My contrarian indicators are now hinting its not the much publicized iPhone usage of video and data competing for access on cell phone towers thats causing capacity problems. It's a signaling issue causing the majority of AT&T's network congestion issues for the iPhone. iPhones and other smartphones are continuously pinging 3G networks and making constant queries of the network as they move among cellular sites to push email, access social networking tools and conduct other repetitive actions. For instance, an IM (instant messenger) user may send a message but then wait a couple of seconds between messages. In order to preserve battery life, the iPhone moves into idle mode. When the user pushes another message seconds later, the device has to set up a signaling path again. Signaling traffic is out-pacing the growth of actual mobile data traffic by to 50%, if not higher.
The cell phone base station controller is spending a lot of its extra resources trying to process the signaling so it can't do other things like allocate additional resources for data. As a result you'll see dropped calls and data service degradation. Moreover, even when the signaling resource is released by the smartphone, the network can't react fast enough to allow for the next station to use resources until several seconds and sometimes minutes. One of the ways iPhone and other smartphone vendors try to alleviate this problem and save battery life on their devices is by incorporating a fast dormancy feature.
Apple upset several operators last year when it implemented firmware 3.0 on the iPhone with a fast dormancy feature that prematurely requested a network release only to follow on with a request to connect back to the network or by a request to re-establish a connection with the network. Apple soon after released firmware 3.1, which removed the feature but spurred complaints among iPhone users when it came to battery life. While fingers point at BlackBerry devices for also being signaling pigs, RIM argues that its devices don't have to wake up as often to query the network.
This is why carriers are continuing to look at a variety of solutions to reduce signaling traffic while preserving battery life including 3GPP which Nokia Siemens began selling this year at Mobile World Congress. There are a number of other solutions operators can use to ease the congestion by offloading data traffic onto femtocells or Wifi hotspots and adding more network resources. HSPA+ (Evolved High-Speed Packet Access) that will enable the networks to reduce their transmission time from idle to active state and should help ease the congestion. Carriers can also monitor and control which devices and applications are generating excessive amounts of signaling or hogging more than their fair share of bandwidth. With this information, carriers can have increased awareness of the overall cost of delivering specific applications and services and can even map out their smartphone portfolios accordingly.