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Archives
 July 1999 Issue
Cover Story
Cable-Tec Expo '99:
Expo Workshops -- Broadband's Acceleration into Hyper-Reality
By the CT Editorial Staff
Before Expo could even get off the ground, droves of engineers landed, storming Orlando's Convention Center for preconference seminars exploring Internet protocol (IP) and advancements in multiplexing technology.
Soon the prelude was over, and Expo '99 launched in full force with an arsenal of workshops that gave more than a few weary broadband explorers a chance to get off their feet and delve into the heart of the cable telecommunications industry's future.
Cable takes on future with IP
IP may be even hotter than Orlando's tropical climate. Famed consultant Walt Ciciora reinforced that notion in his preconference tutorial addressing IP's emerging role in broadband's quest for advanced services deployment.
Internet access via cable modems, voice over IP (VoIP), full telephony service capability and ancillary telephony are some of the emerging IP-based services that will have an immense impact on the Internet's continuing evolution, he said.
"The Internet is changing. Now is an important time to be adding to your skill set," explained Ciciora. "SCTE is your key to all of this." Various materials and training offered by the Society of Cable Telecommunications Engineers are there to help. "It's a critical tool for keeping up with this new world."
Cable's brave new world is one of change, said Ciciora. The Internet and inexpensive personal computers (PCs) have culturally influenced consumers to demand more speed and advanced services from telecommunications providers.
According to Ciciora, cable's information age has been disappointing. There have been many failures and some potentially embarrassing situations for the industry, posing challenges to cable operators, and it is certain that there are more to come.
Boost capacity with DWDM
"Fundamentals of Dense Wavelength Division Multiplexing for CATV," explored the use of DWDM in cable TV networks. Presented by Wes Simpson, director of product management for ADC Telecommunications, the tutorial included a review of fiber-optic physics and examined some proposed architectures.
While engineers have two choices when it comes to designing a DWDM system, Simpson suggested using a mutliplexer/demultiplexer instead of a combiner/splitter. "It is important to see that with this transport system, the DWDM multiplexer and demultiplexer gives you a lot more power available at the output."
Simpson warned of some potential problems in DWDM systems, including linear crosstalk, stimulated Brillouin scattering (SBS) and four wave mixing (FWM).
Simpson suggested a filter solution for linear crosstalk, which rears its head during the channel selection process.
Simpson concluded DWDM currently is being used for a number of applications, and among its transport advantages is the ability of any wavelength to carry any protocol.
Mission: Deploy digital video
"Digital Video Deployment" covered a lot of ground in a little time. Presenters included Virgil Urquhart, director of technical launch services, HITS for AT&T Broadband and Internet Services; Vince Pombo, vice president of engineering, Time Warner Cable of New York City; and Paul Snopko, director of research and development at Zenith Electronics.
Noise remains perhaps the greatest challenge to having an active return path, Urquhart said. "If you've got amplifiers, you've got residual noise," he said. From there, he covered suggestions for activation, troubleshooting and maintenance of the pesky path.
Urquhart also warned attendees about what he called "the great myth" that RF solves nonresponding terminal issues. "Although moving to RF return will stop many definable problems caused by customers, such as disconnecting the phone line from the terminal, in many cases it merely causes a shift in focus to other issues."
Still, he predicted that most operators will soon be using RF return. Effort now to discern what new challenges will come into play can save time and money when RF replaces telco return, he said. "If you've got a return path, using RF makes common sense."
Pombo concluded that it's probably not a good idea for operators to set out for a short-term solution until the long term has been considered. The bandwidth requirements could cause strain on the system and headaches for its engineers.
Snopko delved into consumer interface issues associated with digital TV (DTV) and high definition TV (HDTV) cable carriage. "There's a lot going on with interfaces right now," he concluded.
Demystifying DOCSIS
MediaOne Labs engineers Doug Jones and Pak Siripunkaw conducted an Expo workshop to set the record straight; the Data Over Cable Service Interface Specification (DOCSIS) is no longer a technological mystery wrapped in a specifications riddle.
Essentially, Jones said, DOCSIS is all about opening the retail channels for cable modems and spurring competition among cable modem vendors. At the same time, enabling cable modem retail availability for consumers, he said, should help cable operators lighten their overhead.
As of press time, five cable modem vendors have already gained the coveted DOCSIS interoperability seal (Toshiba, Thomson, 3-Com, General Instrument and Arris) for the specification's 1.0 version. Currently, there are 14 additional cable modems being tested at CableLabs. Concurrently, CableLabs is testing three cable modem termination systems (CMTSs), with Cisco being the first and only CMTS vendor to be given the DOCSIS nod thus far.
"We have 20 different vendors building to the DOCSIS specifications and seven silicon vendors that are providing DOCSIS chip sets," Jones confirmed. "That is very good news because it will spur cable modem competition in the consumer marketplace."
Broadband catches a wave
The DWDM deployment workshop included presentations from Esteban Sandino, AT&T Broadband and Internet Services' manager of network technologies and John Trail, Harmonic's product manager of transmission systems.
Although it's not a new technology, the cable industry currently is exploring the many benefits of deploying DWDM to enhance capacity in delivering two-way broadband services.
Besides allowing cable operators an alternative to deploying costly fiber to increase capacity, DWDM can carry narrowcast analog channels. It also is well-suited for the high-capacity transport of video and data in 256-QAM (quadrature amplitude modulation) format. The workshop addressed how DWDM in the node can provide a cost-effective and future-proof return path.
