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4G Roaming, Pathfinder and IP eXchange

03 августа 2009

Data roaming has been a challenging and complex function for mobile network operators for more than ten years. Roaming is more than the ability of customers to use their mobile phones outside the geographic coverage of their primary network operator. 

Data roaming enables the use of mobile data services including MMS, GPRS, push email, and mobile broadband services while traveling outside the home network.  With the advent of 3G networks, data roaming traffic (measured in megabytes) has been increasing rapidly due to the popularity of data-enabled smartphones and improved network quality and performance.

Initially GPRS data roaming was based on complex relationships between individual operators requiring dedicated links between roaming partners. This meant that mobile data subscribers could only use GPRS roaming if their operator had a direct agreement and dedicated link with the other operator.  Beginning in 2000 the GSMA developed the GPRS Roaming Exchange (GRX) which acts as a hub for GPRS connections between roaming users, eliminating the need for dedicated links between GPRS mobile operators. A GRX is typically based on a private or public IP backbone using GPRS Tunneling Protocol (GTP), and each GRX service provider has a network of routers and links connecting to GPRS operator networks.  For operators this allows quicker implementation of roaming partners, faster time to market for new operators and lower capital expenditures.   GRX service providers also have links to other GRX hubs to support GRX peering between roaming networks.  GRX was developed to facilitate a more efficient way for operators to interconnect networks, and played a large part in the transition to 3G mobile systems.

The GRX was designed to be a highly scalable data roaming solution, since each participating mobile operator could start with low-capacity connections and upgrade them depending on the bandwidth and quality of service requirements of the traffic.  GRX also provides quality of service (QoS), security, monitoring, inter-operator billing, reporting, and real-time troubleshooting tools for GPRS roaming.  As trusted third-parties, GRX service providers provide authentication and AAA proxy services creating a centralized point of control and audit for mobile data roaming administration.  Using a mediation engine, GRX also offers flexible rating, clearing and settlement reconciliation for roaming partners. GRX hubs also provide DNS support for a worldwide “.gprs” DNS root, and GRX operators collaborate by managing the root and connecting each operator’s DNS servers to provide translation of DNS names specific to any one operator.

The first full-service, scalable GRX Peering Exchange (GPE) was established in 2001 at the Amsterdam Internet Exchange (AMS-IX).  More than 20 GRX operators and hundreds of mobile network operators currently exchange GPRS roaming traffic with each other at one or more of the four AMS-IX GRX peering locations in Amsterdam.  In 2008, the AMS-IX GRX peering exchange was co-located in the AM1 Internet Business Exchange (IBX) data center, which was acquired and developed by Equinix.  The result was the first global multi-party peering point which facilitates mobile data roaming as a core component in enabling a truly global mobile Internet.  Since 2008, GSMA selected Equinix to establish two additional peering exchange points in its Singapore and Washington, DC IBX centers for the interconnection of GRX operators seeking to expand their coverage for mobile operator customers in the United States and Asia.  There are now three common neutral peering points for GRX service providers that wish to exchange mobile Internet traffic with their peers of choice.  GRX peering is a fully-managed Ethernet switching infrastructure that facilitates the exchange of “mobile Internet” traffic and the GPE switching platform has a redundant architecture designed to improve resiliency and increase port density.

The global market for mobile data roaming and GPRS exchange services is still quite small, but is now growing rapidly as mobile data and broadband traffic growth is accelerating.  Mobile data roaming is currently between 1.5% and 2% of mobile data traffic, but recent analyst reports estimate this represents between 6% and 10% of mobile data services revenues.   Data roaming revenue has been estimated at 2.3 billion Euros for E.U. countries alone in 2008, two-thirds of which is GPRS/UMTS traffic.  A recent market assessment forecasts a 47% CAGR for data roaming traffic from 2007 to 2012, in part due to the predicted tsunami in IP data traffic as mobile operators implement HSPA and LTE to support mobile broadband applications, content and Internet access.

Many of the largest carrier groups operate their own GRXs, including France Telecom/Orange Group, Belgacom International, Vodafone, Telefonica/O2, Deutsche Telekom, Telia Sonera, Telecom Italia, Bouygues Telecom, KPN Group, Hutchinson 3G and SFR.  The top 20 global GRX service providers support hundreds of mobile operators and their subscribers throughout the world.  There are also several independent mobile data roaming providers that have demonstrated market leadership in GRX and mobile IP interworking service: Syniverse, Aicent, MACH. Other carrier independent participants in the GRX and mobile data roaming/hubbing services market include Comfone AG, Sybase 365 and Transaction Network Services (TNS/Verisign).

