e enables networks to use unused spectrum in other networks and utilize the spectrum in their own networks more efficiently. Dynamic spectrum access continuously monitors spectrum to determine availabil- ity. The available spectrum might be in an organization's own network, in unlicensed spectrum, or in other networks altogether. The spectrum monitoring can be used to prevent interference in an organization's own network. It can monitor the airwaves at a mobile carrier's cell site to ensure that its signals do not interfere with signals that spill over from its adjacent cell sites. (Frequency spillover is a particular issue at the edge of small cell sites in metropolitan areas.) Dynamic spectrum access has the potential to make it possible for mobile net- works to operate without interference on unlicensed spectrum in metropolitan areas. Currently, white space spectrum is planned for fixed Internet access in rural areas where there are fewer possibilities for interference. White spaces are unused bands of frequencies (guard bands) on either side of a channel that prevent wireless sig- nals from adjacent channels from interfering with one another. (See the section "Unli- censed Spectrum for 'Super' Wi-Fi," later in this chapter, for more details on white spaces.) However, the continuous spectrum monitoring would enable new, more pow- erful Wi-Fi networks to be used for mobile e-mail and Internet access without interfer- ing with other networks in busy metropolitan areas. These white-space-based networks Finite Spectrum for Wireless Networks would be operable over multiple spectrum bands SO that if one band has traffic, devices would automatically switch to an available band. Dynamic spectrum access could also be used with applications for which spectrum is used intermittently or only at certain times of the day. Utilities that have spectrum for meter reading and schools that use their wireless networks during the day could make their spectrum available to other organizations when it is idle. Another example of spe