[Commotion-dev] Serval Mesh Helper Device / ISM long-range meshing work

[Paul Gardner-Stephen]

Hi All,

Just a heads up on some stuff we are doing at Serval that I think will
be of interest to Commotion deployments more generally.

We are now actively working on what we call our "Mesh Helper Device",
the prototype of which will consist of a TP-LINK WR703N running
Commotion OpenWRT + servald, connected to an RFD900 ISM 915MHz band
packet radio and a rechargeable battery.

This gives the potential for much greater range than just WiFi, as
well as offering some resistance for 2.4GHz jamming in places where
that is a problem.

The RFD900s with current firmware in urban settings offer 5x to 10x
range compared with WiFi.  For example, I could receive a decent
signal with one radio sitting on my lounge, and the other radio with
me walking around the block, up to about 150m away -- with the signal
path obliquely through perhaps 8 or 10 houses, fences, cats, dogs,
trees and everything else.

With good clear line of sight, and a low noise floor, ranges of 10km
or more are possible, with some evidence pointing to the actual limit
being around 80km - 120km in very ideal conditions.

We have already managed to get Serval Mesh traffic, including some
Rhizome transfers (but not yet voice) running over one of these links:

servalpaul.blogspot.com.au/2013/02/breaking-wifi-barrier-serval-mesh.html

We think a complete Mesh Helper Device, including these really nice
radios could be built and sell for <US$200.  It may also be possible
to use a cheaper compatible (but slightly lower performance) radio and
get the price down to <US$100.

The RFD900 firmware only does point-to-point communications, but it is
entirely possible to make it do "ad-hoc" point-to-multipoint
communications.  Perhaps this is something for us to look at as a
follow on after our current work block is complete.

We are hoping to have a couple of these with us in New Zealand in a
couple of weeks for the KiwiEx field trial. General outline of our
thinking for KiwiEx at present is at:

http://developer.servalproject.org/dokuwiki/doku.php?id=content:exercises:kiwiex2013

If there are other things people would like tested while we are there,
let me know, and we will endeavour to cover them.

Paul.