Arlyn S. Powell, Jr.
About once a year, the Telecommunications Industry Association (TIA--Arlington, VA) holds a premises wiring seminar at which it gathers its committee chairpeople to speak about recent technical developments in the TIA`s working groups concerned with premises wiring standards. To leaven what could otherwise be a dauntingly complicated and dull topic, seminar moderator Paul Kreager, principal consultant for Kreager Associates Inc. (Pullman, WA), asks each speaker to make a prediction for the coming year. Then, at the following year`s seminar, the speakers are expected to defend their predictions.
Last year, Donna Ballast, registered communications distribution designer (rcdd), telecommunications analyst at the University of Texas (Austin), and the standards representative for bicsi (Tampa, FL), predicted that the 25-pound pulling tension limit applied to Category 5 cable will be reviewed and revised to a less conservative number. To illustrate her point, Ballast set up a dynamometer at a recent industry meeting and asked experienced cable pullers to come up from the audience and exert what they felt was normal cable-pulling force. Few, if any, came in below the 25-pound limit. Experienced cable pullers say it is possible to stay within the limit by attaching breakaway swivels to the cable, but it is noteworthy that they reserve this task for their greenest apprentices.
Contacted recently about her prediction, Ballast said that at its December 1996 meeting, the Cabling Installation Task Group requested that the TIA`s TR-41.8.1 Working Group review the recommended maximum pulling tension for 4-pair cable of 25 pounds (lbf), and the Working Group agreed. "We are making progress," Ballast says, "and I hope to see a revision in tia/eia-568b."
Tony Beam, rcdd, who is director of systems marketing for Netconnect Systems at AMP Inc. (Harrisburg, PA), predicted 18 months ago that the TIA and the ATM Forum would continue discussing a new copper cabling category, Category 6. Beam also said he thought the ATM Forum would settle on an OC-48 2.5-gigabit-per-second protocol over 62.5/125-micron multimode optical fiber over a distance of 300 meters as its standard.
Today, according to Beam, "the TIA has started discussion of Category 6, but more importantly, the TIA is discussing additional performance parameters for Category 5 cabling." The leading candidate among higher-data-rate solutions currently appears to be Gigabit Ethernet. Beam believes the ATM Forum will consider this option, as well as protocols that can be run over Category 5, before examining Category 6.
As to the OC-48 protocol, Beam admits that the ATM Forum has not finalized on it yet, but he says discussion has begun and a work item approved. "In 1996," he adds, "the ATM Forum approved a work item to develop solutions ranging from 1.2 to 10 Gbits/sec on optical fiber."
Masood Shariff, who is on the technical staff of Bell Laboratories of Lucent Technologies (Middletown, NJ), identified balance as being an important new electrical parameter to be considered in high-data-rate copper wiring. "It will be investigated as a subject across all twisted-pair cabling components," he said at the 1995 Stargazer`s Review, "and this will lead to better electromagnetic compatibility (EMC) performance, as well as greater understanding of electrical anomalies in cabling."
Recently, Shariff updated his prediction by pointing out that electrical balance had, indeed, received much technical attention over the last year. "Balance is at the top of the list of additional parameters being looked at by the TIA`s UTP Systems Task Group for Category 5 cable, connecting hardware, and links," Shariff says. He adds that TIA`s SP-3723 now has specifications that require testing of connecting hardware with both differential and common-mode terminations to weed out hardware with poor balance, and that new models and measurement procedures are under development to characterize balance at high frequencies.
Just as Shariff was concerned with the electrical characteristic of balance, Kreager was interested in another and supposedly more-familiar electrical parameter--near-end crosstalk. Last year, he felt that near-end crosstalk was not as well-understood as technical people in the industry seemed to assume. "In one year," he predicted, "there will still not exist a widespread understanding within the telecommunications community of how to test and qualify channel near-end crosstalk in a meaningful way."
Today he says, "The general methodology of testing Category 5 cable remains unchanged. Since my prediction was made, one vendor has introduced the `banding` concept, but that has done nothing toward actually testing available near-end crosstalk headroom of a channel."
Technical Trends Predicted for 1997
Some of the speakers at this winter`s Telecommunications Industry Association`s premises wiring seminar also made predictions for the coming year. Here is a sampling:
- Tony Beam: "All the talk about alternate cabling solutions, such as extended- frequency Category 6, plastic optical fiber, and 50/125-micron fiber, will end up being just that--talk. By 1998, it will be more certain than ever that building cabling is a two-media solution: Category 5 unshielded twisted-pair (UTP) copper cable and 62.5/125-micron multimode optical fiber. While additional performance parameters will be developed for Category 5 UTP, no local area network (LAN) applications will evolve that need cabling supporting frequencies above 100 megahertz. And while plastic and 50/125-micron fiber may make some headway in the standards groups, they will be soundly rejected by the marketplace."
- George Lawrence of AMP Inc. (Harrisburg, PA): "There will be much discussion about higher-performance cabling systems or cabling with electrical characteristics better than Category 5 UTP, but little progress will be made. It will be difficult for supporters of higher-performance cabling to define a need for such cabling when equipment manufacturers can provide high-speed LANs already standardized by the Institute of Electrical and Electronics Engineers [ieee--New York, NY] for use with existing cabling."
- Lawrence also predicts: "The remaining test procedures needed to completely define a Category 5 cabling system will be developed and agreed to."
- And: "Good cabling systems will become more important in the residential market."
- Masood Shariff has two predictions for 1997: "The value of structured cabling to customers will increase again by an order of magnitude as Gigabit Ethernet applications become available for enhanced Category 5 UTP and multimode fiber in 1998."
- And: "Bandwidth enhancement techniques, such as restricted launch conditions and receiver equalization, will extend the useful life of multimode fiber by supporting longer distances, increased bandwidth, and a greater number of supported applications. This will parallel the extension in useful life of UTP cabling made possible by coding, scrambling, and equalization."
- George Weller, who performs research and development for modular furniture manufacturer Steelcase Inc. (Grand Rapids, MI), predicts: "For some time, organizations have been moving away from centralized data management, and a few have recently realized that centralized management of large networks is questionable at best. The TIA`s TSB-75 working group and Microsoft`s Win95 peer networking group almost `get it,` but most other providers don`t. I predict that this situation will not change in 1997."
- And finally, Paul Kreager predicts: "The TIA`s TR-41.8.3 group is currently studying horizontal conduit cable fill with the intent of making changes to the tia/eia-569 standard. I predict that, at the end of this study, people will come to realize that the current horizontal fill advice in 569 is not so bad after all."