1,553 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
Orbit evolution, maintenance and disposal of SpaceChip swarms
The combined effect of solar radiation pressure and atmospheric drag is investigated for future mission conceptsfor swarms of satellites-on-a-chip (SpaceChips). The natural evolution of the swarm is exploited to perform spatially distributed measurements of the upper layers of the atmosphere. The energy gain from asymmetric solar radiation pressure can be used to balance the energy dissipation from atmospheric drag. An algorithm for long-term orbit control is then designed, based on changing the reflectivity coefficient of the SpaceChips. The subsequent modulation of the solar radiation pressure allows stabilisation of the swarm in the orbital element phase space. It is shown that the normally short orbit lifetime for such devices can be extended through the interaction of solar radiation pressure and atmospheric drag and indeed selected and the end-of-life re-entry of the swarm can be ensured, by exploiting atmospheric drag
Applying autonomy to distributed satellite systems: Trends, challenges, and future prospects
While monolithic satellite missions still pose significant advantages in terms of accuracy and
operations, novel distributed architectures are promising improved flexibility, responsiveness,
and adaptability to structural and functional changes. Large satellite swarms, opportunistic satellite
networks or heterogeneous constellations hybridizing small-spacecraft nodes with highperformance
satellites are becoming feasible and advantageous alternatives requiring the adoption
of new operation paradigms that enhance their autonomy. While autonomy is a notion that
is gaining acceptance in monolithic satellite missions, it can also be deemed an integral characteristic
in Distributed Satellite Systems (DSS). In this context, this paper focuses on the motivations
for system-level autonomy in DSS and justifies its need as an enabler of system qualities. Autonomy
is also presented as a necessary feature to bring new distributed Earth observation functions
(which require coordination and collaboration mechanisms) and to allow for novel structural
functions (e.g., opportunistic coalitions, exchange of resources, or in-orbit data services). Mission
Planning and Scheduling (MPS) frameworks are then presented as a key component to implement
autonomous operations in satellite missions. An exhaustive knowledge classification explores the
design aspects of MPS for DSS, and conceptually groups them into: components and organizational
paradigms; problem modeling and representation; optimization techniques and metaheuristics;
execution and runtime characteristics and the notions of tasks, resources, and constraints.
This paper concludes by proposing future strands of work devoted to study the trade-offs of
autonomy in large-scale, highly dynamic and heterogeneous networks through frameworks that
consider some of the limitations of small spacecraft technologies.Postprint (author's final draft
An Integrated Framework for Sensing Radio Frequency Spectrum Attacks on Medical Delivery Drones
Drone susceptibility to jamming or spoofing attacks of GPS, RF, Wi-Fi, and
operator signals presents a danger to future medical delivery systems. A
detection framework capable of sensing attacks on drones could provide the
capability for active responses. The identification of interference attacks has
applicability in medical delivery, disaster zone relief, and FAA enforcement
against illegal jamming activities. A gap exists in the literature for solo or
swarm-based drones to identify radio frequency spectrum attacks. Any
non-delivery specific function, such as attack sensing, added to a drone
involves a weight increase and additional complexity; therefore, the value must
exceed the disadvantages. Medical delivery, high-value cargo, and disaster zone
applications could present a value proposition which overcomes the additional
costs. The paper examines types of attacks against drones and describes a
framework for designing an attack detection system with active response
capabilities for improving the reliability of delivery and other medical
applications.Comment: 7 pages, 1 figures, 5 table
Orbit design for future SpaceChip swarm missions
The effect of solar radiation pressure and atmospheric drag on the orbital dynamics of satellites-on-a-chip (SpaceChips) is exploited to design long-lived orbits about the Earth. The orbit energy gain due to asymmetric solar radiation pressure, considering the Earth shadow, is used to balance the energy loss due to atmospheric drag. Future missions for a swarm of SpaceChips are proposed, where a number of small devices are released from a conventional spacecraft to perform spatially distributed measurements of the conditions in the ionosphere and exosphere. It is shown that the orbit lifetime can be extended and indeed selected through solar radiation pressure and the end-of-life re-entry of the swarm can be ensured, by exploiting atmospheric drag
Physics-Based Swarm Intelligence for Disaster Relief Communications
This study explores how a swarm of aerial mobile vehicles can provide network
connectivity and meet the stringent requirements of public protection and
disaster relief operations. In this context, we design a physics-based
controlled mobility strategy, which we name the extended Virtual Force Protocol
(VFPe), allowing self-propelled nodes, and in particular here unmanned aerial
vehicles, to fly autonomously and cooperatively. In this way, ground devices
scattered on the operation site may establish communications through the
wireless multi-hop communication routes formed by the network of aerial nodes.
