ocket telephone handsets that could, in a single unit, replace a home cord- less telephone, wireless office telephone, wireless pay phone, cellular phone, and the planned worldwide Low Earth Orbiting (LEO) satellite mobile phones. With the rapidly growing use of paging and messaging devices, lap- top computers, and personal digital assistants (PDAs), there is an increas- ing need for personal wireless data communication as well. PCSs, which now include all wireless personal communication devices, are distinguished by their personal nature, which allows universal personal communications ser- vices anywhere, anytime, to anyone, in any form. For some PCS applications that require a very high density of mobile voice handsets in an area covered by many cells, the spread-spectrum CDMA type of design is ideal. Here, we examine in some detail a Cylink system design similar to that of the IS-95 digital cellular spread-spectrum CDMA standard but optimized for microcells with roaming mobile users [23]. It serves as another illustration of a high-capacity direct-sequence spread-spectrum CDMA system design with computer simulations of the overall system per- formance. In many high-density PCS applications, the cells in a multicell network are expected to be less than 200 m in diameter. In such microcells, multipath delay differences are quite small, and mobile radio transmissions can be Spread-Spectrum CDMA for PCS and PCN tightly controlled by the base stations. Multipath delays, especially for indoor applications, are typically less than 0.2 usec [24, 25] for such microcells. Qualcomm designed its spread-spectrum CDMA system (IS-95) under the restrictions of existing mobile cellular applications in which cell areas and multipath delays are large, and mobile users can move rapidly in automo- biles. This spread-spectrum radio system designed for PCS assumes no restric- tions on channelization. It illustrates the key advantages of using spread- spectrum CDMA to achieve higher capacity for digital voice applications in a high d