FANDOM


back to http://scratchpad.wikia.com/wiki/Sasecurity

{{{

>5. Using two 200mW NIC's per meshap: 1 for mesh, 1 for subscribers on 
802.11b both with omni's

Your email address implies you're in the UK. EU law limits you to 
100mW, so unless you have large losses in the feed to your antenna you'll be 
breaking the law.

>7. Each node is approx 2km apart (dense deployment because CPE may not 
have LOS)

You may be safer budgetting for 1km or even 500m per node. 
 
>8. Subscriber using indoor USB type radio with 5db antenna

Hmmm... We've found USB radios are poor on the Rx side. You really 
should look at other options which will allow an external high gain (7 to 
12dB).antenna to be connected.


I'm looking at using MeshAP for a fairly large scale network and 
wondered if anyone has any experience or comments of the success or 
suitability for this setup.

The terrain is fairly hilly, hence why I'm looking at meshing to get 
into all the nooks and crannies!  My intended design is like this:

1. Population of city: circa 1,000,000; anticipated audience circa 
3,000 subscribers.
2. Approx 150 meshap nodes structured in a triangular mesh
3. Max two hops before a backhaul node
4. Backhaul using 5.8G propriatary gear
5. Using two 200mW NIC's per meshap: 1 for mesh, 1 for subscribers on 
802.11b both with omni's
6. Use different channels on subscriber radio for adjacent meshap's
7. Each node is approx 2km apart (dense deployment because CPE may not 
have LOS)
8. Subscriber using indoor USB type radio with 5db antenna
9. Excluding obstructions (trees, walls, etc.) subscriber is intended 
to have theoretical >= 20db SOM


So, the general structure of the mesh is something like this:

     B--2km--o-------o-------o-------B
    / \     / \     / \     / \     / \
   /   2   2   \   /   \   /   \   /   \
  /     \ /     \ /     \ /     \ /     \
 o-------o-------o-------o-------o-------o
  \     / \     / \     / \     / \     /
   \   /   \   /   \   /   \   /   \   / 
    \ /     \ /     \ /     \ /     \ /  
     o-------o-------o-------o-------o
    / \     / \     / \     / \     / \
   /   \   /   \   /   \   /   \   /   \
  /     \ /     \ /     \ /     \ /     \
 o-------o-------o-------o-------o-------o
  \     / \     / \     / \     / \     /
   \   /   \   /   \   /   \   /   \   / 
    \ /     \ /     \ /     \ /     \ /  
     o-------o-------B-------o-------o

o = normal node.
B = normal node with backhaul


So, my main concerns are:

    1. What will the performance be like between any given mesh node 
and the home network (accessed via the backhaul node)?  The radio's being 
1/2 duplex gives us a theoretical of 5.5 across the mesh, so presumably 
around 3mbps in practice?
    2. How much will intra-node traffic from different nodes interfere 
with each other?  ie: hidden node issues etc., and will (for example) 
node 10 talking to node 11 interfere with node 12 talking to node 13?

Very much appreciate input from anyone.  Particularly if you have done 
anything of scale with the meshap.
 

Just to support Russell’s post, the UK limit is 100mW EIRP (20dBm) so a 32mW card is
really the only option, but of course if the project is not in the UK ;)
If you want to know more about the advantages and pitfalls of using dual radio MeshAP’s 
drop me a private mail, I have covered this may times on this list.  I use custom built 
dual radio boxes on projects in the UK with great success.

I'm looking at using MeshAP for a fairly large scale network and wondered if anyone
has any experience or comments of the success or suitability for this setup.
 
I also intend to setup a large scale mesh network here in my country, Turkey. Currently we are testing a micro model of mesh with 18 nodes. Even with this relatively small size of mesh, we have run many problems. The biggest one we face is instability of the system without a known reason. Before load planing, take care in to that:
 You will have hangups on boxes either by software and/or hardware related, almost impossible to understand the real cause. As a result, you need a hard reboot, ie. plug it off and on again. If you will place the boxes on top of roofs as most of us do, then make sure that electricity switches are placed so that you can reach easily but no one else can reach :)
 
The distance between antennas is important as well as type of the antennas and the surrounding objects which changes the way of the signal, reflects it etc. Signals do not behave as expected. This part needs a carefull planing, site surveying, measuring and walking around with tools. Takes time, alot... Node may and will not hop as assumed, instead they prefer some other ways. I had some nodes which was connecting to gateway thru 2 hops travelling 2 km while gateway is as close as 100 meters LOS! You need to force them to go the way you like, then you loose some AODV functionality.
On mesh network, you cannot use subscriber radios on different channels. Clients will tune the same channel automatically meshAP uses which user is connected.
 
2 km between nodes is not dense deployment since I have some nodes even 30 meters away from each other due to the some buildings need to be covered. It depends on the buildings which intended audience is living. When nodes are so close, then interference would be a major problem then you need to lower the output power in turn shortens the distance signal can travel and reach. USB radios are acceptable since you may move it to find the best reception indoors. Better to use detachable antennas and cards so users can plug in a higher gain antenna where is legal. (Here is not)
 
For backhaul, I recommend second radios as 802.11/g so you can have 54 MBps which effectively gives around 20 MBps if there is no 11 MBps device hooked onto. But current MeshAP does not support it, you need pro version so you have to pay for it.
We anticipate each node can handle 30 concurrent users nicely and may go up to 100 users in "rush" hours... Thinking such a big network, you need to divide into different meshes on different channels especially since many poeple will signalling into the air at your channel. Many people do not care about or do not know about site survey, just plug their devices and creates noise on or near your channel. And in a big wireless network it is a headache to move your system to another channel.
 

}}}

Ad blocker interference detected!


Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.