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We present a technique that derives the link activation schedule (transmit/receive mode and communications neighbor selection) and routes used for efficient traffic relay through the network.
Attention is given to a narrow-band communication system consisting of a central station trying to receive signals simultaneously from K spatially distinct mobile users sharing the same frequencies. One example of such a system is a group of aircraft and ships transmitting messages to a communication satellite. A reasonable approach to such a multiple access system may be based on equipping the central station with an n-element antenna array where n is equal to or greater than K. The array employs K sets of n weights to segregate the signals received from the K users. The weights are determined by direct computation based on position information transmitted by the users. A description is presented of an improved technique which makes it possible to reduce significantly the number of required computer operations in comparison to currently known techniques.
A lunar surface systems study explores the application of optical communications to support a high bandwidth data link from a lunar relay satellite and from fixed lunar assets. The results show that existing 1-m ground stations could provide more than 99% coverage of the lunar terminal at 100Mb/s data rates from a lunar relay satellite and in excess of 200Mb/s from a fixed terminal on the lunar surface. We have looked at the effects of the lunar regolith and its removal on optical samples. Our results indicate that under repeated dust removal episodes sapphire rather than fused silica would be a more durable material for optical surfaces. Disruption tolerant network protocols can minimize the data loss due to link dropouts. We report on the preliminary results of the DTN protocol implemented over the optical carrier.
The National Aeronautics and Space Administration (NASA) and the Department of Defense (DoD) are planning Space System of Systems (SoS) to address the new challenges of space exploration, defense, communications, navigation, Earth observation, and science. In addition, these complex systems must provide interoperability, enhanced reliability, common interfaces, dynamic operations, and autonomy in system management. Both NASA and the DoD have chosen to meet the new demands with high data rate communication systems and space Internet technologies that bring Internet Protocols (IP), routers, servers, software, and interfaces to space networks to enable as much autonomous operation of those networks as possible. These technologies reduce the cost of operations and, with higher bandwidths, support the expected voice, video, and data needed to coordinate activities at each stage of an exploration mission. In this paper, we discuss, in a generic fashion, how the architectural approaches and processes are being developed and used for defining a hypothetical communication and navigation networks infrastructure to support lunar exploration. Examples are given of the products generated by the architecture development process.
This paper provides an overview of different options at Earth to provide Deep Space optical communication services. It is based mainly on work done for the Mars Laser Communications Demonstration (MLCD) Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It also reports preliminary conclusions from the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telecommunications Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.
In the near future the National Aeronautics and Space Administration anticipates a significant increase in demand for long-haul communications services from deep space to Earth. Distances will range from 0.1 to 40 AU, with data rate requirements in the 1's to 1000's of Mbits/second. The near term demand is driven by NASA's Space Science Enterprise which wishes to deploy more capable instruments onboard spacecraft and increase the number of deep space missions. The long term demand is driven by missions with extreme communications challenges such as very high data rates from the outer planets, supporting sub-surface exploration, or supporting NASA's Human Exploration and Development of Space Enterprise beyond Earth orbit. Laser communications is a revolutionary communications technology that will dramatically increase NASA's ability to transmit information across the solar system. Lasercom sends information using beams of light and optical elements, such as telescopes and optical amplifiers, rather than RF signals, amplifiers, and antennas. This paper provides an overview of different network options at Earth to meet NASA's deep space lasercom requirements. It is based mainly on work done for the Mars Laser Communications Demonstration Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It reports preliminary conclusions from the Mars Lasercom Study conducted at MIT/LL and on additional work done for the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telesat Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.
Applied Expertise surveyed the users of the deployed Technology Utilization Network System (TUNS) and surveyed prospective new users in order to gather background information for developing the Concept Document of the system that will upgrade and replace TUNS. Survey participants broadly agree that automated mechanisms for acquiring, managing, and disseminating new technology and spinoff benefits information can and should play an important role in meeting NASA technology utilization goals. However, TUNS does not meet this need for most users. The survey describes a number of systematic improvements that will make it easier to use the technology transfer mechanism, and thus expedite the collection and dissemination of technology information. The survey identified 26 suggestions for enhancing the technology transfer system and related processes.
The Multi-Compatible Network Interface Unit (MCNIU) is intended to connect the space station's communications and tracking, guidance and navigation, life support, electric power, payload data, hand controls, display consoles and other systems, and also communicate with diverse processors. Honeywell is now marketing MCNIU commercially. It has applicability in certain military operations or civil control centers. It has nongovernment utility among large companies, universities and research organizations that transfer large amounts of data among workstations and computers. *This product is no longer commercially available.
In this paper we present a peer-to-peer sensor network architecture using space-division optical retro-reflector to provide energy efficient communication services for in-situ science applications.
A synopsis of research on computer viruses and computer security is presented. A review of seven technical meetings attended is compiled. A technical discussion on the communication plans for the ASRM facility is presented, with a brief tutorial on the potential local area network media and protocols.
