Showing papers by "Theodore S. Rappaport published in 2001"

System and method for design, tracking, measurement, prediction and optimization of data communication networks

Abstract: A system and method for design, tracking, measurement, prediction and optimization of data communications networks includes a site specific model of the physical environment, and performs a wide variety of different calculations for predicting network performance using a combination of prediction modes and measurement data based on the components used in the communications networks, the physical environment, and radio propagation characteristics.

System and method for efficiently visualizing and comparing communication network system performance

Abstract: A method for visualizing and efficiently making comparisons of communication system performance using predicted or measured performance, or other performance data sets (Steps 200-260). In the method, A 3-D environment database is created or modified (200), a complete wireless communication system is formed in the database is predicted (220). Then a system in a real-world environment is built (230), measurement data is collected (240), and the predicted and measured data is compared (250).

System, method, and apparatus for portable design, deployment, test, and optimizaton of a communication network

Abstract: A system and method which employs one or more portable hand held computers (102) with one or more servers (100), to provide field engineers the ability to complete the entire design, deployment, test, optimization, and maintenance cycle required to implement successful communication networks.

Wireless Network Evolution: 2G to 3G

Abstract: From the Publisher: 3G networks: architecture, planning, migration, management, and optimization. Network architectures, planning, management, and optimization 3G air interfaces: UTRA/W-CDMA and cdma2000 3G data services: UTRA/W-CDMA, cdma2000, GPRS, and EDGE Evolutionary paths for 2G networks WLL, WAP, and more New 3G systems will trigger an explosion in wireless Internet and data applications by delivering far higher data rates than have ever been possible in wireless systems before. In Wireless Network Evolution: 2G to 3G, renowned wireless expert Vijay K. Garg covers key 3G standard and every technical issue associated with planning, management, and optimization of 3G systems. Garg reviews the fundamental principles underlying existing 2G systems, then offers specific, practical guidance on migration to 3G. Coverage includes: 3G standards activities 3G European and North American systems 3G data services for UTRA/W-CDMA, cdma2000, GPRS, and EDGE networks Wireless Application Protocol (WAP) and 3G systems Major 3G enhancements for WLL applications New RF optimization techniques for 3G systems Wireless Network Evolution: 2G to 3G will be an invaluable resource for every practicing telecommunications engineer and technical decision maker involved in 3G planning, deployment, or management.

Method and system for analysis, design, and optimization of communication networks

Abstract: A method for engineering management and planning for the design of a wireless communications network in three-dimensions (3-D) combines computerized organization, database fusion, and radio frequency (RF) site-specific planning models. The method enables a designer to keep track of wireless system performance throughout the process of pre-bid design, installation and maintenance of a wireless system. Using a database of information that defines the desired environment, predictions of antenna coverage, system coverage and interference, and other wireless system performance criteria, such as frame error rate and network throughput, can be made. Watch points are created to ensure, in real time, that any modifications to the design of the wireless system do not degrade the performance of the system with respect to the watch point locations.

Textual and graphical demarcation of location from an environmental database, and interpretation of measurements including descriptive metrics and qualitative values

Abstract: A computerized system allows for collecting data for a spatially distributed group of objects or networks by either skilled or unskilled personnel and for analyzing the collected data in an environmental database.

Method and system for automated selection of optimal communication network equipment model, position and configuration in 3-d

Abstract: A method for engineering management and planning for the design of a communications network in three-dimensions (70) which combines computerized organization, database fusion, and site-specific communication system performance prediction models (70, 90, 100, 110, 120, 130). Various metrics are used to optimise the layout, placement and design of the communications network (90, 130).

Textual and graphical demarcation of location, and interpretation of measurements

Abstract: A computerized system allows for collecting data for a spatially distributed group of objects or networks by either skilled or unskilled personnel and for analyzing the collected data in an environmental database.

Statistical analysis of co-channel interference in wireless communications systems‡

Abstract: Summary Co-channel interference is recognized as one of the major factors that limits the capacity and link quality of a wireless communications system. An appropriate understanding of the statistical behavior of the co-channel interference is therefore required when analyzing and designing techniques that mitigate its undesired effects. The total co-channel interference in a wireless communications system is usually modeled as the sum of lognormally distributed signals, and is generally assumed to be itself lognormally distributed. Based on this assumption, several methods for estimating the moments of the resulting lognormal distribution have been proposed. The accuracy of these methods has been studied in previous works, under the assumption of having all summand signals (individual interference signals) identically distributed. Such an assumption rarely holds in practical cases of emerging wireless communications systems, where co-channel interference may stem from far-away macrocells and nearby transmitters, causing the interference signals to have different moments. In this paper we present an analysis of the accuracy of two popular methods for computing the moments of a sum of lognormal random variables, namely Wilkinson’s method and Schwartz and Yeh’s method, for the general case when the summands have different mean values and standard deviations in decibel units. We show that Schwartz and Yeh’s method provides better accuracy than Wilkinson’s method and is virtually invariant with the difference of the mean values and standard deviations of the summands. Copyright © 2001 John Wiley & Sons, Ltd.

