Brief papers by Lloyd Wood
SaVi, a program for visualizing satellite orbits, movement, and coverage, is maintained at the Un... more SaVi, a program for visualizing satellite orbits, movement, and coverage, is maintained at the University of Surrey. This tool has been used for research in academic papers, and by industry companies designing and intending to deploy satellite constellations. It has also proven useful for demonstrating aspects of satellite constellations and their geometry, coverage and movement for educational and teaching purposes. SaVi is introduced and described briefly here.
This brief paper outlines the reasons for the creation and adoption of this protocol, discusses h... more This brief paper outlines the reasons for the creation and adoption of this protocol, discusses how it differs from and complements other protocols, and summarises the worldwide collaboration that is making this development possible.
Delay-tolerant networking (DTN) is a term invented to describe and encompass all types of long-de... more Delay-tolerant networking (DTN) is a term invented to describe and encompass all types of long-delay, disconnected, disrupted or intermittently-connected networks, where mobility and outages or scheduled contacts may be experienced. 'DTN' is also used to refer to the Bundle Protocol, which has been proposed as the one unifying solution for disparate DTN networking scenarios, after originally being designed solely for use in deep space for the 'Interplanetary Internet.' We evaluated the Bundle Protocol by testing it in space and on the ground. We have found architectural weaknesses in the Bundle Protocol that may prevent engineering deployment of this protocol in realistic delay-tolerant networking scenarios, and have proposed approaches to address these weaknesses.
International Conference on Ultra Modern Telecommunication (ICUMT), Oct 14, 2009
This position paper is intended to encourage discussion of the role, scope, and adoption of the B... more This position paper is intended to encourage discussion of the role, scope, and adoption of the Bundle Protocol.
IEEE Communications Society Satellite and Space Communications Technical Committee newsletter, Nov 2008
Describes an awk script for measuring packet delay and latency in ns-2 network simulator simulati... more Describes an awk script for measuring packet delay and latency in ns-2 network simulator simulations.
Journal papers by Lloyd Wood
Journal of the British Interplanetary Society, Mar 2014
We propose an addition of known elliptical orbits to the new equatorial O3b satellite constellati... more We propose an addition of known elliptical orbits to the new equatorial O3b satellite constellation, extending O3b to cover high latitudes and the Earth's poles. We simulate the O3b constellation and compare this to recent measurement of the first real Internet traffic across the newly deployed O3b network.
International Journal of Satellite Communications and Networking, Sep 1, 2010
We describe the first use from space of the Bundle Protocol for Delay-Tolerant Networking (DTN), ... more We describe the first use from space of the Bundle Protocol for Delay-Tolerant Networking (DTN), and lessons learned from experiments made and experience gained with this protocol.
International Journal of Satellite Communications, Jan 1, 2001
This paper examines strategies for implementing and operating IP routing effectively within satel... more This paper examines strategies for implementing and operating IP routing effectively within satellite constellation networks, given known constraints on the constellation resulting from satellite mobility, global visibility, routing and addressing.
International Journal of Satellite Communications and Networking, Mar 2007
An Internet router was integrated into the UK-DMC remote-sensing satellite as a secondary experim... more An Internet router was integrated into the UK-DMC remote-sensing satellite as a secondary experimental payload. This commercial product has been orbiting in space for over three years. We describe the integration of the router and satellite and the successful on-orbit testing of the router, which took place using the Virtual Mission Operations Center (VMOC) application as part of a larger systems internetworking exercise. Placing this Cisco router in Low Earth Orbit (CLEO) onboard a small satellite is one step towards extending the terrestrial networking model to the near-Earth space environment as part of a merged space-ground architecture.
Other papers by Lloyd Wood
a method for selective performance enhancement of traffic flows, such as a Transmission Control P... more a method for selective performance enhancement of traffic flows, such as a Transmission Control Protocol (TCP) flow, on devices where enhancement of a limited number of concurrent flows is supported, or where a limited number of TCP accelerated or IP (Internet Protocol) compressed flows are supported.
IEEE Aerospace Conference
This is intended to prototype delivery of data across dedicated astronomy radio telescope network... more This is intended to prototype delivery of data across dedicated astronomy radio telescope networks on the ground, where networked sensors in Very Long Baseline Interferometer (VLBI) instruments generate large amounts of data for processing and can send that data across private IP- and Ethernet-based links at very high rates.
Earth-Sun System …, Jun 2005
a Cisco Internet router (Cisco Systems, Inc., San Jose, CA) was launched into low Earth orbit onb... more a Cisco Internet router (Cisco Systems, Inc., San Jose, CA) was launched into low Earth orbit onboard the UK-DMC, the disaster-monitoring satellite built by Surrey Satellite Technology Limited (SSTL, Guildford, UK). This router has since been successfully tested and demonstrated by an international government and private sector collaboration, showing how IP can be used to communicate with satellite payloads in space.
IEEE Aerospace Conference
This sender-based TFRC is shown to share the bottleneck-bandwidth fairly under various network co... more This sender-based TFRC is shown to share the bottleneck-bandwidth fairly under various network conditions, allowing Saratoga to be adapted for shared links or for the congested Internet, while still supporting the asymmetric environments that Saratoga was originally developed for.
IEEE Aerospace Conference
We examine the utility of Light-Emitting Diodes
(LEDs) for short-range intersatellite links (ISLs... more We examine the utility of Light-Emitting Diodes
(LEDs) for short-range intersatellite links (ISLs), and
compare and contrast LEDs with existing laser technologies
used for long-distance ISLs.
International Conference on Ultra Modern Telecommunication (ICUMT), Oct 14, 2009
Taking MIME and HTTP as a starting point, and adopting the well-understood need for different "co... more Taking MIME and HTTP as a starting point, and adopting the well-understood need for different "convergence layers" to carry HTTP in different challenged environments where TCP may not be suitable, this paper outlines work in progress to run HTTP over different transports, and how this can be used to create a simple, yet powerful, approach to relaying content in delay- and disruption-tolerant networks (DTNs).
Aerospace conference, 2009 …, Mar 1, 2009
We examine the Bundle Protocol and its related architecture closely, and discuss areas where we h... more We examine the Bundle Protocol and its related architecture closely, and discuss areas where we have found that the current Bundle approach is not well-suited to many of the operational concepts that it was intended to support.
This is the first successful use of the DTNRG Bundle Protocol in a space environment.
2010 IEEE Global Telecommunications Conference GLOBECOM 2010, Dec 2010
We use Delay-Tolerant Networking (DTN) to break control loops between space-ground communication ... more We use Delay-Tolerant Networking (DTN) to break control loops between space-ground communication links and ground-ground communication link to increase overall file delivery efficiency, as well as to enable large files to be proactively fragmented and received across multiple ground stations.
NASA Earth Science Technology Conference (ESTC), Jun 2008
This paper describes the first DTN bundle protocol testing from space, using the United Kingdom D... more This paper describes the first DTN bundle protocol testing from space, using the United Kingdom Disaster Monitoring Constellation (UK-DMC) satellite in Low Earth Orbit (LEO).
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Brief papers by Lloyd Wood
Journal papers by Lloyd Wood
Other papers by Lloyd Wood
(LEDs) for short-range intersatellite links (ISLs), and
compare and contrast LEDs with existing laser technologies
used for long-distance ISLs.
(LEDs) for short-range intersatellite links (ISLs), and
compare and contrast LEDs with existing laser technologies
used for long-distance ISLs.