Convergence evolves the coming together of separate entities into a single new entity. In mobile communications, convergence combines legacy and emerging technologies to produce simpler, easier-to-manage and more efficient networks. Streamlining infrastructure enables operators to leverage their embedded capital investments and reduce operational costs of managing their networks. At the same time, converged mobile networks are becoming more intelligent, distributed and virtualized. They not only continue to support existing services but also make it possible for operators to deliver new services. Those services, such as LTE, improve the end-user experience and thereby create additional revenue streams.

By Stuart BeningtonThe question becomes exactly which aspects of the network to converge, when, and how to do it. Convergence can mean a lot of things in different parts of the network. For example, convergence already has happened in the mobile backhaul space at both the physical and virtual layers. At the same time, different flavors of traffic continue to converge across 2G, 3G and 4G radio technologies. The traditional boundaries between "transport-like" devices and switches and routers are beginning to blur. All of this convergence has produced a user plane which drives capital expenditures (CAPEX) efficiencies, because it is simpler and more resilient than ever before.

In addition, by combining existing and new solutions, operators can now save other forms of operating expenditures (OPEX). They can simplify the network by converging technologies and network elements through the control plane and the management plane. Although the packet core mainly handles network signaling and control chores, a converged signaling and control plane enables operators to better manage the user plane — the traffic that goes over the network. Intelligence in the packet core can manage that traffic dynamically, in real time and, in a distributed manner. This network can deliver 3 significant benefits to operators as follows:

  1. minimization of the operational cost
  2. minimization of capital equipment deployments via its integration of the signaling and control functions
  3. enhancement of the end-user experience by providing faster responses for data connections, more resiliency and less downtime.

The packet core and the backhaul belong together
Such convergence stems from the principle that the packet core and the backhaul belong together. As the packet core evolves, it converges 3G technologies with 4G or pre-4G standards such as WiMAX or LTE. As this convergence progresses, it gives operators opportunities to use network intelligence to create new services and new revenue streams. But how do operators converge the mobile backhaul and packet core to take advantage of the tight link between these different segments of the network?

A viable solution is to populate routers and switches with some of the packet core intelligence. Distributing packet core intelligence into the backhaul enables operators to administer their networks much more efficiently. It also help operators to provide a better communications experience for their subscribers.

The right packet core platform can do a lot of things
An operator can take advantage of functionalities on mobile packet core platforms, which traditionally have served as an ASN Gateway in a WiMAX network. By deploying that type of platform at an aggregation point, such as a remote radio network controller (RNC) location, the operator can use the platform's offload function to intercept Internet-bound traffic. This way, before traffic reaches the packet core, the platform diverts it, via the Gi interface, to the Internet peering point.

By distributing that function into the backhaul network, operators can manage Internet-bound traffic much more efficiently. Operators can free up the Serving GPRS Support Nodes (SGSNs) and Gateway GPRS Support Nodes (GGSNs) in the packet core to handle non-Internet-bound traffic more efficiently. By freeing up capacity and sessions on the SGSNs and GGSNs, the platform enables operators to use those assets for revenue-generating services, such as business VPNs.

Another option is to use GGSN function on mobile packet core platform. By deploying it as a distributed GGSN in a mobile switching office or at any relevant point on the provider edge, the operator can use not only the platform's Internet-handoff ability but also its enhanced functionalities. Deploying superior intelligent GGSN's at the edge of the network allows the operator to introduce Deep Packet Intrusion (DPI) functionalities with the applications ranging from device security, monetary analytics to comprehensive user report.

Through software upgrades, the platform will evolve to function also as a distributed LTE gateway, making its distributed intelligence dovetail nicely with the "flattened" LTE architecture.

This type of packet core platform can deliver even more benefits to operators, via its ability to deliver line-rate and real-time intelligence about subscriber behavior. By combining that content-awareness with Ethernet switch/routers and multiservice switch/routers, the operator can increase the efficiencies of the backhaul network.

Operators can apply that content-awareness to traffic-forwarding and classification decisions to deliver flow-based quality of service (QoS) levels and enforce service level agreements (SLAs). With the ability to distinguish among various types of traffic, these three elements in combination enable the operator to improve the end-user experience and create new revenue opportunities in the process.

Convergence demands getting the right pieces in place...
Converged technologies and functions need to produce financial benefits for operators and experiential benefits for their subscribers. To do that, operators need to assemble the right network elements and couple them with the idea of managing all 3 planes — user, control and management.

In the packet core, operators need a platform based on a scalable hardware and software architecture. As operators recognize, virtual scalability stems from a hardware platform designed to scale dramatically and to deliver line-rate content inspection and session management.

In the backhaul segment, operators have to put in place a network that can evolve seamlessly from 2G to 3G to 4G. That network needs to feature a significant functionality not just at Layer 2 but also at Layer 3. As triple-play services become IP-oriented, IP awareness in the backhaul becomes critical. Finally, the backhaul network must administer traffic on a per-flow basis. That means the ability to apply QoS and SLA parameters, to have visibility into network management, and to use DPIto tie more intelligence to those traffic flows. The backhaul elements have to accommodate higher-level intelligence further into the network.

...And putting them together in the right way
That intelligence comes from the packet core and its ability to incorporate these functionalities into backhaul elements. The packet core works seamlessly by making forwarding and classification decisions based on content awareness. By deploying the appropriate backhaul solutions and coupling them with the right packet core solution, operators can realize the promises of convergence. They can reduce CAPEX by using embedded investments, lower OPEX by integrating separate functions and deliver services that exceed their subscribers' expectations.

Stuart Benington is Director, Global Portfolio Strategy at Tellabs.