23,637 research outputs found
Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View
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
System Design for a Long-Line Quantum Repeater
We present a new control algorithm and system design for a network of quantum
repeaters, and outline the end-to-end protocol architecture. Such a network
will create long-distance quantum states, supporting quantum key distribution
as well as distributed quantum computation. Quantum repeaters improve the
reduction of quantum-communication throughput with distance from exponential to
polynomial. Because a quantum state cannot be copied, a quantum repeater is not
a signal amplifier, but rather executes algorithms for quantum teleportation in
conjunction with a specialized type of quantum error correction called
purification to raise the fidelity of the quantum states. We introduce our
banded purification scheme, which is especially effective when the fidelity of
coupled qubits is low, improving the prospects for experimental realization of
such systems. The resulting throughput is calculated via detailed simulations
of a long line composed of shorter hops. Our algorithmic improvements increase
throughput by a factor of up to fifty compared to earlier approaches, for a
broad range of physical characteristics.Comment: 12 pages, 13 figures. v2 includes one new graph, modest corrections
to some others, and significantly improved presentation. to appear in
IEEE/ACM Transactions on Networkin
Wireless body sensor networks for health-monitoring applications
This is an author-created, un-copyedited version of an article accepted for publication in
Physiological Measurement. The publisher is
not responsible for any errors or omissions in this version of the manuscript or any version
derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0967-3334/29/11/R01
Frequency Offset Correction in a Software Defined HiperLAN/2 Demodulator using Preamble Section A
In our Software Defined Radio project we perform a feasibility study of a software defined radio for two communication standards: HiperLAN/2 and Bluetooth. In this paper the Matlab/Simulink implementation of the HiperLAN/2 demodulator for the demonstrator of the project is discussed, with special attention for the frequency offset corrector. This type of correction is necessary to prevent large bit error rates that are caused by inter-subcarrier interference. The method that is proposed in this paper uses preamble section A to estimate the frequency offset. Simulation results for an AWGN channel show that the method is capable of correcting frequency offsets up to the boundary defined in the standard [1]. It was observed that frequency offset correction using only preamble section A is sensitive to Âżfor exampleÂż synchronization errors in case real-life analog front-end signals are used
Internet of Things-aided Smart Grid: Technologies, Architectures, Applications, Prototypes, and Future Research Directions
Traditional power grids are being transformed into Smart Grids (SGs) to
address the issues in existing power system due to uni-directional information
flow, energy wastage, growing energy demand, reliability and security. SGs
offer bi-directional energy flow between service providers and consumers,
involving power generation, transmission, distribution and utilization systems.
SGs employ various devices for the monitoring, analysis and control of the
grid, deployed at power plants, distribution centers and in consumers' premises
in a very large number. Hence, an SG requires connectivity, automation and the
tracking of such devices. This is achieved with the help of Internet of Things
(IoT). IoT helps SG systems to support various network functions throughout the
generation, transmission, distribution and consumption of energy by
incorporating IoT devices (such as sensors, actuators and smart meters), as
well as by providing the connectivity, automation and tracking for such
devices. In this paper, we provide a comprehensive survey on IoT-aided SG
systems, which includes the existing architectures, applications and prototypes
of IoT-aided SG systems. This survey also highlights the open issues,
challenges and future research directions for IoT-aided SG systems
- âŠ