iOS 4.2 supports fast dormancy

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    Posted: 01 December 2010 10:00 AM

    Via NSN Blog

    With its latest iPhone iOs 4.2 software, it looks like Apple is joining efforts to cut smartphone signalling down to size. Tests by Nokia Siemens Networks have shown that iPhone iOs 4.2 supports a technology called Network Controlled Fast Dormancy, which we have already introduced into our networks. Basically, the technology makes the network and the handset work together to create the best conditions for smartphones to work quickly, yet have a long battery life and minimize network congestion.

    Smartphones connect constantly to the network, often driven by applications. But this creates a huge amount of signalling as smartphones switch from an idle mode to an active state so that they can interact with the network, for example to get emails or pull in the latest tweets.

    When it has gathered the information it needs, usually working in the background so you don?t even notice it?s happening, some smartphones then switch immediately into the idle state in order to conserve battery power. So when you next want some data from the network, the smartphone has to reconnect. This involves the network and phone exchanging many small signals.

    All this disconnecting and reconnecting takes time and can cause a frustratingly slow network response.  On the other hand, leaving the smartphone in an active mode all the time drains the battery very quickly.

    For additional background Ars Technica had a good article which highlighted the issue

    The first problem that O2 encountered was that the iPhone uses more power saving features than previous smartphone designs. Most devices that use data do so in short bursts?a couple e-mails here, a tweet there, downloading a voicemail message, etc. Normally, devices that access the data network use an idling state that maintains the open data channel between the device and the network. However, to squeeze even more battery life from the iPhone, Apple configured the radio to simply drop the data connection as soon as any requested data is received. When the iPhone needs more data, it has to set up a new data connection.

    The result is more efficient use of the battery, but it can cause problems with the signaling channels used to set up connections between a device and a cell node. Cell nodes use signaling channels to set up the data connection, as well as signaling phone calls, SMS messages, voicemails, and more. When enough iPhones are in a particular area, these signaling channels can become overloaded?there simply aren’t enough to handle all the data requests along with all the calls and messages.