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Technology Stocks : PairGain Technologies -- Ignore unavailable to you. Want to Upgrade?

To: DWCraig who wrote (31207)	5/12/1999 9:45:00 AM
From: Joseph Moran	Respond to of 36349

The following is from Telecommunications Magazine May 1999 issue, re: The 10 Hottest Technologies. HDSL2: Something Old, Something New ADC Telecommunications calls it “a new twist on an old pair.” The technology behind high bit rate digital subscriber line version 2 (HDSL2) isn't brand new; indeed, it is similar to the original HDSL. HDSL2, however, enables T1 communications to be delivered over a single pair of copper wires rather than the conventional two-pair with the same robustness, reach and spectral capability. According to John Griffin, general manager of ADC's Loop Division, “HDSL2 is the most significant development for T1 and E1 delivery in years.” With T1 rates growing at about 30 percent a year, the ability to double capacity on a pair is attractive to both incumbent and competitive service providers. A spiffed up modulation scheme developed to deliver service is one of the differences HDSL2 has to offer: overlapped pulse amplitude modulation with interlocking spectra (OPTIS), an advanced PAM 2B1Q line code. “With a technology like asymmetric DSL (ADSL), interference is a key concern,” said Claude Romans, director of forward loop access for RHK. “Within some binder groups you can have crosstalk between signals and cause interference, so there is a spectral compatibility issue. This isn't the case with HDSL2. There's high tolerance for the services being offered on adjacent pairs.” According to Dataquest, HDSL2 has mixed crosstalk performance at less than 5 decibels, making it a fit for deployment in worst-case environments. Another difference is standards: HDSL is mostly proprietary technology based on broad definitions developed by Bellcore and The American National Standards Institute (ANSI). The HDSL2 standard is estimated to be 90-percent complete and vendors are already announcing interoperability plans between their HDSL2, line and network termination units. Commercial availability could happen as soon as Q3 99. ADC and PairGain recently announced successful interoperability testing, and the two companies, along with Adtran, have released prestandards versions to trial customers. A third benefit of HDSL2 is reach: While HDSL and HDSL2 have approximately the same reach (12,000 feet before signal regeneration is required), two-pair HDSL2 could increase that reach to 16,500 feet, depending on copper conditions. ILECs are mostly interested in the technology to provide solutions in high-demand areas that are suffering from copper exhaust. The CLECs, however, see dollar signs: The cost savings could be tremendous, considering that CLECs on average get half of their revenues from T1 services. According to industry estimates, CLECs will control as much as 40 percent of all T1 business by 2002. Using one pair instead of two also frees up a CLEC's reliance on an ILEC to provide timely access to the copper loop. The cost savings won't be much of an initial factor for ILECs because of their installed base of HDSL equipment. HDSL2 is a direct competitor to HDSL, but the extent that one replaces the other is dependent on price, Romans said. About half of the T1s delivered last year were over copper, the other half over fiber. “Last year about 600,000 HDSL modems were delivered to customers, so the potential is there for HDSL2 to really take off,” he concluded.