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Backbone Transmission Technology Development

A high-speed backbone network is needed for adequate Internet data traffic flow. A weak or overutilized backbone network adds unnecessary bottlenecks and prevents data from getting to its final destination.

Keeping expenses in check is critical since the laying down of fiber, especially in large urban areas, can be costly. New methods of further expanding the capabilities of existing fiber have been produced by the use of increased optics instead of electronics.

Additional scientific experimentation concerning backbone networks includes photonic fiber, which eliminates glass transmission media altogether.

Dense Wavelength Division Multiplexing

Dense wavelength division multiplexing (DWDM) is an optical technique for creating parallel transmission paths on a single fiber. Each path or wavelength can carry as much information as a single-strand optical fiber once carried. So, a 64-wavelength DWDM on one strand of fiber is the equivalent of 64 individual strands of fiber without DWDM.

The concepts regarding DWDM are simple. Remember that prism you needed in high school? Colors are transmitted through the air together and can mix. A prism, however, separates the white light from the sun into a spectrum of colors. In DWDM, each wavelength or color is used as a separate channel (Figure 10.2).

As improvements in optical networks and DWDM increase, the cost of back

Figure 10.2Figure 10.2 DWDM.

The costs associated with digging up streets and laying fiber are astronomical. In addition, carriers must negotiate right-of-way, which has become even more expensive in recent years. Generally, it makes economic business sense to use existing resources (fiber) and add DWDM equipment to it.

Ever-increasing bandwidth demands have forced backbone providers to install DWDM equipment. In fact, with DWDM, the bandwidth of fiber can be increased within a few weeks, whereas digging up the streets to install new fiber can take several months or years to accomplish.

The biggest problem with DWDM is the technology itself. Presently, DWDM is in its early stages of development but is rapidly expanding. Each year, more and more wavelengths are made available with newer equipment design. Existing telecommunications carriers must take a gradual approach with DWDM because today's technology will not be tomorrow's state-of-the-art.

Photonic Fiber

For the past 20 years, optical fiber has provided improved telecommunications over longer distances at ever-increasing speeds. There is a physical limit to fiber's transmission speeds. Ideally, we would like to transmit at the speed of light, but this goal cannot be achieved with glass fiber.

The transmission of light through glass fiber varies with its intensity (as opposed to light through free space). More intense light provides a faster speed. If too much light is transmitted with fiber, distortion will result and the signal will degrade.

Scientists are looking at other possibilities for high-speed data transmission besides fiber. Hollow-core photonic fibers or thin air technology may replace fiber altogether. A light is used for signal transmission, and amplification or regeneration is not necessary. Several companies and research institutions are experimenting with this technology, which could someday again revolutionize the Internet.

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