[e2e] Bandwidth Estimation workshop

Constantine Dovrolis dovrolis at cc.gatech.edu
Tue Sep 30 08:27:25 PDT 2003

We had that discussion with Alex Cannara in this mailing list in last
July. I'm not going to repeat my opinion on this issue, following a
request from the mailing list administrator back then to not continue
that thread.

On a personal note: I teach CS-networking and my students know very well
the distinction between physical-layer bandwidth and network-layer
bandwidth. The difference in the units between the two measures avoids
any confusion. Overloading of technical terms with various meanings
in different areas happens commonly. Your general claims about CS people
sound absurd to say the least.


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, 30 Sep 2003, David P. Reed wrote:

> It's very sad to see that the vernacular use of "bandwidth" to mean
> "information rate" has been adopted by the networking
> community.  Information rate is a perfectly sound concept.
> It's a mark of the ignorance of the community as a whole that it cannot
> think clearly and make clear distinctions.   I am sure that there are many
> professors of computer science and Ph.D.s in packet communications who may
> not even understand the technical distinction (since we don't teach signals
> and systems to CS people).
> This would not be so bad, except there is no word or even an easy phrase
> for what "bandwidth" was coined to mean - which is the range of frequencies
> occupied by a modulated signal.   Those of us who work on RF and photonic
> systems (as well as those who deal with audio) are impoverished by this
> theft of a term, because for us, it is important to distinguish quite
> clearly between the information rate of a signal and its bandwidth in our work.
> Bandwidth is measured in Hertz.   Information rate (or bitrate) is
> typically measured in bits/second (and I am considering a formal proposal
> to IEEE to call for a new unit, the Shannon, to deal with the lack of a
> named unit).   They are NOT at all equivalent.
> It's as ignorant to say bandwidth when you mean bitrate as it is to say
> "light-year" when you mean a unit of time.   Except that physicists don't
> do that, and communications folks do.
> Christian Huitema pointed out to me a week ago that we probably have to
> live with this loss of  a word.   So I suppose we'll have to coin a new
> word for the important old meaning.  I have proposed "frequespan"
> (FREE-kweh-span) to mean the range of frequencies occupied by a
> signal.   Of course, the voracious ignorance of CS professionals will
> probably colonize that one as well ...

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