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Network performance of pLEO topologies in a high-inclination Walker Delta Satellite Constellation

March 4, 2023
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Conference Paper
Author:
Thomas H. Shake
…
Published in:
IEEE Aerospace Conf. Proc., 4-11 March 2023, 188722.
Topic:
satellites
R&D area:
R&D group:

Summary

Low-earth-orbit satellite constellations with hundreds to thousands of satellites are emerging as practical alternatives for providing various types of data services such as global networking and large-scale sensing. The network performance of these satellite constellations is strongly dependent on the topology of the inter-satellite links (ISLs) in such systems. This paper studies the effects of six different ISL topologies, coupled with three configurations of ground relay terminals, on path failure rate, path latency, and link transmission efficiency in an example highly-inclined Walker Delta constellation with 360 satellites. These network performance parameters are calculated in the presence of satellite failures in the constellation. Trade-offs between ISL connection density and overall performance are examined and quantified. Topologies with 4 active ISLs per satellite are shown to perform significantly better than topologies requiring fewer, especially as the average number of active ISLs per satellite becomes significantly less than three. Latencies for a topology requiring 3 active ISLs per satellite are shown to be between 15 and 60% higher than for a 4-ISL reference topology. Path availabilities for the 3-ISL topology are shown to be on the order of 30% lower for a benchmark case of 10 satellite failures. The performance of near-minimal topologies (e.g., an average of 2.2 active ISLs per satellite) is much worse. Latency reductions of 10-30% and path failure rate improvements on the order of 45% are shown to be obtainable by the inclusion of 2 to 5 strategically located ground relay stations
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Summary

Low-earth-orbit satellite constellations with hundreds to thousands of satellites are emerging as practical alternatives for providing various types of data services such as global networking and large-scale sensing. The network performance of these satellite constellations is strongly dependent on the topology of the inter-satellite links (ISLs) in such systems. This...

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Network performance of pLEO topologies in a high-inclination Walker Delta Satellite Constellation

Contingent routing using orbital geometry in proliferated low-earth-orbit satellite networks

November 28, 2022
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Conference Paper
Author:
Thomas H. Shake
…
Published in:
2022 IEEE Military Communications Conf., MILCOM, 28 November - 2 December 2022.
Topic:
satellites
R&D area:
R&D group:

Summary

Optimum adaptive routing in proliferated low-earth-orbit (pLEO) satellite networks requires intensive computation. The very small size, light weight, and low power of individual satellites in such networks makes a centralized, terrestrial, SDN-like approach to routing computation an attractive solution. However, it is highly desirable to have a distributed backup routing capability onboard each satellite that can maintain service if the central computational node(s) fail or lose their pathway(s) to upload routing data frequently to each satellite. This paper presents a routing algorithm based on orbital geometry that has a very low computation and storage requirements and is suitable as a backup routing capability in the event of failure of a centralized routing calculation node or nodes. Path failure rate, path latency, and link resource usage are simulated for a 360-satellite Walker Delta constellation with 4 inter-satellite link (ISL) terminals per satellite, and with up to 10% of the satellites having failed. For the fully intact satellite constellation, path failure rate is zero (identical to a shortest path routing algorithm), while mean latency and average link resource usage are shown to be approximately 12% and 13% higher, respectively, than with shortest path routing. With 10 random satellite failures in the constellation, the geometric algorithm has a path failure rate of less than 0.5%, while the mean latency and link resource usage are approximately 12% and 16% higher, respectively, than with shortest path routing.
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Summary

Optimum adaptive routing in proliferated low-earth-orbit (pLEO) satellite networks requires intensive computation. The very small size, light weight, and low power of individual satellites in such networks makes a centralized, terrestrial, SDN-like approach to routing computation an attractive solution. However, it is highly desirable to have a distributed backup routing...

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Contingent routing using orbital geometry in proliferated low-earth-orbit satellite networks

Failure resilience in proliferated low earth orbit satellite network topologies

November 28, 2022
  |
Conference Paper
Author:
Thomas H. Shake
…
Published in:
2022 IEEE Military Communications Conf., MILCOM, 28 November - 2 December 2022.
Topic:
satellites
R&D area:
R&D group:

Summary

The vision of continuous network connectivity for users located anywhere on Earth is increasingly being enabled by satellite constellations with hundreds to thousands of satellites operating in low altitude orbits (typically somewhere between a few hundred and two thousand km). These constellations are often referred to as proliferated Low Earth Orbit (pLEO) constellations. Potential military use of such constellations would require a high degree of resilience against various types of failures. This paper examines how resilience to satellite failures in particular is affected by topology and topology management for a moderate-sized constellation of 360 low-earth-orbit satellites providing 2X-redundant global coverage. We present simulations quantifying the effects of two vs. four inter-satellite links (ISLs) per satellite, and of dynamic post-failure topology reconfiguration vs static topology management. Simulations show differences of 65-80% in mission connectivity between 4-ISL topologies with dynamic topology reconfiguration and 2-ISL topologies with static topology using two different traffic scenarios.
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Summary

The vision of continuous network connectivity for users located anywhere on Earth is increasingly being enabled by satellite constellations with hundreds to thousands of satellites operating in low altitude orbits (typically somewhere between a few hundred and two thousand km). These constellations are often referred to as proliferated Low Earth...

