An Introduction to Spread Spectrum Systems

This report is a tutorial introduction to spread spectrum communication systems, and it should be accessible for a reader who has basic knowledge of digital modulation and channel coding. The authors have chosen to present the more advanced topics in the report from a signal space and channel coding point of view. While other approaches are certainly possible, the authors feel that the chosen approach is the most beneficial for the communications engineer. Since the original applications for spread spectrum systems were military, we will introduce spread spectrum links as a means of overcoming intentional jamming. The reader who dislikes military applications may be comforted by the fact that the problem of communicating in the presence of jamming is very much akin to the problem of communicating over fading channels. Hence, by finding out how to defeat jamming by spread spectrum will also reveal how to overcome fading. Today, spread spectrum links are also used in many civilian systems to overcome nonintentional jamming (or interference), and the report is concluded with an overview of current commercial spread spectrum systems. The authors welcome comments and corrections to the material. Please send these to Erik Ström at [email protected].