Lloyd Wood's publications

Lloyd Wood and his colleagues argue in favor of breaking the "bent pipe" system architecture in which the satellite is seen as a relay point between two ground stations. They would add inter-satellite communication links and routers to decouple the up and downlink locations. -- Press, First Monday.

Publications to date by Lloyd Wood, in reverse-chronological order, most recent first. These are listed in Google Scholar, in CiteSeer, and in BibFinder. A summary reference list in text is available. Some of our work in progress as internet-drafts can also be read, as can slides from recent and old talks.

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IPv6 and IPsec Tests of a Space-Based Asset, the Cisco router in Low Earth Orbit (CLEO)
Will Ivancic, Dave Stewart, Lloyd Wood, Chris Jackson, James Northam, James Wilhelm.
Describes the CLEO Cisco router in Low Earth Orbit.
NASA Technical Memorandum 2008-215203. Read the related IAC 2007 paper below.
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.
IPv6 and IPsec Tests of a Space-Based Asset, the Cisco router in Low Earth Orbit (CLEO) (1.2M)

IPv6 and IPsec on a satellite in space
Lloyd Wood, Will Ivancic, Dave Stewart, James Northam, Chris Jackson, Alex da Silva Curiel.
Describes the CLEO Cisco router in Low Earth Orbit.
Conference paper IAC-07-B2.6.06, 58th International Astronautical Congress, Hyderabad, India, 24-28 September 2007.
This is the first time that IPsec and IPv6 have been operated onboard a satellite in orbit.
IPv6 and IPsec on a satellite in space (1.2M)
IPv6 and IPsec on a satellite in space - presentation slides (1M)

TCP's protocol radius: the distance where timers prevent communication
Lloyd Wood, Cathryn Peoples, Gerard Parr, Bryan Scotney, Adrian Moore.
Peer-reviewed conference paper, International Workshop on Space and Satellite Communications (IWSSC '07), Salzburg, Austria, 13-14 September 2007.
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.

TCP's protocol radius (203K)
Cathryn Peoples' protocol radius presentation (145K) and photos of Salzburg.

DOI 10.1109/IWSSC.2007.4409409 | IEEExplore workshop proceedings.

Saratoga: a Delay-Tolerant Networking convergence layer with efficient link utilization
Lloyd Wood, Wes Eddy, Will Ivancic, Jim McKim, Chris Jackson.
Describes Saratoga.
Peer-reviewed conference paper, International Workshop on Space and Satellite Communications (IWSSC '07), Salzburg, Austria, 13-14 September 2007.
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)
Wes Eddy's Saratoga slides (1.1M)

DOI 10.1109/IWSSC.2007.4409410 | IEEExplore workshop proceedings.

Using Internet nodes and routers onboard satellites
Lloyd Wood, Will Ivancic, Dave Hodgson, Eric Miller, Brett Conner, Scott Lynch, Chris Jackson, Alex da Silva Curiel, Dave Cooke, Dan Shell, Jon Walke, Dave Stewart.
Describes the CLEO Cisco router in Low Earth Orbit.
refereed journal paper, special issue on Space Networks, International Journal of Satellite Communications and Networking, vol. 25 issue 2, pp. 195-216, March/April 2007. Preprint revised for publication 3 January 2007. Includes and expands on all content of our earlier End-to-end, Small Satellite Conference and IAC conference papers.
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 sat.870

Operating a terrestrial Internet router onboard and alongside a small satellite
Lloyd Wood, Alex da Silva Curiel, Will Ivancic, Dave Hodgson, Dan Shell, Chris Jackson, Dave Stewart.
Describes the CLEO Cisco router in Low Earth Orbit. Read and cite the IJSCN journal paper above instead.
Acta Astronautica, volume 59, issues 1-5, July-September 2006, pp. 124-131. Conference paper IAC-05-B-05-03, Selected Proceedings of the 56th International Astronautical Congress, Fukuoka, Japan, 17-21 October 2005.
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 j.actaastro.2006.02.026

CLEO and VMOC: enabling warfighters to task space payloads
Lloyd Wood, Dan Shell, Will Ivancic, Brett Conner, Eric Miller, Dave Stewart, Dave Hodgson.
Describes the CLEO Cisco router in Low Earth Orbit.
Refereed conference paper, unclassified track, IEEE Milcom 2005, Atlantic City, New Jersey, 17-20 October 2005.
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 MILCOM.

