ANSI - American National Standards Institute
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New ITU Standards Increase the Capacity of Fiber Optics


New York, Nov 12, 2003

The data traveling on the information superhighway is moving at the speed of light, and the traffic is a nightmare. According to the International Engineering Consortium, when U.S. telecom networks were first built, bandwidth capacity forecasts were calculated on the presumption that a given individual would only use network bandwidth about six minutes of each hour. The formulas did not factor in the amount of traffic generated by Internet access, faxes, multiple phone lines, modems, teleconferencing, and data and video transmission. Today’s usage numbers reflect a common bandwidth equivalent of 180 minutes or more each hour. A new international standard from the International Telecommunication Union (ITU) aims to allow network operators to increase the capacity of fiber optic networks in response to industry needs.

Fiber optics are long, thin strands of optically pure glass about the diameter of a human hair. Hundreds or thousands of these optical fibers are gathered in bundles called optical cables and used to transmit light signals and digital information over long distances. Fiber optics have dramatically increased the speed and amount of information that can be transmitted through a telecom network at any given time, and because several miles of optical cable can be made cheaper than equivalent lengths of copper wire, fiber optics are more cost-effective for providers and consumers alike.

While the advantages of fiber optics over conventional metal wiring are vast (cheaper, thinner, higher capacity), no one could have predicted the enormous bandwidth demand that exists today, and technology is responding as quickly as possible to meet these needs. Unfortunately, service providers cannot simply answer the congestion problem with the installation of more fiber optic cable into their infrastructure – it is extremely costly and at times logistically impossible to undertake construction to increase the thousands of miles of cable in the U.S. As an alternate solution, a technique called Dense Wave Division Multiplexing (DWDM) combines multiple wavelengths in a transmission, each representing a separate data channel, suddenly giving the same optic fiber the bandwidth capacity of multiple cables. For applications in metropolitan areas, the more bandwidth available per fiber, the more cost-efficient the network becomes. It is much less expensive to add an additional wavelength than it is to install another fiber.

ITU-T Recommendation G.695 applies to a technology called Coarse Wave Division Multiplexing (CWDM) that is seen as an even cheaper and simpler alternative to DWDM. ITU experts estimate that carriers with sufficient deployed fiber could make savings of up to 30 percent deploying a CWDM solution compared with the DWDM alternative. The growing demand for bandwidth in this area has created a need to better utilize existing infrastructure and for a new standard to ensure interoperability.

According to Peter Wery, chairman of ITU-T Study Group 15 responsible for the Recommendation, "CWDM systems have the flexibility to be deployed in point-to-point connections and in rings. Their suitability to carry Ethernet traffic and to interconnect Storage-Area-Network (SAN) islands make these systems of interest to large and medium-sized carriers, but also to cable TV companies and for enterprise network operators."

The meeting at which agreement on this standard and other work in the fibre-optics field was completed had the highest participation level of any standardization meeting at ITU since 2001 - a sign of industry's interest in this area and its commitment to the work of ITU. The standard was developed under ITU's fast track approval process (Alternative Approval Process).

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