Physics: Principles and Problems


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A Fiber-Free Internet
Posted May 2002

If you're reading this, chances are that you have an Internet connection in your classroom. The Internet has become a valuable tool not just for schools and universities, but also for businesses. It allows people to work from home as easily as in an office. It connects people from around the world to share information and build communities.

The biggest technical problem facing the Internet today is bandwidth. Bandwidth is the amount of data that can be transferred over a data line per second. When the Internet first opened to the public, most of the data ran over phone lines using modems to connect computers to their networks. As technology progressed, modems were able to utilize higher bandwidths and deliver more information to remote machines.

Some businesses and schools have fiber lines that connected them to the Internet rather than a dial-up connection. This results in much higher bandwidth performance. As the Internet grew, Internet service providers (ISPs) laid optical fibers throughout the country, across the ocean floor, and around the world.

As high-bandwidth demands grew for businesses, and residential users, other options were utilized - including cable modems and digital subscriber lines (DSL). These high-bandwidth lines allow users to connect to the Internet without using a phone line.

Even today, Internet users are pushing the limits on available bandwidth. As more and more bandwidth is needed, scientists are finding ways to deliver it while minimizing the costs. The biggest problem with fiber optics is that they are so expensive to install. Not only are there substantial material costs, but it takes money - and time - to bury the fiber optic cables. Estimates for building a city-wide fiber optic network range from $100,000 to $500,000 per mile.

One option, that is becoming more and more appealing, uses lasers to transmit data across a city grid. The biggest advantage to this is that a laser network could run through the air and not rely on fiber to transmit the signal.

Such a network would have hubs on top of buildings and towers that contain laser diodes that can transmit two-way data. The lasers are low-power infrared signals that can reach other hubs simply by aiming at them. Enough of these hubs scattered throughout a city can potentially cost the fraction of the price tag to ensnare the area in fiber optics - and the laser hubs could be constructed in a matter of days rather than months.

Of course, anyone with a satellite dish knows that there are drawbacks to running a signal through the air. Such low-power lasers could be blocked by a thick fog or other bad weather. This may end up being an unfortunate trade-off to low-cost bandwidth.

Use the Internet to research Internet bandwidth. With a partner, design a model of a laser-driven city-wide network.


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Physics: Principles and Problems