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.

Portable real time cellular telephone and pager network system monitor

Abstract: A portable real-time monitoring system for field testing and troubleshooting a cellular telephone network, paging network, or mobile radio system employs a user friendly interface between a user and a scanning radio receiver which displays, monitors and stores parameters related to real-time performance. A portable all-band radio receiver capable of receiving cellular and paging frequencies is connected to a computer, such as, for example, a lap-top computer suitable for mobile operation at remote sites, personal computer (PC) or workstation. An interface circuit is installed within the radio receiver which taps available signals within the receiver as well as allows the computer to control the receiver frequency selection, band designation and demodulation setting. The interface hardware and microcode cooperate to process and decode received signals according to cellular and paging network industry standards. An application running on the computer is provided which utilizes the processed signals to permit complete automated reception, display and storage of cellular, paging, and mobile radio data as well as the signal strength (RSSI) for each signal. All monitored activity is displayed on the PC screen and is written to a disk in an organized ASCII or HEX file for instant retrieval and analysis. Masks can also be specified by the user which allow only selected data to pass or not pass through the system. The masks may be used to trigger alarms and print data when selected data is detected.

Radio-wave propagation for emerging wireless personal-communication systems

Abstract: The present survey paper summarizes radio-propagation measurements and models for emerging wireless personal-communication systems. Both indoor and microcell-propagation environments are considered, and the problem of RF penetration into buildings is identified as an important area of research for emerging wireless-communication systems. >

Effects of radio propagation path loss on DS-CDMA cellular frequency reuse efficiency for the reverse channel

Abstract: Analysis techniques for quantitatively describing the impact of propagation path loss and user distribution on wireless direct-sequence code-division multiple-access (DS-CDMA) spread spectrum systems are presented. Conventional terrestrial propagation models which assume a d/sup 4/ path loss law are shown to describe modern cellular and personal communication system channels, poorly. A two-ray propagation model and path loss model derived from field measurements are used to analyze the impact of path loss on the frequency reuse efficiency of DS-CDMA cellular radio systems. The analysis shows that the frequency reuse efficiency (F) of the reverse channel with a single ring of adjacent cells can vary from a maximum of 71% in d/sup 4/ channels with a favorable distribution of users, to a minimum of 33% in d/sup 2/ channels with a worst-case user distribution. For three rings of adjacent users, F drops to 58% and 16%, respectively. Using the two-ray model, it is shown that F can vary over a wide range of values due to the fine structure of propagation path loss. >

Small-Scale, Local Area, and Transitional Millimeter Wave Propagation for 5G Communications

Abstract: This paper studies radio propagation mechanisms that impact handoffs, air interface design, beam steering, and multiple-input multiple-output for 5G mobile communication systems. Knife-edge diffraction (KED) and a creeping wave linear model are shown to predict diffraction loss around typical building objects from 10 to 26 GHz, and human blockage measurements at 73 GHz are shown to fit a double KED model, which incorporates antenna gains. Small-scale spatial fading of millimeter wave (mmWave)-received signal voltage amplitude is generally Ricean-distributed for both omnidirectional and directional receive antenna patterns under both line-of-sight (LOS) and non-line-of-sight (NLOS) conditions in most cases, although the log-normal distribution fits measured data better for the omnidirectional receive antenna pattern in the NLOS environment. Small-scale spatial autocorrelations of received voltage amplitudes are shown to fit sinusoidal exponential and exponential functions for LOS and NLOS environments, respectively, with small decorrelation distances of 0.27–13.6 cm (smaller than the size of a handset) that are favorable for spatial multiplexing. Local area measurements using cluster and route scenarios show how the received signal changes as the mobile moves and transitions from LOS to NLOS locations, with reasonably stationary signal levels within clusters. Wideband mmWave power levels are shown to fade from 0.4 dB/ms to 40 dB/s, depending on travel speed and surroundings.

Effects of multipath angular spread on the spatial cross-correlation of received voltage envelopes

Abstract: This paper presents a simple formula relating multipath angular spread to small-scale fading statistics. This formula is then applied to find an approximate spatial cross-correlation function for received voltage envelopes. The analytical approach is compared to 67 cross-correlation functions simulated with non-omnidirectional multipath. The equations in this paper provide insight for applying spatial diversity techniques to receivers operating in the presence of non-omnidirectional multipath.

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.