Re: VJCC vs. Keshav
Jon Crowcroft <[email protected]>
| Newsgroups | gmane.network.end2end |
|---|---|
| Message-ID | <[email protected]> |
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 scheme)) 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 <[email protected]>, Detlef Bosau typed: >>Am 18.04.2013 14:53, schrieb Jon Crowcroft: >>> In missive <[email protected]>, 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 >>Rayleigh-fading. >> >>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. >> >>-- >>------------------------------------------------------------------ >>Detlef Bosau >>Galileistraße 30 >>70565 Stuttgart Tel.: +49 711 5208031 >> mobile: +49 172 6819937 >> skype: detlef.bosau >> ICQ: 566129673 >>[email protected] http://www.detlef-bosau.de >> cheers jon