[Commotion-discuss] Battlemesh talk about mesh-wide channel hopping (for DFS, etc)

[Ben West]

Simon Wunderlich gave a talk at this year's Battlemesh about progress in
implementing DFS (dynamic frequency selection) in mesh networks, whether
through user-space tools or in kernel space.

http://www.battlemesh.org/BattleMeshV7/Agenda?action=AttachFile&do=view&target=2014-05-17_wbmv7_DFS.pdf

The intended application from Simon's perspective is to permit automated
channel hopping for meshes, as required for operating on those 5.8GHz bands
shared with radar installations.  Although his talk focused on the EU
regulatory environment, the incentives for using these channel in the US
would be similar (avoiding otherwise crowded channels).

My understanding is that the FCC presently requires unlicensed 5.8GHz
radios operating on these channels to be be able to sense the present of
radar and hop to another channel, and Ubiquiti stock firmware for their
AirMAX products (e.g. Nanostation M5) now does this.  W/r/t running adhoc
networks on DFS channels, I'm not sure if the FCC explicitly forbids
beaconing, or if radios may sample the band for 30secs before sending out
beacons.  The FCC regs may be vague on this detail right now.

I'm pointing out this particular talk, however, because the ability for a
mesh to reliably channel-hop would also be *very useful* for 2.4GHz
meshes.  That band now sees potentially destructive noise from
channel-hopping neighbors, i.e. one day your mesh works, the next day it
doesn't.  Manually keeping up where a clear channel happens to be becomes
increasingly untenable.

Any high-level thoughts about mesh-wide noise sensing and channel hopping
schemes for a platform like Commotion?

-- 
Ben West
http://gowasabi.net
ben at gowasabi.net
314-246-9434
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