(10/14/99, 1:36 p.m. EDT)
SANTA CLARA, Calif.— Integrated Telecom Express Inc. (ITEX) today unveiled its latest chip set for asynchronous digital subscriber line (ADSL) services, hoping to accelerate the technology's slow start in the broadband-access market by extending its physical reach to 20,000 feet.
ITEX's chip set, called the scalable ADSL modem (SAM), consists of one analog front-end chip and one digital controller with a PCI interface. Rather than using a dedicated processor such as a DSP, SAM off-loads most of the actual processing to a system's CPU.
The trade-off is that the chip set uses a portion of the system's CPU cycles. ITEX's long-term plan is to be "part of the Intel solution," possibly as a product that's someday integrated onto a PC motherboard, said Brian Gillings, vice president of marketing for ITEX. SAM takes up 17 percent of the Mips from a 500-MHz CPU, and would consume 8 percent of the Mips from a 700-MHz CPU, he said.
Gillings said that the portion of CPU cycles consumed by SAM is considered reasonable. "We were told by Intel and PC manufacturers that as long as CPU utilization was less than 25 percent, it was a viable product," he said.
ITEX's reliance on the PC CPU makes for a smaller chip set — 1 million transistors, compared with as many as 5 million for DSP-driven chip sets, ITEX officials said. The result is a $30 chip set for ITEX compared with $38 to $40 for competing chip sets, Gillings said. ITEX believes it can drive the SAM price below $20 eventually.
The SAM chip set conforms to the G.Lite standard, which was ratified by the International Telecommunications Union in June. But some of the advantages of G.Lite over "full-rate" G.dsm ADSL — which allows downloads at 8 Mbits/second rather than 1.5 Mbits/s — have been diluted. For example, ADSL operation initially required a splitter, a box that had to be installed by the telecom carrier in the home of each recipient. G.Lite did away with the splitter, and essentially replaced it with a user-installed filter that's needed for older phones. But full-rate ADSL has now caught up, and is also developing a splitterless mode.
G.Lite still offers some advantages, namely lower power consumption per port and higher port densities on the carrier end, said Stewart Hulett, applications engineer with FlowPoint Corp. (Santa Clara, Calif.). But the distance at which ADSL can be offered remains a handicap against alternatives such as cable modems.
Estimates of maximum ADSL loop length vary. ITEX officials quoted a practical figure of 16,000 feet from the central office, while 18,000 feet is the theoretical maximum so far, Hulett said. "We've seen loop lengths up to 22,000 feet, but in the service, they're not going to go that far to the edge. They want to promise something they can deliver," he said of service providers.
ITEX claims SAM can operate in households 20,000 feet from the central office. ITEX was able to extend distances through "optimization of filtering chips, as well as echo-canceling schemes," Gillings said. In July, Lucent Microelectronics announced a similar 20,000-foot capability for its WildWire ADSL modem technology.
The extra distance can add to ADSL's target markets substantially, according to a study by DSL vendor Orckit Communications Ltd., which is headquartered in Tel Aviv, Israel. "[Orckit] said at 12,000 feet only 50 percent of the people can be covered [by ADSL]. By extending out to 18,000 feet, 80 percent of the people can be covered," said Will Strauss, president of research firm Forward Concepts (Tempe, Ariz.).
Competitors say they haven't found a way to extend the reach of ADSL without hitting some compromise. Usually that means that the carrier-end box, known as a DSLAM, has to have a chip set compatible with that in the ADSL modem.
"We have looked at alternatives to be able to improve reach and make our products immune to potential crosstalk, but my understanding is, it's always a compromise," said Sassan Babaie, vice president of marketing with Pulsecom Communications Inc. (Herndon, Va.).
ITEX claims its SAM chip is compatible with any DSLAM chip set that operates on the G.Lite or G.dsm standard.
ITEX also claims the SAM chip set increases the speed of G.Lite, hitting download speeds of 3.5 Mbits/s and matching the G.dtm upload speed of 640 kbits/s.
ADSL deployment has been slow, Strauss said, despite the high numbers reported by some vendors. High volumes of chip sets have been shipped, for example, but many have gone into PCs whose owners probably aren't even aware they've bought DSL capability, he said.
All told, central offices will be equipped to handle 1 million ADSL lines this year, well up from 75,000 last year, Strauss said.
"Telcos don't do things quickly," Gillings said. "I don't think you'll see G.Lite distributed until the first quarter of next year."
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