Subject: Re: [manet] MANET testing in realistic environment

From: "Pete Sholander" <[email-masked]>
Date: Wed, 26 Feb 2003 08:53:14 -0500

Berner,

In the open/academic literature ... David Johnson published some early
"open-air" results for DSR.  Maybe check his web-site at Rice?  Fred
Templin and the TBRPF folks have published some tests that included a
few ground nodes, and a radio-controlled helicopter (see
http://www.erg.sri.com/publications.html).  So, real-world MANET over
WLAN results are out there ... 

--Pete Sholander

>>> "Berner Vegge" <[email-masked]> 02/26/03 05:25AM >>>
Hello all!
I have made some testing on AODV, OLSR and LUNAR in a realistic
environment (i.e. not simulations). The tests are performed
within an office building with ORINOCO GOLD WLAN cards. I have
used WLAN IEEE802.11b as physical/link layer. The testing has
very often revealed problems and constraints in the WLAN
technology, such as interference when several nodes are close
to each other so that the throughput drops dramatically.
Changes in signal/noise relation leading do links that drop out
etc has also been a problem. Finally we have seen that
routing messages are lost very often at high load, so that
the connections are taken down for that reason (this is probably
due to lack of priority on routing packets, and as these are
broadcasted with no ack and resending, they are very easily lost).
I know that a lot of work is ongoing within IEEE to improve WLAN,
so hopefully MANET over WLAN will be possible in a year or so.

My question is if anyone else has performed realistic tests by
running MANET over WLAN and if anyone has any experiences,
documented results etc, that they would share with me.

Thanks a lot!
Best Regards  Berner

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From: "Pete Sholander" <[email-masked]>
Date: Thu, 27 Feb 2003 08:25:33 -0500

ns-2 is known to have inexact wireless models, as Phillipe notes below. 
Have folks had better results (e.g., better agreement between
simulation, emulation and "open-air" experiments) with GloMoSim, OPNET,
or QualNet?  

--Pete Sholander

>>> Joe Macker <[email-masked]> 02/26/03 04:20PM >>>
Berner you raise salient engineering points that are reasonably
protocol agnostic. We have done significant realistic test outdoors and
indoors (and with an emulation environment using 802.11) with working
systems and have achieved significant imrpovements with some minor
modifications..  We modified older INRIA OLSR code to add a link sensing
hysteresis algorithm to improve robustness and it works reasonably well
for us in many trials to date including highly congested ones (better
link layer sensing info --lower layer triggers, etc-- would be a further
plus for any neighbor management algorithm).  We are dealing with
naturally time-varying channels and highly unpredictable anomalies in
many wireless scenarios not wired behavior and we should be cognizant of
that fact.  Also, related to your noticing routing message being lost,
for Linux (RH dists) we quickly added ToS packet markings that improved
the priority under network congestion for routing control packets (we
tested!
 that this actually did improve things for the OS and queueing engine
we were using).  This code is available at http://pf.itd.nrl.navy.mil
under the project INRIA OLSR with NRL mods.    Packet jittering for
distributed control events,etc may also be important this was also added
and parameterized in the above experimental prototype code (very
important in a simulation)..We also have newer code developments that
should be released in the near future that we feel further improve the
link sensing process,etc.

-Joe

At 08:33 PM 2/26/2003 +0100, Philippe Jacquet wrote:
>We have run many realistic testing with IEEE 802.11 in the past. We
>experienced several link instabilities due to frequent variation in
link
>quality from remote nodes. Similar effects were also reported in NRL.
This
>is the reason why advanced neighbor sensing has been introduced in
OLSR.
>This kind of effect were never detected in ns-2 simulations.
>
>Philippe
>----- Original Message -----
>From: Berner Vegge <[email-masked]>
>To: <[email-masked]>
>Sent: Wednesday, February 26, 2003 11:25 AM
>Subject: [manet] MANET testing in realistic environment
>
>
>> Hello all!
>> MSN Messenger http://www.msn.no/messenger - Den korteste veien
mellom deg
>og