tes, consider a direct-sequence spread-spectrum QPSK modulation in which we assume that interference derives from other similar synchronized radios. Here, we examine an exam- ple in which interference derives from cross-correlation stemming from the specific codewords used in the network. Propagation delays and time off- sets are taken into consideration in this simulation. The system considered here is a spread-spectrum S-CDMA design with full-duplex operation using TDD. The following are its signal carrier fea- tures: A PCS S-CDMA System Type of modulation DS/QPSK Voice transmission 32 kbps ADPCM digital voice Data transmission 4.8 kbps signaling channel Processing gain 32 chips/bit QPSK symbol burst rate 1.536 M symbols/sec The S-CDMA system requires time synchronization for the network of microcells on the order of a burst chip-time interval, which is 651 nanosec- onds (nsec). This delay is much larger than the multipath delays expected for microcells, especially for indoor applications. The digital European cord- less telephone (DECT), a TDMA system to be discussed later, has a burst bit rate of 1.152 mbps, which requires time synchronization on the order of a bit time interval of 868 nsec. Thus, time synchronization issues are similar for these two systems. 3.6.3.1 Bit-Error Probabilities Most textbook analyses of communication systems are based on the assumption that the receiver front-end noise is the limiting performance fac- tor. Even when performance limitations derive from other sources of inter- ference in the communication channel, most analyses approximate this interference as noise. For communication systems, the usual performance measure is bit error probability, with interference modeled as white Gaussian noise with spectral density denoted No. The bit error probability, Pb, is typically expressed in terms of the ratio of the energy per bit, Eb, to noise, Eb/No. Except for a few cases, it is generally difficult to arrive at an exact closed- form expression for the bit error probability of a comm