The International Mobile Telecommunications - 2000 (IMT-2000) standard and more specifically the Satellite component of it, is investigated as a potential alternative for communications to aircraft mobile users en-route and in terminal area. Its application to Air Traffic Management (ATM) communication needs is considered. A summary of the specifications of IMT-2000 satellite standards are outlined. It is shown via a system research analysis that it is possible to support most air traffic communication needs via an IMT-2000 infrastructure. This technology can compliment existing, or future digital aeronautical communications technologies such as VDL2, VDL3, Mode S, and UAT.
In order to benefit from experience gained from the synchronization of operational wideband digital networks, a survey was made of three such systems: Data Transmission Company, Western Union Telegraph Company, and the Computer Communications Group of the Trans-Canada Telephone System. The focus of the survey was on deployment and operational experience from a practical (as opposed to theoretical) viewpoint. The objective was to provide a report on the results of deployment how the systems performed, and wherein the performance differed from that predicted or intended in the design. It also attempted to determine how the various system designers would use the benefit of hindsight if they could design those same systems today.
The realization of the full potential of the National Information Infrastructure (NH) and Global Information Infrastructure (GII) requires seamless interoperability of emerging satellite networks with terrestrial networks. This requires a cooperative effort between industry, academia and government agencies to develop and advocate new, satellite-friendly communication protocols and modifications to existing communication protocol standards. These groups have recently come together to actively participating in a number of standards making bodies including: the Internet Engineering Task Force (IETF), the Asynchronous Transfer Mode (ATM) Forum, the International Telecommunication Union (ITU) and the Telecommunication Industry Association MA) to ensure that issues regarding efficient use of these protocols over satellite links are not overlooked. This paper will summarize the progress made toward standards development to achieve seamless integration and accelerate the deployment of multimedia applications.
Analyzed optical DTE (direct to earth) and lunar relay satellite link analyses, greater than 200 Mbps downlink to 1‐m Earth receiver and greater than 1 Mbps uplink achieved with mobile 5‐cm lunar transceiver, greater than 1Gbps downlink and greater than 10 Mpbs uplink achieved with 10‐cm stationary lunar transceiver, MITLL (MIT Lincoln Laboratory) 2013 LLCD (Lunar Laser Communications Demonstration) plans to demonstrate 622 Mbps downlink with 20 Mbps uplink between lunar orbiter and ground station; Identified top five technology challenges to deploying lunar optical network, Performed preliminary experiments on two of challenges: (i) lunar dust removal and (ii)DTN over optical carrier, Exploring opportunities to evaluate DTN (delay-tolerant networking) over optical link in a multi‐node network e.g. Desert RATS.
This novel structure is a heterojunction phototransistor which can be used as an emitter-detector, and when placed in a quiescent mode, the device becomes a passive transmitter. By varying the voltage bias, this novel device will switch between all three modes of operation. Such a device has broad application in network environments with operation speeds of less than 50 MHz and distances of less than 1 km, e.g. automobiles, airplanes, and intra-instrumentation. During this period, the emission mode for this device was studied and mathematically modeled.
The architecture of the telecommunication network as the first step in the design of the LMSS system is described. A set of functional requirements including the total number of users to be served by the LMSS are hypothesized. The design parameters are then defined at length and are systematically selected such that the resultant system is capable of serving the hypothesized number of users. The design of the backhaul link is presented. The number of multiple backhaul beams required for communication to the base stations is determined. A conceptual procedure for call-routing and locating a mobile subscriber within the LMSS network is presented. The various steps in placing a call are explained, and the relationship between the two sets of UHF and S-band multiple beams is developed. A summary of the design parameters is presented.
The National Airspace System is a highly complex system of systems within which a number of participants with widely varying business and operating models exist. From the airspace user's perspective, a means by which to operate flights in a more flexible and efficient manner is highly desired to meet their business objectives. From the air navigation service provider's viewpoint, there is a need for increasing the capacity of the airspace, while maintaining or increasing the levels of efficiency and safety that currently exist in order to meet the charter under which they operate. Enhancing the communication between airspace operators and users is essential in order to meet these demands. In the spring of 2015, a prototype system that implemented an airborne tool to optimize en-route flight paths for fuel and time savings was designed and tested. The system utilized in-flight Internet as a high-bandwidth data link to facilitate collaborative decision making between the flight deck and an airline dispatcher. The system was tested and demonstrated in a laboratory environment, as well as in-situ. Initial results from these tests indicate that this system is not only feasible, but could also serve as a growth path and testbed for future air traffic management concepts that rely on shared situational awareness through data exchange and electronic negotiation between multiple entities operating within the National Airspace System.
The Space Station DMS (Data Management System) is the onboard component of the Space Station Information System (SSIS) that includes the computers, networks and software that support the various core and payload subsystems of the Space Station. TAVERNS (Test And Validation Environment for Remote Networked Systems) is a distributed approach for development and validation of application software for Space Station. The TAVERNS concept assumes that the different subsystems will be developed by different contractors who may be geographically separated. The TAVERNS Emulator is an Ada simulation of a TAVERNS on the ASD VAX. The software services described in the DMS Test Bed User's Manual are being emulated on the VAX together with simulations of some of the core subsystems and a simulation of the DCN. The TAVERNS Emulator will be accessible remotely from any VAX that can communicate with the ASD VAX.