Comments on publications can be made to L.Wood@society.surrey.ac.uk.
Academic research and technical publications by Lloyd Wood, listed in reverse-chronological order, most recent first. Related slides from presentations and talks given are listed separately.
Research areas include intersatellite links, internet networking in space, delay-tolerant networking, the Interplanetary Internet, networking for the Square Kilometre Array, and router-modem integration. These short summary papers, each only two pages, will give a quick overview of recent work:
Some of our work in progress as internet-drafts can also be read, as can patent applications.
The papers below are listed in ResearchGate, in Mendeley, in Google Scholar, in IEEExplore, in arXiv and in Microsoft Academic Search. A summary reference list and h-index evaluation of this research output are available.
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|US Patent 8,305,896|
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.
Selective performance enhancement of traffic flows (134K)
US patent office | Free Patents Online | PatentBuddy.
In order to autonomously condition traffic and allow the network to get the most out of the modem's link capacity, the upstream devices and applications need to be informed of the modem's link conditions.Modem Link-Property Advertisements (424K)
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.Saratoga: scalable, speedy data delivery for sensor networks (284K)
SaVi is introduced and described briefly here.SaVi: satellite constellation visualization (1M)
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.Assessing and improving an approach to delay-tolerant networking (150K)
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.Taking Saratoga from Space-Based Ground Sensors to Ground-Based Space Sensors (266K)
DOI 10.1109/AERO.2011.5747332 | arXiv:1101.2172
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.A Sender-based TFRC for Saratoga (285K)
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.Large File Transfers from Space using Multiple Ground Terminals and Delay-Tolerant Networking (693K)
DOI 10.1109/GLOCOM.2010.5683304 | cites in Google Scholar
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.
Experience with delay-tolerant networking from orbit (972K)
DOI 10.1002/sat.966 | 40+ cites in Google Scholar | earlier version published at ASMS 2008: DOI 10.1109/ASMS.2008.37
This paper describes network-centric operations, where a virtual mission operations center autonomously receives sensor triggers, and schedules space and ground assets using Internet-based technologies and service-oriented architectures.
Virtual Mission Operations of Remote Sensors with Rapid Access to/from Space (2M)
AIAA archive | Also known as NASA Technical Memorandum TM-2010-216364.
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.
Using Light-Emitting Diodes for intersatellite links (316K)
LED ISL presentation slides, given by Will Ivancic, 10 March 2010. (704K. Images from DARPA F6 and NASA, used with attribution.)
DOI 10.1109/AERO.2010.5446711 | CiteSeer
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).
Moving data in DTNs with HTTP and MIME (100K)
HTTP-DTN slides presented by Ioannis. (96K)
DOI 10.1109/ICUMT.2009.5345656 | CiteSeer.
This position paper is intended to encourage discussion of the role, scope, and adoption of the Bundle Protocol.
Sharing the dream (65K)
Sharing the dream slides presented by Ioannis. (99K)
DOI 10.1109/ICUMT.2009.5345655 | CiteSeer.
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.
A Bundle of Problems (288K)
A Bundle of Problems slides, presented 11 March 2009 (3.8M)
DOI 10.1109/AERO.2009.4839384 | 40+ cites in Google Scholar
The team of NASA Glenn Research Center, Cisco Systems and Surrey Satellite Technology Ltd has now gained considerable practical experience and leadership both with taking the Internet into space, and with delay-tolerant networking.
Investigating operation of the Internet in orbit: Five years of collaboration around CLEO (1.3M)
arXiv: 1204.3261 | Cites in Google Scholar.
This is the first successful use of the DTNRG Bundle Protocol in a space environment.
Related: UK-DMC satellite first to transfer sensor data from space using 'bundle' protocol, SSTL press release, 11 September 2008.
Use of the Delay-Tolerant Networking Bundle Protocol from Space (1.1M)
Slides for Use of the Delay-Tolerant Networking Bundle Protocol from Space (4.7M)
IAC Archive | CiteSeer | 10+ cites in Google Scholar | Also known as NASA Technical Memorandum TM-2009-215582.
|Vint Cerf, T-shirt (de?)signer.|
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).
Delay/Disruption-Tolerant Network Testing Using a LEO Satellite (300K)
CiteSeer | 10+ cites in Google Scholar | later published at ASMS 2008: DOI 10.1109/ASMS.2008.37.
On Thursday, 29 March 2007, NASA Glenn Research Center, Cisco Systems and SSTL performed the first configuration and demonstration of IPsec and IPv6 onboard a satellite in low Earth orbit.