Although the overwhelming majority of mobile operators worldwide operate within the GSM/GPRS standard, many independent roaming hub operators also support mobile broadband data roaming for CDMA Roaming Exchange (CRX) for operators and subscribers of 1xRTT and EV-DO (Release 0 and Rev. A) networks.   Some GRX operators are also extending their roaming and hubbing services to include Wi-Fi broadband and most recently mobile WiMAX networks.  The WiMAX Forum recently announced that 14 ecosystem leaders are now participating in the first ever commercial WiMAX interoperability and roaming trials. These trials will provide a baseline for establishing roaming services and agreements for WiMAX worldwide to enable users to automatically access networks when traveling outside the geographical coverage area of their home network.  The participants in the first end-to-end test of roaming over live WiMAX networks include:

  • Mobile WiMAX network operators including Clearwire and DigitalBridge Communications;
  • Infrastructure equipment vendors and device manufacturers such as Intel, Motorola, Alvarion, Cisco and Juniper Networks;
  • Roaming clearinghouses represented by Syniverse, Aicent, MACH, Comfone AG, iPass, Bridgewater Systems and TNS/Verisign.

This is one example of an industry-wide interoperability solution that will enable 4G network operators to manage global roaming and routing of mobile IP traffic.  There are now a number of technical platforms, services and solutions being developed to help operators offer 4G roaming, scalable access to multimedia content, applications and mobile Internet services.  GSMA is conducting Open Connectivity (OC) Roaming Hub Trials and leading industry-wide initiatives designed to enable operators to leverage their 4G network investments and manage global roaming and routing of mobile IP traffic, such as Pathfinder and IP eXchange.

The GSMA recently announced the successful completion of the pilot of its Carrier ENUM service, now branded ‘PathFinder’TM.  PathFinder is a managed service for global routing of IP interconnect traffic which offers a private global address registry for dynamic route discovery with rich policy capabilities. PathFinder is now operated by NeuStar, a leading provider of clearinghouse and directory services to the global communications and Internet industry.  PathFinder automatically translates a phone number into an IP-based address, making it simple and transparent for users to initiate a wide range of IP-based communications via their existing phone numbers and handset address books.  The PathFinder service facilitates global IP service interoperability by translating telephone numbers to a logical “endpoint name” based on the source network, and is available to all participants in the traffic/service delivery supply chain, including Mobile and Fixed Network Operators, Transit Carriers/IPXs, ISPs, Hubs/Aggregators, content/application providers and other trading partners.  Under the umbrella of the GSMA PathFinder Service Initiative, several companies are developing managed services to exchange large and growing volumes of global IP interconnect traffic, manage multimedia content, deliver hosted applications and provide mobile Internet connectivity.

As the mobile industry evolves toward 4G and as mobile network operators move more of their services and traffic to IP networks, the complexity required to interconnect with other operators has grown dramatically. This is in part because of the continuing need to support their existing TDM infrastructure and interwork services provided via both TDM and IP networks (e.g. VoIP and traditional TDM voice). Because of this the architecture and strategy carriers have used for interconnect has been somewhat ad hoc. Today it generally requires service providers to negotiate individual agreements with every other service provider they wish to connect with, an approach that is complex, costly and has proven difficult to scale. In addition to the need to interconnect different service providers’ networks, many network operators own multiple, geographically separated heterogeneous networks and are interested in interconnecting them across a private IP backbone. The requirements for these types of networks are in many ways similar to those for inter-operator interconnect as both require the ability to support a diverse set of IP and TDM signaling protocols, ensure end-to-end quality of service, and provide low cost but high quality media transport.

In response, the GSMA has defined and carriers are now testing a new standardized interconnection service - IP Packet Exchange (IPX).  IPX has been designed as an evolution of the GSMA’s existing GRX service, and is a service-aware, global, private IP network that provides end-to-end QoS and cascade billing features in support of interconnect and roaming services. While the GSMA serves the GSM mobile community, the IPX offers a standardized architecture for interconnecting 2G and 3G GSM and CDMA mobile operators, fixed line operators as well as connectivity to content and application service providers.  The expectation is that there will be multiple providers of IPX service and that each will be fully interconnected to form a global IPX domain.  Numerous GSMA-sponsored tests of IPX have been completed, and the first commercial IPX services are being launched in 2009 by companies such as Syniverse.

The IPX promises to offer service providers a true end-to-end, service specific QoS guarantee defined by service availability, jitter, packet loss and delay. Each IPX service provider not only guarantees the performance of its network but also that of any IPX network to which it connects. Unlike the volume-based GRX charging model, IPX includes support for a wide variety of charging schemes triggered by different factors (e.g. originating party pays, terminating party pays, revenue share, volume based, event based). This will enable service providers to choose an optimal charging model for each of the services they wish to interconnect over the IPX. IPX offers network operators three models of interconnect: Bilateral Transport Only, Bilateral Service Transport and Multilateral Hubbing. Each of these models offers a different level of service and connectivity. The combination of different charging and interconnect models provides IPX customers with a high degree of flexibility in how they use the IPX service.

Story by Berge Ayvazian


Источник: 4G Trends

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