 means more capacity, in the form of more channels for FDMA and TDMA systems and more bits when using CDMA technology. We refer to radio frequency ranges as bandwidth or spectrum. The usual discussion is about the frequency range, with the geographic coverage region assumed. There are hot debates over where one region ends and a neighboring region begins, but we will concentrate on the bandwidth issues in our CDMA discussions. Readers should keep in mind, however, that negotiating with geographic neighbors for compatible service is every bit as important as making sure radio transmission is contained within allocated spectrum. We will discuss the technical issue of calls being served by different wireless systems in Sec. 12.5.5. As in any other acquisition, some frequencies are more desirable than others. Just as the downtown real estate commands a premium in most big cities, so also, in radio, lower frequencies are less demanding to operate. Lower-frequency amplifiers and an- tennas are simpler, and radio coverage is broader at a given power level. The lower fre- quencies are already firmly claimed by radio and television stations, police communi- cations, and other long-established users. In the early days of cellular, we were lucky enough to get radio spectrum allocations in the 900-MHz band, the upper end of "the UHF wasteland." We called it that because cable television was clearly alleviating the need for 70 UHF TV stations. Even before cable, most of us remember there being only a few U.S. TV stations numbered 14 through 83. More recently, wireless has been pushed up into the microwave band. Much of this push is a consequence of our own success. As the demand for wireless telephone service has increased, we have become hungry for more bandwidth to satisfy that demand, that bandwidth is out there in the microwave band. 1.5 Amplitude and Power The amplitude of a radio wave is the electromagnetic voltage level as it propagates through space. Similarly, the amplitude of a sound wave is the pressure variation a