Last week’s LTE World Summit included a pre-focus day on signaling for the first time. It was also one of the few times a pre-focus day meant a full room with several standing delegates, many more than the conference team had predicted.
So what made this day particularly interesting? The focus of the signaling day was split in two broad categories: RAN generated signaling and Diameter. The first topic was heavily overshadowed by Diameter, perhaps due to dedicated vendors now offering products to optimize and enhance Diameter while RAN signaling is a topic usually addressed by introducing additional capacity in Radio Network Controllers (RNCs) in 3G networks and by understanding user behavior and handset functionality. Both of these are somewhat harder to predict and mitigate and require cooperation between infrastructure vendor, operator, handset manufacturer and developer to fully understand. So it is somewhat expected that Diameter dominated the show, while RAN signaling was discussed – but not at a great extent.
Diameter is a relatively new and hot topic for the mobile value chain. Although it is a AAA protocol (Authentication, Authorization and Accounting), it is perhaps considered as an interface between the business side of mobile operators (Online Charging, HSS) to the network side (PCRF) and also associated with monetization rather than only cost savings or network efficiency. So it is natural that operators and the value chain are attempting to understand Diameter and how the control plane for LTE networks is different to legacy networks.
Diameter is inherently more complex than SS7 since it operates in a flatter IP network and Diameter transactions do not follow a specific route through the network. Diameter is also a new protocol currently being deployed and mobile operators are experiencing what this means – in some cases in a hard way.
US operators that have been aggressive on LTE deployments have experienced outages that are believed to be caused by Diameter network components. Outages are perhaps not uncommon in mobile networks – certainly in new deployments – but Diameter infrastructure may be considered as the nervous system of the LTE network, meaning that an outage may disrupt a nationwide network or even spill over to a roaming network if proper safety and security measures are not taken into account.
Having experienced these initial deployments, vendors are now proposing new ways of deploying Diameter components, namely distributed throughout the network with redundancy to make sure that failures do not affect user experience. There are also several use cases for Diameter components being proposed and several new are expected as LTE deployments mature:
The above – and more use cases – may be bundled in what is called a Diameter Signaling Controller (DSC) which provides a broader set of Diameter functionality.
The Diameter value chain is also being redefined:
There are also several new and older companies now offering software for Diameter and have different routes to market.
Diameter is a critical piece of LTE networks. Operators are struggling to understand why, how and when to deploy Diameter equipment while the vendor landscape is currently in flux.