About: Smart antenna is a(n) research topic. Over the lifetime, 8368 publication(s) have been published within this topic receiving 124858 citation(s). The topic is also known as: adaptive antenna.
01 Oct 2004-IEEE Communications Magazine
TL;DR: An overview of the developments in cooperative communication, a new class of methods called cooperative communication has been proposed that enables single-antenna mobiles in a multi-user environment to share their antennas and generate a virtual multiple-antenn transmitter that allows them to achieve transmit diversity.
Abstract: Transmit diversity generally requires more than one antenna at the transmitter. However, many wireless devices are limited by size or hardware complexity to one antenna. Recently, a new class of methods called cooperative communication has been proposed that enables single-antenna mobiles in a multi-user environment to share their antennas and generate a virtual multiple-antenna transmitter that allows them to achieve transmit diversity. This article presents an overview of the developments in this burgeoning field.
01 Jun 2002-
TL;DR: This work shows that true beamforming gains can be achieved when there are sufficient users, even though very limited channel feedback is needed, and proposes the use of multiple transmit antennas to induce large and fast channel fluctuations so that multiuser diversity can still be exploited.
Abstract: Multiuser diversity is a form of diversity inherent in a wireless network, provided by independent time-varying channels across the different users. The diversity benefit is exploited by tracking the channel fluctuations of the users and scheduling transmissions to users when their instantaneous channel quality is near the peak. The diversity gain increases with the dynamic range of the fluctuations and is thus limited in environments with little scattering and/or slow fading. In such environments, we propose the use of multiple transmit antennas to induce large and fast channel fluctuations so that multiuser diversity can still be exploited. The scheme can be interpreted as opportunistic beamforming and we show that true beamforming gains can be achieved when there are sufficient users, even though very limited channel feedback is needed. Furthermore, in a cellular system, the scheme plays an additional role of opportunistic nulling of the interference created on users of adjacent cells. We discuss the design implications of implementing. this scheme in a complete wireless system.
01 Nov 1987-IEEE Transactions on Vehicular Technology
TL;DR: The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.
Abstract: The conditions for antenna diversity action are investigated. In terms of the fields, a condition is shown to be that the incident field and the far field of the diversity antenna should obey (or nearly obey) an orthogonality relationship. The role of mutual coupling is central, and it is different from that in a conventional array antenna. In terms of antenna parameters, a sufficient condition for diversity action for a certain class of high gain antennas at the mobile, which approximates most practical mobile antennas, is shown to be zero (or low) mutual resistance between elements. This is not the case at the base station, where the condition is necessary only. The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.
01 Apr 1999-
Abstract: From the Book: 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 useThis 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 coursesThe material and organization of this book stemmed from the first author's 1995 PhD dissertation on the subject of CDMA and smart antennas Since then, a great deal of work has transpired in the field, including the adoption oftheIS-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 antennasChapter 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 usefulThe 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 MPRGThe 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 usefulJ C L, JrT S R
01 Oct 2004-IEEE Communications Magazine
TL;DR: Classic results on selection diversity, followed by a discussion of antenna selection algorithms at the transmit and receive sides, and extensions of classical results to antenna subset selection are presented.
Abstract: Multiple-antenna systems, also known as multiple-input multiple-output radio, can improve the capacity and reliability of radio communication. However, the multiple RF chains associated with multiple antennas are costly in terms of size, power, and hardware. Antenna selection is a low-cost low-complexity alternative to capture many of the advantages of MIMO systems. This article reviews classic results on selection diversity, followed by a discussion of antenna selection algorithms at the transmit and receive sides. Extensions of classical results to antenna subset selection are presented. Finally, several open problems in this area are pointed out.