A signal too noisy: Operators at risk of signaling traffic deluge

Is the signaling traffic from BlackBerries, iPhones, and Android smartphones creating just as much congestion in cellular networks as actual data traffic is? There is considerable disagreement among those that I talk to, and mobile operators are not too keen to share data–but it is a topic you are likely to hear more about in the future as the implications of signaling traffic in networks dominated by data traffic become better understood.

Signaling used to be a low-impact, boring business. It attracted more interest as SMSs, which use the signaling channel, became the first success story in mobile data. With data-centric devices, signaling traffic is exploding, as these devices and the applications they run are always on, running background processes to keep subscribers up to date, and establishing frequent but short connections to preserve battery power.

One interesting thing to note is that the signaling traffic that these devices generate is largely independent of the data traffic actively generated by the subscriber. It depends on the device, and the number and type of applications installed (e.g., a location-based application that keeps constant track of where you are is likely to generate more signaling traffic than an application to upload photos on the web). So this is not something that operators can easily manage with traffic caps–and also a fact that may justify the fixed fees that mobile operators have started to make mandatory for smartphones. Even if you do not constantly stream YouTube videos, your phone may be busy just checking updates on Facebook and contributing to network congestion, without you suspecting anything (you may start suspecting that something is going on when you are roaming and are charged by the MB).

When signaling traffic exceeds capacity, both data and voice traffic is affected in GSM and HSPA networks (this is not true of CDMA networks where data and voice use different channels, and this may explain why so far Verizon seems to have been less affected by congestion). And this is bad news: mobile operators carry more voice than data traffic, but they make their profit from voice, so they are not too glad to see voice performance worsen as a result to the increase in data-related signaling.

For more on this topic, see my article on FierceBroadbandWireless here.