With the rising use of the mobile Internet, the amount of signaling required to set-up and maintain radio bearers is changing. While in pre-mobile Internet times, radio and core networks were mainly dealing with location updates and signaling due to SMS and voice calls, always-on smartphones are used quite differently. Lets do a little comparison:
Someone who's only two applications that require network interaction are SMS messages and voice calls might have the following signaling pattern:
- 4 radio bearer setups a day for incoming SMS messages
- 4 radio bearer setups a day for outgoing SMS messages
- 2 outgoing voice calls (some with handovers, which increase signaling load)
- 2 incoming voice calls (some with handovers, which increase signaling load)
- 5 location updates a day (periodic and some triggered because the user as he moves)
- no routing area updates since the mobile is only attached to the circuit switched side of the network
- These numbers are obviously for someone who doesn't move a lot and who is, by today's definition, someone with a low usage. The young generation often sends and receives my more SMS messages a day.
Personally, my CS messaging load is a bit different. I send and receive fewer SMS messages as I mostly use e-mail for text messaging as my friends are distributed throughout the world and these exchanges are usually also not required to be had in real time. But I usually make and receive more than two calls. I try to minimize calls when moving as I find it impolite to talk on the phone while on a public transport and also prefer some privacy when calling. But for the calls I do make while on public transport I am glad handovers exist.
But now lets go to the packet switched side and see how things are here:
- I am always-on and receive about 4 e-mails per hour. In other words, there are 4 signaling evens per hour or about 4 * 15 hours (per day) = 60 events per day for this application alone. That easily surpasses all my CS signaling
- While on public transportation I often use the time to read my favorite blogs and browse my favorite news web sites. Let's say I browse on 30 pages a day and read each long enough for the radio link to go back to idle. In other words, 30 signaling events.
- While I am moving the radio link has to be maintained and handed over to neighboring cells which creates quite a significant amount of signaling, especially with my 'old' N95 that doesn't have fast dormancy and hence the network needs to work more to maintain the established but not really required radio bearer after background push/pull requests.
- Also during quick breaks I try to catch a news bite or two to know what's going on in the world. Lets say that's an extra 10 signaling events per day.
- No instant messaging or other push applications are running in the background but more and more people are doing that these days, too.
In total that's easily 100 signaling events on the PS side per day. Compared to the 15 signaling events on the CS side for voice and SMS, that's quite a difference, not only for the network but also for the mobile, i.e. the impact on the battery charging interval is significant.