HDSL4 tries to break out and extend reach

DENVER (Telephony)—At this week’s DSLCon, several vendors were touting the new four-wire variation of the HDSL2 standard, HDSL4. The objective of the technology is to complement HDSL2 and extend the reach of the carrier servicing area (CSA) by reaching circuits beyond the CSA range.

The HDSL4 technology is optimized for DS1 transport and allows repeatered deployment for extra reach while it maintains spectral compliance. The Spectrum Management Standard (T1.417) details the allowable amount of crosstalk that new technologies may create when deployed with ADSL and other DSL flavors.

“Providers will be able to extend their CSAs 25% to 30%,” said Jay Wilson, director of product management for ADTRAN. “It has the added benefit of being spectrally friendly with ADSL.”

While the added reach and the compatibility sounds good, no standard has been established for the technology. ADTRAN’s Wilson expects to take the technology to lab and field trials by the end of the year. According to Wilson, incumbents such as SBC Communications are taking a serious look at the new technology.

Other vendors such as ADC also are helping develop the technology.