SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 7 - April 07, 2006
32 COMMUNICATIONS AND RADAR
Includes radar; radio, wire, and optical communications; land and global communications; communications theory.
For related information see also 04 Aircraft Communications and Navigation; and 17 Space Communications, Spacecraft Communications, Command and Tracking; for search and rescue, see 03 Air Transportation and Safety; and 16 Space Transportation and Safety.
20060009128 Newcastle-upon-Tyne Univ., Newcastle, UK
Grid Computing Using Web Services
Parastatidis, S.; Watson, P.; Webber, J.; Aug. 2005; 22 pp.; In English Report No.(s): PB2006-103554; CS-TR-926; Copyright; Avail.: National Technical Information Service (NTIS)
Service-Oriented Architecture (SOA) is the contemporary paradigm of choice for developing scalable, loosely-coupled applications that span organizations. However the architectural paradigm that is SOA is often confused with the implementation technology that is Web Services. In this paper we aim to clarify the fundamental tenets of SOA and their relevance to Internet-scale computing (or Grid computing). We then show how to apply the principles of SOA to building Internet-scale applications using Web Services technologies and how to avoid software pitfalls by adhering to a number of deliberately simple architectural constraints. NTIS
Communication Networks; Grid Computing (Computer Networks); Interprocessor Communication
20060009130 Newcastle-upon-Tyne Univ., Newcastle, UK
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Design and Performance Study of Crash Tolerant Protocols for Broadcasting and Reaching Consensus in MANETs
Vollset, E.; Ezhilchelvan, P. D.; Aug. 2005; 30 pp.; In English Report No.(s): PB2006-103553; CS-TR-925; Copyright; Avail.: National Technical Information Service (NTIS)
The mobile ad-hoc networking (MANET) technology offers an ideal medium for hosting self-organized collaborative applications in terrains with no infrastructure support for untethered communication. Collaboration involves users with potentially different initial opinions deciding identically, i.e., reaching consensus. Efficient consensus solutions require efficient broadcast support. This paper presents four crash-tolerant broadcast protocols which are designed (1) to provide the maximum broadcast coverage that can ever be guaranteed, and (2) to suit a wide range of MANET types: from a connected MANET (no partitions) to intermittently disconnected one (partitions occurring rarely and healing swiftly) to an intermittently connected one (partitions taking longer to heal and re-appearing swiftly). The resulting design challenges are addressed systematically, beginning with formulating a MANET liveness property and deriving two foundational results that would guide the protocol design. The protocols' performance is then studied through simulations for a range of node speeds and network densities. The one with the smallest overhead is used to support a known, randomized consensus protocol. The consensus overhead and the latency remain surprisingly small even as the number of nodes with distinct initial opinions increases. NTIS
Broadcasting; Communication Networks; Crashes; Protocol (Computers)
20060009132 Newcastle-upon-Tyne Univ., Newcastle, UK
Optimization of Encounter Gossip Propagation in Mobile Ad-Hoc Networks
Cooper, D. E.; Ezhilchelvan, P.; Mitrani, I.; Vollset, E.; Jul. 2005; 16 pp.; In English Report No.(s): PB2006-103551; CS-TR-921; Copyright; Avail.: National Technical Information Service (NTIS)
Encounter Gossip is a family of message propagation protocols for mobile ad-hoc networks. The coverage of message propagation (the fraction of nodes that receive it), can be made arbitrarily close to 1, but the cost of increased coverage is an increase in message traffic. This paper proposes modifications which aim to minimize the number of broadcasts without compromising the achieved coverage. Two approaches to broadcast reduction are pursued: timer based and history based. The effectiveness of each of these approaches is assessed through an extensive set of simulation experiments in the context of two mobility models. NTIS
Communication Networks; Messages; Protocol (Computers); Traffic
20060009475 Coast Guard, Groton, CT, USA
Intelligent Gateway Design and Development. Final Report
Oct. 1996; 40 pp.; In English Report No.(s): PB2006-103590; No Copyright; Avail.: CASI: A03, Hardcopy
The Intelligent Gateway (IG) is a Research and Development (R&D) effort to design an algorithm to provide computer-aided routing of ACP-123/X.400 messages by a USA Coast Guard (USCG) Communications Area Master Station (CAMS). The algorithm is designed to be implementation independent; i.e. it is not dependent on a particular programming language, methodology, or hardware platform. The IG development is a proof-of-concept effort and is not intended to be fielded as a stand alone Defense Message System (DMS) component. Instead the USCG is working with the U.S. Navy and DMS product vendors to incorporate IG functionality into future Commercial Off-The-Shelf (COTS) DMS products. NTIS
Algorithms; Messages
20060009481 Small Business Administration, Washington, DC, USA
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Broadband Use by Rural Small Businesses
Dec. 2005; 36 pp.; In English Contract(s)/Grant(s): SBAHQ-02-M-0528 Report No.(s): PB2006-101287; No Copyright; Avail.: National Technical Information Service (NTIS)
This research explores two popular beliefs pertaining to the deployment and use of broadband services.
