white spaceWhite space, in a communications context, refers to underutilized portions of the radio frequency ( RF ) spectrum. With the proliferation of wireless networks, remote-control devices, and personal communications services , some frequency band s in the RF spectrum have become crowded, causing interference problems. Other portions of the spectrum, particularly old terrestrial television broadcast channels, have fallen into underuse as a result of the evolution of alternative communications and broadcasting modes such as digital television . Several corporations have proposed that new methods and procedures be adopted in order to make more effective use of the RF spectrum, which, like real estate, is a finite resource. Historically, frequency allocations have been made to various services by government fiat according to application, such as radio broadcasting, television broadcasting, satellite communications, remote control, medical telemetry, aviation, military communications, and public communications. In recent years, a market-oriented philosophy has arisen, particularly in the United States, where blocks of RF spectrum could be sold or auctioned off to specific enterprises for use in limited geographic regions. Proponents of this approach argue that it could help to ensure the optimum usage of available RF spectrum space throughout the world. The market-oriented allocation scheme is complicated by the fact that RF signals, unlike users of real estate, do not respect physical boundaries. The distance that an RF signal will travel on a given frequency depends on numerous factors such as the transmitter output power, the location and elevation of the transmitter, the type of antenna used, and atmospheric conditions. Opponents of the market-oriented approach to RF spectrum allocation fear that, if not responsibly implemented, it could give rise to unexpected instances of disruptive and potentially dangerous interference between different services using the same frequencies at the same time. In the United States, frequency allocations in the RF spectrum are made by the Federal Communications Commission (FCC).
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May 23, 2006 |
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