ABSTRACT

When speaking of computers and the Internet, we often hear complaints about bandwidth. There never seems to be enough of it, but just what is it? Bandwidth is the amount of data that can move or be transmitted down a given channel. Think of it as a multilane freeway. The more lanes a freeway has, the more traffic it can handle at a faster pace. This is important, especially during rush hours. As lanes are taken away, traffic begins to slow as cars and trucks begin to move into the remaining lanes. As congestion worsens, traffic slows even further. In many instances, an eight-lane freeway suddenly becomes a two-lane freeway, creating a bottleneck. This holds true in bandwidth for computers and the Internet as well. As more users log on, more and more data packets are sent along the same paths. Traffic is especially slowed as big, multitrailer semitrucks carry multimedia-streaming content over the lanes. Bandwidth is not only an issue of traffic, but of the physical “road” as well. Copper lines that were designed to carry voice signals are now required to carry data as well. These lines are noisy and require software-based error control; this, too, slows traffic. A better road is fiber optics. Fiber-optic cables can deliver close to 1,000 billion bits per second, whereas the best copper can achieve is 56,000 bits per second. A fiber about the size of a human hair could transmit a million channels of television simultaneously. Of course, individuals do not yet have access to fiber in their homes. This is why compression is so important. As individual users become increasingly interested in content that is larger and, consequently, slower to download or view, bandwidth must be made to keep up. DSL (digital subscriber lines) and Internet cable services offer about 1.5 million bits per second, though bandwidth drops as more neighborhood users go online.