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  • Nippon Telegraph and Telephone to Offer ADSL Service
  • December 21, 1998 (TOKYO) -- Nippon Telegraph and Telephone Corp. (NTT) decided to offer a high-speed data communications service using asymmetric digital subscriber line (ADSL) technology.
    NTT's service will start in some areas in the fall of 1999 and its nationwide deployment is scheduled for the fall of 2000.

    ADSL had not been a viable choice for NTT, because ASDL technologies are based on copper lines, while NTT's corporate policy centers around optical-fiber cables for access lines. However, NTT has admitted that more than ten years is required to complete the overall implementation of optical-fiber cables, and the company has decided to adopt ADSL during the construction of the optical-fiber networks.

    ADSL Service to Begin in the Fall of 1999

    "NTT hopes that in the fall of 1999 we will be able to start telecom services based on ADSL. Although there is no change in the priority we assign to providing optical-fiber cables, NTT continues to utilize copper telephone lines as complementary means to optical fibers," said Junichirou Miyazu, president of NTT.

    Using conventional methods, implementation of high-speed access lines at megabit speeds is impossible without laying new optical-fiber cables. However, with ADSL, it is realized by simply connecting ADSL modems with existing metallic telephone lines.

    The first application to provide an end-user service via ADSL is likely to be the Open Computer Network (OCN) run by NTT as an Internet connection service.

    NTT will add to its OCN service the OCN-ADSL Access (tentative name) based on the ADSL Access Line (tentative name), which operates at 1.5Mbps downstream and at 512kbps upstream. Also, NTT might specify more than two speed settings in a range between 384kbps and 1Mbps. (See chart.)

    The access charge of OCN-ADSL at 128kbps will be set higher than the OCN Economy priced at 38,000 yen (US$330) per month, and the access charge at 1.5Mbps will be set lower than the OCN Standard priced at 350,000 yen (US$3,020) per month, said Shogo Yokoi, executive manager of the OCN Service division.

    International Standards Solve Technical Issues

    NTT has several reasons for announcing the upcoming start of the new commercial service.

    First, on Dec. 10, NTT completed the xDSL Field Experiment that had been underway since February 1998. The ADSL service tests were successful, and thus NTT had to decide on its next policy.

    Second, the technical specifications of ADSL were adopted as an international standard. On Oct. 23, the Telecommunication Standardization Sector of the International Telecommunications Union (ITU-T) fixed technical specifications of the ADSL standard including G.992.1 (formerly called G.dmt) and G.992.2 (formerly G.lite) as the centerpieces. Setting the standards created an environment in which modems conforming to the standard specifications can be used worldwide.

    Also, the specifications of G.dmt and G.lite are equipped with a method called dual bitmap (DBM). The method minimizes interference with ADSL lines, NTT said.

    Third, NTT took into account requests from the Ministry of Posts and Telecommunications (MPT) and the U.S. government. A request from the MPT served as the trigger behind the xDSL experiment. The ministry requested in October 1998 the use of optical fibers and xDSL technology for Internet connections at schools.

    Also, the U.S. government requested that Japan remove regulations and barriers that were obstacles to implementation of the xDSL technology.

    NTT did not yield to external pressure on the issue of providing ADSL service. The company came up with its own initiative to upgrade access lines from current copper lines to optical fibers.

    NTT has promoted the diffusion of optical fibers, applying them to access lines. The offering of ADSL service, on the other hand, requires that all the subscriber lines should be copper lines.

    Even if subscribers can now use the ADSL service, they won't be able to continue using the ADSL service when optical-fiber cables are applied to their subscriber lines.

    NTT now specifies an upgrade policy from the ADSL service using copper lines to services based on optical fibers. User network interfaces will be standardized, NTT said.

    "Customers needing the ADSL service will be encouraged to use it as much as they want," said Kenichi Narimiya, executive manager of NTT's Advanced Technology Planning Section. "While doing so, NTT will promote the provision of cheaper and faster services than ADSL, by means of optical-fiber cables. If users choose to upgrade their lines to those of optical fibers, it will be best for NTT."

    NTT's Optical-Fiber Project Still Face Challenges

    NTT's decision is a major step forward. However, the telecom giant does face some big challenges.

    NTT maintains a target that optical-fiber transmission lines up to feeder lines will be installed throughout the country by 2010. However, this arrangement of supplying optical-fiber lines up to feeder lines is insufficient for providing some optical services.

    Therefore, NTT may need to review and reorganize access network facility plans including those for ADSL, provision of optical fibers up to feeder lines, the "pie" system, and fiber to the home (FTTH) as well as practical service plans.

    Chart: ADSL is added to NTT OCN Service.
    NTT East Japan and NTT West Japan, both of which are due to be established after the reorganization of NTT in July 1999,
    will provide OCN access lines based on the ADSL technology for NTT Long Distance.
    NTT Long Distance will start the service as the OCN-ADSL Access menu in the autumn of 1999, if all goes according to plan.

    (return to news)

    Related stories:
    � NTT to Launch ADSL Service in Summer 1999
    � NTT to Start General ADSL Service in Summer 2000
    � NTT Readies Optical Fiber Network for Connection to Homes

    (Hiroyasu Mizuno, Hiromi Nakagawa, Staff Editors, Nikkei Communications)



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    Updated: Sun Dec 20 17:06:58 1998 PDT