[wsfii-discuss] DUMBO

Wed Feb 4 13:00:42 UTC 2009

Hello Sylvia, Paul & list members -

I had a - very brief - look at the DUMBO proposal. The idea is great but I see 
three significant problems that must be addressed IMHO before the system can 
actually work in the field.

1.) 802.11 Ad-Hoc driver and implementation problems.

Currently there are only two to three working drivers/chipsets that are up to 
the challenge of wireless mesh networking:

* Madwifi for Atheros-based PCI/mPCI/SoC wireless devices for Linux OS with 
fixed IBSSID and nosbeacon option - with all patches from recent OpenWRT 
Kamikaze. The drivers offered at madwifi.org will NOT work reliably.  

* Proprietary Broadcom driver for Linux kernel 2.4 with IBSSID fix hack in 
OpenWRT

* A few (old and dated) Atheros chipsets work with the mac80211-based ath5k 
driver available in the newest Linux kernel (2.6.28) or with newest 
compat-wireless update compiled against 2.6.24 and newer. The situation of 
Linux drivers is now rapidly improving.

Everything else will work flaky at best, lock up your machine, create 
cell-splits and so on. So the NOKIA web tablets are not an option for a MANET 
because they use a Texas Instruments chipset.

2.) INRIA OLSR RFC routing protocol is a terrible choice

http://www.docstoc.com/docs/3317312/olsr-story

While being popular in academic research amongst scientists that have to 
produce a certain amount of papers and RFC-drafts per year, OLSR from INRIA 
is a protocol that is performing miserably at best once you leave the theory 
and put the academic ideas into a real-life test. Hence community mesh 
networks around the world use a hacked (heavily modified) version of OLSR 
from Olsr.org or a flavor of B.A.T.M.A.N.  for Layer 3  (main or 
experimental) or Layer 2 (Batman-Advanced). All are available as packages for 
Openwrt. There are ready to roll firmware images available for some wireless 
routers:

Freifunk Firmware (OLSR on Broadcom-based hardware)
RO.B.I.N.	(B.A.T.M.A.N.  on Atheros-based hardware)
Nightwing (B.A.T.M.A.N.  on Atheros-based hardware)

Sources for popular mesh protocols:
www.open-mesh.net
www.olsr.org

(All firmware flavors are based on Openwrt)

3.) You shouldn't rely crucial communications too much on mobile mesh nodes 
that go on and off and move around

WiFi is mostly line-of-sight communication. If a mesh cloud of mobile devices 
is dense (many nodes) and you have a well-working and fast-acting protocol 
(say Batman with Originator (network announcements) interval of 200ms) you 
can multiply the coverage/range of a wireless device by factor 2-4 (just an 
estimation). However the WiFi range of PDAs is generally not overwhelming.

I'd recommend to use battery-powered mesh routers at exposed locations to 
improve the quality and range of the wireless ad-hoc cell. And for good range 
on the ground I'd connect a small mesh router to my mobile device (via USB, 
power consumption if my favorite mesh router is 2 Watts at 5 Volts) Range of 
such a device from a exposed location is 1km (free line of sight) at least 
without large antennas, with strong antennas much more.  (I have a Atheros 
mPCI card in my EEE PC with Openwrt patched Madwifi driver which also serves 
me well and range is decent.)

Also WiFi and full mesh routing performed by a PDA will drain the battery 
quickly. Especially if the protocol is configured for quick response to 
topology changes)

Cheers,
elektra

On Wednesday 04 February 2009 09:44:03 wsfii-discuss-request at lists.okfn.org 
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>    1. Wireless in Burma - DUMBO project (Sylvia Cadena)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 20 May 2008 11:51:18 +1000
> From: Sylvia Cadena <sylvia at colnodo.apc.org>
> Subject: [wsfii-discuss] Wireless in Burma - DUMBO project
> To: Discuss list on the World Summit on Free Information
> 	Infrastructure	<wsfii-discuss at lists.okfn.org>, Paul Wilson
> 	<pwilson at apnic.net>
> Message-ID: <48322E96.1060405 at colnodo.apc.org>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi everybody,
>
> APNIC General Director (in copy f this message), is trying to find more
> support for the DUMBO project. If you know anyone who might be interested
> to collaborate it will be great if you can share that information with him.
> The information about the DUMBO project is attached.
>
> All the best,
>
> Sylvia
>
>
>
>
>
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