74,945 research outputs found
MIRAI Architecture for Heterogeneous Network
One of the keywords that describe next-generation wireless communications is "seamless." As part of the e-Japan Plan promoted by the Japanese Government, the Multimedia Integrated Network by Radio Access Innovation project has as its goal the development of new technologies to enable seamless integration of various wireless access systems for practical use by 2005. This article describes a heterogeneous network architecture including a common tool, a common platform, and a common access. In particular, software-defined radio technologies are used to develop a multiservice user terminal to access different wireless networks. The common platform for various wireless networks is based on a wireless-supporting IPv6 network. A basic access network, separated from other wireless access networks, is used as a means for wireless system discovery, signaling, and paging. A proof-of-concept experimental demonstration system is available
Optical communication on CubeSats - Enabling the next era in space science
CubeSats are excellent platforms to rapidly perform simple space experiments.
Several hundreds of CubeSats have already been successfully launched in the
past few years and the number of announced launches grows every year. These
platforms provide an easy access to space for universities and organizations
which otherwise could not afford it. However, these spacecraft still rely on RF
communications, where the spectrum is already crowded and cannot support the
growing demand for data transmission to the ground. Lasercom holds the promise
to be the solution to this problem, with a potential improvement of several
orders of magnitude in the transmission capacity, while keeping a low size,
weight and power. Between 2016 and 2017, The Keck Institute for Space Studies
(KISS), a joint institute of the California Institute of Technology and the Jet
Propulsion Laboratory, brought together a group of space scientists and
lasercom engineers to address the current challenges that this technology
faces, in order to enable it to compete with RF and eventually replace it when
high-data rate is needed. After two one-week workshops, the working group
started developing a report addressing three study cases: low Earth orbit,
crosslinks and deep space. This paper presents the main points and conclusions
of these KISS workshops.Comment: 7 pages, 5 figures, 2 tables, Official Final Report of KISS (Keck
Institute for Space Studies) workshop on "Optical communication on CubeSats"
(http://kiss.caltech.edu/workshops/optcomm/optcomm.html
Quantum well lasers -- Gain, spectra, dynamics
We discuss a number of theoretical and experimental issues in quantum well lasers with emphasis on the basic behavior of the gain, the field spectrum, and the modulation dynamics. It is revealed that the use of quantum well structures results in improvement of these properties and brings several new concepts to optical semiconductor devices
DSRC – NEW PRINCIPLES AND IMPLEMENTATIONS IN ITS ROMANIA
Cities around the world are suffering from severe traffic congestion resulting in economic losses via delayed time, fuel consumption, traffic accidents, air pollution and traffic noise. An efficient wireless technology used in the road-to-vehicle radio communication can help reducing this negative effects and improve traffic parameters. Active DSRC is one of the most reliable road-to-vehicle communication methods available in the market today, since it has wide communication area and high-speed communication and is the most suitable for non-stop toll collection system, especially for multi-lane free-flow toll collection system, where vehicles can pass the toll gantry without reducing speed. The Active DSRC also supports other ITS applications related to road-to-vehicle communication applications that need high speed communication, and can improve public transportation, help to reduce air pollution, NOx and CO2, and road noise via a decline in traffic.ITS
The Future of Mobile Industry
This paper discusses the future of mobile industry along with some of the background
leading to the emergence of wireless technology. First, it gives an overview of today’s
telecommunication network and the major differences between fixed wired networks and
wireless networks. The discussion then focuses on the challenges facing the wireless
industry and the way out through aggressive innovation by employing Wireless Intelligence
Network (WIN) technology. The paper also discusses some important trends in wireless
industry and the customers expectations which are also part of the challenges for the
mobile industry. Finally particular reference is made to the developing nations especially
Nigeria in the ongoing trends in mobile communication industry
Recent developments in monolithic integration of InGaAsP/InP optoelectronic devices
Monolithically integrated optoelectronic circuits combine optical devices such as light sources (injection lasers and light emitting diodes) and optical detectors with solid-state semiconductor devices such as field effect transistors, bipolar transistors, and others on a single semiconductor crystal. Here we review some of the integrated circuits that have been realized and discuss the laser structures suited for integration with emphasis on the InGaAsP/InP material system. Some results of high frequency modulation and performance of integrated devices are discussed
Communication satellites: Guidelines for a strategic plan
To maintain and augment the leadership that the United States has enjoyed and to ensure that the nation is investing sufficiently and wisely to this purpose, a strategic plan for satellite communications research and development was prepared by NASA. Guidelines and recommendations for a NASA plan to support this objective and for the conduct of communication satellite research and development program over the next 25 years were generated. The guidelines are briefly summarized
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