[Ns-developers] [NS3 - CSMA] Lack into implementation

Mehdi Moussouni mmoussouni.study at gmail.com
Wed Jun 25 12:14:24 PDT 2014


Currently working on CSMA/CA during an internship i have to use NS3 and i
saw *a problem in the implementation* of this protocol in NS3 :
When entering a backoff phase, also called a contention window, a
pseudo-random number between "m_minslots" and "m_maxslots" is taken (let's
call it Wl). In the actual implementation, this number is multiplied by the
length of a slot and the function waits this amount of time (this means
that Wl is *decremented each slot*) before trying to send the packet again.
In the CSMA/CA standard, At each slot, Wl is *decremented only if the line
is in idle state*.

I think it could be useful to correct the implementation in NS3. I'm
currently modifying the scripts (backoff.cc//h - csma-net-device.cc//h)
locally but I'm a beginner in programming so my code will probably *need to
be reviewed* before being exported to the NS3 project. To summarize, I'll
need some help to review my code and implement it of the NS3 project.

PS: To check what i'm talking about, you could check the fig. 1 page 2 into
this scientific book (and many other) talking about CSMA/CA (
http://bit.ly/1qwA6At ).
PPS: Sorry for mistakes, I'm not native English speaker.

Mehdi Moussouni,
Élève-Ingénieur 2nde année (p2017) - Engineering Student 2nd year,
mehdi.moussouni at grenoble-inp.org ,
+336 42 38 54 15

École nationale supérieure en système avancés et réseaux (Esisar)
Institut National Polytechnique de Grenoble - National Institute of
Chercheur invité équipe GRETI UdeMoncton - Guest Researcher team GRETI
50 rue Laffemas - BP 54
26902 VALENCE Cedex 9

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