"DWDM is a reality today," said Sandino. "It minimizes disruptions to system services and has been successful in delivering broadcast and narrowcast services."
Even taking some care and learning from experience, physical network limitations may pose some deployment challenges, Sandino said. Those challenges, however, are well worth the effort in terms of economics as well as system performance.
"As the demand for services increases, the demand on the return path will grow," predicted Trail. "Clearly, DWDM has a long way to go with HFC (hybrid fiber/ coax). It's going to be around for awhile."
OpenCable on track, retail just around the corner
Retail was the buzz at the "OpenCable Demystified" session.
"We don't have a finished spec yet; however, there have been some definite results coming of the project," said Don Dulcinos, director of business development for CableLabs' OpenCable project.
"After OpenCable was announced, we saw an increased deployment of first-generation digital set-top boxes," said Dulcinos. He added that these deployments helped to drive prices downward to the point where mass deployment was feasible.
As its objective, OpenCable seeks to build on existing open platforms and standards to create an interoperable, next-generation digital set-top box. Part of its mission is to pave the way to a retail model for set-top availability, and an important part of this is security.
The OpenCable project has addressed the issue of copy protection as well. "What we negotiated with Hollywood, cable and consumer electronics was a solution called 5C, which is a method of copy protection over the 1394 interface," said Paul Zimmerman, systems integration manager at CableLabs. "It's not the only copy protection solution, but it is at least one that was agreed upon by everyone involved."
Detecting problems in the return path
Testing for interference in your return path has never been more critical than it is today, warned John Downey, training development engineer at Wavetek Wandel Goltermann, and Dean Becker, senior principle engineer at Cheetah Technologies, during their Expo workshop on forward and reverse plant maintenance.
Downey reminded engineers of the need for testing to be nonintrusive. "You can't justify taking the system down. That will be unacceptable to subscribers," he said, explaining that customers may lose communication, get a slower throughput or experience periodic "clicking" in their telephone calls if testing is intrusive.
Becker added that as networks get more complex, you may need a palette of tools to test your return path. He noted that the usefulness of spectral analysis is primarily in narrowband measurements. "We're doing power measurement on the signal in a particular narrow bandwidth. If there is broadband energy, the only way you'll see it is a piece at a time."
To overcome those limitations, Becker suggested adding time domain methods such as autocorrelation and histograms to your testing arsenal. He also advised keeping a record of test results showing the different characteristics of the signal.
Network upgrades for enhanced services
Engineers dropped what they were doing to learn what Robert Palm, network specialist with Philips Broadband, and Farr Farhan, manager of R&D at Scientific-Atlanta, had to say at the workshop on "Upgrading Your Network for Enhanced Services."
Palm compared the cost and performance of the various fiber options available today. As cable companies continue to push fiber optics deeper into their networks, they are faced with the decision to go with 1,310 nm or 1,550 nm fiber and whether to use DWDM with that fiber, he explained.
S-A's Farhan noted that problems in the reverse path will drive digital problem solving. By converting analog traffic to digital between the hub and the headend, and between the node and the hub, cable operators will see several benefits, Farhan said. They'll get full use of the reverse path, which becomes better and cheaper. And data signal processing can be centralized at the headend, so operators won't need routers in the hub.
"Operators are facing a dilemma. They need to push their equipment and nodes farther out so they can deliver more bandwidth on a per node basis. This costs money9more nodes, more demodulators. That goes away from the concept of centralization to share resources," Farhan explained. By moving to a digital scheme, operators avoid that scenario.
Broadband network integration: A recipe for success
Assembling a broadband network isn't like pouring Cornflakes into a bowl, dousing it with milk and then calling it a done deal. Rather, it's an elaborate recipe that calls for the correct portions and the right ingredients.
In essence, it's all about planning, explains Internetwork Integration President James Ludington, who conducted a broadband network workshop at the show. Moreover, it's about business planning.
"Building a broadband network is a philosophy," Ludington explained. "It's a decision a company makes, not a solution. You have to install a specific business strategy because all of your businesses, not just your technology, are managed by this network."
Part of that strategy begins with developing the integration process. From there, he suggests that companies create a step-by-step approach to the integration process and involve all facets of the business, including the engineering and technology, operations, information technology (IT), and marketing departments.
Then, during the execution stage of the project, Ludington recommends that companies keep a detailed analysis of the network's functionality. This analysis includes performing tests, comparing specifications and expected performance, constant reviewing of documentation and results, and maintaining a database that logs and tracks the project's history.
Cable telephony deployment
Ham Matthews, director of IP business development for ADC Telecommunications, and Thomas Sloane, vice president of corporate technology for Alpha Technologies, addressed a packed house for their cable telephony seminar.
"The path from circuit-switched to IP telephony over HFC networks is full of pitfalls and distractions," Matthews said. "Standards development and implementation have been slow and tedious."
"Standards aren't the only obstacles the industry faces in deploying IP telephony," he said, adding that a service rollout is more like "putting on a parachute while falling through the sky" than "adding another channel to a crowded lineup."
The emergence of primary lifeline IP telephony services over HFC fills an obvious need in the industry, he said. Now, "vendors are once again scrambling" to stay on top of market needs.
Sloane and Cox Communications' Hugh McCarley charged into HFC powering issues and recommended curbside engine-generators (E-Gs) with a one-hour standby period for legacy power installations that support telephony.
The E-G, they agreed, offers a more convenient and reliable method of upgrading standby times. In HFC systems especially, the E-G can't be beat, Sloane said, especially not by the expensive, weather-vulnerable batteries typically used in the industry. CT
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