Convergence, including the concept of Fixed/Mobile Convergence, refers to the ability of a service provider to give access to its services and applications across more than one type of access technology and device.  In the area of Fixed/Mobile Convergence it refers specifically to the act of combining together devices that can operate on multiple network types, as well as the combination of separate networks to create a single networking infrastructure.

 

For example, in a popular current example of Fixed/Mobile Convergence, a user’s mobile phone becomes his only phone.  In the wide area network, the phone operates using a 3G mobile wireless technology.  In the home environment, for example, the phone operates using a local area wireless LAN technology.  Convergence is achieved in the device, which can operate on these different network types, and convergence has also been achieved in the network, since the mobile network operator is providing the same service over multiple networks.

Network architectures for convergence are being standardized in the main standardization organizations for mobile wireless communications, 3GPP and 3GPP2.

Within the 3GPP organization, the architecture for convergence is addressed by Technical Specification 23.234, “3G system to Wireless Local Area Network (WLAN) interworking”.  This specification shows an architecture for convergence in which a gateway element, the Packet Data Gateway (PDG) is responsible for

  • Securing the traffic coming over the WLAN,
  • Assigning IP addresses,
  • Authenticating users and services,
  • Generating accounting information, and
  • Applying QoS policies.

Figure 1: The 3GPP Convergence Reference Architecture

Within 3GPP2 a similar architecture has been defined in the document X.P0028-200, “Access to Operator Services and Mobility for WLAN Interworking”.  A gateway element with similar functionality has been defined by this group.  This Packet Data Interworking Function (PDIF) is responsible for

  • Providing access to packet data services,
  • Implementing end-to-end secure tunnels,
  • Allocating IP addresses
  • Encapsulating and de-encapsulating traffic,
  • Enforcing the cdma2000 operator's policies such as packet filtering and routing,
  • Supporting user authentication, and
  • Collecting and transmiting per-tunnel accounting information.

Figure 2: The 3GPP2 Convergence Reference Architecture

Mobile broadband carriers are evolving their network architectures to include the use of alternate access technologies, in a way that is being defined in both of these standards organizations.  This will allow them to decouple their service offering from their network access offering, and will allow them to offer a rich suite of services and applications over any available IP-based network.

The Airvana UAG implements all the functions of the 3GPP Packet Data Gateway, the 3GPP2 Packet Data Interworking Function and more, with its mobility functionality via Mobile IP and MOBIKE.