Milestones:ADSL

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Title

Asymmetric Digital Subscriber Line (ADSL) Enabling Broadband Internet, 1993-1997

Citation

In 1997, Alcatel’s A1000 ASAM product revolutionized broadband Internet access by providing multi-megabit per second downstream speeds over ubiquitous but decades-old and ill-conditioned subscriber telephone lines. A team based in Antwerp, Belgium began development of the product in 1993. The combination of ADSL technology, innovative signal processing, cutting-edge silicon integration, and a revolutionary architecture brought affordable broadband Internet to nearly one billion people worldwide.

Street address(es) and GPS coordinates of the Milestone Plaque Sites

Copernicuslaan 50, Antwerp, Belgium. Coordinates: 51.21398430096457, 4.423222477297228, Copernicuslaan 50, Antwerp, Belgium. Coordinates: 51.21398430096457, 4.423222477297228

Details of the physical location of the plaque

The intended site to place the plaque is the site where the development department that did the work reside. At the moment there are no historical markers at this site. The plaque will be placed in the lobby of this building.

How the intended plaque site is protected/secured

The lobby is accessible to the public during office hours, when a guard is present. Besides, there is video surveillance in the lobby 24/7.

Historical Significance

Around 1995, the Internet was still in its infancy, with around 20 Million active users. For most of those 20 Million users, the Internet experience was very different than today. It involved establishing a dial-up connection, which after a minute or so, provided a connection in the range of 14 to 34 kbit/s. Although such speeds allowed for basic Web services, none of today’s plethora of Internet and Cloud services were possible at all: YouTube, Maps, Netflix, Microsoft OneDrive, …

A fundamental bottleneck was affordable and scalable access technology. Yes, fiber access technologies existed - either point-to-point or Passive Optical Networks, e.g. APON (ATM Passive Optical Network) - but FTTH (Fiber-to-the-Home) technology was not affordable on a large scale. The other available option was cable networks (coax based). It took till the late ‘90s until the DOCSIS 1.0 standard started to get traction (reference Wikipedia – Cable Modem). But cable only reached a limited part of the global population. If only a technology would exist that could provide Broadband Internet access over the legacy of 800 million of copper telephone lines.

Early 1990s, Digital Subscriber Line technology was in full development. Be it as part of the ISDN (Integrated Services Digital Network) standard providing 144 kbit/s over approximately 5 km of copper (standardized in the mid to late 1980s), or as the HDSL (High bit rate Digital Subscriber Line) technology enabling symmetrical 2 Mbit/s or 1.5 Mbit/s over shorter loop lengths, with repeater capabilities (standardized by ANSI in 1994 and by ETSI and ITU in 1998). HDSL was mainly intended for high-speed connections to corporations and businesses. ADSL (Asymmetric Digital Subscriber Line) technology was in the prototyping phase, a.o. driven by Prof. John Cioffi, with a major milestone at the Bellcore ADSL Olympics early in 1993. At this competitive testing event the Discrete Multi-Tone (DMT) prototype of Amati (founded in 1991 by Prof. John Cioffi) showed its superiority over the single-carrier (CAP and QAM) technologies. This resulted in the selection of DMT as line code for ADSL by the ANSI T1E1.4 Committee in March 1993. This line code decision by ANSI was the start for the Antwerp based Alcatel team to accelerate its research and development of a scalable and affordable ADSL technology, that would revolutionize fixed access, and expedite Broadband Internet for society (see Footnote 1)).

The historical significance of Alcatel’s ADSL achievements is also described in [1] that examines how Alcatel successfully explored and exploited the promises of Broadband Access Technology. In the period between 1993 and 1997, the Alcatel team invented and developed an end-to-end ADSL solution that had all the right capabilities to bring Broadband Internet to millions, and later multiple hundreds of millions of households. In parallel, Alcatel actively contributed to the standardization of ADSL in ANSI T1E1.4 and took up the editorship role of the Issue 2 of this standard (T1.413-1998 Issue 2, approved Nov. 1998). Moreover, from the beginning, Alcatel addressed all challenges inherent to large-scale deployment by creating an eco-system of partners, organizing interoperability events, licensing its technology and patents, facilitating end-user self-installation and enabling large scale manufacturing and multi-sourcing. These efforts established a viable ADSL business model for telecom operators, at an affordable price point and excellent service experience for the end-user. As a result of this, ADSL had a tremendous impact on the acceleration of global affordable Broadband Internet Access. Although the underlying technology itself is highly complex, Alcatel created a standard compliant product that was easy to deploy on the 800 million legacy copper telephone lines present in the world. Alcatel’s ADSL took full benefit of the telecom operators’ already available infrastructure, i.e. the existing copper lines and the existing Central Offices. And the end-user could simply self-install the ADSL modem. No truck-roll or professional service was required to set up the connection at the end-user. No trenching, digging or other civil works were needed. The solution could be deployed in overlay on any existing type and brand of telephony central office switches, creating a truly open market, without restrictions and lock-in of legacy equipment and vendors. Moreover, the interface between the central office equipment and the end-user ADSL modem was fully standardized and open, creating a wide choice of end-user devices.