Related: Cisco router on UK-DMC first to use IPv6 onboard a satellite in orbit, SSTL news item, 29 March 2007.
IPv6 and IPsec Tests of a Space-Based Asset, the Cisco router in Low Earth Orbit (CLEO) (1.2M)
NASA Technical Memorandum TM-2008-215203 | cites in Google Scholar.
This is the first time that IPsec and IPv6 have been operated onboard a satellite in orbit.
Related: Cisco router on UK-DMC first to use IPv6 onboard a satellite in orbit, SSTL news item, 29 March 2007.
IPv6 and IPsec on a satellite in space (1.2M)
IPv6 and IPsec on a satellite in space - presentation slides (1M)
IAC archive | CiteSeer | cites in Google Scholar.
We examine how the design of the Transmission Control Protocol (TCP) implicitly presumes a limited range of path delays and distances between communicating endpoints.Errata: Figure 5's y axis has values that should be multiplied by 8, thanks to dividing goodput in bytes per second by throughput in bits per second. The graph is otherwise correct, and the axis is shown correctly in the presentation slides.
This paper led to a change in ns behaviour to vary the number of TCP SYNs sent.
See also: Using Opnet 11.5 to Determine the Protocol Radius of TCP, p. 9-11, Ulster Opnet usage summary, 2008.
TCP's protocol radius (203K)
Cathryn Peoples' protocol radius presentation (145K) and photos of Salzburg.
DOI 10.1109/IWSSC.2007.4409409 | 10+ cites in Google Scholar.
We examine how Saratoga can be adapted to serve as an efficient convergence layer for Delay-Tolerant Networking (DTN), by transferring DTN bundles as well as files.Saratoga (1M)
DOI 10.1109/IWSSC.2007.4409410 | CiteSeer | 30+ cites in Google Scholar.
Putting 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.Using Internet nodes and routers onboard satellites (3.2M)
DOI 10.1002/sat.870 | CiteSeer | 20+ cites in Google Scholar.
After twenty months of flying, testing and demonstrating a Cisco mobile access router, originally designed for terrestrial use, onboard the low-Earth-orbiting UK-DMC satellite as part of a larger merged ground/space IP-based internetwork, we use our experience to examine the benefits and drawbacks of integration and standards reuse for small satellite missions.Operating a terrestrial Internet router onboard and alongside a small satellite (725K)
DOI 10.1016/j.actaastro.2006.02.026 | IAC archive | AIAA archive | CiteSeer | cites in Google Scholar
The combination of the CLEO and VMOC initiatives together provides a framework to define, test, and field a 'system of systems' based on the Internet Protocol (IP), capable of supporting secure distributed mission operations of IP-based platforms and sensors.
CLEO and VMOC were demonstrated at the Cisco Systems booth in the Milcom exhibition, with live satellite telemetry and live access to the onboard router.
CLEO and VMOC: enabling warfighters to task space payloads (US letter, 400K)
CLEO and VMOC slides (8.8M)
DOI 10.1109/MILCOM.2005.1606128 | CiteSeer | cites in Google Scholar.
|Packet magazine cover.|
With governments no longer able to afford or justify unrestricted budgets, and with a new generation of space enthusiasts mastering the principles of space technology and rocket propulsion, the commercial market has stepped up its involvement in space activity.Internet to orbit (334K)
Japanese translation of Internet to Orbit from Packet Japan, Winter 2005, pp. 26-31. See also Japanese papers on UK-DMC testing.
Chinese translation of Internet to Orbit (textual summary) from Cisco Networking China, fifth issue of 2005, no. 32, pp. 36-39.
Reprinted condensed as Make Internet Available on the Aerospace Orbit, China New Telecommunications, no. 12, 2006, pp. 81-83 (textual summary, abstract).
cites in Google Scholar.
After a year of testing and demonstrating a Cisco mobile access router intended for terrestrial use onboard the low-Earth-orbiting UK-DMC satellite as part of a larger merged ground/space IP-based internetwork, we reflect on and discuss the benefits and drawbacks of integration and standards reuse for small satellite missions.Adopting Internet standards for orbital use (724K, portrait US letter)
Also known as NASA Technical Memorandum TM-2005-213881 | CiteSeer | cites in Google Scholar.
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.
NASA Technical Memorandum TM-2005-213556 | CiteSeer | abridged report (proceedings of Earth-Sun System Technology Conference 2005)
20+ cites in Google Scholar
A Cisco Internet router is orbiting onboard the UK-DMC satellite as a secondary experimental payload, and has been tested successfully.Print errata: p. 2: NASA Glenn's headquarters.
Cites in Google Scholar.
