[CUWiN-Dev] degradation between hops, antennas, etc.

[Stephen Ronan]

Quantum Scientific wrote:

>All this throughput loss per hop has been quite a concern for me.  My answer 
>is two radios per node, because I will have quite a bit of linear hopping 
>going on.
>
>Carl Cook
>  
>

Thanks, Jim and Carl. As you may have seen, there's a new thread on 
Slashdot (access points costing $2,900):

Linux-based Mesh Router Aims at VoIP and Video Wireless Networking
"A startup in Santa Clara, Calif. is shipping a Linux-based mesh router 
aimed at VoIP and video.
http://www.linuxdevices.com/articles/AT8452908209.html
The Mesh Dynamics Module uses multiple radios -- along with custom 
real-time Linux extensions -- to create a duplexing backhaul network 
said to improve bandwidth more than 64 times over conventional mesh 
technology. Normal, single-radio access points function in a half-duplex 
manner, a limitation that reduces bandwidth by 50 percent for each hop 
in the mesh. Mesh Dynamics http://www.meshdynamics.com/ is attempting to 
solve this problem by dedicating separate radios to upstream and 
downstream traffic of a 'backhaul' network that relays traffic between 
mesh nodes, thus simulating full-duplex operation."

Read More...
http://slashdot.org/article.pl?sid=05/03/06/1432243&tid=193


Also, thought this might be of interest, especially the "Research 
Challenges"  on page 3:
http://www.techforall.org/TFA-TAPS-bkgd.pdf

They mention approximately 15% degradation and say the access points 
could support two radios but they're only using one. I wonder whether 
the 15% is what's theoretically achievable with two radios rather than 
what they're getting in practice.

Here's more about their project:
http://www.techforall.org/tfa_wireless.html

That project involved Rice U. researchers and here's one involving 
Villanova:
http://ulysses.qrc.com/pfi-public/fullprofile.cfm?awd_id=96&display=inst
It refers to "advances in knowledge through fundamental research on
smart antennas, low-profile antennas." Anyone know more about what 
they'r up to?

  - Steve Ronan