ORL

Technical Reports and Papers


Author:
Maurice Wilkes
Title:
A Personal Revisitation of Neural Nets
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2002.1.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2002.1.ps
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
David Riddoch,
Steve Pope
, Kieran Mansley
Title:
VIA over the CLAN Network
Abstract:
The Virtual Interface Architecture is an industry standard for high performance networking in system-area networks, and the same model is proposed for Infiniband. Existing implementations suffer from high complexity, and scaling to higher bandwidths and large numbers of endpoints is likely to be problematic.

We present a novel implementation of VIA that consists of a thin software layer over the CLAN network. Performance of CLAN VIA is comparable with native solutions. The software implementation is highly flexible: we show that performance optimisations and extensions to the standard are easy to add.

The CLAN network has a very simple network model with very low overhead, that we believe scales well to very high bandwidths and large numbers of endpoints. These desirable properties are thus inherited by CLAN VIA.

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.14.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.14.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Glenford Mapp
Title:
Is IPv6 The Key to a Global Network Infrastructure ?
Abstract:
When IPv6 was devised, it was seen as an enhancement of IPv4, providing extra bits for addressing, etc. The world has moved on and new technologies, including mobile phones, ATM backbones, GPS systems and residential network access have now become ubiquitous.

There is a need to define a global network infrastructure to make all these services operate seamlessly and yet be compatible with systems based on IPv4.

This talk examines proposed enhancements to IPv6 to allow it to become a key part of a new Global Network Infrastructure

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.13.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Hoffmann, James Scott,
Mike Addlesee
, Glenford Mapp, Andy Hopper
Title:
Data Transport on the Networked Surface
Abstract:
Networked Surfaces are surfaces such as desks which provide network connectivity to specially augmented de-vices, for example handheld computers. When the devices are physically placed on top of the surface, they can connect to different kinds of services mainly, but not exclusively to send and receive data. This paper discusses challenges in implementing Net-worked Surfaces, paying particular attention to data flow issues, focusing on how the various software and hardware entities comprising the Surface interact to transport data to and from objects. Keywords: Mobile Networking, Sentient Computing
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.12.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.12.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
David Scott, Richard Sharp
Title:
Abstracting Application-Level Web Security
Abstract:
Application-level web security refers to vulnerabilities inherent in the code of a web-application itself (irrespective of the technologies in which it is implemented or the security of the web-server/back-end database on which it is built). In the last few months application-level vulnerabilities have been exploited with serious consequences: hackers have tricked e-commerce sites into shipping goods for no charge, usernames and passwords have been harvested and confidential information (such as addresses and credit-card numbers) has been leaked.

In this paper we investigate new tools and techniques which address the problem of application-level web security. We (i) describe a scalable structuring mechanism facilitating the abstraction of security policies from large web-applications developed in heterogenous multi-platform environments; (ii) present a tool which assists programmers develop secure applications which are resilient to a wide range of common attacks; and (iii) report results and experience arising from our implementation of these techniques.