This document provides advice to the designers of digital communication equipment, link-layer protocols, and packet-switched local networks (collectively referred to as subnetworks), who wish to support the Internet protocols but may be unfamiliar with the Internet architecture and the implications of their design choices on the performance and efficiency of the Internet.
90+ cites in Google Scholar | CiteSeer.
The co-located satellites in the orbital slot together form a network and, particularly when using and communicating with the Internet Protocol, can be viewed as a network 'cloud' that provides functionality in a flexible manner.
cites in Google Scholar | CiteSeer. AIAA archive. Also given as Surrey Space Centre Guest Lecture, Tuesday 28 October 2003.
Reviewed by Ioanis Nikolaidis, New Books and Multimedia Column, IEEE Network, vol. 17 no. 4, July-August 2003, p. 7.
Reviewed by Mile Stojcev, Microelectronics Reliability, vol. 44 issue 2, February 2004, pp. 363-364.
|Zhang with wood: blue-sky research|
Chapter 2: Satellite constellation networksPrint errata: p. 29: a well-designed hierarchy of address blocks...
Satellite constellations are introduced. The effects of their orbital geometry on network topology and the resulting effects of path delay and handover on network traffic are described. The design of the resulting satellite network as an autonomous system is then discussed.
cites in Google Scholar | CiteSeer | Internetworking and Computing over Satellite Networks is available from Amazon (UK, Canada, France, Germany, Japan).
This document presumes that the designers wish to support Internet protocols, but may be unfamiliar with the architecture of the Internet and with the implications of their design choices for the performance and efficiency of Internet traffic carried over their links.
120+ cites in Google Scholar
Here, we examine networking and internetworking issues affecting satellite networking in complex satellite constellation networks, and determine what is needed in order to support services based on the TCP/IP suite well in satellite constellations.
The rosette satellite constellation network with intersatellite links (ISLs) presents unique properties, in providing locally separate ascending and descending network surfaces of interconnected satellites with which the ground terminal can communicate. We present a novel approach exploiting this rosette geometry, by use of control of handover and management of satellite diversity, to determine which surface a ground terminal will select for communication.
Errata: the 'occasional (but small) gap in coverage' in the Celestri simulation was due to adding the phase offset when we should have been subtracting it -- but you still need broader beams to get double surface coverage. The SaVi Celestri simulation has been adjusted.
10+ cites in Google Scholar | University record.
The authors introduce the types of satellite constellation networks, and examine how overall performance ofPrint errata: Figure 3(b)i reverses the colours of the seamed and seamless Teledesic delay traces, although the hop traces are correct. Figure 5(b)i has the legends for 50ms and 500ms reversed, as is clear from their positions.
TCPcommunications carried across such a network can be affected by the choice of routing strategies used within the network.
This paper and Ch. 4 of my PhD thesis are not aware that real IP networking devices do load balancing by hashing on source and destination addresses, so that TCP flows are not reordered by round-robin multipath forwarding.
DOI 10.1109/35.910605 | 40+ cites in Google Scholar | CiteSeer | University record.
This paper examines strategies for implementing and operating
IProuting effectively within satellite constellation networks, given known constraints on the constellation resulting from satellite mobility, global visibility, routing and addressing.
Preprint errata: Originally scheduled for November/December 2000, as indicated by the note on the first page. Published in the January/February 2001 issue.
DOI 10.1002/sat.655 | 140+ cites in Google Scholar (second most cited paper in that journal) | CiteSeer.
In this paper we present a traffic conditioner able to provide fairness between responsive and unresponsive flows originating from the same customer network, using a Fair Two-Rate Three-Color Marker. Its capability for fairness is based on the use of the
FREDfair active buffer algorithm to control the token allocation of the token buckets residing in the traffic conditioner.
DOI 10.1109/ICC.2000.853610 | 40+ cites in Google Scholar | CiteSeer | University record | DBLP record.
Here, the networking aspects of the broadband satellite constellations are discussed, and the suitability of the constellations for multicast is assessed.
DOI 10.1049/cp:19980038 | 10 cites in Google Scholar | CiteSeer | IEEExplore | CAT.INIST | University record | full paper online.
An ideal, simplified, non-geostationary satellite constellation network, with varying numbers of intersatellite links on each satellite, is presented and analysed, using a minimum-path, circuit-switching approach.
The documents contained here are presented as a means of ensuring timely dissemination of scholarly and technical work on a non-commercial basis. Copyright and all rights therein are maintained by the authors or by other copyright holders, notwithstanding that the works are offered here electronically.
I have also acted as an anonymous reviewer for conferences and journals. There is a page noting sundry acknowledgements.