Smart Antennas for Wireless Communications: IS-95 and Third Generation CDMA Applications

Description

71928-6

IS-95 and Third Generation CDMA Applications.

The one-stop source for engineering CDMA adaptive antennas.

New adaptive ("smart") antenna arrays can enhance the performance of virtually any CDMA system, including IS-95, IMT-2000 and Wideband CDMA. Smart Antennas for Wireless Communications is the first book that brings together all the real-world data and expertise communications engineers need to develop smart antennas for CDMA.

Start out with a detailed overview of IS-95 PCS and Cellular CDMA, including uplink and downlink signal formats and link budgets. Next, understand the full range of smart antenna technology, from simple beamforming networks to advanced multi-user spatial processing systems. Learn how adaptive antenna systems can change patterns dynamically, adjusting to noise, interference, and multipath as they track mobile users.

Learn the key elements of smart antenna development, including vector channel impulse response, spatial signatures, spatial diversity, diversity combining, sectoring, and transmission beamforming. Understand important CDMA-related issues, including non-coherent and coherent CDMA spatial processors, dynamic re-sectoring, and the use of spatial filtering to increase range and capacity. Master all these fundamental design techniques:

• Characterization of spatio-temporal radio channels.
• The geometrically-based single bounce elliptical model.
• Optimal spatial filtering and adaptive algorithms.
• Direction-Of-Arrival estimation algorithms.
• This book reflects the latest developments in CDMA and smart antennas, including the IS-95 and J-STD-008 CDMA standards, 14.4K vocoders, and techniques for designing RF location systems that meet the FCC's stringent E-911 requirements. Whether you're designing for today's CDMA systems or tomorrow's, you'll find it invaluable.

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Table of Contents

1. Introduction.

The Cellular Radio Concept. Evolution of Wireless Communications. Spread Spectrum and Code Division Multiple Access. Antenna Systems. Basic Concepts in Radiowave Propagation. Small Scale Fading. Large Scale Path Loss. Summary.

Cellular and PCS Frequency Allocation. How IS-95 CDMA PCS Systems Work. Typical Link Budgets for IS-95 PCS. Reverse Traffic Channel Transmission for IS-. IS-95 Forward Channel Signals. IS-95 Evolution and cdma. Summary.

Key Benefits of Smart Antenna Technology. Introduction to Smart Antenna Technology. The Vector Channel Impulse Response and the Spatial Signature. Spatial Processing Receivers. Fixed Beamforming Networks. Switched Beam Systems. Adaptive Antenna Systems. Wideband Smart Antennas. Spatial Diversity, Diversity Combining, and Sectoring. Digital Radio Receiver Techniques and Software Radios for Smart Antennas. Transmission Beamforming. Array Calibration. Summary.

Non-Coherent CDMA Spatial Processors. Coherent CDMA Spatial Processors and the Spatial Processing Rake Receiver. Multi-User Spatial Processing. Dynamic Re-sectoring Using Smart Antennas. Downlink Beamforming for CDMA. Summary.

Range Extension In CDMA. Single Cell Systems with Spatial Filtering at the IS-. Base Station. Reverse Channel Performance of Multi-cell Systems with Spatial Filtering at the Base Station. Reverse Channel Spatial Filtering at the WLL Subscriber Unit. Range and Capacity Analysis Using Smart Antennas - A Vector-Based Approach. Summary.

Wireless Multipath Channel Models, Environment, and Signal Parameters. Spatio-Temporal Channel Models for Smart Antennas. Spatial Channel Measurements. Application of Spatial Channel Models. Summary.

Simulation of Multipath Component Parameters in GBSBEM. Marginal Distribution of the Direction-Of-Arrival in the GBSBEM Model. Doppler Spectra and the Fading Envelope. Selection of the Maximum Path Delay, tm. Summary.

Impact of Multipath on Optimal Spatial Filtering. Performance of Underloaded and Overloaded Adaptive Arrays. Adaptive Algorithms. Adaptive Algorithms for CDMA. Multitarget Decision-Directed Algorithm (MT-DD). Least Squares De-spread Re-spread Multitarget Array (LS-DRMTA). Least Squares De-spread Re-spread Multitarget Constant Modulus Algorithm. Summary.

Conventional Methods for DOA Estimation. Subspace Methods for DOA Estimation. Maximum Likelihood Techniques. DOA Estimation under Coherent Signal Conditions. The Iterative Least Squares Projection Based CMA. The Integrated Approach to DOA Estimation. Detection of Number of Sources in Eigen Decomposition. Summary.

Direction Finding PL Systems. True Ranging PL Systems. Elliptical PL Systems. Hyperbolic PL Systems. Hyperbolic versus DF PL Systems. TDOA Estimation Techniques. Measures of Position Location Accuracy. Summary.

References.

