ser terminals, the most numerous and expensive part of a wireless telephone system is the collection of base stations. At a typical busy-hour occupancy of 70 percent, this radio equipment is idle three-tenths of the time. There are ways to design the equipment to handle this inefficiency more economically, but this is the reality of small numbers, the reality of wireless traffic engineering. The financial planners are usually not telephony engineers. They have to understand that they cannot divide the radio count by the length of busy-hour calls to get the busy- hour capacity of their systems. There are a two major reasons for this. First, in conventional cellular systems with mixed cell sizes, the frequency-allocation pattern actually reduces the number of radios available on some faces. In CDMA, we cannot count the number of calls by counting the number of radios, but increased use in surrounding cells does add interference and reduce capacity at each cell. Second, we cannot use all the voice links all the time and maintain an acceptable block- ing rate. This adds a complex statistical element to our calculations. The mathematical models for this are discussed in Chap. 23, but here are some of the essential issues: The moment-by-moment demand during the busy hour follows a statistical Poisson dis- tribution that depends on the average call demand level. The number of calls at any given instant can vary considerably from the average. Keeping the system available for subscriber calls is the same as maintaining a low block- ing rate. Two percent blocking is excellent service, and 10 percent may still be acceptable. The number of available voice links required to maintain a low blocking rate can be sig- nificantly more than the average demand. As a result, the links are occupied only some of the time even during the busy hour. Lower engineered blocking rates require lower occupancy, which means less efficient use of voice links. While smaller demands require smaller numbers of voice links, the occupancy required fo