[e2e] Wireless Channel Properties

Detlef Bosau detlef.bosau at web.de
Sat Sep 3 10:20:12 PDT 2005

Detlef Bosau wrote:
> One way to hide delay spikes from a sender are PEP.
> Another, perhaps much more appealing way (and _please_, if this sounds 
> reasonable and no one did it, let me the chance to publish it 
> myself....) because it does not require any PEP or splitting or 
> something else on L3 and above is to exploit the robustness TCP 
> following actual RFCs against packet reordering, is to interleave the
> radio blocks of more than one TCP packet and thus to spread delay spikes 
> about several packets. It´s just a rough idea now. However, if it is 
> helpful, please leave it to me. If it is nonsense, please tell it to me 

Of course, there is one problem.

One could prove this in a "scientific manner", i.e. assume some more or 
less sophisticated "system model" and conclude something from that.

This would not be convincing, but a pure "ivory tower" way of thinking.

What would be needed, are _real_ traces of _real_ channels.
In a trace, a channel has two states: good and bad.
Not because I only can count: 0, 1, inf..... ;-) But because in mobile 
wireless networks a sender sends a sequence of radio blocks. And a radio 
block either will reach the sender or get lost.

Is there any possibility to obtain traces like this? Anything else would 
be pure hand waving.

It is just interesting to see, wether a channel behaves like this:

+: radio block is delivered
-: radio block fails

Example 1:


or like this:

Example 2:


or linke this:

Exampel 3:


the list can be continued.

I expect, possible Interleaving strategies must reflect these patterns 
in order to really _spread_ a delay spike about several packets.


Detlef Bosau
Galileistrasse 30
70565 Stuttgart
Mail: detlef.bosau at web.de
Web: http://www.detlef-bosau.de
Mobile: +49 172 681 9937

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