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

[Jeremy Lakeman]

The stock firmware's time division scheme splits the time on each
channel in half and gives each device that time to send packets. This
is probably the main reason why the round trip latency seems to be
between 100-300ms.

Andrew Tridgell gave a talk on his firmware at linux conf last week.
Here's the talk details and video if you are interested.

http://linux.conf.au/schedule/30080/view_talk?day=thursday
http://mirror.linux.org.au/linux.conf.au/2013/mp4/Building_a_free_software_telemetry_radio_system.mp4

On Fri, Feb 8, 2013 at 6:53 AM, Paul Gardner-Stephen
<paul at servalproject.org> wrote:
> Hello,
>
> On Fri, Feb 8, 2013 at 12:42 AM, Seamus Tuohy <s2e at opentechinstitute.org> wrote:
>> Hey Paul,
>>
>> This sounds great. I would be quite interested in seeing what kind of
>> QOS and energy consumption you get running various types of traffic over
>> this device. Having some clearer idea of the throughput, jitter, and
>> delay would be a great starting point for conversations around use cases.
>
> Our focus at present is on long-range communications, in particular
> for Rhizome bundle-oriented traffic.  As such we have done nothing as
> yet to minimise latency and jitter.  Nonetheless, MDP pings have been
> as low as a few hundred milliseconds.
>
> From a Commotion perspective, I would imagine that some of the more
> interesting use-cases that come immediately to mind include (all
> sitting on top of Serval Rhizome):
>
> 1. Distribution of updates to Commotion project and related software
> 2. A Twitter-like mesh-based micro-blogging service (possibly with a
> gateway to Twitter itself)
> 3. Distribution of either introduced or locally produced news/content
> 4. Delivery of voicemail and SMS traffic between commotion OpenBTS's
> and mesh nodes
>
> Essentially it is best to think of it as a courier service between
> nodes, like an inter-campus mail service, rather than a bulk real-time
> transport. Of course, in many instances it can do better than that,
> but this perspective will, I think, help with the exploration of the
> kind of service that it can enable.
>
> Paul.
>
>> s2e
>>
>> On 02/07/2013 12:00 AM, Paul Gardner-Stephen wrote:
>>> 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.
>>>
>>> _______________________________________________
>>> Commotion-dev mailing list
>>> Commotion-dev at lists.chambana.net
>>> https://lists.chambana.net/mailman/listinfo/commotion-dev
>>>
>>>
>
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