Subject: Possibly silly question: Fourier transform bandwidth information?

From: Michael Welzl <[email-masked]>
Date: Wed, 22 Sep 1999 10:50:37 +0200

Hi all,

First of all, thanks to everyone who helped me out with my question
about non-poisson models of Internet traffic. I'm still looking for
ways to estimate the "current" bandwidth based on some kind of
bandwidth history.

Given the self-similar nature of Internet traffic, I wonder if it
would be possible to determine whether we're momentarily "sitting on
a ripple" by looking at the spectrum; shorter-term bursts would
naturally result in higher frequencies. But can the frequency be
used to predict the size of the "ripple" ?

What do you all think of this? Nonsense or an interesting idea?

Or has anyone even tried this before? I could not find any comment
on spectrum analysis in any of the related papers.

Regards,
Michael Welzl

---

From: Frank Wetzels <[email-masked]>
Date: Wed, 22 Sep 1999 13:52:29 +0200 (MET DST)

On Wed, 22 Sep 1999, Michael Welzl wrote:

fpmw>First of all, thanks to everyone who helped me out with my question
fpmw>about non-poisson models of Internet traffic. I'm still looking for
fpmw>ways to estimate the "current" bandwidth based on some kind of
fpmw>bandwidth history.
fpmw>
fpmw>Given the self-similar nature of Internet traffic, I wonder if it
fpmw>would be possible to determine whether we're momentarily "sitting on
fpmw>a ripple" by looking at the spectrum; shorter-term bursts would
fpmw>naturally result in higher frequencies. But can the frequency be
fpmw>used to predict the size of the "ripple" ?
fpmw>
fpmw>What do you all think of this? Nonsense or an interesting idea?
fpmw>
fpmw>Or has anyone even tried this before? I could not find any comment
fpmw>on spectrum analysis in any of the related papers.

I have not looked into the subject pratically, but i guess that this
search is comparable with finding trends in the stockrates at some
stock exchange.

Yoy will propably not even find a trend that can be associated with
night and day traffic because the traffic is globally and not locally
(speaking of The Internet traffic). Routing  updates (etc) 'ripples' are
too small to be visible in the total amount of traffic.

But you sure may try look into the matter.

Frank

---

From: Matthew Roughan <[email-masked]>
Date: Sat, 25 Sep 1999 10:40:27 +1000

> used to predict the size of the "ripple" ?

The idea you are talking about seems to have some relationship to the
wavelet transform methods of analysis that we have been working on.
Please have a look at Darryl's page at www.serc.rmit.edu.au/~darryl to
have a look at some of the work that has been done.

The wavelet transform is similar to the Fourier transform except that it
transforms into a time-scale domain rather than frequency domain. The
advantage is that the wavelet domain has a natural scaling that
corresponds to the scaling in the data. 

I believe that some work has even been done on using the wavelet
transform to implement a Call-Admission Control, for instance see:
@InProceedings{droz97:_wavel_based,
  author =       {Patrick Droz},
  title =        {Wavelet-Based Resource Allocation in {ATM} Networks},
  booktitle =    {IEEE Global Telecomunications Conference,
GLOBECOM'97},
  year =         1997,
  annote =       {http://zurich.ibm.com/~dro}
}

Cheers,
Matt

-- 
Matthew Roughan                  
Software Engineering Research Centre, RMIT University
110 Victoria St, Carlton, Vic 3053,  AUSTRALIA
Ph:    +61 3 9925 4093      
Fax:   +61 3 9925 4094     
Email: [email-masked]     
WWW:   http://www.serc.rmit.edu.au/~matt