I wonder how much of it is related to bouncing between towers and the phone reauthenticating; which is why some people are still on in the same city where other's have been bumped off. I have several towers near work; one is about 500' away, and a couple with in a mile or so. I just lost 4G on my Xoom down to 3G in the last few minutes, while my Nexus is still a full 4 bars at 4G. It's perplexing.
-Mike
-Mike