Showing papers by "Theodore S. Rappaport published in 2003"

Cross-layer design for wireless networks

Abstract: As the cellular and PCS world collides with wireless LANs and Internet-based packet data, new networking approaches will support the integration of voice and data on the composite infrastructure of cellular base stations and Ethernet-based wireless access points. This article highlights some of the past accomplishments and promising research avenues for an important topic in the creation of future wireless networks. We address the issue of cross-layer networking, where the physical and MAC layer knowledge of the wireless medium is shared with higher layers, in order to provide efficient methods of allocating network resources and applications over the Internet. In essence, future networks will need to provide "impedance matching" of the instantaneous radio channel conditions and capacity needs with the traffic and congestion conditions found over the packet-based world of the Internet. Furthermore, such matching will need to be coordinated with a wide range of particular applications and user expectations, making the topic of cross-layer networking increasingly important for the evolving wireless buildout.

Principles of Communication Systems Simulation with Wireless Applications

Abstract: The hands-on, example-rich guide to modeling and simulating advanced communications systemsSimulation is an important tool used by engineers to design and implement advanced communication systems that deliver optimal performance This book is a hands-on, example-rich guide to modeling and simulating advanced communications systems The authors take a systems-level approach, integrating digital communications, channel modeling, coding, elementary statistical estimation techniques, and other essential facets of modeling and simulation This is the first book to present complete simulation models built with MATLAB that can serve as virtual laboratories for predicting the impact of system design changes Coverage includes: Role of simulation in communication systems engineering Simulation approaches and methodologies Signal and system representations, filter models, noise generation, Monte Carlo simulation, and postprocessing Advanced techniques for modeling and simulating nonlinear and time-varying systems Waveform level and discrete channel models Performance estimation via Monte Carlo simulation Semianalytic simulation techniques Variance reduction techniques Co-channel interference in wireless communication systems, and more The authors also present detailed case studies covering phase-locked loops, CDMA systems, multichannel nonlinear systems, as well as a start-to-finish simulation of an advanced cellular radio systemPrentice Hall Series in Communications Engineering & Emerging Technologies, Theodore S Rappaport, Editor

System and method for automated placement or configuration of equipment for obtaining desired network performance objectives

Abstract: A method is presented for determining optimal or preferred configuration settings for wireless or wired network equipment in order to obtain a desirable level of network performance. A site-specific network model is used with adaptive processing to perform efficient design and on-going management of network performance. The invention iteratively determines overall network performance and cost, and further iterates equipment settings, locations and orientations. Real time control is between a site-specific Computer Aided Design (CAD) software application and the physical components of the network allows the invention to display, store, and iteratively adapt any network to constantly varying traffic and interference conditions. Alarms provide rapid adaptation of network parameters, and alerts and preprogrammed network shutdown actions may be taken autonomously. A wireless post-it note device and network allows massive data such as book contents or hard drive memory to be accessed within a room by a wide bandwidth reader device, and this can further be interconnected to the internet or Ethernet backbone in order to provide worldwide access and remote retrieval to wireless post-it devices.

System and method for indicating the presence or physical location of persons or devices in a site specific representation of a physical environment

Abstract: A system and method for providing security to a wireless communication system having wireless communication components positioned at different locations within a physical environment are provided. The wireless communication components include an access point and a network device. A site-specific computerized representation of the physical environment displays the location of the wireless communication components including the access point and network device. The access point and network device identify the presence or a physical location of a possible intruder or intruder devices. An indicator is presented in the site-specific representation on the display when an erroneous authentication request or other undesired transmission is received by the network device or the access point.

Mobile Radio Communications

Abstract: Mobile communications has been of interest since the earliest days of wireless communications. First applications involved ship-to-shore and ship-to-ship telegraphy as well as telegraphy to moving trains. The development of AM radio, and later FM radio, resulted in mobile voice communication systems. The development of the cellular radio concept gave to rise to mobile telephones that were both practical and inexpensive. The growth of the cellular telephone industry exceeded all expectations and, in many environments, the bulk of telephone traffic is now handled by wireless cellular systems. This article details this history and describes the essential features of mobile radio systems, including the cellular concept, mobile radio channels, and multiple access techniques. First, second and third generation commercial cellular systems are discussed and their capabilities are compared. Keywords: wireless communications; mobile communications; cellular systems; multiple access systems; CDMA; time-division multiple access; frequency-division multiple access

Wideband measurements of angle and delay dispersion for outdoor and indoor peer-to-peer radio channels at 1920 MHz

