g delays and implementation costs. In this analysis, we assume a network of evenly distributed microcell sites and randomly distributed mobile voice radios. We assume the network is time-synchronized SO that all cell sites have a common time reference (obtained, e.g., from GPS receivers). Each active mobile unit is slave to the corresponding cell-site radios and therefore synchronized to the basic net- work clock. Of course, in practical systems, time errors will occur and will affect overall performance and capacity. Note that conventional TDMA sys- tems also require a similar network time synchronization. Because of this assumed network synchronization, all base stations transmit TDD packe- tized bursts followed by all the mobile units transmitting their packetized bursts. Figure 3.6 illustrates cell sites simultaneously transmitting their packetized bursts. Note that during this time interval, each mobile unit receives the data burst from its assigned cell sites together with interference from other cell sites. Signals that are transmitted by their assigned cell site and are intended for other mobile units assigned to the same cell cite use orthogonal code- words. During the inbound time frame, all mobile units transmit their packets to their cell sites. As shown in Figure 3.7, each cell-site receiver must handle reception of all the mobile unit signals assigned to its cell under interference from all mobile units in other cells. In this analysis, we assume S-CDMA for both inbound and outbound channels. For microcells in which multipath time delays are smaller and Spread-Spectrum CDMA for PCS and PCN HANDSET DESIRED SIGNAL STATION Figure 3.6. Outbound simulation model (base to handset). HANDSET DESIRED SIGNAL BASE STATION Figure 3.7. Inbound simulation model (handset to base). Commercial Applications mobility is limited to roaming by pedestrians using these mobile units, this assumption is valid as long as all multipath delays are small compared to the chip-time interval. Given ideal synchronization of cell si