[e2e] Congestion control as a hot topic in IETF

Jon Crowcroft Jon.Crowcroft at cl.cam.ac.uk
Sat Mar 9 02:28:05 PST 2013

In missive <513A3C4A.5060805 at web.de>, Detlef Bosau typed:

 >>Am 08.03.2013 16:54, schrieb Jon Crowcroft:
 >>> In missive <513A04BE.4060505 at web.de>, Detlef Bosau typed:
 >>Merely nothing. When I move around my laptop in my apartment, I use WLAN 
 >>to access my DSL router, the power level will change.
 >>However: Hardly that much that the packet corruption level is affected.

when you switch from 55Mpbs to 11Mbps and to 2Mbps, without any
other users around, why do you think that happens....
 >>Unfortunately, in my appartment I see up to 8 (eight) WLANs.

if you buy a WiFI router with MIMO you might solve your
interference problems - dense mode stuff is getting tackeld but you
ill still find the data rate switches down to lower rates as you
get further from your AP

 >>So, what do you think affects my data rate notebook - router? Me moving 
 >>around in the apartment or my neighbours surfing the Internet?
 >>In addition, the SNR sinks continuously when moving around. The packet 
 >>corruption ratio doesn't.
 >>It is a theoretical game with numbers.
no, its a basis for sound system design.

 >>> eventually the signal (to background noise) is too low level to carry any info in any way distinguishable
 >>>   >>Data corruption is a phenomenon which occurs at the receiver. The
 >>>   >>problem is that the receiver cannot successfully rebuild a packet from
 >>>   >>what he received. The air interface has no idea of which waves are
 >>>   >>travelling along and whether they make any sense at all.
 >>> you're confusing interference with other sources and misreading the honorably Dave Reed
 >>I'm quite sure that I'm not misreading Dave Reed.

you are conflating two (or three) completely different facets of
wireless nets...
 >>> secondly, you are ignoring absorption (e.g. by water vapour which gets a little bit hotter)
 >>> and also _self_ interferance (aka Ricean fading) and scattering (rayleigh fading)
 >>So, a model which correctly describes wireless channels is that flexible 
 >>that it fits anything - and has no use at all.

incorrect - it is a sound basis for design. 

 >>I don't think I misread Dave Reed - to the contrary, in some particular 
 >>respects I share his anger.

not sure why you are angry - this is a technical forum, not a
personal chat forum.
 >>Detlef Bosau
 >>Galileistraße 30
 >>70565 Stuttgart                            Tel.:   +49 711 5208031
 >>                                            mobile: +49 172 6819937
 >>                                            skype:     detlef.bosau
 >>                                            ICQ:          566129673
 >>detlef.bosau at web.de                     http://www.detlef-bosau.de



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