802.11b while going 100 mph?

Does anyone know if there are any constraints regarding using 802.11
while one endpoint is moving (at relatively high speeds, about 100
mph) with respect to another endpoint such as in the case of an ad hoc
network? Not signal range issues, but rather proper reception issues.
I understand that cellular networks have constraints (e.g. GSM is
stable until about 100 mph). Does wifi have it too?

There would be two factors. What is the relative speed and distance between
the two end points.

For example, if two planes were traveling at 100 mph in the same direction
and say a constant 50 ft between them I would think it would work.

With 801.11 anything, distance is the big factor. Speed would too but
unless your going to do 100 mph in a 50 foot circle around another end
point, distance is what is crucial.

"Gerald" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Does anyone know if there are any constraints regarding using 802.11
> while one endpoint is moving (at relatively high speeds, about 100
> mph) with respect to another endpoint such as in the case of an ad hoc
> network? Not signal range issues, but rather proper reception issues.
> I understand that cellular networks have constraints (e.g. GSM is
> stable until about 100 mph). Does wifi have it too?

"Gerald" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Does anyone know if there are any constraints regarding using 802.11
> while one endpoint is moving (at relatively high speeds, about 100
> mph) with respect to another endpoint such as in the case of an ad hoc
> network? Not signal range issues, but rather proper reception issues.
> I understand that cellular networks have constraints (e.g. GSM is
> stable until about 100 mph). Does wifi have it too?

I have used a (UK) GSM phone while in a private aircraft travelling at about
200mph
without problem. The ratio of RF speed over the vehicle speed is so high
that the vechicle
movement is irrelevant in general terms. A small amount of doppler shift
will exist but this
shouldn't matter with these systems.

Look out for the following radio related issues; RF Flutter and multi-path
interference caused
by reflections from surrounding objects.

Get the non-mobile receiver up high so it is likely to be visible to the
mobile unit at all times.

Rv!

You will not encounter *ANY* performance issues as long as you stay under
the speed of light or the speed of radio waves in the 2.4gigahertz range.
Which ever is slower.

Peter

"Gerald" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Does anyone know if there are any constraints regarding using 802.11
> while one endpoint is moving (at relatively high speeds, about 100
> mph) with respect to another endpoint such as in the case of an ad hoc
> network? Not signal range issues, but rather proper reception issues.
> I understand that cellular networks have constraints (e.g. GSM is
> stable until about 100 mph). Does wifi have it too?

Hate to be a spoiler, but performance and reliability will be a problem long
before light speed, and as slow as 60mph but usually more. If the relative
speed between two points is enough to shift the frequency you can have
issues. Frequency shifts starts (abet small) once two points start moving
to or from each other.

And if frequency shift doesn't get you, in a Boeing at 500 mph you would
pass through cell sites so fast the hand off probably wouldn't work for very
long. And a 801.11b, you would be in and out before you could blink. (say
200 ft).

"pete" <(E-Mail Removed)> wrote in message
news:OiS5b.4436$(E-Mail Removed) ...
> You will not encounter *ANY* performance issues as long as you stay under
> the speed of light or the speed of radio waves in the 2.4gigahertz range.
> Which ever is slower.
>
> Peter
>
> "Gerald" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) om...
> > Does anyone know if there are any constraints regarding using 802.11
> > while one endpoint is moving (at relatively high speeds, about 100
> > mph) with respect to another endpoint such as in the case of an ad hoc
> > network? Not signal range issues, but rather proper reception issues.
> > I understand that cellular networks have constraints (e.g. GSM is
> > stable until about 100 mph). Does wifi have it too?
>
>

I stand corrected. Thank you. How about if the access point was in the
middle and he traveled at the speed of light or the speed of the radio
transmission around in circles, keeping the distance the same?

Peter

"Dave" <(E-Mail Removed)> wrote in message
news:2VS5b.36120$(E-Mail Removed)...
> Hate to be a spoiler, but performance and reliability will be a problem
long
> before light speed, and as slow as 60mph but usually more. If the
relative
> speed between two points is enough to shift the frequency you can have
> issues. Frequency shifts starts (abet small) once two points start moving
> to or from each other.
>
> And if frequency shift doesn't get you, in a Boeing at 500 mph you would
> pass through cell sites so fast the hand off probably wouldn't work for
very
> long. And a 801.11b, you would be in and out before you could blink. (say
> 200 ft).
>
> "pete" <(E-Mail Removed)> wrote in message
> news:OiS5b.4436$(E-Mail Removed) ...
> > You will not encounter *ANY* performance issues as long as you stay
under
> > the speed of light or the speed of radio waves in the 2.4gigahertz
range.
> > Which ever is slower.
> >
> > Peter
> >
> > "Gerald" <(E-Mail Removed)> wrote in message
> > news:(E-Mail Removed) om...
> > > Does anyone know if there are any constraints regarding using 802.11
> > > while one endpoint is moving (at relatively high speeds, about 100
> > > mph) with respect to another endpoint such as in the case of an ad hoc
> > > network? Not signal range issues, but rather proper reception issues.
> > > I understand that cellular networks have constraints (e.g. GSM is
> > > stable until about 100 mph). Does wifi have it too?
> >
> >
>
>

In message <mQR5b.24850$(E-Mail Removed)>, Dave
<(E-Mail Removed)> writes

Snipped...

>There would be two factors. What is the relative speed and distance between
>the two end points.
>
>For example, if two planes were traveling at 100 mph in the same direction
>and say a constant 50 ft between them I would think it would work.
>
>With 801.11 anything, distance is the big factor. Speed would too but
>unless your going to do 100 mph in a 50 foot circle around another end
>point, distance is what is crucial.

It's my understanding that Doppler effect (which seems the issue here)
has nothing to do with distance between, but all on relative velocity.

I would speculate that any problems that might arise would be worst at
the "before" and "away" transition point.

Don't know about 802.11b, but the impact of Doppler effect in other
application areas gets greater as the frequency increases.
--
Tony Morgan
Half the people in the World are below average.

"Gerald" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Does anyone know if there are any constraints regarding using 802.11
> while one endpoint is moving (at relatively high speeds, about 100
> mph) with respect to another endpoint such as in the case of an ad hoc
> network? Not signal range issues, but rather proper reception issues.
> I understand that cellular networks have constraints (e.g. GSM is
> stable until about 100 mph). Does wifi have it too?

I did a test with an Access Point along the road and driving by at 120
kilometers/hr.
I got connected to the AP from 600 meters and disconnected after 700 meters.
During the connection, I was able to download a large file from a webserver
like normal!

Regards,
Thor.

> I got connected to the AP from 600 meters and disconnected after 700 meters.
> During the connection, I was able to download a large file from a webserver
> like normal!

Let me get this straight...

You were driving at 2km per minute and therefore had connectivity for 39
seconds.

In that 39 seconds, your machine obtained an IP address and you then
manipulated the machines user interface to be able to download a large
file....

all while driving at 2km/minute!

Hmm.

David.

Didn't you know it's legally not allowed to download a file while driving?

--

Eric P. van Westendorp Tel: +31(0252)210579
Reigerslaan 22 2215NN Voorhout Netherlands

Thor Spruyt wrote:
> I did a test with an Access Point along the road and driving by at 120
> kilometers/hr.
> I got connected to the AP from 600 meters and disconnected after 700 meters.
> During the connection, I was able to download a large file from a webserver
> like normal!
> Regards,
> Thor.