Monday, May 23, 2011

NS3: Generate Statistical Result

By default, NS3 generates exactly same result when you run a simulation. If you want to collect statistical behavior by running the simulation multiple times, you need to avoid this default setting of NS3. One way to do this is using different seed for every simulation. Just add the following line before calling the run() method.

Here the current system time is used as the seed which ensures that seed will be different for every simulation and hence the simulation result.

Saturday, May 14, 2011

NS3: Apply a Patch to Source

Sometimes it is necessary to apply patch to update NS3 source. Use the following steps to apply patch.

  • Download desired patchFile
  • Open shell
  • Goto ns3 root directory (cd /...path to .../ns-3***)
  • run the command 'patch -p1 < /...path to ../patchFile'

Friday, May 13, 2011

Add Header, Footer, Page Numbers to a PDF File

There are many software that can add header/footer/pageNumber in a pdf files but many of the software need license. Here is a link to do it in linux for free!.

Wednesday, May 11, 2011

Bangla Font Problem in Firefox

Some versions of firefox web browser has problem in showing Bangla font properly. It generally occurs after an update of firefox to the next version. Please follow the following steps if you have this problem.

  • Download UTF-8 compliant bangla font (ex., Siyam Rupali) if you already don't have
  • In the firefox menu, go to option->option ->content
  • Select the tab 'Font & Color'
  • Select the Bangla font and save.

Monday, May 9, 2011

Android: UDP Receiver

For my android app, I needed a UDP receiver which can receive broadcast packets. So I tried to create a UDP socket using the following.

mySocket = new DatagramSocket(PORT, ADDRESS);

But this socket could only receive unicast packets not the broadcast ones. I had to change it as follows to make it work for broadcast.

mySocket = new DatagramSocket(PORT);

NS3: Wireless Jamming Model

The basic implementation of NS3 does not include anything for wireless jamming but wireless jamming is interesting research topic for wireless network security. Good news is Network Security Lab, University of Washington is working on a jamming model for NS3. Use the following link for more information.

Thursday, May 5, 2011

Latex: Italic Underline Problem

Some Latex compiler underlines the the italic text, more precisely the text inside \emph{your text}. If you don't want the text underlined, just add "\normalem" after the line "\begin{document}" !

Wednesday, May 4, 2011

NS3: Constant Speed Mobility

NS3 does not support constant speed mobility but it has a very good class RandomWalk2dMobilityModel which supports random speed and direction based on defined time or distance. If you need to simulation constant speed mobility, use the following steps:

  1. Open file '..../ns-3-dev/src/mobility/'
  2. In function DoStartPrivate()
    • comment the line 'double speed = m_speed.GetValue ();'
    • add a line 'double speed = your_constant_speed_value'
  3. Recompile ns-3 and you are done.