Mojtaba,
Glad I could help. I understand how frustrating it can be when you're
first starting out.
As for the text file... Basically it's a noise trace, meaning that they
took Received Signal Strength (RSS) measurements over a long period of
time. They use this input to train a model to generate similar (but not
replaying the trace) noise values. Each time a node in TOSSIM attempts
to send a packet, it first performs a CCA. This takes an RSS
measurement to determine whether anyone else is transmitting at the same
time. Obviously if there is another node and the link between them,
TOSSIM can deal with this, but when you want to simulate interference
from other devices, such as WiFi or microwaves, it uses the noise
figure. This noise figure is also used to determine whether the Signal
to Noise Ratio(SNR) is sufficiently high to prevent corruption of a
packet in the form of bit-inversions. If this corruption occurs, TOSSIM
just drops the packet (in my experience anyways) instead of flipping
some bits.
There are most likely academic papers describing in detail how TOSSIM
uses the CPM model to generate noise values, but I'm not in the lab
right now, so I can't look for any in particular that would help you
out. If you don't have access to academic paper repositories like
ACM/IEEE, then the best place to look is the code itself. I've found
that being very good at looking for particular variables/keywords in an
entire project using grep is an invaluable tool when i'm trying to
understand the inner.
Regards,
-Paul
mojtaba raznahan wrote:
Paul,
Thank you veryyyyyyy much!!!.It worked!
I had seen this page several times but i wasn't accurate enough and so
i didn't used the noise model at all.
Really you gave me a big help! Thank you.
But what is this numbers ? It claimed that you should use at least 100
entry of this numbers so the CPM can create the statistical model.Have
you any sources to read more about this topic and it's usage ?
your sincerley,
Mojtaba <http://www.raznahan.com>
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