When we hear about signaling and the signaling storm, we instantly think about all of the negative aspects of signaling and the costs of supporting signaling traffic in the network. However, not all signaling is “bad” traffic.

Bad News First

Radio Access Network (RAN) signaling can be considered the “bad” kind of signaling. These messages are only for establishing an Internet connection so that the data itself can reach the device.

Revenues for connections themselves are very small, yet the amount of signaling messages required to establish and then release the connection is significant.

For example, when a subscriber wishes to connect to the Internet and download an email, 50 or more signaling messages traverse back and forth between the RAN and the Gateway GPRS Support Node (GGSN). Now consider a subscriber who connects to Facebook and plans on staying logged into the account all day. The service provider, though, does not maintain the Internet connection all day. Instead, the connection ends after the initial data is sent and received. The device will then reestablish the data connection seconds later, poll the Facebook server for updates, and release the connection – requiring another round of RAN signaling messages.

Let’s assume that the connection required 50 signaling messages for setup and tear down (a conservative number). At a cycle of every 2 seconds, that’s 1500 messages an hour, 36000 messages a day. Multiply this number by 10 million subscribers and we are talking about 360,000,000,000 signaling messages in a single day!

Yes, There Is “Good” Signaling

Diameter signaling traffic, on the other hand, directly correlates to operators’ increased data revenues and provides profits they would otherwise never realize. Diameter enables personalized mobile data services, including tiers, loyalty programs, quality of service (QoS) for specific applications, over-the-top (OTT) applications value-add and RAN-congestion controls.

This “good” signaling increases as service providers begin monetizing their data networks. For example, when a subscriber wishes to purchase a higher service tier, the GGSN/Packet Gateway (PGW) will send a Diameter message to the Policy Control and Rules Function (PCRF) to find out what restrictions are to be applied based on the subscriber plan. The PCRF will then send a Diameter message to the Subscriber Profile Repository (SPR) database to retrieve the subscriber’s profile (data quota, etc.) and send this data back to the PCRF. The PCRF in turn sends this information to the GGSN/PGW for enforcement. That’s around five Diameter messages to support one interaction on a tiered service plan (and this is a simple example).

Diameter is also the protocol that:

• Connects the PCRF with the Deep Packet Inspection (DPI) equipment and the other policy enforcement control points;
• Communicates policy rules to the enforcement points throughout the network: and
• Provides the connection between the PCRF and the billing and charging domains.

The Diameter traffic that results from new revenue streams is a strong contrast to its predecessor in voice and text networks, SS7. SS7 signaling was about connecting voice facilities or, in the case of wireless networks, connecting to the Home Location Register (HLR) to support roaming.

In sum, it’s easy to have a negative association with increased signaling. But when thinking about signaling and the impact it has in the core network, remember that an increase in Diameter signaling is a good thing. It is a natural byproduct of an increase in revenue generation, and hopefully will only continue to increase as operators introduce more innovative and creative mobile data plans.