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.
Acrobat Reader or similar is needed to view and print these portable document format (pdf) files. You may need to set an A4 page size and shrink to fit in Page Setup... when printing. If you need postscript, Print to file... in Acrobat Reader. The Acrobat browser plugin loads in articles page by page, which can be disastrous over dialup connections, and is best turned off in Reader.
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)
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)
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.
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 | IEEExplore workshop proceedings.
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)
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)
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)
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).
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.
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.
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.
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.
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.
CiteSeer entry. 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.
CiteSeer entry. Internetworking and Computing over Satellite Networks is now 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.
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.
CiteSeer entry | 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.
CiteSeer entry | DOI 10.1109/35.910605 | 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.
CiteSeer entry | DOI sat.655.
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.
CiteSeer entry | DOI 10.1109/ICC.2000.853610 | 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.
CiteSeer entry | DOI 10.1049/cp:19980038 | 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.