[e2e] Random losses on very high speed networks
dovrolis at cc.gatech.edu
Tue Jul 22 20:37:28 PDT 2003
Alex, "bandwidth" is certainly not the first technical term
that is being overloaded, even in the scientific/research
literature, with multiple meanings.
Even within the context of its "physical" interpretation (Hz),
the term "bandwidth" is used to describe two different things:
1. We talk about the "bandwidth of a signal", defined based
on the range of a signal's spectrum that carries most of the
2. We also talk about the "bandwidth of a channel", or system
in general, defined by the difference of the cutoff frequencies
in the system's transfer function.
There is nothing wrong with overloading a term, as long as
it is clear from the context which concept you refer to.
Of course I will not reply to the bashing part of your message..
Constantinos Dovrolis | 218 GCATT | 404-385-4205
Assistant Professor | Networking and Telecommunications Group
College of Computing | Georgia Institute of Technology
dovrolis at cc.gatech.edu
On Tue, 22 Jul 2003, Cannara wrote:
> I don't believe anyone was whining Constantine. It's simply that bandwidth is
> the wrong word to use in English for data rate, capacity, etc. It remains
> wrong no matter who uses, or used it, and for how long. In an engineering
> sense it's a wrongful confusing element in communication with others, so in
> one sense its misuse is bad sientific manners, especially for text read by
> people new to the discipline.
> In fact, it clouds the scientific background of research that has gone on,
> since before Shannon and Nyquist, into symbol transmission. It's hard to
> justify misuse of the term when explaining how much effort has gone into
> optimal signal encoding over many decades, in particular the amazing efforts
> by modem designers, including Hayes. No technical discussion of how modem
> designers plowed the fertile field of bandwidth to increase capacity over the
> years would make sense if bandwidth equalled capacity.
> Personally, I find it humorous to see how many folks who advertise themselves
> as learned in the field use "bandwidth" so incorrectly and persistently --
> almost as if it's PC, and they're afraid to rock anyone's boat from whom they
> may need funding or some other support in the future. It's an intersting
> social phenomenon to me, becuase it demonstrates how some folks will sacrifice
> even scientific accuracy for personal comfort. In any case, my students don't
> misuse the terms on homework & tests. :]
> Constantine Dovrolis wrote:
> > > > I agree with you that "bandwidth" is largely misused in the
> > > > networking and CS community -- anyone who takes a networking class
> > > > and still misuses bandwidth for capacity (at any layer) shoulda
> > > > flunked. :]
> > >
> > Folks, frankly, it is way too late to whine about
> > the use of the term "bandwidth" in the networking context. People
> > have been using this term to refer to "capacity or throughput" (bps),
> > as well as to "physical bandwidth" (Hz), for decades. I can
> > recall the former use of the term in Jacobson's 88 paper, but I am
> > sure that there are earlier references too.
> > Besides, the context in which the term is used is so different
> > for Hz vs bps that probably it never causes confusion. And at the
> > end of the day, the two "bandwidth" concepts are not totally
> > irrelevant after all - see Shannon's law.
> > Constantinos
> > --------------------------------------------------------------
> > Constantinos Dovrolis | 218 GCATT | 404-385-4205
> > Assistant Professor | Networking and Telecommunications Group
> > College of Computing | Georgia Institute of Technology
> > dovrolis at cc.gatech.edu
> > http://www.cc.gatech.edu/fac/Constantinos.Dovrolis/
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