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.

Indoor radio communications for factories of the future

Abstract: The need for reliable, real-time communication for automated factories is discussed. The ability of narrowband digital radio systems to meet that need is examined. The major problems encountered in multipath propagation, resulted from multiple reflections of the transmitted signal from the building structure and surrounding inventory. Radio wave propagation experiments at 1300 MHz, which were conducted by the author in five operational factories, are described. Other studies of multipath propagation are discussed, and techniques for overcoming it are considered. Research on multiple-access networking is summarized. >

Analytical results for capacity improvements in CDMA

Abstract: Examines the performance enhancements that can be achieved by employing spatial filtering in code division multiple access (CDMA) cellular radio systems. The goal is to estimate what improvements are possible using narrow-beam adaptive antenna techniques, assuming that adaptive algorithms and the associated hardware to implement these systems can be realized. Simulations and analytical results are presented which demonstrate that steerable direction antennas at the base station can dramatically improve the reverse channel performance of multicell mobile radio systems, and new analytical techniques for characterizing mobile radio systems which employ frequency reuse are described using the wedge-cell geometry of Rappaport and Milstein (1992). The authors also discuss the effects of using directional antennas at the portable unit. Throughout the paper the authors use phased arrays and steerable, fixed pattern antennas to approximate the performance of adaptive antennas in multipath-free environments. >

Path loss, scattering and multipath delay statistics in four European cities for digital cellular and microcellular radiotelephone

Abstract: The authors present typical and worst-case root mean square (RMS) delay spreads and excess delay spreads (10 dB) and mean channel path loss at 900 MHz in four European cities using typical cellular and microcellular antenna locations. Several thousand power delay profile measurements were made at six typical cellular and microcellular base station locations in the four cities. The data were obtained at local worst-case time-dispersion locations over hundreds of kilometers of typical operating routes, such as highways, bridges, and city streets, and form the basis for statistical models which can be used to predict the percentage of locations or the percentage of time in which channels will possess particular values of RMS delay spread and excess delay spread. The effect of reference distance on wideband path loss and the propagation path loss laws for cellular and microcellular radio channels are given. Radar cross sections computed from the data for typical scatterers in cellular and microcellular radio channels are given. >

Method and system for managing a real time bill of materials

Abstract: An automated method for quickly generating a complete bill of materials and total cost information in real time. A design engineer builds a model of the desired wireless communications system (106) and specifies each component necessary to provide sufficient or optimal system performance. A parts list is maintained, in real time, that contains a definition of each system component and its associated performance and cost parameters. As the user changes wireless system designs through a series of 'what-if' scenarios, components are replaced with substitute components, cable lengths are modified, antenna systems and base station parameters are re-designed and moved to alternate locations, etc. The bill of materials is automatically updated and component costs and total system costs are immediately available to the design engineer. The designer may choose to swap components for less expensive components or may investigate several alternate radio frequency distribution and antenna schemes, etc. The performance characteristics of the system are automatically updated.

On-Chip Integrated Antenna Structures in CMOS for 60 GHz WPAN Systems

Abstract: We present several on-chip antenna structures that may be fabricated with standard CMOS technology for use at millimeter wave frequencies. On-chip antennas for wireless personal area networks (WPANs) promise to reduce interconnection losses and greatly reduce wireless transceiver costs, while providing unprecedented flexibility for device manufacturers. We present the current state of research in on-chip integrated antennas, highlight several pitfalls and challenges for on-chip design, modeling, and measurement, and propose several antenna structures that derive from the microwave and HF communication fields. We also describe an experimental test apparatus for performing measurements on RFIC systems with on-chip antennas at The University of Texas at Austin.

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.