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Failure resilience in proliferated low earth orbit satellite network topologies

Rate control with autoregressive forecasting for high frequency communication

November 28, 2022
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Conference Paper
Author:
Allan Ko
…
Published in:
2022 IEEE Military Communications Conf., MILCOM, 28 November - 2 December 2022.
Topic:
communications
R&D area:
R&D group:

Summary

This work introduces a data-driven framework for rate control and applies it to high frequency (HF) communication systems that propagate via the Earth’s ionosphere. The rate control approach uses statistical techniques to forecast channel state with an autoregressive (AR) model, which has previously been applied to different forms of wireless fading, including "medium" timescale fading at HF. The objective of rate control is to maximize the data rate while constraining the rate of packets decoded in error. We show that under ideal assumptions, the rate controller selects the rate by backing off from the forecast average signal-to-noise ratio (SNR) by a factor of sigmaQ^-1(Beta), where sigma^2 correlates with fading variance, Beta denotes a constraint on decoder errors, and Q(.) is the complementary cumulative distribution function of the Gaussian distribution. Simulation results on an HF channel model show that compared with naive schemes, AR forecasting provides a good balance between achieving high rate and ensuring reliability.
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Summary

This work introduces a data-driven framework for rate control and applies it to high frequency (HF) communication systems that propagate via the Earth’s ionosphere. The rate control approach uses statistical techniques to forecast channel state with an autoregressive (AR) model, which has previously been applied to different forms of wireless...

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Rate control with autoregressive forecasting for high frequency communication

Robust network protocols for large swarms of small UAVs

March 5, 2022
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Conference Paper
Author:
Thomas B. Stahlbuhk
…
Published in:
2022 IEEE Aeropsace Conf., AERO 2022, 18 p.
Topic:
UAVs
R&D area:
R&D group:

Summary

In this work, we detail a synchronized channel hopping network for autonomous swarms of small unmanned aerial vehicles (UAVs) conducting intelligence, surveillance, and reconnaissance (ISR) missions in the presence of interference and jamming. The core component of our design is Queue Length Informed Maximal Matching (QLIMM), a distributed transmission scheduling protocol that exchanges queue state information between nodes to assign subdivisions of the swarm to orthogonal hopping patterns in response to the network’s throughput demands. QLIMM efficiently allocates channel resources across large networks without relying on any centralized control or pre-planned traffic patterns, which is in the spirit of a swarming capability. However, given that the control messaging must scale up with the swarm’s size and the challenging interference environments we consider, fragility could be a concern. To observe under what conditions control fails, we test our protocol against both simulated partial-band noise jamming and background interference. For the latter, we use data collected from a small unmanned aircraft system to characterize the interference seen by a UAV in the 2.4 and 5 GHz bands in both urban and rural settings. These measurements show that the interference can be 15 dB higher at a 50-meter flight altitude when compared to observations on the ground. Using this data, we conduct extensive network simulations of QLIMM in Riverbed Modeler to show that, under moderate jamming and interference, it outperforms traditional channel access methods as well as other scheduling protocols that do not pass queue state information.
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Summary

In this work, we detail a synchronized channel hopping network for autonomous swarms of small unmanned aerial vehicles (UAVs) conducting intelligence, surveillance, and reconnaissance (ISR) missions in the presence of interference and jamming. The core component of our design is Queue Length Informed Maximal Matching (QLIMM), a distributed transmission scheduling...

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Robust network protocols for large swarms of small UAVs

Cloud computing in tactical environments

October 23, 2017
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Conference Paper
Author:
Warren W. Smith
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Published in:
MILCOM 2017, 23-25 October 2017.
Topic:
energy systems
R&D area:
R&D group:

Summary

Ground personnel at the tactical edge often lack data and analytics that would increase their effectiveness. To address this problem, this work investigates methods to deploy cloud computing capabilities in tactical environments. Our approach is to identify representative applications and to design a system that spans the software/hardware stack to support such applications while optimizing the use of scarce resources. This paper presents our high-level design and the results of initial experiments that indicate the validity of our approach.
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Summary

Ground personnel at the tactical edge often lack data and analytics that would increase their effectiveness. To address this problem, this work investigates methods to deploy cloud computing capabilities in tactical environments. Our approach is to identify representative applications and to design a system that spans the software/hardware stack to...

