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Re: [ns] RE: Bandwidth in 802.11 simulation
i agree....there is an ambiguity about changing the bandwidth of 802.11
in its present form...the dependence on physical layer parameters is "not
clear"..
-Vikram
> My understanding is that the bandwidth in 802.11
> depends on many parameters, which are not all in the
> 802.11 code (some are in phy.cc...). Anyway I think
> this 802.11 was developped to model a certain device,
> with all values hard-coded, and some day a smart guy
> decided have the bandwidth_ parameter modifiable from
> Tcl, without checking what this bandwidth_ parameter
> was about. For instance, the parameter used to
> calculate the contention time (Which should change
> with the bandwidth) is called DSS_slottime or
> something and is hardcoded somewhere.
>
> I also did some experiments, changing the bandwidth_
> gradually and recording the number of packets actually
> exchanged by 10 nodes, and the results were
> desesperately random. Moreover at the time I saw 2
> posts in the ns list about found bugs in 802.11...
>
> I just needed a working mac layer, not a special
> bandwidth, so I replaced 802.11 by a fake and
> irrealistic Mac layer called mac-null. It has an
> infinite bandwidth. You can find the mac-null code in
> my zrp bundle.
> (http://www.ee.cornell.edu/~haas/Software/zrp.tar.gz)
>
>
>
> > -----Original Message-----
> > From: Gaurav Jain [mailto:[email protected]]
> > Sent: Wednesday, April 04, 2001 11:41 AM
> > To: [email protected]
> > Subject: Bandwidth in 802.11 simulation
> >
> >
> > Hi Robin...
> >
> > I see in the ns archives that you had posted a
> question about 802.11
> > bandwidth about 6 months back.. I am facing the same
> problem
> > to change the
> > wireless BW from the default 2MB (It's strange that
> now I
> > even can't see 2Mb
> > anywhere in the ns code {mac-802.11.cc/h,
> wireless-phy.cc/h}..
> >
> > Could you please let me know if you found any
> solution to the
> > problem..
> >
> > Regards,
> > Gaurav.
> >
>
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