rum radios? 2. Multipoint-to-Point: How well can a receiver simultaneously detect and decode several spread-spectrum signals transmitted from spatially sep- arated radios? For the point-to-point channel, multiple access is achieved only at baseband using a multiplexer and demultiplexer at the transmitter and receiver, as shown in Figures 2.1 and 2.2. The corresponding multipoint-to-point system is illustrated in Figures 2.3 and 2.4. Here multiple access can be achieved at radio frequencies. The above questions arise in military digital radio networks. We assume throughout that in these networks spread-spectrum signals are used primar- ily to combat intentional jamming. Since they are designed to combat chan- nel interference of all kinds, they have certain multiple access capabilities as well as some tolerance to mutual interference. 1In this chapter we examine DS/BPSK and FH/MFSK signals. SOURCE LOCAL SOURCE PROCESSOR SOURCES POINT-TO-POINT - - CHANNEL SOURCE Figure 2.1. The multiplexer channel. Multiple Access SOURCE PROCESSOR Figure 2.2. The demultiplexer. SOURCE SPATIALLY SEPARATE DATA SOURCES CENTRAL DESTINATION SOURCE SOURCE Figure 2.3. Distributed multiple access channel. Military digital radio network design principles are not as well understood or developed as those for commercial digital networks. For one thing there is a much wider variety of military network types compared with commer- cial networks. Radios here are often mobile, subject to jamming and physi- cal attack, and must operate in all types of environments [1]-[3]. In addition, to reduce vulnerability terrestrial tactical digital radio networks often require distributed network control. Other higher level networks, such as a satellite Networks SPATIALLY DISTRIBUTED DESTINATIONS SOURCE Figure 2.4. Distributed broadcast channel. network, may have centralized network control [4]. To motivate the multi- ple access analysis of this chapter we first briefly describe two generic mil- itary digital radio networks. After this we discuss mutual interf