REFLECTOR:Cell phones and airplanes

[Mike Pollock]

Actually, the problem is a technical one.  Since a lot of cell phones today
(Sprint, etc.) use CDMA technology (a technology that uses one frequency but
multiple digital codes from a specific cell cluster), the problem has to do
with the power being received at each cell site.  CDMA technology causes the
base (tower) to send a code to the receiver (cellphone) to keep the receive
power being received at the tower from the cellphone at a constant level.
When using a CDMA phone in a plane, the speed and altitude of the plane
cause several cells to try to lock on to the signal from the phone and each
cell tries to send compensation signals to the cellphone.  This ties up
bandwidth and we don't want you to do that because it causes other phone
users to not be able to get through (ever had that problem).  Satellite
phones do not have this problem.

Michael Pollock
Network Integration Lab
MCI Communications Corp.




-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Bernard Despins
Sent: Thursday, June 12, 2003 7:15 PM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:Storm Scope Probe


Nice theory, but since people use cell phones from sky scrappers and are
definitely line of sight with multiple towers (since towers are
concentrated in populated areas), the system is quite able of dealing
with these situations.

The problem is not technical, but is rather a combination of myth and
government.

Bernard

Jim Agnew wrote:

>The problem is not with the FAA, it is with the FCC.  The
>typical cell phone setup uses a triad of antennas that can
>pick up the signal, they then negotiate and the strongest
>one wins opening up space on the others as you move this
>process repeats.  From the air you are line of sight and
>may lock up a bunch of antennas since they may all have the
>same signal strength.
>
>That is the major reason for the "non aircraft use."  In an
>emergency I doubt that the FAA or the FCC will get too
>upset.
>
>Jim
>
>


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