The objective of the research is to establish basic design principles to achieve robust communication over channels corrupted by thermal noise and by unknown interfering signals of bounded power, using pseudo-random communication systems. This work will complement and extend current research on communication using error-control coding, interleaving and spread-spectrum modulation. Such systems are special cases of those considered in this research project. Two general issues are addressed. The first aims at establishing the potential coding gain offered by pseudo-random communication systems. This question will be addressed in the context of code-division multiple-access and interference suppression (anti-jamming) applications. A key aspect of this problem is to quantify the role of interleaving in robust systems. In the second part of this research, the principal investigator will introduce and examine the structure and performance of a new class of robust coding systems, called pseudo-random codes, which generalize coding systems with interleaving and spread-spectrum modulation. As in spread- spectrum these codes are driven by pseudo-random parameters; however, coding, interleaving and spectral spreading are performed simultaneously. Theoretical results show that within this family of codes are some that, in some situations, achieve coding gains much greater than those that can be achieved with spread-spectrum techniques for the same expended power, bandwidth and complexity.//