Jim Machi, Dialogic

Jim Machi, vice president of product management for Dialogic

In my last blog I discussed the architectures needed to roam between WiFi and 3G/4G networks. In order to enable interoperability between the different architectures, a mediation and interworking platform is required to support the different scenarios in which RADIUS, Diameter and SS7 are used.


As discussed in my prior blogs, RADIUS is critical for interworking with WiFi networks. Authentication and authorization of roaming subscribers is performed through RADIUS messages over an inter-operator interface between the visited network provider and home service provider. The interface can be implemented directly between two operators or through an intermediary, like an IPX or WRIX provider. The interworking functionality can be placed within either the visited or home operator’s networks, an IPX/WRIX provider or all three locations.

While most of the authentication and authorization traffic is RADIUS-based, many 3GPP operators are moving to an evolved packet core (EPC) as they prepare and implement LTE in the radio access network (RAN). This results in the need to interwork RADIUS and Diameter messages when establishing roaming with WiFi operators. Also, incompatibility in signaling protocols can occur not only between a pure-play WiFi operator and a 3GPP-based wireless operator at the network-to-network interface (NNI), but also between two 3GPP operators with one using the RADIUS-based Wd interface with its AAA proxy and the other using the Diameter SWd interface.

Finally, a 3GPP operator may need to interwork RADIUS, Diameter or even HTTP, in some cases, between its AAA proxy and its HLR or HSS, depending on what the proxy uses to request information on authorized IMSIs for validation purposes. Often, service providers have to deploy stand-alone gateways to remedy any interworking issues between their AAA server and HSS/HLR, or hope their AAA vendor can accommodate their migration to 4G interfaces or need for RADIUS support.

fig1_p3The demand for WiFi hotspots is heating up. Mobile operators are turning to WiFi as a means to meet consumer demand for mobile data services by improving coverage and capacity, and organizations like the WBA, WiFi Alliance, GSMA and 3GPP are working to set the standards for improving users’ experiences as they move between 3G, 4G and WiFi networks.

By applying technology that includes interworking of RADIUS, Diameter and SS7/MAP interfaces, today’s WiFi operators can accelerate connectivity between different types of networks, better leverage existing investments in infrastructure and upgrade to new technology and architectures in a more controlled manner.

To explore the evolution of Diameter Signaling Controllers in depth click here.


Comments on: "WiFi Offload/Roaming Part 3: Diameter and LTE Interworking Is Crucial" (1)

  1. Jim, I agree with your assessment, but I believe the ROI for implementing the signaling and policy solutions needs to be understood holistically in terms of not only what it affords the carriers in terms of potential additional revenue and backhaul savings, but macro capacity and overall performance of the network at the same time. “Application coverage” a term coined by Ericsson is critical for the MNOs to embrace. http://bit.ly/1jLJmAU please reach out to me at michael @ ivpcapital dot com to discuss further.

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