Theodore S. Rappaport

Bio: Theodore S. Rappaport is an academic researcher from New York University. The author has contributed to research in topics: Path loss & Multipath propagation. The author has an hindex of 112, co-authored 490 publications receiving 68853 citations. Previous affiliations of Theodore S. Rappaport include University of Waterloo & University of Texas at Austin.

Two-branch diversity simulation of the effects of non-zero signal correlation on average fade duration

Abstract: This paper provides a simulation method that provides two Rayleigh fading signal envelopes of a desired correlation coefficient. This is based on previous work and uses an improved technique (iterative step) to achieve higher numerical accuracy between the desired and the resultant cross correlation coefficient. The average fade duration is used as a measure of the diversity scheme performance, and various diversity combining techniques (switch combining: pure selection and threshold selection-switch and stay, switch and examine) are examined. It is shown that non-zero cross correlation affects the performance of the particular combining technique differently. A model to predict the diversity performance, for a given correlation coefficient and signal level, is examined.

Millimeter Wave Position Location using Multipath Differentiation for 3GPP using Field Measurements.

Abstract: 3GPP air interface standards support meter-level position location of a user in a cellular network. With wider bandwidths and narrow antenna beamwidths available at mmWave frequencies, cellular networks now have the potential to provide sub-meter position location for each user. In this work, we provide an overview of 3GPP position location techniques that are designed for line-of-sight propagation. We discuss additional measurements required in the 3GPP standard that enable multipath-based non-line-of-sight position location. Further, we validate the concepts in this paper by using field data to test a map-based position location algorithm in an indoor office environment which has dimensions of 35 m by 65.5 m. We demonstrate how the fusion of angle of arrival and time of flight information in concert with a 3-D map of the office provides a mean accuracy of 5.72 cm at 28 GHz and 6.29 cm at 140 GHz, over 23 receiver distances ranging from 4.2 m to 32.3 m, using a single base station in line-of-sight and non-line-of-sight. We also conduct a theoretical analysis of the typical error experienced in the map-based position location algorithm and show that the complexity of the map-based algorithm is low enough to allow real-time implementation.

Wireless Personal Communications: Research Developments

Abstract: In this book, the state-of-the-art and future vision of wireless communications is presented in the form of a number of new services. Wireless personal communications is clearly a different service than today's cellular radio or cordless telephone, but there is an evolutionary connection between the three services. This book addresses questions about what features of personal communication services (PCS) will be met by existing or enhanced digital cellular radio technology. The regulatory and standards aspects of wireless communications are currently in a crucial stage of their formulation. A section of the book is devoted to the opinions of representatives from regulatory agencies and standards organizations on the future of this critical area. One of the most intriguing questions about the future of wireless communications has to do with the choice of multiple access technique. The trade offs between time division multiple access (TDMA) and code division multiple access (CDMA) have been the topic of many a heated discussion amongst members of the wireless community. This book presents a thorough discussion of a number of the topics which are instrumental in making a fair comparison of TDMA and CDMA; these topics include: analytical performance evaluation techniques, capacity studies, equalization requirements, and shared spectrum comparisons. Many of the technologies associated with wireless personal communications are reaching the design stages. This book presents a number of alternatives for designs of both base stations and user terminals. Some of the key questions of equalization, control channel requirements, multi-path diversity and channel allocation strategies have been addressed. Invariably, system designs and performance are tied to the characteristics of the radio channel. This book introduces several novel techniques for predicting propagation and system performance in a variety of indoor and outdoor environments. These techniques include analytical as well as computer simulation algorithms for predicting signal strenghts and other channel parameters based on the local topographical features. This book serves as an excellent reference source and may be used as a text for advanced courses on wireless communications, cellular radio, or digital mobile radio.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Cooperative diversity in wireless networks: Efficient protocols and outage behavior

Abstract: We develop and analyze low-complexity cooperative diversity protocols that combat fading induced by multipath propagation in wireless networks. The underlying techniques exploit space diversity available through cooperating terminals' relaying signals for one another. We outline several strategies employed by the cooperating radios, including fixed relaying schemes such as amplify-and-forward and decode-and-forward, selection relaying schemes that adapt based upon channel measurements between the cooperating terminals, and incremental relaying schemes that adapt based upon limited feedback from the destination terminal. We develop performance characterizations in terms of outage events and associated outage probabilities, which measure robustness of the transmissions to fading, focusing on the high signal-to-noise ratio (SNR) regime. Except for fixed decode-and-forward, all of our cooperative diversity protocols are efficient in the sense that they achieve full diversity (i.e., second-order diversity in the case of two terminals), and, moreover, are close to optimum (within 1.5 dB) in certain regimes. Thus, using distributed antennas, we can provide the powerful benefits of space diversity without need for physical arrays, though at a loss of spectral efficiency due to half-duplex operation and possibly at the cost of additional receive hardware. Applicable to any wireless setting, including cellular or ad hoc networks-wherever space constraints preclude the use of physical arrays-the performance characterizations reveal that large power or energy savings result from the use of these protocols.

Cognitive radio: brain-empowered wireless communications

Abstract: Cognitive radio is viewed as a novel approach for improving the utilization of a precious natural resource: the radio electromagnetic spectrum. The cognitive radio, built on a software-defined radio, is defined as an intelligent wireless communication system that is aware of its environment and uses the methodology of understanding-by-building to learn from the environment and adapt to statistical variations in the input stimuli, with two primary objectives in mind: /spl middot/ highly reliable communication whenever and wherever needed; /spl middot/ efficient utilization of the radio spectrum. Following the discussion of interference temperature as a new metric for the quantification and management of interference, the paper addresses three fundamental cognitive tasks. 1) Radio-scene analysis. 2) Channel-state estimation and predictive modeling. 3) Transmit-power control and dynamic spectrum management. This work also discusses the emergent behavior of cognitive radio.

An application-specific protocol architecture for wireless microsensor networks

Abstract: Networking together hundreds or thousands of cheap microsensor nodes allows users to accurately monitor a remote environment by intelligently combining the data from the individual nodes. These networks require robust wireless communication protocols that are energy efficient and provide low latency. We develop and analyze low-energy adaptive clustering hierarchy (LEACH), a protocol architecture for microsensor networks that combines the ideas of energy-efficient cluster-based routing and media access together with application-specific data aggregation to achieve good performance in terms of system lifetime, latency, and application-perceived quality. LEACH includes a new, distributed cluster formation technique that enables self-organization of large numbers of nodes, algorithms for adapting clusters and rotating cluster head positions to evenly distribute the energy load among all the nodes, and techniques to enable distributed signal processing to save communication resources. Our results show that LEACH can improve system lifetime by an order of magnitude compared with general-purpose multihop approaches.