FEATURE: Meeting customer expectations means optimizing network backhaul and transport

Starting off life with a mobile phone in their pockets, Echo Boomers (born between the early 1980s and 1995) are the first generation to grow up in the Digital Age. Their lifestyles demand advanced, high-bandwidth wireless applications. To stay competitive, service providers must support advanced services to retain the loyalty of this large and lucrative demographic.

Industry analysts forecast dramatic growth in 3G high-speed mobile data subscriber connections. This projection poses a risk for service providers: revenue growth may be outpaced by the costs required to provide sufficient network capacity.

Anticipating market demand, service providers are migrating from second-generation (2G) to third-generation (3G) networks. This migration is forcing technology change within the network, both in the radio access network (RAN) and in the mobile core.

In a 3G migration, service providers have several objectives for RAN backhaul networks. First, rapidly and cost-efficiently deploy 3G services. Second, invest once and then leverage this investment into the future. Third, lower RAN transport costs through Ethernet backhauling.

To meet these objectives, service providers are grappling with multiple evolution paths. Often, use of existing backhaul infrastructure is the best solution.

T-1 transmission is the dominant transport service used for mobile backhaul solutions. Enhancements to the current backhaul equipment enable operators to leverage the existing infrastructure by delivering higher bandwidth services over bonded T-1 pairs and by making more efficient use of capacity. Also Ethernet over synchronous optical network (SONET) enhancements make the reuse of existing SONET platforms more cost-efficient for the delivery of Ethernet connectivity. As traffic demand grows and data services begin to dominate, service providers will not rely purely on SONET or T-1s. They will require new multi-protocol label switching (MPLS)-based platforms that are optimized for mobile data traffic.

Time division multiplexing (TDM), asynchronous transfer mode (ATM) and now Ethernet are present in GSM networks. As the RAN evolves from GSM to UMTS, service providers must backhaul and aggregate all three types of traffic as efficiently as possible. GSM service providers that efficiently adapt existing infrastructure to perform this aggregation will benefit by minimizing expenses and maximizing the speed of service deployment.

In a similar way, CDMA networks are evolving. CDMA is moving from frame-based protocols and T-1 transport to bonded T-1 pairs and eventually to Ethernet-based transport. Backhaul solutions must support efficient migration of the existing infrastructure towards Ethernet to minimize expenses.

As the RAN evolves toward packet-based networks, the mobile core network is going through a similar evolution. ATM in the mobile core has the same issues as in the RAN when transporting high-bandwidth data. It is burdened with a "cell tax" and data overhead on the network. And with ATM, the core is not IP-aware, so service providers would have to maintain two topologies, one for IP and one for ATM, increasing the network's complexity.

Here, IP/MPLS is becoming the choice core network. Using this technology, one network can carry multiple services with a single management system. MPLS was designed with multi-service capabilities in mind, which means that it can transport all the different services in one infrastructure.\An IP/MPLS network can be traffic-engineered to deliver multiple levels of QoS for different services, giving high priority to some while allocating best-effort to others. MPLS provides true Quality of Service (QoS) for voice and premium data services.

Driven by new subscriber expectations, the migration from 2G to 3G wireless technologies is in full swing. The most advanced 3G applications will drive more bandwidth to the mobile phone. Mobile backhaul networks must accommodate this growth.

The process is causing a fundamental change in the backhaul network to support these high-bandwidth services. It affects the network from end-to-end, from cell site clear through to the switching core. This change requires a true multi-service architecture that can support voice and premium data services.

Service providers must find a cost-efficient way to rapidly migrate from their existing 2G networks to 3G technology. This migration must be done with lower infrastructure investments and without impacting resulting revenue growth.

The result is an IP/Ethernet-driven network starting with data-centric upgrades to the existing backhaul equipment and ending with deployment of MPLS-based multi-service routing devices for Ethernet-based backhaul. The optimal mobile core network is built with MPLS-based multi-service routers from the start of 3G migration. The MPLS control plane guarantees QoS across the network and supports multiple services including voice, data and more advanced applications based on IP Multimedia Subsystem (IMS).  

Ultimately, this means one thing: Echo Boomers' demands are fully met and service providers are ready for the next wave of applications.

Antti Kankkunen is vice president, Network Evolution, Office of the CTO, with Tellabs.

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