Operators Fight Back on Smartphone Signaling

Mobile operators have demanded that smartphone makers support a newly standardized feature in their devices that will reduce the signaling traffic load on their networks.

The move is viewed as operators taking back some control over the amount of smartphone signaling traffic, which has overwhelmed their networks and even crippled some to an extent that has prevented basic voice calls from being made. (See What if Capacity Isn't AT&T's iPhone Problem?, iPhone Troubles Might Go Beyond Signaling, 02 Felt iPhone Crunch Too, and AT&T: Don't Choke Us.)

To address this problem, operators have told their smartphone suppliers to implement a newly standardized version of a state transition feature, called "fast dormancy," which is part of the 3rd Generation Partnership Project (3GPP) Release 8 set of specifications. This feature sets parameters on how, and how often, a smartphone switches between being in an idle or active mode, while also helping to save handset battery life.

“Handset requirements are set by the operators, so we’re told, 'These are the features we want,'” said Johanna Dwyer, senior director for standards at BlackBerry , speaking at the recent Mobile Broadband World conference in London. “[Release 8 fast dormancy] has been requested by everybody. It’s unusual to have a feature universally requested."

This feature is expected to appear in smartphones and network equipment next year. For example, Dwyer said RIM's devices will support Release 8 fast dormancy from the first quarter of 2011, and that all handsets are expected to support it early next year as well.

Non-standardized versions of fast dormancy have been used by smartphone vendors as a way to save handset battery power. But while these proprietary tactics prolonged battery life in the device, they caused unpredictable and unprecedented levels of signaling traffic in the network.

Fast dormancy is a technique used to switch a smartphone to an idle state when a data connection is not needed, which saves battery power. But every time a device sets up and disconnects a connection with the network, many signals have to be sent back and forth. And this has been the source of operators' smartphone signaling woes, leaving them with overloaded networks in some cases.

"Fast dormancy is essential to stop phones from being in a connected data state [all the time]," says Phil Twist, head of marketing for network systems at Nokia Networks , which has implemented a complementary approach for reducing signaling traffic in its network equipment. "It's a big advantage for handset vendors, but chaos for networks."

But the new and improved standard version of fast dormancy, specified in Release 8, strikes a compromise between saving battery time and using appropriate network resources.

Even so, the GSM Association (GSMA) has published a set of best practice guidelines for implementing fast dormancy.

This is one line of attack operators are taking to reduce smartphone signaling. But given the continued growth in smartphones, the challenge of cost-effectively managing signaling traffic could be a lingering problem.

— Michelle Donegan, European Editor, Light Reading Mobile

phil-tw 12/5/2012 | 4:22:00 PM
re: Operators Fight Back on Smartphone Signaling

Good summary - thanks Michelle

This is Phil Twist, quoted in the article. The non-standards fast dormancy worked by the user device dropping itself to idle state while falsely telling the network it had lost connection - which the network was unable to distinguish from a real signalling failure.  Crude but effective, but as you say, causes a lot of signalling to re-set up the radio access bearer with every always-on heartbeat.  This new 3GPP standardised version is much smarter: the user device actually politely asks the network to drop it to idle state. This avoids unnecessary radio access bearer setup signalling  and enables the network to identify real signalling connection problems.

But Fast Dormancy is still only a partial solution.  We recommend setting up the network to drop the user device down not to the idle state but to the paging channel - which is also 3GPP specified, and standardised 5 years ago; mandatory for use in all handsets, optionally available in networks. Using the paging channel not only substantially reduces the signalling even further but also extends the device battery life significantly.  And it works very nicely in conjunction with Fast Dormancy if networks don't support the paging channel.



Michelle Donegan 12/5/2012 | 4:22:00 PM
re: Operators Fight Back on Smartphone Signaling

Thanks, Phil.

I take your point about fast dormancy being just part of the solution. So that means there are more angles to cover here.

I'm interested in which other vendors have implemented, or plan to implement, the paging channel option.


Michelle Donegan 12/5/2012 | 4:22:00 PM
re: Operators Fight Back on Smartphone Signaling

This is such a complex area, and I think Rel. 8 fast dormancy is just one of several ways signaling traffic can be contained.

Martin Sauter explains it well on his WirelessMoves blog. Check it out:




phil-tw 12/5/2012 | 4:21:54 PM
re: Operators Fight Back on Smartphone Signaling

Nokia Siemens Networks has fully implemented the paging channel which means (excuse the acroynms) offering both cell_PCH and URA_PCH.  We've seen excellent results in independent comparative tests.

There's also a nice side benefit of using the paging channel: much shorter response time between pressing a button and getting a response back from the internet.

phil-tw 12/5/2012 | 4:21:53 PM
re: Operators Fight Back on Smartphone Signaling

And - also note PCH can work with the older, non-standardised version of Fast Dormancy provided the network timers are set so that the transition from DCH->FACH and then from FACH->PCH are set to be shorther than Fast Dormany timer forces the UE to Idle.

[typically operators might set both DCH and FACH inactivity timers to be something like 15-30 seconds if PCH is not supported in their radio network, but only 2-5 seconds if it is available. So it is perfectly possible to configure the network to drop the user device down to PCH before the Fast Dormancy timer cuts in]

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