sate, and some calls can be lost. The increase in variability is more subtle. In conventional reuse and in spread spec- trum, we rely on the radio signal path decreasing as distance increases. The greater the "random" component of path gain, the less we can rely on distance to discriminate be- tween near and far signals. 2 This means not only that are cell boundaries fuzzy but also that cells can even have noncontiguous components, little pockets of isolated real es- tate in their service areas. The CDMA equations in Eq. (28.17) tell us that the amount of radio resource con- sumed by a radio link is 1.0 for the serving cell sector plus the path gain ratios to other sectors. Highly variable and irregular radio paths contribute to the off-diagonal cross terms in these equations and contribute to other-cell-sector interference. The variation in urban radio paths is not just greater but more rapid. A suburban subscriber walking in a shopping mall does not have the rapid signal fluctuations of a city subscriber coming around the corner and out from behind a building's radio shadow. This keeps both power-control and handoff processes busy, and the service provider has to leave larger performance margins for the same overall performance level. With hundreds of power adjustments each second, it is tempting to think of CDMA power control as some kind of iron control of received power, but this is not the case. It takes a few tenths of a second for power control to compensate for a large signal path change. CDMA service providers have to leave some margin for out-of-balance received power levels from imperfect power control, and areas with larger and more rapid vari- ation require greater margins. The urban environment also has many smooth surfaces, paved roads, and building faces, creating more radio paths with less attenuation. As we discussed in Sec. 8.4, the These extra components are not truly random at all, but they are independent of distance. This makes them "random" from this point of view. Just as one call's sign