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Cloud computing in tactical environments

Competing cognitive resilient networks

March 1, 2016
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Journal Article
Author:
Siamak Dastangoo
…
Published in:
IEEE Trans. Cognit. Commun. and Netw., Vol. 2, No. 1, March 2016, pp. 95-109.
Topic:
networking
R&D area:
R&D group:

Summary

We introduce competing cognitive resilient network (CCRN) of mobile radios challenged to optimize data throughput and networking efficiency under dynamic spectrum access and adversarial threats (e.g., jamming). Unlike the conventional approaches, CCRN features both communicator and jamming nodes in a friendly coalition to take joint actions against hostile networking entities. In particular, this paper showcases hypothetical blue force and red force CCRNs and their competition for open spectrum resources. We present state-agnostic and stateful solution approaches based on the decision theoretic framework. The state-agnostic approach builds on multiarmed bandit to develop an optimal strategy that enables the exploratory-exploitative actions from sequential sampling of channel rewards. The stateful approach makes an explicit model of states and actions from an underlying Markov decision process and uses multiagent Q-learning to compute optimal node actions. We provide a theoretical framework for CCRN and propose new algorithms for both approaches. Simulation results indicate that the proposed algorithms outperform some of the most important algorithms known to date.
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Summary

We introduce competing cognitive resilient network (CCRN) of mobile radios challenged to optimize data throughput and networking efficiency under dynamic spectrum access and adversarial threats (e.g., jamming). Unlike the conventional approaches, CCRN features both communicator and jamming nodes in a friendly coalition to take joint actions against hostile networking entities...

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Competing cognitive resilient networks

Fast online learning of antijamming and jamming strategies

December 6, 2015
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Conference Paper
Author:
Youngjune L. Gwon
…
Published in:
2015 IEEE Global Communications Conf., 6-10 December 2015.
Topic:
communications
R&D area:
R&D group:

Summary

Competing Cognitive Radio Network (CCRN) coalesces communicator (comm) nodes and jammers to achieve maximal networking efficiency in the presence of adversarial threats. We have previously developed two contrasting approaches for CCRN based on multi-armed bandit (MAB) and Qlearning. Despite their differences, both approaches have shown to achieve optimal throughput performance. This paper addresses a harder class of problems where channel rewards are time-varying such that learning based on stochastic assumptions cannot guarantee the optimal performance. This new problem is important because an intelligent adversary will likely introduce dynamic changepoints, which can make our previous approaches ineffective. We propose a new, faster learning algorithm using online convex programming that is computationally simpler and stateless. According to our empirical results, the new algorithm can almost instantly find an optimal strategy that achieves the best steady-state channel rewards.
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Summary

Competing Cognitive Radio Network (CCRN) coalesces communicator (comm) nodes and jammers to achieve maximal networking efficiency in the presence of adversarial threats. We have previously developed two contrasting approaches for CCRN based on multi-armed bandit (MAB) and Qlearning. Despite their differences, both approaches have shown to achieve optimal throughput performance...

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Fast online learning of antijamming and jamming strategies

Development and use of a comprehensive humanitarian assessment tool in post-earthquake Haiti

May 13, 2014
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Journal Article
Author:
Marc A. Zissman
…
Published in:
Procedia Eng., Vol. 78, 2014, pp. 10-21.
Topic:
human language technology
R&D area:
R&D group:

Summary

This paper describes a comprehensive humanitarian assessment tool designed and used following the January 2010 Haiti earthquake. The tool was developed under Joint Task Force -- Haiti coordination using indicators of humanitarian needs to support decision making by the United States Government, agencies of the United Nations, and various non-governmental organizations. A set of questions and data collection methodology were developed by a collaborative process involving a broad segment of the Haiti humanitarian relief community and used to conduct surveys in internally displaced person settlements and surrounding communities for a four-month period starting on 15 March 2010. Key considerations in the development of the assessment tool and data collection methodology, representative analysis results, and observations from the operational use of the tool for decision making are reported. The paper concludes with lessons learned and recommendations for design and use of similar tools in the future.
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Summary

This paper describes a comprehensive humanitarian assessment tool designed and used following the January 2010 Haiti earthquake. The tool was developed under Joint Task Force -- Haiti coordination using indicators of humanitarian needs to support decision making by the United States Government, agencies of the United Nations, and various non-governmental...

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Development and use of a comprehensive humanitarian assessment tool in post-earthquake Haiti
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