Preface

To a great extent, this book was inspired by the Defense Advanced Research Project Agency project called NETEX. The program manager, Stephen Griggs, recognized that far too little information about Ultra Wideband (UWB), particularly pulse-based UWB systems, appeared in the literature. Moreover, he believed that the UWB information available in the public domain is sometimes incorrect and misleading, particularly regarding interference issues with UWB. Thus, the program participants were encouraged to widely disseminate the results of the NETEX program to help clarify many of these outstanding issues. Much of the information presented in this book is a direct result of this program and other UWB research programs from Virginia Tech and the Army Research Lab.

UWB activity has picked up immensely since the Federal Communication Commission's 2002 decision to allow for the transmission of UWB and the subsequent standardization efforts with the Institute of Electrical and Electronics Engineers, Inc. Some see UWB as an enabling technology for new wireless applications that span from high-data-rate transmission of raw multimedia video to new location-aware, low-data-rate, and low-power communication of sensor data. Non-communication applications, such as through-the-wall imaging and ground-penetrating radar, also capture the imagination of researchers and entrepreneurs.

The controversy surrounding the standardization efforts illustrates the many debatable issues of UWB. From an academic perspective, many fundamental research issues remain unresolved, including the best modulation types for particular applications, efficient broadband antennas with a desirable form factor, propagation characteristics of UWB in various environments, the impact of UWB physical layer attributes on the networking layers, and the list continues. UWB will certainly be the subject of many theses and dissertations to come.

This book provides a broad technical view of UWB. Chapters 2 and 3 deal with simulation of propagation issues, modeling, and channel simulation, and much of this information is presented in the public domain for the first time. Chapter 4 focuses on antennas and outlines some surprising differences in antenna performance with respect to narrowband systems. Chapter 5 examines transmitter design issues and covers some of the basic modulation principles of UWB. Chapter 6 presents an overview of receiver design issues and explains how impulse UWB systems are particularly different from conventional carrier-based systems. Chapter 7 addresses the controversial interference issues of UWB; unlike traditional communications, UWB may intentionally transmit co-channel with other communication signals. Chapter 8 examines how to simulate UWB systems; such simulation requires more finesse because broadband signals encounter excessive simulation time if structured incorrectly. Chapter 9 describes how the physical layer capabilities of UWB impact the performance and design of upper layers. Finally, applications and case studies of existing UWB systems are addressed in Chapter 10.

We hope readers will find this book of interest and will check the web site (www.mprg.org/publications/Reed/UWBbook.shtml) for additional information about UWB and this book.

Jeffrey H. Reed

Virginia Tech, 2004