INDUSTRY SPOTLIGHT: Final tests anticipate HDSL2 standard ratification

In anticipation of approval by the American National Standards Institute (ANSI) T1E1.4 committee, six HDSL2 (high-bit-rate digital-subscriber-line) telecommunications vendors

In anticipation of approval by the American National Standards Institute (ANSI) T1E1.4 committee, six HDSL2 (high-bit-rate digital-subscriber-line) telecommunications vendors have initiated a test plan that seeks to swiftly overcome interoperability issues so that industry-wide implementation can be realized before summer.

HDSL2 provides symmetric high-bandwidth transmission over only one pair of copper telephone wires rather than traditional 2-pair deployment. Once a standard has been approved, a warm industry embrace is anticipated because HDSL2 doubles the utilization of the local copper-wire loop. The technology delivers full T1 performance, making it ideal for regional operators and competitive local- exchange carriers that want to deliver cost-effective, high-speed data services to small to medium-sized businesses, telecommuters, and remote enterprise users.

In cooperation with the University of New Hampshire's InterOperability Laboratory, the HDSL2 Consortium-ADC Telecommunications Inc. (Minneapolis, MN), ADTRAN Inc. (Hunts-ville, AL), Conexant Systems Inc. (Newport Beach, CA), GlobeSpan Inc. (Red Bank, NJ), Level One Communications Inc. (Sacramento, CA), and PairGain Technologies Inc. (Tustin, CA)-is hoping to have a testing framework fully in place by early spring. Other members of the consortium include Metalink Ltd. (Tel Aviv, Israel) and Teltrend Inc. (St. Charles, IL).

The consortium's first technical "community plug-fest," according to Scott Valcourt, UNH InterOperability Lab manager for HDSL2, was planned for early this month. A final plan, slated for completion by March 30, will then be used by the consortium to test HDSL2 products for interoperability. Even while waiting for standards approval, consortium vendor PairGain (which helped author the standard) is already guaranteeing compliance with their fledgling HDSL2 products and will provide free upgrades to any changes that may result from the final standard approval.

While other consortium vendors have introduced HDSL2-compatible products, PairGain recently introduced what it claims is the industry's first complete HDSL2 implementation. The HiGain Solitaire system, PairGain says, provides guaranteed multivendor interoperability.

Meanwhile, ADTRAN has tested the HDSL2 waters with transceiver units for central-office and remote use as well as a repeater. The company issues a caveat with its repeater, however, saying that repeater technology has yet to be fully addressed in the pending standard, primarily due to unresolved and potentially lethal tradeoffs involving asymmetric digital subscriber line (ADSL). In essence, repeaters require significantly higher line powering voltages than are currently addressed in HDSL2, and because of performance tradeoffs, repeatered HDSL2 can "kill" ADSL in the same binder group. For that reason, PairGain has opted to stay out of the repeater business for now.

Other consortium members are focusing on transceiver/chipsets. Teltrend's ASTS-2HCU and 2HRU for central-office and remote use, respectively, are targeted for integration with PairGain's HDSL2-groundbreaking chipsets and systems. Metalink offers a dual SDSL2/

HDSL2 digital-signal-processor (DSP) chipset that includes the company's proprietary algorithmic solutions for optimal decoding and power consumption. Conexant's ZipWire2 chipset offers variable data-rate operation, which lets users trade off data rate (anywhere between 144 to 4640 kilobits per second on 8-kbit/sec boundaries) to attain desired performance.

Earlier this year, Level One was one of the first vendors to deliver HDSL2 to customers with its SK70740/41/42 chipset. Its pulse-amplitude-modulation transceiver is HDSL2-ready and can provide rates down to 144 kbits/sec for transmissions over longer distances and harsher environments. Also jumping out of the gate early was GlobeSpan with its G2237 chipset for HDSL2 modem applications. Samplings to its customers began as early as October 1998.

"HDSL2 is more than simply single-pair T1," notes George Zimmerman, chief scientist at PairGain Technologies. There are many technical challenges involved, he says, and "giving these systems the robust performance that will hold up under the real-world challenges in the local loop requires careful testing and experience."

While some vendors have claimed their single-pair T1 1.554-Mbit/sec systems are HDSL2-compatible, Zimmerman believes that "in most cases, the reaches claimed are in minor or minimal crosstalk situations or under particular laboratory test scenarios. Deployment at these reaches in the real world makes the user vulnerable to interference from other circuits, either at the time of installation or at some future date."

Adds UNH's Valcourt, "Having an HDSL2 test plan is essential if the industry is to avoid problems such as interoperability issues that occurred with early Integrated Services Digital Network deployments."

-Steve Smith

Moves, Adds & Changes


Mike Lima, former director of sales and finance at Pinacor (Tempe, AZ), has been named chief operating officer at Cablesoft (Tempe, AZ), where he will assist the IT infrastructure modeling software company with expansion and new-product strategy.

ISI Inc. (Shaumburg, IL) has named Jerry Owen national cabling product manager for its Infortel-Cable Management System. Owen is the former owner and president of U.K.-based EXAN Technologies, a cable-documentation and management-software company.

BICCGeneral (Highland Heights, KY) has appointed Stephen J. Smith as vice president and treasurer. He will have worldwide responsibility for treasury management and investor relations concerning the company's copper, aluminum, and fiber-optic wire and cable products. Previously, Smith was vice president, treasurer, and assistant secretary of Insilco Holding Co. (Columbus, OH).

Colonial Electric Supply (King of Prussia, PA), a wholesale distributor serving eastern Pennsylvania, New Jersey, and Delaware, has formed a division dedicated entirely to the sales of structured cabling products for the data-communications contractor market. Mike Lynch, formerly of Hubbell Wiring (Milford, CT) and Leviton Telcom (Little Neck, NY), heads the group. He is joined by Bill Hummel, a 14-year veteran at Anixter Inc. (Skokie, IL), and Ted Schalles, who has 15 years' experience in sales.

The Wiremold Co. (West Hartford, CT), a supplier of wire- and cable-management and connectivity systems, has acquired the connectivity group of Radiant Communications Inc. (South Plainfield, NJ). The Radiant division manufactures fiber-optic cabling systems and components used to transmit multimedia.

The Siemon Co. (Watertown, CT) recently opened a 172,000-square-foot manufacturing facility, which will be used primarily for its growing line of telecommunications-cabling systems.

Two new buildings encompassing more than 90,000 sq ft have been opened on Anritsu Co.'s campus in Morgan Hill, CA. The communications test-equipment manufacturer's facilities will house manufacturing/R&D operations and serve as a training center to support employee development.

Ortronics Inc., a worldwide manufacturer of extensive cabling and connectivity systems, has moved its global headquarters to 125 Eugene O'Neill Dr., New London, CT. The telephone number is (860) 445-3800.

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