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Showing papers by "Theodore S. Rappaport published in 1995"


Journal ArticleDOI
TL;DR: The authors describe the type of signals that occur in various environments and the modeling of the propagation parameters, which are divided into outdoor environments, indoor environments, and radio penetration from outdoor to indoor environments.
Abstract: The authors describe the type of signals that occur in various environments and the modeling of the propagation parameters. Models are essentially of two classes. The first class consists of parametric statistical models that on average describe the phenomenon within a given error. They are simple to use, but relatively coarse. In the last few years a second class of environment-specific models has been introduced. These models are of a more deterministic nature, characterizing a specific street, building, etc. They are necessarily more time consuming to use, but are also more revealing concerning physical details and hopefully more accurate. Some key parameters and the measurement of them are discussed and then the different wireless environments are treated. The latter topic is divided into outdoor environments, indoor environments, and radio penetration from outdoor to indoor environments. >

808 citations


01 Jan 1995
TL;DR: In this paper, a simplified expression for the improved Gaussian approximation (SEIGA) is presented for accurately evaluating Direct Sequence Code Division Multiple Access (DS-CDMA) bit error rates in multipath channels and systems with imperfect power control.
Abstract: In this paper, a Simplified Expression for the Improved Gaussian Approximation (SEIGA) is presented for accurately evaluating Direct Sequence Code Division Multiple Access (DS-CDMA) bit error rates in multipath channels and systems with imperfect power control. Previous techniques for evaluating bit error rate performance of these systems can lead to overly optimistic results under a variety of conditions, particularly when directional or adaptive antennas are used at the base station. In this paper, we demonstrate the accuracy of these new techniques for evaluating bit error rates in both narrowband and wide band multipath channels and illustrate these techniques by providing a system example in which adaptive antennas are applied to CDMA cellular radio systems.

22 citations


Book
01 May 1995
TL;DR: Leaders in the field give key information on fundamental system design, speech coding, cellular networking, modulation techniques, and standards in some of the most useful papers available.
Abstract: From the Publisher: This collection of 40 articles will be invaluable to students, practicing engineers, and researchers. Leaders in the field give key information on fundamental system design, speech coding, cellular networking, modulation techniques, and standards in some of the most useful papers available.

8 citations


Book ChapterDOI
01 Jan 1995
TL;DR: An interactive software tool has been developed which can be used to assess the coverage of RF transceivers within multifloor buildings and should prove to be very useful in the specification of wireless LAN systems.
Abstract: An interactive software tool has been developed which can be used to assess the coverage of RF transceivers within multifloor buildings. Using AutoCAD as a foundation, this system displays floor plans and permits the user to place transceivers at arbitrary locations within a building. The user can interactively set communication parameters and can view the resulting coverage regions, which depend on the locations and material properties of walls and partitions. Such a tool should prove to be very useful in the specification of wireless LAN systems.

5 citations


Proceedings ArticleDOI
24 Jul 1995
TL;DR: In this article, the authors provide an overview of the fundamental concepts used in cellular radio communications and illustrate the likely evolution and growth of the personal communications field, and summarize some of the most popular wireless standards used throughout the world.
Abstract: This tutorial paper provides an overview of the fundamental concepts used in cellular radio communications, and illustrates the likely evolution and growth of the personal communications field. This paper also summarizes some of the most popular wireless standards used throughout the world.

3 citations


Book
01 Mar 1995
TL;DR: In this paper, the state-of-the-art and future vision of wireless communications is presented in the form of a number of new services, and the opinions of representatives from regulatory agencies and standards organizations on the future of this critical area.
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.

2 citations



Proceedings ArticleDOI
TL;DR: The method used by the site modeling tool to estimate coverage for both directional and omnidirectional antennas is described, expected to be very useful in the specification of indoor wireless systems.
Abstract: This paper describes a system which assists in the strategic placement of rf base stations within buildings. Known as the site modeling tool (SMT), this system allows the user to display graphical floor plans and to select base station transceiver parameters, including location and orientation, interactively. The system then computes and highlights estimated coverage regions for each transceiver, enabling the user to assess the total coverage within the building. For single-floor operation, the user can choose between distance-dependent and partition- dependent path-loss models. Similar path-loss models are also available for the case of multiple floors. This paper describes the method used by the system to estimate coverage for both directional and omnidirectional antennas. The site modeling tool is intended to be simple to use by individuals who are not experts at wireless communication system design, and is expected to be very useful in the specification of indoor wireless systems.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