First, that these services provide tangible benefit to the overall economy. Second, that rural deployment lags urban deployment.
It has often been suggested that the universal provision of broadband services in rural areas was cost prohibitive; thus creating the urban-rural digital divide. This study investigates and verifies these assertions, specifically, as they apply to rural small businesses. It relies primarily on data from the Federal Communications Commission (FCC) and an Office of Advocacy survey.
The study finds that an urban-rural digital divide does exist in the provision and adoption of broadband services. This difference in broadband use is statistically significant. A major concern is that many benefits have been associated with the availability and adoption of broadband services, and rural small businesses are not obtaining them. NTIS
Broadband; Commerce; Communication Networks; Rural Areas; Telecommunication
20060009497 National Inst. of Justice, Washington, DC, USA
Working Together To Bridge the Communications Gap to Save Lives. A Guide for Public Officials
Feb. 2003; 76 pp.; In English Report No.(s): PB2006-103631; No Copyright; Avail.: CASI: A05, Hardcopy
In an era where technology can bring news, current events, and entertainment to the farthest reaches of the world, many law enforcement officers, firefighters, and emergency medical service personnel working in the same jurisdiction cannot communicate with one another. The inability of our public safety officials to readily communicate with one another threatens the publics safety and often results in unnecessary loss of lives and property. Recognizing that solutions to this national issue can only be achieved through cooperation between all levels of government, 18 national associations representing State and local elected and appointed officials and public safety officials formed a task force to address this issue. The case studies and articles contained in this document are the result of the significant commitment by members of this task force who shared their knowledge, experience, and wisdom. NTIS
Telecommunication; Radio Communication
20060009929 National Telecommunications and Information Administration, Washington, DC USA
Proceedings of the International Symposium on Advanced Radio Technologies. Held in Boulder, Colorado on March 7-9, 2006
Raush, P. J.; Novik, K. E.; Mar. 2006; 190 pp.; In English; International Symposium on Advanced Radio Technologies., March 7 - 9, 2006, Boulder, Colorado Report No.(s): PB2006-107719; NTIA-SP-06-438; No Copyright; Avail.: National Technical Information Service (NTIS)
The International Symposium on Advanced Radio Technologies (ISART) brings together technical researchers, business leaders, government policy makers, and regulators for the purpose of forecasting the development and application of radio frequency technologies. NTIS
Conferences; Radio Equipment
20060009965 Fermi National Accelerator Lab., Batavia, IL, USA, Indiana Univ., Indianapolis, IN, USA, Chicago Univ., Chicago, IL USA, Florida Univ., Gainesville, FL, USA
Grid2003 Monitoring Metrics, and Grid Cataloging System
Grundhoefer, L.; Quick, R.; Hicks, J.; January 2005; 20 pp.; In English Report No.(s): DE2005-15016967; FERMILAB-CONF-04-458; No Copyright; Avail.: National Technical Information Service (NTIS)
Grid computing involves the close coordination of many different sites which offer distinct computational and storage resources to the Grid user community. The resources at each site need to be monitored continuously. Static and dynamic site information needs to be presented to the user community in a simple and efficient manner. NTIS
Grid Computing (Computer Networks); Coordination
20060010005 NASA Glenn Research Center, Cleveland, OH, USA
A Novel, Free-Space Optical Interconnect Employing Vertical-Cavity Surface Emitting Laser Diodes and InGaAs Metal-Semiconductor-Metal Photodetectors for Gbit/s RF/Microwave Systems
Savich, Gregory R.; Simons, Rainee N.; March 2006; 19 pp.; In English; Photonics West 2006, 21-26 Jan. 2006, San Jose, CA, USA; Original contains black and white illustrations Contract(s)/Grant(s): WBS 953033.01.03.12 Report No.(s): NASA/TM-2006-214251; E-15496; Paper number 6126-11; Copyright; Avail.: CASI: A03, Hardcopy
Emerging technologies and continuing progress in vertical-cavity surface emitting laser (VCSEL) diode and metalsemiconductor- metal (MSM) photodetector research are making way for novel, high-speed forms of optical data transfer in communication systems. VCSEL diodes operating at 1550 nm have only recently become commercially available, while MSM photodetectors are pushing the limits of contact lithography with interdigitated electrode widths reaching sub micron levels. We propose a novel, free-space optical interconnect operating at about 1Gbit/s utilizing VCSEL diodes and MSM photodetectors. We report on development, progress, and current work, which are as follows: first, analysis of the divergent behavior of VCSEL diodes for coupling to MSM photodetectors with a 50 by 50 m active area and second, the normalized frequency response of the VCSEL diode as a function of the modulating frequency. Third, the calculated response of MSM photodetectors with varying electrode width and spacing on the order of 1 to 3 m as well as the fabrication and characterization of these devices. The work presented here will lead to the formation and characterization of a fully integrated 1Gbit/s free-space optical interconnect at 1550 nm and demonstrates both chip level and board level functionality for RF/microwave digital systems. Author
Laser Cavities; Diodes; Semiconductor Lasers; Surface Emitting Lasers; Photometers; Free-Space Optical Interconnects
Source: NASA
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