[Random thoughts related to PAIR, ADI, AWRE, COMS, TXN, WSTL. . .]
Pigboy ---
First of all, for Trey's sake, I think it's time to explain your moniker. :)
Now to some random thoughts. Today I spoke with Aware's CEO, Amati's VP of business development --- just back from TI where folks from COMS were also visiting --- and Siemens' West Coast Director of ADSL.
My topic? G.Lite, or DSL-Lite, or splitterless ADSL, whatever you want to call it.
My reason? Aware demonstrated its new DSL Lite for editors and analysts last week at their Bedford headquarters and because I couldn't attend, JB phoned to summarize. Once I hung up, I made some phone calls to bring myself up to speed.
In lieu of my describing splitterless DSL, here's a quick backgrounder, for anyone who doesn't know what it is. Skip to end for summary.
aware.com
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What is meant by splitterless?
The original ADSL standard, T1.413 incorporates a POTS Splitter in both the remote terminal and the central office. The splitter is designed to separate the voice band from the DSL spectrum. The idea is to protect both signals from interfering with one another. The issue of where the POTS Splitter belongs in both locations has been widely debated and is yet satisfactorily resolved. In most cases the Splitter is a separate physical device that requires a skilled technician to install.
DSL-Lite eliminates the need for a POTS Splitter, hence the term splitterless. It is designed to be implemented on a modem chipset with a PC. PCs that today provide 32Kbps and maybe 56Kbps will be capable of hundreds of kilobits using DSL Lite. At a home a PC user simply plugs the DSL Lite Modem into the phone jack. This simplification will enable rapid mass deployment of DSL technology. The removal of the splitter removes the requirement of a "truck roll" by the service provider to install the device. This greatly facilitates mass deployment.
Will I need new wiring in my home?
No, DSL-Lite has been designed to work with existing home wiring. It is important to note that this environment is as widely variable as the local loop itself. Here, the topology is largely random with different gauge wires, flat pairs etc. Also, every phone jack in the home represents a bridged tap.
What's a bridged tap?
A bridged tap is an unterminated wire pair that sits in parallel to the main wire pair. In the local loop they appear when the local phone company "taps' off an existing pair to provision a new service to a new subscriber. Typically, they do not remove the un-used cable segment and a bridged tap is created.
In the home, every unused phone jack represents a bridged tap.
Bridged taps create an impairment to the transmission system. The signal traverses down the un-terminated cable and reflects back to the main pair affecting the main signal. The reflection can severely affect the primary signal.
What data rates are supported?
For CSA type loops payload data rates of over 1.5 Mbps downstream and over 384 kbps upstream are supported with the splitterless configuration. For longer loops the system achieves payload rates of over 512 kbps downstream and 128 Kbps upstream. For those requiring symmetrical rates DSL-lite can support 384 Kbps symmetric over the 18,000 foot loops. All these data rates are supported simultaneously with voice band services such as POTS, fax, and modems.
Why DMT?
Discrete MultiTone modulation is the technology used in T1.413 for full rate ADSL. It has proven over and over again that it is extremely robust in the local loop environment. By using Aware's DMT technology in the DSL lite application interoperability with full rate is easily achievable.
Why is interoperability with full rateT1.413 important?
Local exchange carriers must deploy access equipment in thousands of Central Offices and Digital Loop carrier systems. With the major LECs having over 10 million local loops, the equipment they select for deployment must be technically robust and available from multiple vendors. Thus, standards play an important role. T1.413 compliant central office and outside loop equipment is coming on the market from numerous vendors including many of the large established vendors. The DMT technology that Aware is proposing for DSL lite is such that it can be made to talk to standard compliant ADSL T1.413. In the event that DSL Lite was not interoperable with T1.413 the LEC would be faced with deploying two systems or perhaps none at all, preferring to wait for the standards to settle.
Recently, a large industry consortium presented their support of DMT for Splitterless DSL at the T1E1.4 standards body.
Can I make a Phone call while using the DSL-Lite modem? Fax? Voice band modem call?
Yes, DSL-Lite enables simultaneous use of the voice band for all voice band services.
How does it compare to ISDN?
ISDN is a switched service that is transported through the PSTN. It supports data rates of 64K and 128K. DSL-Lite is primarily targeted at IP data services. IP/PPP is transported over the loop in ATM cells or other frame based packets such as FUNI or HDLC like frames. Once it reaches the CO or DLC cabinet the data is transported to the ISP via the LECs ATM interoffice WAN. Thus the data never reaches the PSTN freeing up ports on the voice switches.
What does "always on" mean?
Current dial-up services require the user to "make a call" to the ISP. The connection is only active during the duration of the call. DSL-Lite enables the connection to be always on in a fashion similar to a LAN. When you get to the office you turn on your computer and stay on the LAN all day. DSL-Lite will be similar in that once you connect to the network you can remain on for as long as you'd like. Thus, you'll be able to receive an EMAIL when it arrives. No longer will you have to dial-in just to download your email. Additionally, advances in push technology can leveraged to create new exciting applications.>>>>
alcatel.com
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Paris, December 2, 1997 -- Alcatel has taken a further step in its continuing effort to improve the ease of use and ease of installation of ADSL.
