Design is a forward-looking practice. But when it comes to creating systems for mobile networks and devices, the future can’t completely break from the past. This is particularly true as the market designs technology for LTE-based mobile networks where the dominant control plane protocol is Diameter.

Diameter network signaling enables smart-phone users to check in over LTE mobile networks. It also lets companies deploy location-based services and authenticate, authorize, and charge for mobile applications running on LTE. All of these activities are in demand now and will continue to be as LTE expands. However, designers can’t leave 2G and 3G behind yet. SS7 remains the primary signaling protocol on many such networks, making mixed-protocol capabilities a must-have for system designers.

Outpacing Protocol Shifts

Consumers are snapping up smart phones, and that market demand rightfully influences mobile network design. We are already seeing a significant boost in LTE network Diameter signaling traffic, and design engineers need to be ready with products that offer LTE capabilities.

Those capabilities can’t come at the expense of existing SS7 functionality, though. That’s because LTE will likely account for only 10% of global access networks by 2017. Clearly, legacy interworking will be critical over the near term. If there is one thing we know about mobile device consumers, it’s their love for being on the go. As smart-phone users roam between LTE and 2G/3G networks, they’ll need networks and systems capable of interworking between Diameter and SS7.

With total LTE dominance still some years away, the market should also plan for interworking efforts to cover Wi-Fi data offload. It will require signaling conversion from Diameter to Remote Authentication Dial in User Service (RADIUS), an authentication, authorization, and accounting (AAA) protocol used for Wi-Fi network access.

In addition, the market will need some form of IP Multimedia Subsystem (IMS) interworking. In the voice over Internet protocol (VoIP) space, Session Initiation Protocol (SIP) may be on one device, but that doesn’t mean it can talk to another SIP device seamlessly. Different SIP versions might be in use, or vendors might interpret specifications in slightly different ways, resulting in poor interworking.

Design engineers can expect the same for Diameter, which already has many different variants—a real challenge as stakeholders work toward more unified standards. As the control plane signaling protocol for LTE, Diameter presents electronic designers with opportunities to develop systems supporting the next generation of mobile devices. Whilst doing so, however, designers will also have to consider systems that enable applications to interwork with existing 2G/3G and Wi-Fi networks.

Future Possibilities

While electronic designers, manufacturers, and carriers grapple with the challenge of ensuring LTE network mobile subscribers can roam across 2G and 3G networks, application developers are ensuring that the effort will pay off. Already, Diameter-based applications are moving beyond roaming from one network type to another.

For example, applications that support Equipment Identity Register functionality allow operators to control which handsets or devices can be used in their networks. So if a user’s mobile device is stolen, it can be disabled.

Even more exciting for application developers is the use of credit control application support, which enables smart phones and tablets to facilitate mobile payments, price inquiries, prepaid service charging, real-time service charging, and more. A customer using a smart phone will be able to charge for a unit of whatever the smart phone app is doing, whether that means paying for something with money over the Internet, charging against a unit of time, using prepaid services, and more.

The demand for Diameter-enabled systems exists today. SS7-reliant 2G and 3G networks are still pervasive across the mobile landscape, though. As system designers respond to the LTE Diameter opportunity, they cannot turn their backs on those 2G and 3G networks. At least for the next few years, LTE-2G/3G interworking should remain a crucial consideration for designers.

Stephen Madden is a product manager at Dialogic, the Network Fuel company. He manages the development cycles for Dialogic’s Diameter signaling products portfolio. He holds a BEng, Hons, in electronic engineering from the University of Sussex.