GTE validates HFC networks for standard video

Apr 1st, 1996

GTE validates HFC networks for standard video

PAUL PALUMBO

GTE Media Ventures has won approval from the City of Thousand Oaks, CA, to build a 750-megahert¥hybrid fiber/coaxial- cable (HFC) video network that expects to pass some 122,000 households by year-end 1998. The build initiates what is planned to be a nationwide thrust by GTE to deploy a video network that will eventually pass more than 7 million households.

GTE Media Ventures, a unit of GTE Corp. located in Dallas, began construction in Ventura County, CA, in March. This phase of network construction will parallel a concerted effort to acquire customers in lock-step with infrastructure completion, a strategy expected to begin by this summer, according to GTE.

In addition to building in Ventura County, GTE will soon begin deploying an HFC network past 400,000 homes in its Florida market. Both builds will be going on simultaneously.

Mike Morrison, manager of network planning for video dial tone at GTE, says the California venture is basically utilizing HFC architecture, with fiber-optic supertrunks from the headend out to optical nodes. These nodes will be located in neighborhoods serving approximately 500 homes. This type of HFC video network configuration is similar to the kind that cable multiple system operators, including Cox, Cablevision Systems and TCI, are moving toward as a digital upgrade standard. It has been adopted by telephone companies as well. "It`s GTE`s standard video network architecture," Morrison says.

Charlotte Wolter, technology analyst and editor of New Media Strategist, says, "HFC networks are the standard cable-TV plant upgrade, and everybody is working to get their systems up to that level." Wolter predicts that 60% of U.S. TV households will be passed by this architecture by the year 2000. She notes that analog channels typically occupy bandwidth from 50 to 550 MHz, with return path bandwidth slotted in the 5- to 50-MH¥range.

Morrison expects that, in addition to data services, the 5- to 50-MH¥bandwidth range will be able to handle upstream traffic from applications such as the company`s MainStreet interactive programming service. Digital video channels and applications reside above 550 MHz.

Many industry analysts believe that the lure of 750-MH¥systems is that the equipment is available and the technology is relatively stable. Moreover, these systems allow operators to provide new types of two-way services that they think will prove valuable in acquiring new subscribers from incumbent operators.

"Right now, the economics of deploying video networks will probably track closely with what makes sense for cable-TV operators, and those infrastructure investments will also make sense for GTE," says telecommunications analyst Mitch Shapiro. Shapiro adds that both cable and telephone company operators will deploy a "fairly comparable distribution platform."

GTE selected an "overbuild" network because the company will now go head-to-head against incumbent cable-TV operators Falcon Cable TV and Ventura County Cablevision. GTE`s video network will parallel the same fiber and infrastructure route deployment paths as the company`s telephony network but will not utilize any elements of that existing network.

Fiber selection

Initially, GTE is deploying a 750-MH¥analog broadcast cable-TV network, but it will transition to a digital platform by year`s end. Morrison says fiber is always one of GTE`s primary considerations. "The first critical deployment decision GTE made was choosing the fiber," he says.

According to Morrison, GTE has standardized its video network fiber requirements, which essentially mirror standards developed for its telephony transport system. GTE`s basic network architecture is defined by singlemode fiber and typically utilizes 1550-nanometer optics for the supertrunk. GTE employs 1310-nm electronics for feeder routes and nodes and then runs coaxial cable from the nodes to the home (see figure).

GTE`s systems integrator is Lucent Technologies (formerly AT&T), which is also providing much of the optics and electronics. General Instrument is providing most of the radio frequency equipment.

GTE is also deploying synchronous optical network (Sonet) 622-megabit-per-second OC-12 protocol in a ring configuration to tie in all the offices. Morrison says that OC-12 will also position GTE to better handle interactive services as they become available. GTE recently announced that Tellabs Titan family of wideband and narrowband digital crossconnect systems would be used to directly interface fiber-optic rings at the OC-12 level for its telecommunications networks. GTE has selected a vendor to provide Sonet equipment for its video network but has not announced the company, pending signing of the contract.

As a network planner, Morrison says, he would like the network to have the flexibility to migrate and evolve into one that serves GTE`s distribution needs. "Starting off with OC-12 gives GTE the framework that the company can build from," he says. While Morrison acknowledges that moving up the Sonet protocol is difficult to predict "because it`s difficult to determine what the take rates are going to be for some of these interactive services," GTE would consider upgrading to OC-48 at speeds of 2.5 gigabits per second or even OC-192 at speeds of 10 Gbits/sec, depending on the needs of the marketplace and the availability of the products.

Inherent challenges

The top technical and organizational challenges in building the company`s 750-MH¥network are coordinating the construction efforts and integrating the hardware components. Morrison says that GTE has not undertaken construction on this scale-- simultaneous builds in California and Florida--in some time.

Analysts are quick to point out that few 750-MH¥network systems have been deployed and activated, whereas 550- and 440-MH¥networks have been operating for several years. The problem is that 750-MH¥networks still employ relatively new technology, even though it has been commercially available for three to five years. According to Morrison, a number of network products and components for such networks are indeed standard and stable.

But when jumping forward to full HFC deployment of 750 MHz, integrating components and electronics is a complex cycle. After matching the architecture with the service sets to be provided, Morrison says that GTE must be able to integrate different components. That includes not only the transport network but also all the support systems that go along with it, such as network monitoring. "They must all be integrated to deploy a homogenous platform," he says. "Integration is a tremendous challenge to everybody because many network components are developed independently and only come together in deployment."

Upgrading the network to digital is going to be a function of availability, according to Morrison. "The available analog technology allows GTE to put together a competitive service offering right now." While digital technology is not yet ready, when it can meet GTE standards it will be deployed, says Morrison.

Digital technology issues run from the set-top box, controller and multiplexer; all must work together so the signals can go through. Morrison notes that the entire digital platform "has not matured enough to be commercially available and deployable." Even though the first problem has been settled--a standard for Motion Picture Experts Group 2 (MPEG-2) compression--Morrison says the problem within MPEG-2 is that there are different standards for audio and bit transfer rates.

For GTE, that adds up to investing in 750-MH¥analog networks now. These networks can, at a minimum, deliver sufficient programming so the company can begin establishing a position in a new business segment and build consumer loyalty in the video marketplace. q

Paul Palumbo writes from Seaside, CA.

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