Through a high level of integration, the Alcatel solution realized a breakthrough in cost, making the technology extremely affordable, also for lower income regions. With all these benefits, Telecom Operators around the world successfully deployed the ADSL technology, providing affordable Broadband Internet access to hundreds of millions of households around the world. The spread of the ADSL Broadband technology around the world was a key contributor to the further development of the Internet and World Wide Web. The ADSL technology provided the bandwidth capacity and low latency that was required to develop a wide range of applications and services. Including as example: high speed file download, IPTV and video streaming, videoconferencing, work at home, interactive gaming, cloud services, advanced advertising, surveillance services, … Thanks to the invention of affordable and scalable ADSL technology the availability of these application and services was accelerated.

Features that set this work apart

The former work of Prof. John Cioffi and Amati laid the technology foundation and set the direction for ADSL. The achievements of the Alcatel Antwerp team however go much beyond this. The team innovated andeveloped the technology such that it was compatible with the hundreds of millions of copper lines around the world. It also created and developed a performant, cost effective and scalable ADSL end-to-end solution, enabling global coverage. It also scaled production, global distribution and support to fuel the mass market.

Hundreds of technical challenges were tackled and resolved, witnessed by the amount of (standard essential) patents generated and scientific publications made. The high level of ASIC integration and the design of ATM based and linear scalable Central Office products that could be produced in high volume at low cost, enabled the global mass adoption of the technology. The magnitude of investment in standardization and interoperability and the technology licensing resulted in the creation of a single global ADSL market.

Footnotes

1) Alcatel had been performing research on ADSL since the beginning of 1992 but did not participate to ANSI T1E1.4 till May 1993.

2) There is no unique worldwide standard for telephone cables and even within a single country typically many different cable types have been deployed.

3) Two types of interference exist between adjacent pairs in the same cable: Near-End Crosstalk (NEXT) is interference between a transmitter at one cable end and near-end receivers. Far-End Crosstalk (FEXT) is interference between a transmitter at one cable end and far-end receivers. NEXT and FEXT coupling increase with frequency.

4) Examples of (semi-)stationary alien noise are crosstalk from symmetric xDSL flavors, e.g. HDSL or pick up of medium- and longwave radio signals. Later xDSL flavors occupying higher frequencies could also experience interference from shortwave radio, and even FM broadcast, amateur radio, public safety and emergency communication, etc.

5) Impulse noise is a temporary signal that can be narrowband or wideband and that occurs randomly, caused by a variety of sources such as light switches, electromotors, dimmers, and rogue equipment.

6) Single wire contacts, capacitive contacts, intermittent contacts, flat pairs, and split pairs are examples of single pair faults.

7) Bridged taps are side branches of the telephone twisted pair between the DSLAM and the CPE. Bridged taps can occur in the outside plant (e.g. to allow the telephone operator to assign the pair to one house or another) and at the end-user’s premises (e.g. to connect different telephone sets). Bridged taps cause reflections and therefore distort the ADSL signal.

8) Water ingress typically increases the capacitance and conductance per cable length and can cause pair unbalance.

References

[1] B. Van Looy and K. Visscher, "Organizing Innovation within Incumbent Firms: Structure Enabling Strategic Autonomy," pp. 147-166, January 2011. Media:Ref 1 VanLooyVisscher2011.pdf

[2] P. Reusens, D. Van Bruyssel, J. Sevenhans, S. Van Den Bergh, B. Van Nimmen and P. Spruyt, "A practical ADSL technology following a decade of effort," IEEE Communications Magazine, vol. 39, no. 10, pp. 145-151, Oct. 2001. Media:Ref 2 00956126.pdf

[3] L. Van Hauwermeiren, P. Spruyt and D. Mestdagh, "Offering video services over twisted pair cables to the residential subscriber by means of an ATM based ADSL transmission system," in International Switching Symposium (ISS), Berlin, Germany, April 1995. Media:Ref 3 video services ATM ADSL (ISS 1995).PDF

[4] D. Mestdagh, P. Spruyt and B. Biran, "Analysis of clipping effect in DMT-based ADSL systems," in International Conference on Communications, New Orleans, LA, USA, 1994. Media:Ref 4 00369042.pdf

[5] J.-F. Van Kerckhove and P. Spruyt, "Adapted optimization criterion for FDM-based DMT-ADSL equalization," in Proceedings of International Conference on Communications (ICC/SUPERCOMM), Dallas, TX, USA, 1996. Media:Ref 5 00533625.pdf

[6] P. M. P. Spruyt and P. P. F. Reusens, "Multicarrier transmitter or receiver with phase rotators". Patent EP 0 820 171, 15 July 1996. Media:Ref 6 EP0820171B1.pdf

[7] K. Adriaensen, F. Van Beylen, S. Van Hoogenbemt, H. Van de Weghe, J. De Laender, G. Verhenne and P. Reusens, "Single chip DMT-modem transceiver for ADSL," in Proceedings Ninth Annual IEEE International ASIC Conference and Exhibit, Rochester, NY, USA, 1996. Media:Ref 7 00551976.pdf

[8] F. O. Van Der Putten and P. M. P. Spruyt, "Method to transparently transport an incoming clock signal over a network segment, and related transmitter and receiver unit". Patent EP 0 841 767, 8 Nov 1996. Media:Ref 8 EP0841767B1.pdf

[9] D. Veithen, P. Spruyt, T. Pollet, M. Peeters, S. Braet, O. Van de Wiel and H. Van De Weghe, "A 70 Mb/s variable-rate DMT-based modem for VDSL," in IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, CA, USA, 1999.Media:Ref 9 00759222.pdf

Supporting materials

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