Packet Magazine
Internet to orbit
Daniel Floreani, Lloyd Wood.
Describes the CLEO Cisco router in Low Earth Orbit.
Magazine article, Cisco Systems Packet Magazine, vol. 17 no. 3, pp. 19-23, third quarter 2005.
Given a Cisco Achievement Program (CAP) team award by Packet Magazine.
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.
Chinese translation of Internet to Orbit (textual summary) from Cisco Networking China, fifth issue of 2005, no. 32, pp. 36-39.
Reprinted shortened as Make Internet Available on the Aerospace Orbit, China New Telecommunications, no. 12, 2006, pp. 81-83 (textual summary, abstract).

Adopting Internet standards for orbital use
Lloyd Wood, Will Ivancic, Alex da Silva Curiel, Chris Jackson, Dave Stewart, Dan Shell, Dave Hodgson.
Describes the CLEO Cisco router in Low Earth Orbit. Read and cite the IJSCN journal paper above instead.
Conference paper SSC05-IV-03, Session 4: The year in retrospect, 19th Annual AIAA/USU Conference on Small Satellites, Logan, Utah, 8-11 August 2005.
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.

Secure, Network-Centric Operations of a Space-Based Asset: Cisco Router in Low-Earth Orbit (CLEO) and Virtual Mission Operations Center (VMOC)
Will Ivancic, Dave Stewart, Dan Shell, Lloyd Wood, Phil Paulsen, Chris Jackson, Dave Hodgson, James Northam, Neville Bean, Eric Miller, Mark Graves, Lance Kurisaki.
Describes the CLEO Cisco router in Low Earth Orbit.
NASA Technical Memorandum TM-2005-213556, May 2005.
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.
full NASA memorandum | abridged report (proceedings of Earth-Sun System Technology Conference 2005)

Testing a router onboard a satellite in space
Lloyd Wood.
Describes the CLEO Cisco router in Low Earth Orbit. Read and cite the IJSCN journal paper above instead.
Seminar paper, pp. 83-85, Proceedings of The End-to-End Challenges of Broadband via Satellite, IEE Savoy Place, London, 26 January 2005, ISBN 0-86341-491-5.
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.
Testing a router onboard a satellite in space

Advice for Internet subnetwork designers
Phil Karn (ed.), Carsten Bormann, Gorry Fairhurst, Dan Grossman, Reiner Ludwig, Jamshid Mahdavi, Gabriel Montenegro, Joe Touch, Lloyd Wood.
Request for Comments document in the Best Current Practices series, Internet Engineering Task Force.
IETF RFC3819/BCP89, July 2004.
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.
RFC3819 (RFC3819/BCP89 published as paginated text)

CiteSeer entry.

Slot clouds: getting more from orbital slots with networking
Lloyd Wood, Alex da Silva Curiel, Javad Anzalchi, Dave Cooke, Chris Jackson.
Conference paper IAC-03-U.4.07, 54th International Astronautical Congress, Bremen, Germany, 29 September - 3 October 2003.
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.

Print errata: p. 2: Replicating a decoded baseband transmission to... In not having to pass through the atmosphere, intersatellite links are...
slides, p. 10: IP overlays can be in individual clouds. p. 16: and the launcher was a Kosmos-3M.

Slot clouds paper (corrected, 79K)
Slot clouds slides, originally presented Thursday 2 October 2003. (corrected, 2.6M, landscape US letter)

CiteSeer entry. AIAA archive. Also given as Surrey Space Centre Guest Lecture, Tuesday 28 October 2003.

Satellite constellation networks
Lloyd Wood.
Chapter 2, Internetworking and Computing over Satellite Networks, Yongguang Zhang (ed.), Kluwer Academic Press, ISBN 1-4020-7424-7, pp. 13-34, March 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.
Photo of Zhang's Internetworking... volume, published by Kluwer.
Zhang with wood: blue-sky research

Chapter 2: Satellite constellation networks
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.
Print errata: p. 29: a well-designed hierarchy of address blocks...
Chapter 2: satellite constellation networks (340K)
Book table of contents (17K)

CiteSeer entry. Internetworking and Computing over Satellite Networks is now available from Amazon (UK, Canada, France, Germany, Japan).