Abstract: The paper presents spatio-temporal measurements for the peer-to-peer radio channel at a center frequency of 1920 MHz with 140 MHz of radio-frequency bandwidth. The measurements were taken using a spread-spectrum channel sounder and an automated spatial probing system that uses precise computer-controlled positioning and orientation of omnidirectional and directional (30/spl deg/ beamwidth) antennas to measure both the angles-of-arrival and time-delays of multipath components. We use a unitless definition of angular spread which we proposed previously (see Durgin, G.D. and Rappaport, T.S., IEE Electron. Lett., vol.34, no.25, p.2431-2, 1998). Transmitter-receiver configurations include six outdoor-to-outdoor cross-campus locations at Virginia Polytechnic Institute and State University (17-219 ns rms delay spread, 0.36-0.91 angular spread), three outdoor-to-indoor locations (27-34 ns rms delay spread, 0.78-0.98 angular spread), and three indoor-to-indoor locations (29-45 ns rms delay spread, 0.73-0.90 angular spread). The paper also quantitatively describes a trend that shows how angular spread increases with increasing delay spread.

Method and system, with component kits for designing or deploying a communications network which considers frequency dependent effects

Abstract: A computerized model provides a display of a physical environment in which a communications network is or will be installed. The communications network is comprised of several components, each of which are selected by the design engineer and which are represented in the display. Errors in the selection of certain selected components for the communications network are identified by their attributes or frequency characteristics as well as by their interconnection compatibility for a particular design. The effects of changes in frequency on component performance are modeled and the results are displayed to the design engineer. A bill of materials is automatically checked for faults and generated for the design system and provided to the design engineer. For ease of design, the design engineer can cluster several different preferred components into component kits, and then select these component kits for use in the design or deployment process.

Method and system for displaying network performance, cost, maintenance, and infrastructure wiring diagram

Abstract: A network which includes electromagnetic components, such as a wireless communications system, is designed, optimized, modified and/or saved or exported to another applications program using a graphical interface. A display may present a graphical rendering of performance characteristics in a site specific manner showing elements such as walls, doors, windows, furniture, people, foliage, and terrain. The locations where performance characteristic information are presented can be automatically selected and adjusted to present more or less information. The display can be viewed at multiple perspectives, and the viewing angle can be adjusted. In one embodiment, the display can graphically present information related to two different performance characteristics. An infrastructure wiring diagram can be generated for analysis or for exportation to other applications using the system, wherein after components are positioned and connected within the context of a site map, the site map itself is eliminated or significantly reduced in prominence.

The evolution of ultra wide band radio for wireless personal area networks

Abstract: U ltra wideband (UWB) wireless networks are in their infancy, but are poised tci become a valuable component of consumer electronics and computer equipment. The IEEE 802.15.3a task group is currently developing a UWB standard that involves most oftlie major chip manufacturers, including Texas Instruments, Intel, Motorola, and Xtreme Spectrum. This article provides a snapshot of the current state of the UWB standards process. According to the present timetable, drafts are now being completed and the standards should be determined by 2004. We also discuss the benefits ofUWB radio, the regulatory environment of UWB, and the design i~sues that WPAN standards makers niust consider.

Connectivity of sensor networks with power control

Abstract: In this paper, we consider a sensor network with an average of n nodes randomly placed over a region of unit area. We assume that each node is equipped with a wireless transceiver, and are interested in the minimum transmit power required for maintaining connectivity of the network when power control is employed (i.e., each node can choose a power level for transmission independent of any other node). We show that the average power gain per node (the ratio of the transmit power required without and with power control) increases with the (average) number of nodes n as (logn)/sup /spl alpha//2/, where /spl alpha/ is the path loss exponent.

BSML: A binding schema markup language for data interchange in problem solving environments

Abstract: We describe a binding schema markup language (BSML) for describing data interchange between scientific codes. Such a facility is an important constituent of scientific problem solving environments (PSEs). BSML is designed to integrate with a PSE or application composition system that views model specification and execution as a problem of managing semistructured data. The data interchange problem is addressed by three techniques for processing semistructured data: validation, binding, and conversion. We present BSML and describe its application to a PSE for wireless communications system design.

Overview of wireless networks and security issues for wifi networks

Abstract: W . ireless local area networks (WLAN s) provide wireless connectivity between PCs, laptops and other equipment in corporate, public and home environments. Today, tens of millions of users rely on shortrange wireless connectivity between computers or automation equipment using WLAN modem gear that complies with well-known Figure 1. Evolution ofWLAN standards. standards such as IEEE 802.11, 802.11 a, 802.11 b and 802.llg. The first WLAN standard IEEE 802.11, initially contemplated in the late 1980's, was finalized in 1997 (10 years later!) and provided interoperability standards for equipment makers compatible 'with IEEE 802.11 b and 802.11 standards. · Figure 1 illustrates the evolution of IEEE WLAN · standards. An overview of the evolution of WiFi is