[Tinyos-help] Building topologies - TOSSIM

Pedro Nunes pmrnunes at gmail.com
Thu Nov 11 13:54:21 PST 2010


Hello all.

I've been trying to build topologies using the tool provided along with the
TinyOS distribution: LinkLayerModel (which can be found under
$TOSDIR/support/sdk/java/net/tinyos/sim).
The tool has its documentation here:
http://www.tinyos.net/tinyos-2.x/doc/html/tutorial/usc-topologies.html
And although I did everything as they said, I always get an "almost-full"
disconnected network.

If you try to use the tool with the 2nd example given on the tool's
documentation webpage - a network of 49 nodes on a 100x100 open field - you
will see that only one or two pairs of nodes will be able to communicate.
All others will just stay disconnected from the network.

If someone wants to give it a try, you'll just have to copy the 2nd example
to a txt file and then: $ java net.tinyos.sim.LinkLayerModel
<that_txt_file_you_just_created>. This will create 2 files: "linkgain.out"
and "topology.out". If you open "linkgain.out" you'll see that the majority
of the links will get gains in a -130 to -150 dBm range (when I used links
with -80 dBm gain I had more than 50% packet loss) which just won't work.

Also, in http://en.wikipedia.org/wiki/DBm they refer that "Typical range
(-60 to -80 dBm) of wireless received signal power over a network (802.11
variants)".

Does the LinkLayerModel tool have some sort of bug? Or am I missing
something here?

PS: I'm working with large networks so I think that building the topology
manually isn't an option.

Kind regards,
Pedro Nunes
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