RESTON, Va. Four months after the G.Lite plugfest spelled the end of the short-lived Universal ADSL Working Group, activity among carriers and OEMs working in digital subscriber line services indicates that there is anything but universal agreement on the virtues of splitterless ADSL. At the DSLcon symposium this week, advocates of full-rate ADSL systems could argue convincingly that no carrier orders to date have specified the splitterless version of ADSL, standardized as ITU 992.2.
Lucent Technologies Inc. and other vendors launched full-rate chips, while 2Wire Inc. founder and president Brian Hinman went so far as to call his conference speech "G.Lite is G.dumb." At the same time, central office equipment manufacturer Copper Mountain Networks Inc. (Palo Alto, Calif.) elected to leapfrog past full-rate ADSL by moving directly to G.Lite in a 24-port line card for its CopperEdge DSL Access Multiplexer, using multichannel transceiver chips from Centillium Inc.
Even symmetrical DSL services at DSLcon won advocates outside the business-access community where SDSL and HDSL-2 were born. Xpeed Inc. (Santa Clara, Calif.) debuted SDSL-based USB modems and PCI network interface cards inexpensive enough to sell to mass markets, while proponents of the new HDSL-2 standard announced a marketing coalition to propel the symmetric T1-speed standard into a broader range of business applications.
A skeptical observer might say that fragmentation of line rates and services was hurting DSL's chances against cable modems, although the DSLcon show here was larger than ever, and developers were excited about long-delayed plans for true deployment of DSL services by many incumbent carriers. Still, the diversity of modulation schemes and services at the show underscored the mistakes made by the UAWG group in trying to move a single flavor of DSL into the mass market.
If any company was destined to represent the quintessential G.Lite customer, 2Wire (Milpitas, Calif.) would have been it. The startup, founded by members of the videoconferencing team at Polycom Inc., needed a simple and inexpensive home-network interface for its universal residential gateway system. But 2Wire's Hinman said that splitterless ADSL didn't eliminate the need for splitters in the home, it just pushed the requirement out to bandpass filters that must be attached to each phone in the house. If carriers are looking for a multiservice package for customers, Hinman said, G.Lite is an inferior solution because the fast-retrain algorithms it uses after a phone goes off-hook cause unacceptable latency for voice and video. Using an analog circuit-switched phone near a DSL modem produced intermodulation noise that was not quantized, Hinman said, but instead caused a "continuum of annoyance" for phone users.
Rather than convince the world to go full-rate ADSL, 2Wire decided to design passive microfilters that it will ship to carriers along with its residential gateway. While showing the microfilter, Hinman joked that "there is probably more money to be made in this than in chip sets," although 2Wire vice president of marketing Brad Kayton emphasized the company never wanted to be diverted into passive components design, but felt it had to offer solutions for G.Lite in the home, since G.Lite deployment seemed inevitable.
As an indicator of the continued strong market for full-rate ADSL, Lucent launched a dual-channel transceiver for central offices, the 16370 chip set, which handles only full-rate ADSL. Motorola introduced a cost-optimized single-channel central office chip, the MC145660, which can handle both full rate and G.Lite, although Ken Cavanaugh, Motorola's ADSL product line manager, stressed that preserving full-rate coding as an option was essential given current states of ADSL deployment.
Still, many of the OEMs who hesitated to commit to an ADSL design are jumping straight into G.Lite. Diana Helfrich, vice president of marketing at Copper Mountain, said that the competitive carriers to whom Copper Mountain sells its symmetric DSLAMs, are just waking up to the potential of asymmetric services as an entry to residential markets. A white paper on G.Lite prepared by Centillium was co-authored by Copper Mountain, and by Mark Peden, a former Intel executive who recently joined CLEC Northpoint Communications Inc., an indicator of how seriously Northpoint treats the provisioning of G.Lite as a vehicle to enter consumer markets, Helfrich said.
Advocates of SDSL (a midspeed symmetric DSL service), HDSL-2 (a T1-speed service using only a single copper pair) and VDSL (a very high bit-rate service designed for very short copper loops) were out in force at DSLcon, claiming their services offer wider options than ADSL. The HDSL-2 vote of confidence from six companies carried a touch of irony, in that Intel Corp. subsidiary Level One Communications Inc. is leading the charge. Intel had been a founder of UAWG, but Peden, its G.Lite evangelist, defected to Northpoint, and Intel's own efforts are driven more by Level One talents these days.
Ron Cates, division manager for DSL products at Conexant Systems Inc. (Newport Beach, Calif.), said his company remains as committed to HDSL-2 as it is to SDSL. In the latter market, Conexant ships 1 million units of its ZipWire modem per quarter, but still would like to adhere to true standards in symmetric services. The problem, Cates said, is that the International Telecommunication Union is turning to a "G.shdsl" standard for multirate symmetrical services, using a different spectral mask than HDSL-2, and the divergence in standards may make it too difficult for chip-set suppliers to keep up.
The ITU and American National Standards Institute earlier this month tried to agree on seven spectral classes of DSL service, but failed to pass a ballot vote. Cates said a working group would meet in Huntsville, Ala., next week to try to reach a compromise. However, Paul Nurflus, product manager for Metalink Ltd., said he is "less than optimistic" that agreement on spectral masks is possible, since incumbent and competitive carriers are treating service spectra as a zero-sum game, with the CLECs in particular wanting to extend the length of SDSL, to the detriment of ADSL.
Even the tried-and-true SDSL may enjoy a bit of a renaissance, as the increasing use of streaming video and MP3 files push the wider use of bidirectional broadband services. Xpeed, an early pioneer in ADSL interface cards and standalone modems, came to DSLcon with USB-based SDSL modems in standalone boxes and PCI-based SDSL network interface cards, priced low enough to compete with higher-end analog modems. Rick Hatton, Xpeed's product marketing director, said symmetric services will be offered primarily to telecommuters and other remote business customers, but the modems must be self-configuring and easy to use because neophytes will be installing them.
The obsession with voice-over-DSL services continued unabated at the DSL conference here. Paradyne Corp. (Largo, Fla.) joined a long list of DSLAM developers that have agreed to collaborate with all three players in the VoDSL gateway space: TollBridge Technologies Inc., CopperCom Inc. and Jetstream Communications Inc. Netopia Inc. (Alameda, Calif.), a router and DSL access specialist that announced a similar tripartite deal with the gateway vendors in June, capped off its VoDSL strategy this week by acquiring StarNet, a company working on embedded voice DSP solutions that could become part of Netopia's router and access products.
Paradyne also launched a high-end member of its HotWire family, dubbed GranDSLAM, that resembles an all-purpose broadband concentrator more than a DSLAM. The system can handle a variety of voice, frame relay, IP and ATM traffic and can natively treat time-division multiplexed traffic as true circuit-switched traffic. The GranDSLAM system does not just handle ATM cells through a segmentation/reassembly device, said marketing director Ron Stein, but has a native ATM switching fabric capable of handling 8,000 ATM virtual circuits.