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Archive for category Troubleshooting

Bug in Mac80211 in MiXiM backoff when channel busy

Posted by on Thursday, 15 December, 2011

This post describes a bug in MiXiM’s Mac80211 which seems to be a fundamental error: when the MAC gets a packet from the Netw and the channel is busy, it schedules a senseChannelWhileIdle(currentIFS + remainingBackoff) after the ongoing transmission ends. Unfortunately, remainingBackoff is often 0 as post-backoff is likely to have completed. The result? Many synchronised collisions one IFS after the ongoing transmission. Read the rest of this entry »

OMNeT++: Error during startup: No user interface (Cmdenv, Tkenv, etc.) found

Posted by on Wednesday, 7 December, 2011

After an update of GCC (on Kubuntu 11.10) this error shows up when running simulations after recompilation.
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Matlab: increasing precision

Posted by on Wednesday, 19 October, 2011

Sometimes Matlab does not always perform as expected. This can be because of the IEEE 754 binary double precision floating point (double) representation used by Matlab: there is a finite number of digits to represent a number and this may not always be enough. We discuss how to use the Symbolic Toolkit to circumvent this. Read the rest of this entry »

Moving files to a Linux box

Posted by on Thursday, 13 October, 2011

Moving files to (and from) a GNU/Linux box is trivial for those well-seasoned in the use of the commandline. For Mac or windows users who need to make use of a Linux box (read my article on Clustercomputing with Torque) this may be the first problem they encounter. Easily overcome, though tough if you don’t know how it works. Read the rest of this entry »

Gnuplot: increasing readability of plots

Posted by on Friday, 23 September, 2011

Gnuplot is a great way to plot your data. It is very powerful, easily attached to all your analysis tools and scripts and provides publication-ready vector output (or to any other thinkable printer, image format, character device etc.). It’s just not always that easy to find the correct commands to do what you want. Read the rest of this entry »