Priority 1: The Mobile Backhaul Network

This has been a landmark year for U.S. mobile operators as they have witnessed data traffic more than double on their networks. AT&T alone reported a 50% year-over-year increase in data revenues in the third quarter, driven by subscriptions to the new iPhone 3G. Mobile networks are starting to resemble wireline broadband networks, as the data traffic they carry begins to outpace voice traffic.

Consequently, operators now are tempted to look at their networks as data networks and to apply many of the same techniques used in wireline toward managing them. One of those techniques is quality of service (QOS), which allows operators to prioritize different types of traffic, guaranteeing set levels of bandwidth, jitter, delay and packet loss for specific applications and services. Operators have used QOS to prioritize voice traffic over data traffic since the inception of packet data, but as data becomes the predominant tenant on the network, the need for advanced QOS techniques that prioritize different types of traffic has become readily apparent, said Stéphane Téral, principal analyst with Infonetics.

“It started out a year ago, when the first reports of data surges emerged in Europe and then here in the U.S.,” Téral said. “Right now, we're starting to see carriers address these problems in the packet core. That's the starting point. They're replacing obsolete [gateway GPRS serving nodes] and ensuring they can manage these surges in data traffic.”

Wireline technologies such as MPLS now are being applied to wireless data traffic, allowing operators to make sense of the packet soup traversing networks. Instead of best-effort service classes being applied to all forms of data, real-time applications such as voice over IP (VoIP) and videoconferencing can be prioritized over video streaming, which may require more bandwidth but has a much greater threshold for delay. Streaming traffic could be prioritized over e-mail, which could be prioritized over Web browsing, and so forth.

Despite the benefits of managing traffic in the core, the advantages are muted once that traffic makes its way to the radio access and backhaul networks. Those networks are where bottlenecks are starting to occur, as more customers begin using more bandwidth-intensive services, and the T-1 and E-1 links connecting most cell sites become overtaxed. New 3G network technologies have begun to tackle QOS in the radio access network (RAN). CDMA 1X EV-DO was the first to offer advanced QOS at the wireless interface, which in turn has allowed Sprint and Verizon Wireless to offer VoIP-based push-to-talk services that prioritize voice sessions over other data traffic. High-speed packet access (HSPA) upgrades also have added advanced QOS capabilities to UMTS networks.