SBC Communications' triple play: Fiber to the neighborhood watch

SBC Communications will invest $4 billion-$6 billion over a five-year period to push fiber deeper into customers’ neighborhoods throughout the 13-state region the carrier serves. A rollout that hinges on a favorable regulatory and economic climate, the fiber to the node (FTTN) initiative would upgrade DSL services of about half the carrier’s residential and business customers to 20 Mbits/sec downstream, enough to support simultaneous transmissions of IP-based voice, video, and data services. Trials to gauge the higher-speed DSL signals over SBC’s loop plant started this summer. FTTN equipment and Microsoft IPTV (Internet protocol television) trials are still in the planning stages but expected to begin this year.

SBC’s ambitious plans, announced in June during a SuperComm keynote by chief executive Edward Whitacre, excited much of the industry. Many people also experienced a touch of déjà vu; the same CEO five years earlier heralded SBC’s first broadband initiative, Project Pronto.

A lot has changed since that first announcement in 1999, but those who recalled Pronto were on the right track. After fits and starts, by early this year, SBC had upgraded the existing networks that passed close to 80% of its roughly four million DSL customers by pushing fiber to within 9,000-12,000 ft of business and residential users to support 1.5 Mbits/sec downstream as Pronto promised. About 50-60% of those customers are served from central-office (CO) DSL access multiplexers (DSLAMs), and the remaining subscribers are connected via remote terminals, also called neighborhood gateways, where an asynchronous DSL (ADSL) digital line unit card acts as a DSLAM in a digital-loop carrier (DLC).

The FTTN initiative is primarily aimed at customers of existing networks. Service rollouts in new subdivisions and other greenfields will most likely be served by fiber to the premises (FTTP). SBC began deploying FTTP in Mission Bay, a community near San Francisco, in 2001. Earlier this year, the company announced FTTP trials in Pabst Farms, a new development near Milwaukee, and in Canton, MI.

SBC’s FTTN initiative will extend standard singlemode fiber-much of it deployed during Project Pronto-to neighborhood cabinets, which are typically located within 3,000-5,000 ft of residents and small businesses. The neighborhood cabinet serves as the demarcation point between the feeder and distribution plant. Each neighborhood cabinet will serve a distribution area of about 300-500 homes. Today, most of the cabinets have copper wires coming in on the feeder side from either a CO or a remote terminal. Those copper wires are then crossconnected at the cabinet location to the distribution copper cables, which go to the home or small business. The new fiber to the cabinet architecture will increase the networks’ xDSL capabilities to 20 Mbits/sec downstream and 1-3 Mbits/sec upstream over the existing copper connections to the premises.

“We are basically going to be leveraging the Pronto infrastructure, and a lot of that fiber takes us all the way to the cabinet,” explains Ralph Ballart, vice president of broadband infrastructure and services at SBC Labs. In cases where the fiber doesn’t extend that far, SBC will install standard singlemode fiber to the cabinet.

The Project Pronto architecture uses OC-3/12 SONET transmission over fiber to connect DLCs housed in remote terminals to other nodes (a dedicated OC-3c is used for data, and a separate OC-3 circuit is used for voice). In the CO, an optical concentrator device routes the OC-3c data to an ATM network.

Under the new initiative, SBC will deploy Gigabit Ethernet (GbE) directly over fiber from the CO all the way to the remote terminals and the cabinets, creating an Ethernet architecture that will make the ATM network obsolete. DSL electronics will be bolted on the side of the cabinet or placed within the cabinet to add a higher-speed DSL signal to the telephony signal already present on the copper wires.

SBC has issued an RFP entitled “Extended-reach DSL.” As yet, the chosen vendors for the DSLAMs and DLCs in the neighborhood cabinets have not been announced. “From a DSL perspective, we are looking for flexible solutions that will allow us to implement a variety of different DSL solutions from the cabinet,” says Ballart, “including traditional ADSL where we need it, ADSL2 and VDSL [very-high-speed DSL].”

While many incumbent and startup vendors are expected to bid, SBC maintains a longstanding relationship with Alcatel, whose equipment it uses for Pronto (Litespan 2000/2012) and its current fiber to the premises (7340 Fiber-to-the-User equipment) deployments. The carrier has also deployed Advanced Fibre Communications’ UMC 1000 DSLAM products for Project Pronto.

Early this year, SBC launched its Dish satellite TV network in some markets as part of its consumer bundle, the result of a July 2003 agreement with EchoStar.

The capability to support digital video is also a key driver of the new architecture. The upgraded networks’ metro architecture will feature a metro headend that would combine national video feeds with regional programming and some video on demand (VoD) traffic, according to Ballart. Layer 2/3 switches that combine IP routing and Ethernet switching will be used to carry the IP video to the CO. The CO will have a Layer 2 Ethernet switch that would transmit the traffic over a GbE fiber link to the individual cabinets. At the cabinet, the video information would be placed over each of the individual copper pairs via higher-speed DSL to each of the homes and small businesses. End customers would have the equivalent of a DSL modem and a home gateway with integrated set-top implementations.

In June, SBC announced an agreement to test Microsoft’s IPTV platform. Microsoft’s IPTV can support VoD and standard and high-definition television (HDTV) on IP-enabled TVs, PCs, portable devices, and the Microsoft Xbox gaming console. “One of the appealing things about the Microsoft solution is their strength across the board in terms of all the different appliances in the home that you would want to reach,” explains Ballart. Although at least four other carriers are in technical trials with the platform, SBC is the first U.S. carrier to announce an IPTV trial.

Next-generation video encoding techniques such as Windows Media Video9 and ITU h.264 will really drive down the bit rates needed to support standard and HDTV, believes Ballart. Video9 offers compression rates almost three times those of MPEG-2, which would enable HDTV at 6-8 Mbits/sec.

“We are confident that we are going to be able to deliver HDTV programming and that the bandwidth we will need to carry that programming will drop quite dramatically over that time,” says Ballart. “In terms of how many programs and when we are going to deliver that and the programming lineup, I don’t have that information. That is something we will develop as we proceed with these trials.”

For FTTN, SBC hasn’t announced any equipment vendors. Says Ballart, “Obviously, comparing and contrasting solutions from different suppliers is a high priority for my lab, and we are preceding to do that now, but I don’t have a schedule when to announce to the industry a selection.” SBC is particularly interested in carrier class element management systems that will enable its network operators to provision, monitor, and test the metro Ethernet and IP-based systems. “These are not enterprise solutions; we want true carrier class solutions from a reliability and availability perspective,” says Ballart. “It’s obvious there is a lot of pressure to make a selection. There is also a lot of pressure to make the right selection, but we’re used to that.”