What if Capacity Isn't AT&T's iPhone Problem?

AT&T Inc. (NYSE: T) is beefing up its mobile backhaul network to answer complaints about coverage and reliability for the Apple Inc. (Nasdaq: AAPL) iPhone. But what if 3G capacity isn't the problem? (See AT&T CTO: We Know What's Best for You and AT&T Says It's Ready for Wireless Growth.)

An analysis published by Ars Technica on Sunday suggests iPhone coverage suffers, not because it hogs bandwidth, but because the phone is continually shutting down and re-establishing its data connection. That would mean the problem is in the signaling network rather than the raw capacity.

Ars Technica came to this conclusion by talking to a source at Telefónica UK Ltd. , the only operator that appears to be having problems similar to AT&T's. (See 02 Felt iPhone Crunch Too.) The source says the iPhone saves battery power by killing its data connection whenever it's not in use. The result is that the iPhone is continually requesting new data connections, overloading the signaling network.

This scenario would also explain why other carriers don't see the problem: Other European nations saw text messaging get adopted quickly, and operators built more signaling capacity as a result. More specifically, those operators used equipment that can shift more spectrum to signaling when needed.

Whether this really is the cause of AT&T's problems is still uncertain. The carrier didn't comment for Ars Technica. (Light Reading has a query in the works.)

But it's something AT&T and other operators might want to keep in mind, because Ars Technica notes that phones using the Google (Nasdaq: GOOG) Android or Palm Inc. webOS platforms use the same kind of battery-saving trick.

— Craig Matsumoto, West Coast Editor, Light Reading