Application of narrow-beam antennas and fractional loading factor in cellular communication systems

Abstract: It is well known that cellular system capacity can be increased by reducing the cell cluster size N. Reducing the cluster size, however, increases cochannel interference. In the literature, several techniques have been proposed for controlling the cochannel interference and simultaneously reducing the cluster size. In this paper, we combine two proposed capacity improvement methods and explore the effectiveness of reducing cochannel interference using narrow-beam antennas ("smart antennas") with the fractional loading factor. As shown in this paper, it is possible to increase capacity by many times by decreasing the cluster size (i.e. increasing frequency reuse), although the proper combination of antenna specifications and fractional loading is surprisingly nonintuitive. The first cochannel mitigation technique uses base-station antennas with narrow beams in the direction of the desired mobile stations and significant side lobe attenuation in the direction of undesired users. The second technique exploits the fact that interference is related to the loading factor p/sub ch/, which defines the probability that a given channel is in use within a cell, We show that large capacity gains with respect to a reference cellular system (N=7, three sectors per cell) can be obtained by combining these two techniques. This paper provides insight for system-level deployment of high-capacity cellular systems and can be extended to fixed wireless systems as well.

Lightweight data management for compositional modeling in problem solving environments

Abstract: We outline various design considerations and implementation options pertaining to lightweight data management in problem solving environments (PSEs). The emphasis is on compositional modeling, in the context of a PSE for wireless communications system design (S4W). By focusing on a restrictive subset of markup languages, we describe how facilities such as management of the execution environment, experiment management, and reasoning about model sequences can be provided.

Channel allocation in SDMA cellular systems

Abstract: Spatial division multiple access (SDMA) is recognized as a promising technique for improving capacity in future cellular systems, by exploiting the spatial filtering capability of adaptive antennas. In SDMA systems, in-cell users can share the same channel, making the channel allocation strategy play an important role in the system performance. In this paper, we analyze by simulation different strategies for channel allocation in cellular systems employing adaptive antennas and SDMA technique. Results show that high performance in SDMA systems is achieved by balancing channel reuse among cells with channel reuse within cells. Attempts to maximize channel reuse within cells may increase excessively cochannel interference, limiting capacity. Results also show that, while carried traffic is not severely affected by high level of user mobility, other performance parameters, such as the number of channel reassignment requests, are strongly affected by user mobility.

Joint angle and delay spread statistics for 1920 MHz peer-to-peer wireless channels

Abstract: This paper presents spatio-temporal channel statistics tabulated during a wideband peer-to-peer measurement campaign conducted on the campus of Virginia Tech. Based on over 2500 power-delay profile (PDP) snapshots made at 12 different local area locations, the measured statistics reveal trends about the spatio-temporal channel at microwave frequencies that are particularly useful for designing wideband wireless modems that operate in mobile ad-hoc networks.

Demarcation graphique et textuelle d'une localisation et interpretation des mesures

Abstract: L'invention concerne un systeme informatise. Ce systeme permet a un personnel qualifie ou non qualifie de collecter des donnees dans un groupe d'objets ou de reseaux a repartition spatiale. Ce systeme permet egalement d'analyser ces donnees collectees dans une base de donnees d'environnement.

Systeme et procede permettant de visualiser et de comparer efficacement le rendement systeme d'un reseau de communication

Abstract: L'invention concerne un procede permettant de visualiser et de comparer efficacement le rendement d'un systeme de communication a l'aide d'un rendement predit ou mesures, ou a l'aide d'autres ensembles de donnees relatives au rendement (etapes 200-260). Selon le mode de realisation decrit dans l'invention, une base de donnees en 3D est creee ou modifiee (200), un systeme de communication sans fil complet est forme dans la base de donnees (210), et le rendement systeme de la base de donnees est predit (220). Ensuite, un systeme est elabore dans un environnement du monde reel (230), des donnees de mesure sont collectees (240), puis les donnees predites et mesurees sont comparees (250).