[Freedombox-discuss] Serval Mesh Extenders

Paul Gardner-Stephen paul at servalproject.org
Thu Jul 11 21:45:23 UTC 2013


Hi All,

As some of you may already be aware we have been working on what we call
the Mesh Extender at the Serval Project.

The Mesh Extender is a combined battery powered embedded Linux router and
UHF packet radio running the Serval Mesh software (which is all GPL, see
github.com/servalproject for the source).

It is intended for mobile and truly ad-hoc deployment where the end user
just turns it on and uses it.

The idea is that it uses the UHF packet radio to mesh over greater
distances than is possible with Wi-Fi, the trade-off being lower bandwidth.

In general, we find that the UHF packet radio has a range of about 10x that
of Wi-Fi when deployed indoors with omni-directional antennae.  This means
it has a range of about a block in a suburban or urban setting compared
with Wi-Fi's range of about one house or apartment.

For example testing it in Boston recently we had coverage over much of the
MIT campus from a single Mesh Extender in my room at a nearby hotel:

http://servalpaul.blogspot.com/2013/05/range-testing-mesh-extenders-in-boston.html
http://servalpaul.blogspot.com/2013/05/range-testing-serval-mesh-extender-on.html
http://servalpaul.blogspot.com/2013/05/crossing-charles-river-by-mesh-extender.html

Extending the range in this way is a critical enabler for the adoption of
mesh communications because it removes the need for skilled installation
and lowers the required penetration rate from near 100% in a local area if
using un-aimed Wi-Fi to below 1%:

http://servalpaul.blogspot.com/2013/05/urban-testing-of-mesh-extender-part-1.html
http://servalpaul.blogspot.com/2013/05/urban-testing-of-mesh-extender-part-2.html

Combined with the always-on end-to-end encryption of voice calls and text
messages of the Serval Mesh we think that this device has the potential to
play a significant role in enabling distributed, resilient and private
communications for people in a wide variety of situations.

We also see that the close alignment of what the Freedom Box and Serval
Project are trying to achieve means that any device like this that we
create could easily be adapted to being both a Mesh Extender and Freedom
Box by adapting the included software inventory.

The necessity of a portable and trivial to deploy enabler of mesh
communications, and the need for this to be completely open, has led us to
the current point where we have setup a crowd funding campaign to develop
this technology, taking it from the prototype stage and to develop an
actual manufacturable product, and do further testing with our humanitarian
partners.

This is the point that our campaign at igg.me/at/speakfreely will take us
to if fully funded.

But to realise the full potential of this we not only need to make an
attractive manufacturable device, but also to improve the open-source
firmware of the packet radios we are using to support true "ad-hoc packet
radio" within the complex regulatory requirements of the ISM 915MHz band,
in particular the need to frequency hop which presents interesting
technical challenges for a fully distributed mesh that does not rely on GPS
timing for synchronisation.

Achieving "ad-hoc packet radio" will require us to not only meet our
current funding goal, but stretch it by a factor of two.

We are conscious that achieving this will require promoting the campaign
far and wide, much wider than the Serval team can achieve alone.

Therefore it would be tremendously helpful if as many of you as are willing
and able would assist us in spreading the word as far and wide as possible.
 We would love to get slash-dotted and reddited off the net. Repeatedly.

So please take a look at our campaign, use the words below if they are
helpful, and help us to get the word out, and ultimately let's make
effective and private long-range mesh communications not only possible, but
practical and easy for the general public so that they can enjoy the
resilient backup communications capability that they need to keep
connected, no matter what disaster may befall them.

Thanks in advance,

Dr. Paul Gardner-Stephen
Founder, Serval Project.
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