s improvement over pure FDMA is even greater when the multiple access signals have different power levels which are known to the optimum multiple access receiver. 2.5 DISCUSSION Spread-spectrum techniques are currently being incorporated into most mil- itary communication systems. One of the most active areas of research and new developments is in military communication networks [149]-[152]. In this chapter we presented an overview of the possible applications of spread- spectrum waveforms in a network environment with an emphasis on some theoretically optimum systems under ideal conditions. In practice, particu- larly in a mobile radio environment, there are many practical problems. Turin [153], for example, has examined experimental multipath fading data for mobile radios and developed more complete channel models. His results show that the multipath fading problems can result in worst performance than one expects with the idealized case presented here [154]-[157]. Our purpose here was to examine various types of multiple access systems using spread-spectrum waveforms. The ideal optimum receiver for multi- point-to-point systems in particular may not be practical today but does serve as a baseline with which to compare practical system designs. Also as our ability to do more complex signal processing at higher speeds develops, we can approach the idealized system designs discussed in this chapter. We are just beginning to understand and develop a new generation of spread- spectrum radios for military communication networks. 2.6 REFERENCES [1] The MITRE Corporation, Definition of Network Management Problems for Large Ground Data Networks, MTR-79W00001, Charles F. Swett, Contract No. F19628-81-C-0001, Washington Operations, McLean, VA, February 1979. The MITRE Corporation, A Survey of Routing Algorithms for Distributed Digital Radio Networks, MTR-81W00074, Richard W. Carpenter, Contract No. F19628-81-0001, Washington Operations, McLean, VA, March 1981. References [3] The MITRE Corporation, Channel Access Methods 