Charter Communications Inc. is taking one of the biggest leaps yet into the cable-infrastructure horizon as it embarks on a three-year upgrade program affecting 75 percent of its plant.
The company intends to transform its networks into high-capacity digital-broadband systems using a potpourri of advanced techniques that are just crossing into wide-scale use in hybrid fiber-coaxial architectures, including dense-wavelength-division multiplexing, baseband digital transmission and 870-megahertz bandwidth capacity.
"We're using these capabilities wherever it makes sense, which includes a large share of the 135,000 plant miles that are included in the upgrade plan," Charter vice president of engineering Larry Schutz said.
Harmonic Inc. is supplying about 65 percent of the overall optical-networking component of the plan, with the remainder going largely to Scientific-Atlanta Inc., Schutz said.
Charter's choice of technical options for meeting near-term service-expansion challenges has also taken into account long-term migration, allowing for reduction in node sizes to as little as 60 homes passed, using fiber installed in the current phase, together with passive optics.
"We're quite confident that we can go to 60 homes passed, although there are some issues that have to be addressed," Schutz said. "We'd have to deploy some DWDM in the field, which means we probably would need field-hardened equipment that's different from the DWDM gear we're using today."
Initially, the number of homes passed per node is 500 or fewer, typically in the range of 380 to 385, Schutz said. By running six fibers to each node and installing dual-return receivers to handle upstream signals from the coax plant, the company is well positioned to subdivide the serving areas to where only 190 to 250 homes are sharing upstream bandwidth, he added, noting that this would probably precede any move to the 60-home level.
While Charter has been upgrading plant to 750-MHz capacity for some time, the company will shift to 870 MHz wherever practical, including partially completed upgrades, Schutz said. "About 80 percent to 85 percent of the 135,000 miles of plant we're targeting will move to 870 MHz," he noted.
Charter is allocating 550 MHz to analog services, leaving 310 MHz to 320 MHz of spectrum for digital services, "depending on which vendor we use," Schutz said. "We keep identifying new things we need bandwidth for on the digital side."
Charter is also moving aggressively into use of DWDM on both the distribution and return sides of the architecture. In many cases, the company will use 1550-nanometer lightwave technology for both broadcast and dedicated services from the headend or primary hubs to secondary distribution hubs, delivering the broadcast signals over one fiber and multiple wavelengths of dedicated services over a second fiber.
"We'll use 1310 [nm] technology for analog-service distribution with a DWDM digital overlay in some places like St. Louis, where we've already started in that direction," Schutz said. "But we'll be all-1550 in many areas."
In areas where the MSO is tying together remote locations-typically involving 25,000 to 30,000 homes-with a central headend, the company is distributing all signals digitally over SONET (synchronous optical network) links to primary hubs and, from there, over the 1550-broadcast and DWDM links to secondary hubs.
DWDM will be used for return signals in many areas, with each secondary hub delivering all of the digital-baseband return signals coming in from the nodes over a separate wavelength back to the headend or primary hub.
"The translation to digital baseband will take place at the nodes, and those signals will be multiplexed together digitally at the secondary hub," Schutz explained.
Charter's move to 870-MHz capacity comes as more operators are moving beyond 750 MHz in new projects. But it's on a larger scale than has been seen so far in North America, Harmonic vice president of marketing Patrick Harshman said.
"With other MSOs, use of 870 spans the space from still just talking about it to using it in selected upgrade and new-build projects," Harshman said. "But there's definitely a strong trend toward 870 where just about every MSO is at least talking about it."
While use of 870 MHz requires that fewer amplifiers be cascaded-typically just one or two-Charter has found that it can go to 870 MHz fully loaded from 550 MHz at cost parity with 750-MHz upgrades, Schutz said.
This marks a major shift in the cost equation for use of fiber, allowing operators not only to add capacity, but to extend fiber deeper than before without incurring cost penalties over 750-MHz upgrades, Harshman noted. "The trend is toward deeper fiber with one- or two-amplifier cascades," he said.
Along with the shift to deeper fiber and 870 MHz, Harmonic is seeing more MSOs moving to multiple-system-upgrade projects, where much larger deals with suppliers result in greater economies of scale and better control over the supply line. "It used to be that our orders were project-by-project, but that's all changing now," Harshman said.
Harmonic is able to bid on such projects because it has expanded its product portfolio to include just about any design need, Harshman added. "These big deals aren't one-size-fits-all," he said.
Charter-which is controlled by Microsoft Corp. cofounder Paul Allen-has put together an arsenal of alliances and strategies to exploit the two-way digital-service capabilities of its new "wired world" of broadband networks.
For example, the company is working with High Speed Access Corp. to test Internet-protocol telephony in Georgia and other markets in hopes of launching commercially during the second half of the year.
Charter-which holds warrants to purchase equity in HSA-recently expanded its agreement with the cable Internet-service provider to add 5 million homes passed to the previous level of 750,000, with incentives to increase the total to 10 million households.
The company is also nearing the consumer-testing phase of a personalized-television service developed with Broadband Partners, a joint venture by Charter, Go2Net, Inc., HSA and Vulcan Ventures Inc., Allen's investment firm.
Such services will be the catalyst for pushing digital-cable penetration beyond 50 percent, according to Mary Pat Blake, senior vice president for marketing and programming at Charter.
Speaking at last month's 2000 CTAM Digital & Pay Per View Conference in Los Angeles, Blake said the Broadband Partners service offers a "whole-house solution," meaning each person in a household can customize the service to his or her interests.
"For example, one person may want to check just the same 10 stocks in her portfolio every day, while another person may customize his screens to show local news, lottery scores and movie schedules," she added.
Charter is also expanding availability of interactive services using the Web-to-TV technology supplied by WorldGate Communications Inc. and the enhanced services offered by Wink Communications Inc.
WorldGate services are now running in seven Charter markets, including a free version to digital set-tops in LaGrange, Ga., in cooperation with the local government. About 60,000 Charter customers got Wink service at the end of March, and that footprint is growing, including in Los Angeles.