Undersea fiber network to link China and U.S.

Feb. 1, 1998

Undersea fiber network to link China and U.S.


A broad consortium of U.S. and international telecommunications companies has agreed to finance a $1 billion undersea fiber-optic network directly linking the United States and mainland China. Service on the network is expected to begin by year-end 1999.

The 18,750-mi (30,000-km) fiber-optic network will be financed and operated by an international group that includes at&t Corp., China Telecom, Chunghwa Telecom, Hong Kong Telecom, Kokusai Denshin Denwa (kdd-Japan), Korea Telecom, mci Communications, ntt Worldwide Network (Japan), sbc Communications, Singapore Telecom, Sprint, Teleglobe usa, Telekom Malaysia, and Telstra Corp.

The project is far less ambitious than ctr Group`s planned $1.4-billion-dollar, 320,000-km global undersea fiber-optic network, which is designed to incorporate 265 landing points in 171 countries (see related story on page 15). However, the new network will target the high-growth Chinese markets that U.S. telecommunications giants are eager to enter.

Peter Krasilovsky, a telecommunications analyst with Arlen Communications, Bethesda, MD, believes this deal shows that U.S. and international telecommunications companies are clearly placing bets on China as the logical network hub in the Asia-Pacific region. "China benefits from the `one billion pairs of shoes` phenomenon. It`s a huge market that is spending tremendously to develop its telecommunications infrastructure. China is a growth market, and that`s where all the action is," he says.

Krasilovsky maintains that other Asia-Pacific countries heretofore looked upon as so-called light telecommunications landing hubs, such as the Philippines, are most likely to be the long-term losers, while Japan, Korea, and Australia are likely to be viewed as less significant than once assumed.

Even so, two of the network`s four legs will land in Korea and Japan. The northern transpacific segment will connect Brandon, OR, to Chongming, China, with additional landing points in Pusan, Korea, and Chikura, Japan. The southern segment will connect San Luis Obispo, CA, to Shantou, China, with additional landing points in Okinawa, Japan, and Tanguisson, Guam. The eastern leg will connect Brandon with San Luis Obispo, and the western portion of the network will link Shantou and Chongming, with landing points in Fangshan, China.

According to representatives of the various companies taking part in the project, the 7815-mi (12,500-km) southern route from San Luis Obispo to Shantou will be the longest direct undersea telecommunications segment in the world. Tyco Submarine Systems (tssl), Alcatel, and Fujitsu will jointly build that part of the network. nec and kdd Submarine Cable Systems (Japan) will construct the north and west segments.

Deployment to begin in 1998

Cheryl McCants, tssl`s director of marketing and public relations, says actual cable deployment will begin in the fourth quarter of 1998. Marine activity will run from December 1998 to January 1999, with three ships working simultaneously (two owned by tssl and one owned by a Chinese firm). McCants says most of the work (including construction of all plant equipment) will take place before the cable is laid. Once the cable is laid, the network will be functional to that point.

The fiber-optic network requires both dry plant (the cable stations on dry land) and wet plant (optical amplifiers or repeaters positioned in the ocean). The specifications call for approximately 200 nautical mi between repeater placements. tssl is supplying the amplifiers, and nec and Fujitsu will provide the cable.

The dry-plant stations will include universal network management equipment (unme), which tracks potential system faults and checks for breaks in the network. unme can also route the flow of traffic across the network. Equipment used to connect with various central offices is also housed in dry-plant stations. Network redundancy is accomplished through a ring topology and multipair fiber configuration. The cable sheath holds four fibers in two pairs, one pair to send and receive, the other pair as backups. Segment protection will be accomplished through traffic rerouting.

The network will be designed to operate at up to 80 Gbits/sec using wavelength-division multiplexing (wdm). It also will incorporate Synchronous Digital Hierarchy (sdh) transmission schemes. sdh is the international equivalent of the Synchronous Optical Network (sonet) protocol established by Bell Communications Research and now prevalent in the United States.

wdm and zero-dispersion-shifted fiber

According to Rajesh Kheny, director of design solutions at tssl, the fiber-optic cable is equivalent to a newer type of zero-dispersion-shifted product, and better realizes zero dispersion of light pulses over higher bandwidth (wdm) rates. "The fiber helps in the propagation of extra wavelengths in the 1530- to 1585-nm window," he explains. "This fiber allows for a broader number of channels to fit in that range, and that`s what wdm is all about."

Because other countries typically follow the European sdh system, the cable system will have an sdh architecture, but it will be compatible with the U.S. sonet standard. Mapping (formatting) software residing in the multiplexing equipment will be able to reformat light signals locally into either standard. On the U.S. part of the network, signals will be mapped into sonet rates. In Asia, they will be mapped into sdh rates.

The International Telecommunication Union has adopted a light-signal formatting structure that equates stm-1 at 155-Mbit/sec rates--equivalent to OC-3--which allows clear mapping between sdh and sonet. stm-4 is equivalent to OC-12 (622 Mbits/sec). Multiplexing that by 16 times equals 2.5 Gbits/sec, equivalent to OC-48 sonet. With wdm, multiplexing a total of eight wavelengths per fiber pair will yield a total network capacity of 80 Gbits/sec. q

Paul Palumbo writes on telecommunications issues from Seaside, CA.

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