The Wireless Spectrum Crunch

One basic method of ensuring that interference does not occur among radio services operating close to each other in frequency and space is to separate these with a range of unused frequency, which is typically referred to as a guard band or as a white space between radio systems. A well‐known example of white space was employed in analogue television broadcasting, where a channel used in one geographic region was not used in neighboring regions. Another type of white space exists when a frequency range is simply not currently in use by a radio system. For example, a holder of a spectrum assignment might decide against deploying a service in a particular region, or they might not be operating at a particular time. Each of these types of white space represents spectrum that is underutilized, and raises the question of whether other radio technologies can operate in these white spaces while not harming incumbent users of the spectrum. Given the demand for, and value of, radio spectrum, exploiting this unused spectrum effectively and efficiently is a challenge that merits consideration. However, regardless of whether it is possible, the question remains whether it is practical and cost efficient to operate in a given white space. This chapter begins by providing historic and technical perspectives on the development of white space access technologies and then considers their application to various service models and the associated emerging standards. This chapter also explores the recent test‐trials of TV white space and discusses the challenges that face wide‐scale commercial deployment. In closing, this chapter considers the potential role of white space in the future 5G mobile standard.