3,388 research outputs found

    Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

    Get PDF
    Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications Surveys and Tutorial

    Benets of tight coupled architectures for the integration of GNSS receiver and Vanet transceiver

    Get PDF
    Vehicular adhoc networks (VANETs) are one emerging type of networks that will enable a broad range of applications such as public safety, traffic management, traveler information support and entertain ment. Whether wireless access may be asynchronous or synchronous (respectively as in the upcoming IEEE 8021.11p standard or in some alternative emerging solutions), a synchronization among nodes is required. Moreover, the information on position is needed to let vehicular services work and to correctly forward the messages. As a result, timing and positioning are a strong prerequisite of VANETs. Also the diffusion of enhanced GNSS Navigators paves the way to the integration between GNSS receivers and VANET transceiv ers. This position paper presents an analysis on potential benefits coming from a tightcoupling between the two: the dissertation is meant to show to what extent Intelligent Transportation System (ITS) services could benefit from the proposed architectur

    Store-and-Forward Message Relay using Microsatellites: The UoSAT-3 PACSAT Communications Payload

    Get PDF
    One of the most promising applications for small satellites in the 10-50 kg class is store-and-forward message relay. A single store-and-forward message relay satellite in a polar orbit can provide a global communications network carrying electronic mail, digitized voice, images or computer data. With appropriate choice of link characteristics, small, low cost ground terminals can be used. When designing an inexpensive microsatellite system to provide store-and-forward communications to small ground terminals, the engineer must challenge the standard assumptions made concerning such things as link frequency, modulation techniques, error-control, and multiple-access arbitration. Beginning with experiments on its UoSAT-2 satellite, the Spacecraft Engineering Research Unit at the University of Surrey (UK) - in collaboration with AMSAT and VITA - has been investigating store-and-forward communications using microsatellites. The UoSAT-2 store-and-forward transponder used a relatively slow 8-bit CPU with only 96 kbytes of message store, but it has been used by stations world-wide, demonstrating system feasibility. The latest experiments undertaken by Surrey will qualify a commercial-capacity microsatellite store-and-forward system. The onboard transponder is based on a 8-MHz, 16-bit, 80C186 CPU, multitasking operating software and 4 Mbytes of RAM message store. The UoSAT/SST modular microsatellite bus provides 9600 baud FSK communications links and other support facilities for the store and forward mission. This payload was launched on the UoSAT-3 satellite in January 1990, and is now successfully operating in orbit

    Current optical technologies for wireless access

    Get PDF
    The objective of this paper is to describe recent activities and investigations on free-space optics (FSO) or optical wireless and the excellent results achieved within SatNEx an EU-framework 6th programme and IC 0802 a COST action. In a first part, the FSO technology is briefly discussed. In a second part, we mention some performance evaluation criterions for the FSO. In third part, we briefly discuss some optical signal propagation experiments through the atmosphere by mentioning network architectures for FSO and then discuss the recent investigations in airborne and satellite application experiments for FSO. In part four, we mention some recent investigation results on modelling the FSO channel under fog conditions and atmospheric turbulence. Additionally, some recent major performance improvement results obtained by employing hybrid systems and using some specific modulation and coding schemes are presented

    SatCom Today in Canada: Significant Research: Broadband Satellite Communications List of CITR related Publications (1998-2003)

    Get PDF
    Journal Papers Conference Papers Contributions to Standards Canadian Space Agency Recent Publication

    Architectures and synchronization techniques for distributed satellite systems: a survey

    Get PDF
    Cohesive Distributed Satellite Systems (CDSSs) is a key enabling technology for the future of remote sensing and communication missions. However, they have to meet strict synchronization requirements before their use is generalized. When clock or local oscillator signals are generated locally at each of the distributed nodes, achieving exact synchronization in absolute phase, frequency, and time is a complex problem. In addition, satellite systems have significant resource constraints, especially for small satellites, which are envisioned to be part of the future CDSSs. Thus, the development of precise, robust, and resource-efficient synchronization techniques is essential for the advancement of future CDSSs. In this context, this survey aims to summarize and categorize the most relevant results on synchronization techniques for Distributed Satellite Systems (DSSs). First, some important architecture and system concepts are defined. Then, the synchronization methods reported in the literature are reviewed and categorized. This article also provides an extensive list of applications and examples of synchronization techniques for DSSs in addition to the most significant advances in other operations closely related to synchronization, such as inter-satellite ranging and relative position. The survey also provides a discussion on emerging data-driven synchronization techniques based on Machine Learning (ML). Finally, a compilation of current research activities and potential research topics is proposed, identifying problems and open challenges that can be useful for researchers in the field.This work was supported by the Luxembourg National Research Fund (FNR), through the CORE Project COHEsive SATellite (COHESAT): Cognitive Cohesive Networks of Distributed Units for Active and Passive Space Applications, under Grant FNR11689919.Award-winningPostprint (published version
    • …
    corecore