Cellcos brace for Diameter signalling upsurge

Caroline Gabriel/Wireless Watch
16 Oct 2013

Signaling volumes on LTE networks will grow at twice the rate of mobile data traffic between 2012 and 2017, according Oracle.

Admittedly this was somewhat self-interested, as the company became a major supplier of Diameter Signalling Routers (DSRs), the main equipment for handling this traffic, since it acquired Tekelec and Acme Packet.

Diameter is the protocol defined by the 3GPP for signalling on HSPA+, LTE and IMS and Oracle predicts it will grow at a CAGR of 140%, from 1.2 million messages per second in 2012 to almost 99 million messages per second in 2017.

The main reason is that personalized mobile services and data plans create new signalling traffic because each one requires its own Diameter-based AAA (authentication, authorization and accounting) messages. The increasing use of network policy tools will account for 6% of Diameter volumes by 2017, says Oracle.

In the early days of the DSR market, the main focus was on carriers investing in the systems to control the “signalling storms” created by “chatty” smartphone applications such as social networking updates, which constantly poll the network. However, as enhancements to device standards start to manage those storms more effectively, the emphasis will shift to harnessing efficient Diameter routing to enable added value LTE services, notably policy-driven personalized services and roaming, according to F5, which got into the DSR space with the acquisition of Traffix.

Diameter-based signalling and IP eXchange (IPX) - a cloud-based system for bilaterial IP traffic roaming between operators, via a single interconnection with end-to-end QoS - are the essential ingredients of the LTE roaming and interworking platforms that are emerging. The dominant one in Europe is BICS, but Orange's wholesale arm last month launched its own challenger. It said its new Multiservice IPX network will provide a Diameter-based signalling service that will enable operators to provide their customers with improved quality of experience on LTE while roaming abroad.

“LTE Signalling is a must-have service that offers both differentiation and the ability to generate additional revenues in an increasingly competitive market,” said Orange's EVP for international carriers, Alexandre Pébereau. "Orange has developed LTE Signalling for operators to allow them to build a high quality 4G roaming service that is fully compliant with GSMA guide-lines. The Group's Open Connectivity policy and extensive peering agreements allow us to provide wholesale clients with the opportunity to benefit from a large coverage.”

Rival BICS, the wholesale arm of Belgium's Belgacom, recently announced the first intercontinental LTE roaming connection between operators in Europe, Asia and North America. It also unveiled a new offering for monitoring, tracking, tracing and reporting 2G, 3G and LTE roaming traffic using the legacy SS7 signalling protocol, now being replaced by Diameter on IP systems.

Despite these signs of progress, however, LTE roaming platforms and services are at a very early stage and may hinder the rollout of VoLTE voice offerings. VoLTE will place a significant burden on the core network. In 3G, voice was handled by simpler charging and rating systems but as voice becomes another data service, and as operators look to differentiate themselves with more and more personalized customer plans, there will be a rise in signalling.

If VoLTE is to be rolled out by most 4G cellcos and not just a handful, there is a need to open up IPX access easily to all the operators. This is the goal of an initiative launched in May by the GSM Association and another industry body, the i3forum. They are to co-ordinate live commercial pilots for voice IPX, to be conducted by mobile and fixed operators including Deutsche Telekom, Orange, Telecom Italia, Telefonica and TeliaSonera. These pilots will be used to formulate the technical and commercial agreements needed to use IPX to interconnect voice services on a broad basis, and avoid the tangle of bilateral roaming deals which characterized – and slowed down – roaming in previous mobile generations.

“As we move to an all-IP world, customers will continue to demand high quality and high reliability for their voice services,” said Alex Sinclair, CTO of the GSMA. “By providing global interoperability, this initiative will help to drive the widespread deployment of services such as VoLTE, with the same quality of service that consumers have come to expect.”

IPX is the next generation, all-IP successor to GRX (GPRS Roaming Exchange, the key roaming framework for 2G and 3G data). In the mobile world it lives within a GSMA-defined communications ecosystem which supports multiple services - voice, data and signalling - over a single IP connection and provides many other benefits, including enhanced voice quality, cascaded billing and payments and – because an IPX is physically and logically separate from the public internet - security.

Within this, IPX enables the use of Diameter signalling for the exchange of policy, authentication and mobility information between networks as users roam, and for local break-out (LBO), a more efficient approach to handling roaming traffic, which reduces latency and boosts data rates by offloading traffic to the roaming network, rather than routing it back to the home system.

An IPX approach could save operators the time and complexity of opening up their individual SIP interfaces to one another to enable VoLTE roaming, but will not, of course, remove the need to negotiate commercial deals or comply with changing regulations. However, the GSMA believes its new partnership will also help to draw up templates for commercial contracts to reduce time to market.

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