Preface

Smart Antennas for Wireless CommunicationsIS-95 and Third Generation CDMA ApplicationsPrefaceThis text has been created to satisfy the growing demand for knowledge in two emerging areas: adaptive antennas (also known as smart antennas) and Code Division Multiple Access. CDMA was commercialized in the early 1990s by Qualcomm, Inc., a San Diego, California, company that pioneered the use of a classic military concept for the burgeoning cellular telephone industry. Adaptive arrays, first conceptualized in the 1960s with the birth of digital signal processing, only recently have become practical for deployment; the intense growth rates of wireless services around the world are beckoning for their commercial use.This text has been developed through years of research by the authors and their colleagues at the Mobile and Portable Radio Research Group of Virginia Tech and at Bell Communications Research. Our goal in creating this text is to provide fundamental and practical information for practicing engineers, students, and researchers in industry as well as in academia. To complement the book, the second author was asked by the Institute of Electrical and Electronics Engineers (IEEE) to provide a compendium of selected readings of key journal papers dedicated to the topic of smart antennas. The compendium, when used in conjunction with this text, provides a convenient single source of literature for use in classrooms or industry short courses.The material and organization of this book stemmed from the first author's 1995 Ph.D. dissertation on the subject of CDMA and smart antennas. Since then, a great deal of work has transpired in the field, including the adoption of the IS-95 J-STD-008 CDMA standard, the new 14,400 bps voice coder for Rate Set 2 channels, new methods and models for implementation and modeling of smart antennas in CDMA, and the stringent wireless E-911 position location requirement 125m, 67% of the time imposed by the Federal Communications Commission. We have worked diligently to include up-to-the-minute information in this text. The text is arranged into 10 chapters. Chapter 1 provides an overview of CDMA and smart antennas; it includes a glossary of terms and a fundamental treatment of synchronous and asynchronous CDMA. Antenna and propagation fundamentals, as they relate to CDMA systems, are also presented. Chapter 2 provides valuable practical information on the IS-95 J-STD-008 standard, and it provides in-depth descriptions of all of the CDMA channels. Also included is an actual link budget design for a PCS CDMA system. Chapter 3 provides fundamental material on adaptive antenna arrays and array theory. The concepts of beamforming, weighting vectors, and fixed-beam vs. adaptive beam antennas are covered. Chapter 4 applies this material to specific CDMA implementations that may be used for today's IS-95 and future CDMA systems. Chapter 5 combines the concepts of CDMA and adaptive antennas to derive analytical expressions that allow wireless system designers to predict the coverage and capacity gains that adaptive antennas provide in a multi-cell CDMA system. This chapter derives classic results that have led to system capacity predictions using CDMA with and without adaptive antennas.Chapter 6 provides an overview of multipath and Direction-Of-Arrival models for wireless channels. A host of propagation models which are useful for analysis and simulation of adaptive array algorithms are presented. Chapter 7 then describes complete details of one multipath propagation model, the Geometrically Based Single Bounce Elliptical Model, which provides complete characterization of a multipath environment in microcell/picocell applications. Chapter 8 describes optimal spatial filtering approaches that use both adaptive arrays and characteristics of the CDMA signals. Building on the fundamentals provided in Chapter 3, this chapter presents optimal methods that null interference while maximizing the carrier-to-noise ratio of a desired user. Chapter 9 describes the algorithmic techniques for determining the Direction-Of-Arrival (DOA) of a signal in a multi-user interference environment. Such capabilities will be required for position location techniques. Chapter 10 concludes this text with a thorough treatment of position location algorithms and approaches. Appendix A covers the derivation of the Gaussian Approximation and its many derivatives for spread spectrum systems. Other appendices provide information that engineers and educators may find useful.The authors wish to acknowledge the invaluable assistance, skill, and patience of Aurelia Scharnhorst, a research associate with Virginia Tech's Mobile and Portable Radio Research Group (MPRG), in formatting this text. The ingenuity and hard work of Zhigang Rong, Rias Muhamed, and George Mizusawa are represented in parts of Chapters 8, 9, and 10 of this book, as portions of their mastersâ theses have been used with their gracious permission. Other MPRG researchers who played an important role in building the knowledge base presented in this text are Rich Ertel, Kevin Krizman, Neal Patwari, Paulo Cardieri, and Tom Biedka. The authors would also like to thank Prof. M. Zoltowski of Purdue University, Prof. A. Paulraj of Stanford University, M. Feuerstein of Metawave, C. Thompson of Virginia Tech, and Prof. W. Tranter and Prof. B. Woerner of Virginia Techâs MPRG for their review of this text and encouragement to pursue this project. Kevin Sowerby of the University of Auckland, New Zealand also helped inspire this work during his 1997 sabbatical at MPRG.The authors would also like to thank Joe Wilkes, Paul Zablocky, and Shimon Moshavi of Bellcore, for valuable discussions regarding IS-95. Daniel Devasirvathm, Scott Seidel, and John Koshy provided insight and assistance that allowed the book to become a reality. This text is the product of funded research supported at Virginia Tech through the MPRG industrial affiliates program. It is our pleasure to bring this book to you, and we hope you find it useful.J. C. L., Jr.T. S. R.

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