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RealTime IT News

Move Over Cable, Here Comes G.Lite

Until now, one of the impediments to the spread of Digital Subscriber Line service has been the lack of a universal standard. That all changed this week with Tuesday's approval of G.lite.

G.lite -- also known as Universal ADSL and referred to as G.992.2 by the International Telecommunications Union or ITU -- allows for high-speed "always on" digital communications over standard copper phone lines. The standard was determined last October and final approval is slated for the end of this month.

While it is based on the same underlying technology as standard ADSL, G.lite carries with it a number of advantages for both ISPs and their customers. Probably the biggest plus is that there's no need for a splitter to be installed at the customer location. This eliminates the need to dispatch a technician. After a customer places an order, the ISP provisions the central office equipment, and the customer simply attaches a G.lite modem. It's a plug-and-play process that is no more difficult than using a standard analog modem to connect to the Internet.

Hardware manufacturers are already rolling out G.lite modems, which, reportedly, will begin showing up in retail outlets in the next month. Compaq Computer Corp. is equipping PCs with the needed hardware and other companies including Ameritech, Bell Atlantic, British Telecommunications, Lucent Technologies, GTE, Intel, MCI WorldCom and Microsoft Corp.have announced services or hardware. Since G.lite is based on the same underlying technology as standard ASDL, the equipment is expected to be compatible with both systems.

Unlike standard ADSL, G.lite works with Digital Loop Carrier, the local loop infrastructure that connects customers located more than 18,000 feet from the central office, which opens the technology to a much wider audience.

"Now that we can support DLCs, it's conceivable that within the next three to five years, the technology will serve 90 to 95 percent of all the homes in America," said Mark Peden, ADSL Forum Ambassador and senior DSL technologist for Intel. "Some 50 percent of new homes in the U.S. are served off a DLC. This resolves a critical issue that has plagued the industry," Peden said.

The tradeoff for the increased availability of G.lite is lower speed. While standard or full-rate ADSL provides downstream speeds of up to 8-Mbps and upstream speeds of 1.5-Mbps, G.lite is limited to 1.5-Mbps downstream and 512-Kbps upstream.

This is still much faster than alternatives like ISDN, which has a top speed 128 K, or satellite delivery systems which top out at 400 K downstream and require a conventional modem for upstream transmissions.

Cable is currently the greatest competition to G.lite, but it has significant limitations and drawbacks of its own: Except for the few areas where two-way service is available, cable modem service currently requires a telephone line for upstream transmission. Cable is also a shared system. With a large number of users sharing bandwidth, both performance and security concerns become critical. By contrast, G.lite and ADSL provide dedicated, point-to-point connections allowing for consistent performance in a secure environment. Finally, like full-rate ADSL, cable requires that a technician be dispatched for installation.

With approximately 500,000 cable modems already in use and an estimated 2,000 more being deployed every day, cable will continue to be a factor in broadband Internet access. But, it now has some serious competition.

"G.lite is going to turn up the heat on the cable companies," Peden said. "The ease of deployment and the relative low cost for consumers will allow ISPs to meet and even exceed the growth of cable as Internet providers."