Advice to link designers on link Automatic Repeat reQuest (ARQ)
Gorry Fairhurst, Lloyd Wood.
Request for Comments document in the Best Current Practices series, Internet Engineering Task Force.
IETF RFC3366/BCP62, August 2002.
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.
RFC3366 (RFC3366/BCP62 published as paginated text)

Internetworking with satellite constellations
Lloyd Wood.
Thesis for award of Doctor of Philosophy (PhD), University of Surrey, June 2001.
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.
Abstract and full PhD thesis

Managing diversity with handover to provide classes of service in satellite constellation networks
Lloyd Wood, George Pavlou, Barry Evans.
conference paper, in the proceedings of the AIAA 19th International Communication Satellite Systems Conference (ICSSC '01), vol. 3, session 35, no. 194, Toulouse, France, 17-20 April 2001.
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.

Managing diversity with handover to provide classes of service in satellite constellation networks. (242K, portrait/landscape A4)

CiteSeer entry | University record.

Effects on TCP of routing strategies in satellite constellations
Lloyd Wood, George Pavlou, Barry Evans.
refereed journal paper, Special issue on Satellite-Based Internet Technology and Services, IEEE Communications Magazine, vol. 39, no. 3, pp. 172-181, March 2001.
The authors introduce the types of satellite constellation networks, and examine how overall performance of TCP communications carried across such a network can be affected by the choice of routing strategies used within the network.
Print 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.

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.

Effects on TCP of routing strategies in satellite constellations (187K, portrait US letter)

CiteSeer entry | DOI 10.1109/35.910605 | University record.

IP routing issues in satellite constellation networks
Lloyd Wood, Antoine Clerget, Ilias Andrikopoulos, George Pavlou, Walid Dabbous.
refereed journal paper, Special issue on IP, International Journal of Satellite Communications, vol. 19 no. 1, pp. 69-92, John Wiley & Sons, January/February 2001.
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.

Preprint errata: Originally scheduled for November/December 2000, as indicated by the note on the first page. Published in the January/February 2001 issue.

IP routing issues in satellite constellation networks (124K, portrait A4)

CiteSeer entry | DOI sat.655.

A fair traffic conditioner for the assured service in a differentiated services Internet
Ilias Andrikopoulos, Lloyd Wood, George Pavlou.
refereed conference paper, in the proceedings of the IEEE International Conference on Communications (ICC 2000), vol. 2, pp. 806-810, New Orleans, 18-22 June 2000.
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 FRED fair active buffer algorithm to control the token allocation of the token buckets residing in the traffic conditioner.
A fair traffic conditioner for the assured service in a differentiated services Internet (69K, portrait A4)

CiteSeer entry | DOI 10.1109/ICC.2000.853610 | University record | DBLP record.

Supporting group applications via satellite constellations with multicast
Lloyd Wood, Haitham Cruickshank, Zhili Sun.
refereed conference paper, pp. 190-194, Griffiths, O'Reilly et al. (ed.), Proceedings of the Sixth IEE Conference on Telecommunications (ICT '98), Edinburgh, United Kingdom, 29 March - 1 April 1998.
IEE Conference Publication no. 451, ISBN 0-85296-700-4, ISSN 0537-9989.
Here, the networking aspects of the broadband satellite constellations are discussed, and the suitability of the constellations for multicast is assessed.
Supporting group applications via satellite constellations with multicast (168K, portrait A4)
Supporting group application slides, presented 2pm, Tuesday 31 March 1998 (272K, landscape A4)

CiteSeer entry | DOI 10.1049/cp:19980038 | IEEExplore | CAT.INIST | University record | full paper online.

Network performance of non-geostationary constellations equipped with intersatellite links
Lloyd Wood.
Thesis for award of Master of Science (MSc) in Satellite Communication Engineering, University of Surrey, November 1995.
Work completed as Rapport 95-9, ENST site de Toulouse (old site), France.
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.
Abstract and full MSc thesis

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.

Also noted

Contributions to Bisante and to the COST 253 final report, which is available online and from Amazon (UK, Canada, France, Germany, Japan).

I have also acted as an anonymous reviewer for conferences and journals. There is a page noting sundry acknowledgements.


Lloyd Wood (L.Wood@surrey.ac.uk)
this page last updated 21 March 2008