White space

Article By:

Webb, William Neul Ltd., Cambridge, United Kingdom.

Last reviewed:2014

DOI:https://doi.org/10.1036/1097-8542.YB140268

White space, often called TV white space, is strictly a method to access radio spectrum owned by others. However, the term has become more widely used to describe applications that might be deployed in such a white-space spectrum. To understand white space, recall that all wireless communications needs some radio spectrum. For cellular communications, this is dedicated spectrum, often sold at auction. For applications such as Wi-Fi, this is unlicensed spectrum, set aside by the regulator to allow all to make use of it on an unprotected basis. As evidenced by the high prices paid at auction, spectrum is in scarce supply, and finding bands that can be repurposed for new uses is becoming ever harder. This scarcity stimulated a search to find ways to make more intensive use of the existing bands. Observations of licensed spectrum use showed that often there appeared to be only about 20% in use at any particular time and place, prompting the concept of shared use, whereby others could opportunistically access the unused parts of the spectrum as long as they did not cause interference to the license holders. An analogy would be someone using a house left vacant by the owners while they were away on vacation subject to it being left in an identical state such that the owners were unaware of any such usage. Research into such access methods, sometimes called cognitive access or dynamic spectrum access (DSA), has been underway since around 2000, with significant annual events such as the IEEE Communications Society Dynamic Spectrum Access Networks (DySPAN) conference.

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