It has demonstrated a high-speed ADSL service that does not need a POTS splitter to be installed in the subscriber's home. The "splitterless" ADSL service is offered over the existing Alcatel DSLAM and ADSL modem.
This further extends the range of services that can be offered with the Alcatel DSLAM to include a rate-adaptive splitterless ADSL-Lite service in addition to the full rate ADSL service. Moreover, the demonstration confirms that splitterless ADSL with simultaneous POTS services can be interoperable with DMT standard-compliant (T1.413) equipment.
Alcatel is active in contributing to the different standardisation bodies currently working on a "Lite" version of ADSL and ensuring that ADSL-Lite modems will be able to interwork with existing standard-compliant DSLAMs. Operators and service providers therefore have choice in offering a wide range of services to subscribers connected to a single type of ADSL DSLAM. This can range from several hundreds of kilobits to multiple megabits, with or without POTS splitters at the subscriber site. ADSL subscribers can be offered service upgrades with an optional installation of a POTS splitter to maximise performance.
Alcatel aims at commercially offering support for ADSL-Lite on its third-generation ADSL DSLAM. The highly-programmable, rate- adaptive DMT chipset currently used in the Alcatel ADSL equipment already offers the flexibility needed to implement this solution.
This new development for splitterless ADSL represents a further move by Alcatel to ensure mass-market availability of high-speed Internet access based on a single, standardised ADSL technology.
Recently, Alcatel has announced other ADSL products improving ADSL's ease of use, such as the ADSL PC-NIC card with Plug 'n Play support (shown at Interop '97, Atlanta) and the ADSL modem with USB interface (shown at Comdex '97, Las Vegas).
This solution offers operators a range of variants, including versions with and without splitters to allow them to extend their service offerings taking into account commercial, regulatory and installed base parameters. In addition, several variants of POTS splitters are available to maximise ADSL performance, as part of easy-to-install solutions.
Alcatel's main customers for ADSL technology are Singapore Telecom, the American operators Ameritech, BellSouth, Pacific Bell and SouthWestern Bell, Telia in Sweden, British Telecom and, more recently, Bell Canada, Belgacom, Telefonica in Spain and France Telecom. Pilot projects have also been ordered by Korea, Japan and Denmark. Today Alcatel holds over 30% of world market, making it the world leader in ADSL technology.
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As I understand it, the T1/E1 committee is considering adding a Lite solution to the standard. The head of the ITUI committee is from COMS and they --- COMS --- want to use a separate standard and have agreed to make it backwards compatible with the ANSI standard. Compatibility is the big issue. TI/ADI/AMTX/ALA are all working towards this. TI/ Alcatel is a slam-dunk --- the others are close.
ADSL vendors met with PC leaders in December and chose DMT as the accepted standard. Their goal is to reach the Christmas '98 market with announcements possibly as early as February.
Q: Will modems be software upgradeable, whether free-standing or installed in box?
A: Yes, if based on DSPs.
Q: Will telcos install standard ADSL so customers can upgrade to higher speeds as wanted or needed?
A: Yes, this is likely.
Q: Are there regulatory issues involved with the FCC?
A: One said, no, one said, yes, one said he'd ask his experts and get back with me.
Q: Who would stand to lose?
A: ISDN and HDSL.
Q: Who will gain?
A: DMT players with Lite solutions. Retail modem makers: COMS, of course, though no one knows whether they'll use ADI or TI for chips. Both are rumored to be in talks.
Q: Does WSTL have a Lite product?
A: I don't know. Anyone???
Q: Strategy behind decision?
A: If computer makers include in boxes, telcos will be forced to upgrade COs. If 2 or 3 PC makers begin, the others will scramble to find OEMs.
Q: Will there be market for stand-alone modems?
A: Yes.
I haven't drawn any profound conclusions other than it appears the PC and telco industries are cooperating, They agree they don't want a split standard, nor do they want to confuse the market. My Siemens contact made this clear as did the others. The decision to push a Lite solution doesn't change telcos thinking on standard ADSL --- they'll most likely install it from the git-go --- and in the meantime not have to worry about provisioning the customer premise. Jim Bender said success actually could lead to a "nightmare scenario" if telcos had to do both ends.
So now I guess we wait for the PC makers to announce "DSL for Christmas," and load up on COMS and ??? in the meantime. I don't own any, but I think the time has come. . .
Incidentally, besides ALA and AWRE and TI, who else has a splitterless solution? I'm too tired to search the different news archives.
Also, we seldom talk about Siemens, but don't be fooled. They're hand-in-glove with TI. And as for Cisco, I wouldn't be surprised if they're in the middle of this somehow, somewhere.
That's it for now.
Night --
Pat |