We further investigate through simulations the behavior of the VFPe protocol,
notably focusing on the way node location information is disseminated into the
network as well as on the impact of the number of exploration nodes on the
overall network performance.Comment: in International Conference on Ad Hoc Networks and Wireless, Jul
2016, Lille, Franc
UAV Swarm-Enabled Aerial CoMP: A Physical Layer Security Perspective
Unlike aerial base station enabled by a single unmanned aerial vehicle (UAV),
aerial coordinated multiple points (CoMP) can be enabled by a UAV swarm. In
this case, the management of multiple UAVs is important. This paper considers
the power allocation strategy for a UAV swarm-enabled aerial network to enhance
the physical layer security of the downlink transmission, where an eavesdropper
moves following the trajectory of the swarm for better eavesdropping. Unlike
existing works, we use only the large-scale channel state information (CSI) and
maximize the secrecy throughput in a whole-trajectory-oriented manner. The
overall transmission energy constraint on each UAV and the total transmission
duration for all the legitimate users are considered. The non-convexity of the
formulated problem is solved by using max-min optimization with iteration. Both
the transmission power of desired signals and artificial noise (AN) are derived
iteratively. Simulation results are presented to validate the effectiveness of
our proposed power allocation algorithm and to show the advantage of aerial
CoMP by using only the large-scale CSI
Orbit design for future SpaceChip swarm missions in a planetary atmosphere
The effect of solar radiation pressure and atmospheric drag on the orbital dynamics of satellites-on-a-chip (SpaceChips) is exploited to design equatorial long-lived orbits about the oblate Earth. The orbit energy gain due to asymmetric solar radiation pressure, considering the Earth's shadow, is used to balance the energy loss due to atmospheric drag. Future missions for a swarm of SpaceChips are proposed, where a number of small devices are released from a conventional spacecraft to perform spatially distributed measurements of the conditions in the ionosphere and exosphere. It is shown that the orbit lifetime can be extended and indeed selected through solar radiation pressure and the end-of-life re-entry of the swarm can be ensured, by exploiting atmospheric drag
Space-based Aperture Array For Ultra-Long Wavelength Radio Astronomy
The past decade has seen the rise of various radio astronomy arrays,
particularly for low-frequency observations below 100MHz. These developments
have been primarily driven by interesting and fundamental scientific questions,
such as studying the dark ages and epoch of re-ionization, by detecting the
highly red-shifted 21cm line emission. However, Earth-based radio astronomy
below frequencies of 30MHz is severely restricted due to man-made interference,
ionospheric distortion and almost complete non-transparency of the ionosphere
below 10MHz. Therefore, this narrow spectral band remains possibly the last
unexplored frequency range in radio astronomy. A straightforward solution to
study the universe at these frequencies is to deploy a space-based antenna
array far away from Earths' ionosphere. Various studies in the past were
principally limited by technology and computing resources, however current
processing and communication trends indicate otherwise. We briefly present the
achievable science cases, and discuss the system design for selected scenarios,
such as extra-galactic surveys. An extensive discussion is presented on various
sub-systems of the potential satellite array, such as radio astronomical
antenna design, the on-board signal processing, communication architectures and
joint space-time estimation of the satellite network. In light of a scalable
array and to avert single point of failure, we propose both centralized and
distributed solutions for the ULW space-based array. We highlight the benefits
of various deployment locations and summarize the technological challenges for
future space-based radio arrays.Comment: Submitte
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