[e2e] VJCC vs. Keshav
Jon.Crowcroft at cl.cam.ac.uk
Thu Apr 18 08:18:29 PDT 2013
yes, actually we can simulate that -
in fact i was on the committee of a very smart PhD student (Gregor Gaertner)in Trinity College
Dublin who did a bunch of empirical studies of wifi propagation in the streets
and then built exactly the hybrid matlab+ns2 simulation I am describing
[note wifi is wideband radio in a sense so this is notionally harder than a single narrow band
yes, it has to do something like the spatial resolution of the 1/2 wavelength of the radio
and temporal resolution of the movement of people/devices over that space (actually it turns out it doesnt for
various interesting reasons) - the simulator and measurements matched well...
no humour involved at all
In missive <51700BB6.2080606 at web.de>, Detlef Bosau typed:
>>Am 18.04.2013 14:53, schrieb Jon Crowcroft:
>>> In missive <516FE1DA.9050708 at web.de>, Detlef Bosau typed:
>>> >>Yes. And being short and frankly: When it comes to mobile networks, I
>>> >>don't believe a word of the packet-pair and packet-train stuff.
>>> >>Even for the radio interface, it simply doesn't make sense to talk about
>>> >>an "average bit rate" in this case, when this is associated with both, a
>>> >>reasonable hight throughput and a reasonably low block corruption rate.
>>> this depends on the model and simulator - if you model the signal
>>> propagation and do it with fine grain enough discrete event rate, then
>>Jon, I once attended a talk where the speaker proposes to do ray traicing...
>>And please keep in mind the GEOMETRIC "period" of minima and maxima in
>>IIRC: Rule of thumb: half of the bearer frequencies wavelength. I.e.
>>with GSM, round abouht 1 GHz, wavelength round about 30 centimetres.
>>I.e. 15 centimetres between two points of maximum receiving power.
>>It was exactly that moment, where I stopped giggling about the persons
>>who I've seen "mobile phone callisthenics" by shifting around their
>>phones 5 cm to the left or 10 cm to the right in order to increase their
>>WWW browsers throughput.
>>And you want to simulate that, perhaps with ray tracing and perhaps a
>>temporal resolution of say 1 ms and a geometric resolution of say 1 cm?
>>Sorry, I cannot take this seriously.
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