim<br>
<br>
<br>
Rajesh Narayanan wrote:
<blockquote
cite="mid8e843e380701310719n6deeaeb7k3b98d15bb5320489@mail.gmail.com"
type="cite">tim,<br>
<br>
maybe i sounded rude in my previous post so I apologise, and maybe I
dont know as much as you either. My only argument against your point is
that you cannot discount a technology just because it has technical
issues that cannot be overcome and made viable.
<br>
<br>
I say it again, MCMR is not a silver bullet. But any limitations are to
be studied and maybe based on our experiences someone may come in to
make the inherent system better by reducing bleed-overs and attenuation
or whatever the true nature of the problem is. <br>
<br>
rgds,<br>
rajesh<br>
<br>
<br>
<br>
<div><span class="gmail_quote">On 1/30/07, <b
class="gmail_sendername">Tim Martin</b> <<a
href="mailto:tmartin159@mchsi.com">tmartin159@mchsi.com</a>> wrote:</span>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000">Maybe there's a multitude of
mesh networking vendors who tout
multi-channel multi radio because they rely on selling to people who
know as little about it as you. If you have two or more radios
broadcasting from the same location at close frequencies there is going
to be a lot of bleedover or at least a lot of attenuation making the
radios far less efficient. You can have one radio in the 11b/g range
and one in the 11a range but having two in the same frequency range is
a waste of time and money.<br>
<br>
Thanks,<br>
Tim<br>
<br>
<br>
Rajesh Narayanan wrote:
<blockquote
cite="http://mid8e843e380701301419p708919bctb9a1431363b0c2e8@mail.gmail.com"
type="cite">
<div><span class="e" id="q_1107623fb7e4941d_1">no offense, but
try explaining that to the multitude of
mesh networking vendors that tout multi-channel multi-radio :-). They
work and they work well! So I dont agree with your assessment as its
too simple.<br>
<br>
You are right about bleedover. There is definitely some cross channel
interference that has been studied. But I dont think it justifies not
looking at multi-radio multi-channel systems. 802.11b/g has only 3
non-interfering channels, while 802.11a has 11 (I think). So the
channel distribution you are talking about is when there are
interfering channels. These are the issues that an intelligent channel
allocation scheme will need to take care of. <br>
<br>
Thanks,<br>
Rajesh.<br>
<br>
<br>
<div><span class="gmail_quote">On 1/30/07, <b
class="gmail_sendername">Tim Martin</b> <<a
href="mailto:tmartin159@mchsi.com" target="_blank"
onclick="return top.js.OpenExtLink(window,event,this)">tmartin159@mchsi.com
</a>> wrote:</span>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> I prefer to use just one
radio because multiple radio's will interfere with each other if placed
close together. Even if one is on channel 1 and the other on channel
11 there can be some bleedover which will cause a lot of lost packets. <br>
<br>
Tim<br>
<br>
<br>
Rajesh Narayanan wrote:
<blockquote
cite="http://mid8e843e380701251442w2e7a7de2qad48f6fd4c776d87@mail.gmail.com"
type="cite">
<div><span>Hi,<br>
<br>
I posted this in the openwrt forum as well. Thought I might as well
stir the hornets nest a little more. Only the OLSR part is specifically
relevant . Has anyone looked at multi-radio multi-channel support in
the OLSR though??? <br>
<br>
I'm trying to look at any open-source implementations for MCMR. If I do
find I'll post it here. <br>
<br>
Thanks,<br>
Rajesh.<br>
<br>
Here is the post <br>
***************************<br>
It just occured to me that there might be a possible for supporting
multi-radio multi-channel support in the OpenWRT platform. Many
mesh-networking companies typically tout multi-radio/multi-channel
support. <br>
<br>
Here is a possible method by which three Linksys routers can be
combined to support multi-radio multi-channel. <br>
<br>
Methodology:<br>
1. Hardware<br>
- Put the three linksys (could be any other device) routers in
Bridge mode. <br>
- The three routers are physically connected via the ethernet LAN
ports <br>
- Lets call these routers LS1, LS2 and LS3.<br>
- I have tested the bridge-mode connection and works quite well<br>
- Essentially provides a very wide Layer2 connection <br>
- These three linksys routers can be stacked on top of each other
essentially providing 3 radios (you could use 2 for 2 radios)<br>
- This will how a Node-group will look like <br>
\ / <-- Radio1 <br>
Node1a<br>
| <----------- Wired link <br>
\ | / <-- Radio2<br>
Node1b<br>
| <----------- Wired link <br>
\ | / <-- Radio3<br>
Node1c <br>
<br>
2. Software<br>
- This is the secret-sauce that needs to be developed. The goal is:<br>
- Launch it in each of the routers LS1, LS2, LS3 <br>
- Communicate among each other to know they are part of the same
bridge <br>
- Have a channel allocation scheme for each router so they do not
mutually interfere with each other.<br>
- This needs to be a modular and scalable architecture so that
nodes can be added to the stack in an on-demand basis. <br>
- The secret sauce could be developed either as a plugin for OLSR
or for the spanning-tree-protocol implementation.<br>
- The STP implementation would mean that its one big layer-2
wireless network with the node-groups forming some kind of non-loop
network <br>
- OLSR-plugin would obviously mean that all node-groups act as
olsr-routers with intelligent channel assignment schemes.<br>
<br>
3. References:<br>
* While writing this post I did some web-search and looks like there is
already some activity that is similar to what I am suggesting - <a
href="http://moment.cs.ucsb.edu/tic/" target="_blank"
onclick="return top.js.OpenExtLink(window,event,this)">http://moment.cs.ucsb.edu/tic/</a><br>
* (more references later) </span></div>
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