The GSM has a frequency hand off between adjacent cells whereas in CDMA, all cells work at same frequency. If a call in progress does not get allocated a new frequency and the handset goes to next ( the third cell) the call gets dropped. Factors which come into picture are cell size and traffic in each of the three cells in which the handset is moving.
One does not get to know of it in either large cells which could be upto 5 kms in size or low traffic  with less than 7 calls in progress at that instant.

--- On Thu, 13/1/11, Bruce Carter <rbrucecarter@yahoo.com> wrote:

From: Bruce Carter <rbrucecarter@yahoo.com>
Subject: [apple-iphone] Re: The New Verizon Offering
To: apple-iphone@yahoogroups.com
Date: Thursday, 13 January, 2011, 2:11

 

> Since as I understand radio travels at close to the speed of light the speed of a moving car (70 mph or 70 kph or 700kph) would be of irrelevant.

I think the original poster was referring to the handoff between cells, which involves some software in the phone and the two BTS's involved. There may have been problems at one time, but increased processing speed on both ends have probably eliminated the problem. I've never had a problem, and I've been on a lot of freeways at high speed. If GSM dropped calls under those conditions, it would be useless as a cell standard. Nobody would want T-Mobile or AT&T. I had more dropped calls on the freeway with CDMA - it was REALLY annoying. I was trying to buy a car remotely (insurance settlement from a wreck). Admittedly I was in the worst canyon in the LA area at the time. But I drove the same canyon last year with GSM, my daughter was on her phone at the exact same place - not a problem at all. Zooming along 60 to 65 MPH both times, only difference was CDMA and GSM. If you told me CDMA had problems with handoffs at freeway speeds, I'd be more inclined to
believe it based on my experience.

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