trum radios, however, these are not the same. The key difference lies in the frequency of reuse among cells in the network, which differs for spread-spectrum radios. The design of networks using spread-spectrum radios can aim to limit mutual interference but cannot necessarily eliminate it completely, as with conventional radio systems. Spread-spectrum radios are designed to toler- ate some level of interference, with their overall capacity limited by how well this mutual inference can be controlled. Conventional radios are limited by the number of non-interfering signals achieved by using complete separa- tion with FDMA or TDMA techniques. Thus, the capacity of spread-spec- trum radio systems is interference-limited, while the capacity of conventional radio systems is limited by the number of non-interfering coordinates. We restate this important difference as follows: THE CAPACITY OF SPREAD SPECTRUM RADIOS IS INTERFERENCE-LIMITED, WHILE THE CAPACITY OF NARROWBAND RADIOS IS DIMENSION-LIMITED. The paradigm for the design of a radio system consisting of a large net- work of cells changes with the use of spread-spectrum radios. When overall capacity is considered, as measured in the total number of active users in an area of many cells (capacity per square kilometer, e.g.), a well-designed spread-spectrum system can achieve a higher overall capacity than one using conventional narrowband radios. In such interference-limited radio net- works, power control is critical to overall capacity. For digital voice networks, the advantage is greater with spread spectrum, because mutual interference can be further reduced (thus increasing capacity) with the use of voice acti- vation. Finally, this type of design puts more pressure on good radio design, in which better performance against interference-which translates to less transmitted power-is critical. Thus, the use of forward error-correction cod- ing can play an important role. Narrowband signals using FDMA need a frequency guard band to sepa- rate the FDMA channels to m