2 citations


01 Jan 1995
TL;DR: This work surveys research an interfering signal is received with higher power than into a variety of techniques which will increase the desired signal, and shows how these techniques can be applied to inventional receivers and crease the capacity of CDMA systems.
Abstract: Code Division Multiple Access (CDMA) · largely on frequency reuse and voice activity gating; based on spread-spectrum techniques finds increasing for. data transmission within a single cell environment,· use in commercial communications. Although CDMA the capacity of the current generation of CDMA sysoffers important advantages for wireless communicatems does ·not approach the capacity of Time or Fretions, current CDMA systems are less spectrally effi. quency Division Multiple Access. Furthermore, current . cient than ·systems employing orthogonal multiple acCDMA systems depend heavily on accurate power concess techniques in a single cell environment, and are detrol to avoid the near-far problem which arises when pendent on accurate power control. We survey research an interfering signal is received with higher power than into a variety of techniques which will increase the specthe desired signal. Even with an elaborate combinatral efficiency and robustness of subsequent generations tion of open~ loop and closed-loop power control, field of CDMA systems. These techriiques include multiuser trials indicate received signal powers will have a variand single user interference rejection techniques, the deance of 1-2 dB about their desired values in a mobile ployment of smart antenna technology, and the develenvironment[4]. This small variation can reduce the opment of advanced error correction coding techniques. capacity of by 15-30%~from the ideal case when conWe show how these techniques can be applied to inventional receivers· are employed[5]. crease the capacity of CDMA systems. New processing techniques· on the horizon will enable

1 citations


01 Jan 1995
TL;DR: The design and development of a software tool that provides a framework for modelers to incorporate new models and test their hypotheses, and system designers and planners to obtain the propagation characteristics in any environment is discussed.
Abstract: Accurate modeling of radio propagation characteristics in and around built-up urban environments is vital to the successful functioning of ~urv~illance and tracking systems utilizing wireless technology. A vast majority of the software tools currently available to military and civilian users are based on very simple models with fairly limited accuracy and are closed architectures. We discuss the design and development of a software tool that prov~des: a) a framework for modelers to incorporate new models and test their hypotheses, and b) system designers and planners to obtain the propagation characteristics in any environment. The interactive software executes on a workstation, uses topographic maps with building overlays to predict signal coverage and channel characteristics for user-specified antenna locations. Work is in progress to improve the accuracy of the prediction software through better diffraction modeling.

1 citations


01 Jan 1995
TL;DR: This tutorial is part of an independent learning program prepared by the authors for the IEEE and will be included in the textbook Wireless Communications: Principles a.;,d Practice published by Prentice-Hall.
Abstract: GSM quickly is emerging as the leading cellular radio standard throughout the world. With the advent of new personal communications frequencies irt the 1.8 2 GHz band, GSM and its PCS offshoot, DCS, may be implemented in North America within the next 12 months to 18 months. This tutorial is part of an independent learning program prepared by the authors for the IEEE. This material is taught as part of an introductory course on wireless communications at Virginia Tech and will be included in the textbook Wireless Communications: Principles a.;,d Practice published by Prentice-Hall. Global System for Mobile Communications Global system for mobile communications (GSM) is a second-generation cellular system standard that was developed to solve the fragm~ntation problems of the first cellular systems in Europe [Mou92]. Unlike the U.S. cellular carriers which implemented the firstgeneration analog mobile phone system (AMPS) throughout the country, the first-genera. tion cellular service providers in Europe took a provincial view of cellular. Before GSM, European countries used different cellular standards throughout the continent, and it was not possible for a customer to use a single mobile phone' throughout Europe. After five years and hundreds of person-years of engineering, the European community developed an amazingly·robust and complex cellular standard that was first to specify digital modulation and network level architectures and service. GSM originally was developed to serve just the pan-European cellular market and promised a wide range of network services through the use of integrated services digital network (ISDN). However, during the past two years, GSM's success has exceeded the expectations of virtually everyone, and it is now the world's most popular standard for new cellular radio and personal communications equipment throughout the world. It is predicted that by the year 2000, there will be between 20 million and 50 million GSM subscribers worldwide ·[Mou92], [Dec93]. The task of specifying a common mobile communication system for Europe in the 900 MHz band was taken up by the GSM (Groupe special mobile) committee, which was a working gl-oup of the Conference of Europe6ene Pastes des et Te6le6communication (CEPT). The setting of standards for GSM is currently under the aegis of the European Technical Standards Institute (ETSI). GSM first was introduced into the European market in 1991. By the end of 1993, several non-European countries in South America, Asia and Australia had adopted GSM and the technically equivalent offshoot, DCS 1800, which supports personal communication services (PCS) in the 1.8-2.0 GHz radio bands recently created by governments throughout the world. GSM Services, Features GSM services follow ISDN guidelines and are classified as either teleservices or data services. Teleservices include standard mobile telephony and mobileaoriginated or baseoriginated traffic. Data services include computer-to-computer communication and packet-