k of this magnitude, we acknowledge many whose efforts should not go unnoticed. Credit is due to Paul Green for originally suggesting xviii Preface to First Edition the research that uncovered the material in Chapter 2, Part 1, and to Bob Price for the tireless sleuthing which led to much of the remarkable infor- mation presented there. Chapter 5, Part 1 benefited significantly from the comments of Lloyd Welch, whose innovative research is responsible for some of the elegant sequence designs presented there. Per Kullstam helped clar- ify the material on DS/BPSK analysis in Chapter 1, Part 2. Paul Crepeau con- tributed substantially to the work on list detectors. Last but by no means least, the authors would like to thank James Springett, Gaylord Huth, and Richard Iwasaki for their contributions to much of the material presented in Chapter 4, Part 5. Several colleagues of the authors have aided in the production of a use- ful book by virtue of critical reading and/or proofing. In this regard, the efforts of Paul Crepeau, Larry Hatch, Vijay Kumar, Sang Moon, Wei-Chung Peng, and Reginaldo Polazzo, Jr. are greatly appreciated. It is often said that a book cannot be judged by its cover. The authors of Spread Spectrum Communications are proud to take exception to this com- monly quoted cliche. For the permission to use the historically significant noise-wheel cover design (see Chapter 2, Part 1, Section 2.2.5), we gratefully acknowledge the International Telephone and Telegraph Corp. Marvin K. Simon Jim K. Omura Robert A. Scholtz Barry K. Levitt Chapter Part 1 INTRODUCTION' TO SPREAD-SPECTRUM COMMUNICATION This Page Intentionally Blank Chapter Chapter 1 A SPREAD-SPECTRUM OVERVIEW Over thirty years have passed since the terms spread-spectrum (SS) and noise modulation and correlation (NOMAC) were first used to describe a class of signaling techniques possessing several desirable attributes for com- munication and navigation applications, especially in an interference envi- ronment. What are these techniques? How are they