Reference:
  • Technical Report 2001.11
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.11.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Diego López de Ipiña, Sai-Lai Lo
Title:
Sentient Computing for Everyone
Abstract:
Sentient Computing gives perception to computing systems so that they can detect, interpret and respond to changing aspects of user contexts. The location attribute of a user's context is of special interest because it makes human-computer interactions more natural. In the last few years, several sophisticated indoor location technologies, which can track user whereabouts, have been developed. However, they are yet to be widely adopted because of their high cost and complexities in deployment, configuration and maintenance. This paper describes a novel vision-based software location system, known as TRIP, whose low-cost, off-the-shelf hardware requirements and easy deployment features overcome other systems' limitations. Nevertheless, in order to foster the deployment of "sentient spaces" that bring services to users wherever they are or about to move to, a location system must also be accompanied by the middleware to facilitate user-bound software service activation, migration and deactivation. LocALE addresses this issue by providing a CORBA-based solution that deals with heterogeneous object lifecycle and location control. Some distributed applications combining TRIP's and LocALE's capabilities are presented to demonstrate that Sentient Computing can be made readily available for everyone and everywhere.
Reference:
  • To appear in Proceedings of the The Third IFIP WG 6.1 International Working Conference on Distributed Applications and Interoperable Systems (DAIS'2001), Krakow, Poland. September 17 - 19, 2001
  • Technical Report 2001.10
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.10.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.10.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Diego López de Ipiña, Sai-Lai Lo
Title:
LocALE: a Location-Aware Lifecycle Environment for Ubiquitous Computing
Abstract:
The LocALE (Location-Aware Lifecycle Environment) framework provides a simple management interface for controlling the lifecycle of CORBA distributed objects. It supports mechanisms for the remote construction, movement, removal and recovery of heterogeneous software objects in a location domain, i.e. a group of hosts on a network within a given physical area. Client applications use LocALE to intelligently control their required services' location and relocation in the network. LocALE offers load-balancing, automatic activation, and fault-tolerance facilities for the services whose lifecycles it controls. It provides the middleware necessary for the efficient implementation of location-aware mobile applications in richly equipped network environments. LocALE's infrastructure has been tested with the development of several follow-me applications that dynamically move with their users as they change location. For illustration, two of these follow-me LocALE-enabled applications are described.
Reference:
  • Proceedings of the 15th IEEE International Conference on Information Networking (ICOIN-15), Beppu City, Japan. January 31 - February 2, 2001 (received ICOIN-15's best student paper award)
  • Technical Report 2001.9
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.9.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.9.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Mike Addlesee
, Rupert Curwen, Steve Hodges, Joe Newman, Pete Steggles, Andy Ward, Andy Hopper
Title:
Implementing a Sentient Computing System
Abstract:
Sentient computing systems, which can change their behavior based on a model of the environment they construct using sensor data, may hold the key to managing tomorrow s device-rich mobile networks.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.8.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
James Weatherall,
Alan Jones
Title:
Ubiquitous Networks and their Applications (Available soon)
Reference:
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
James ''Wez'' Weatherall & David Scott
Title:
Mobile Computing with Python
Abstract:
This paper describes MoPy, a port of the Python 1.5.2 interpreter to the Psion 5/Epoc32 platform and Koala, a CORBA-style Object Request and Event Broker implemented natively in Python. While primarily a direct POSIX-based port of the standard Python interpreter, MoPy also adds thread, socket and serial support for the Psion platform. The Koala ORB is designed particularly with MoPy in mind and aims to support interoperation of devices over the low-power Prototype Em-bedded Network. The low-power requirements of PEN impose severe bandwidth and latency penalties to which conventional RPC technologies are not typically well suited.
Reference:
  • Proceedings of the 9th International Python Conference, March 2001
  • Technical Report 2001.6
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.6.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.6.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Gray Girling
Title:
Interaction Support in a Kernel for the Embedded Environment
Abstract:
As any other systems, those produced for an embedded environment are better developed when specified and implemented in a modular fashion. This paper outlines some infrastructural abstractions that allow the interaction of a wide range of system components; and goes on to describe their implementation optimised for the simplicity of typical embedded applications in a kernel for a component-based operating system. At the same time it explores the extent to which these abstractions can apply to a standard model of computational elements in the Open Distributed Processing environment. It is argued that designing code to use the proposed abstractions may help to extend its utility beyond application to specific embedded systems. Finally, some examples of the practical use of such an infrastructure are described.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.5.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Maurice Wilkes
Title:
The Memory Gap and the Future of High Performance Memories
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.4.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.4.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
David Riddoch,
Steve Pope
Title:
A Low Overhead Application/Device-driver Interface for User-level Networking
Abstract:
Recent user-level network interfaces have placed an increasing proportion of their functionality in hardware, in order to provide an efficient user-level interface. The performance of such systems is significantly better than that of traditional network architectures, but comes at a cost; namely increasing complexity of the hardware, reduced flexibility and limited scalability.

In this paper we present a technique that reduces the overhead of the application/device-driver interface, hence shifting the tradeoff towards a soft implementation. We show how this technique is used to improve the performance of the CLAN user-level network interface. Results given show that the performance of this interface exceeds that of other technologies that provide a direct user-level interface to the hardware, whilst retaining the flexibility and simplicity of a software interface.

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.3.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.3.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Joseph Newman
, David Ingram, Andy Hopper
Title:
Augmented Reality in a Wide Area Sentient Environment
Abstract:
Augmented Reality (AR) both exposes and supplements the user's view of the real world. Previous AR work has focussed on the close registration of real and virtual objects, which requires very accurate real-time estimates of head position and orientation. Most of these systems have been tethered and restricted to small volumes. In contrast, we have chosen to concentrate on allowing the AR user to roam freely within an entire building. At AT&T Laboratories Cambridge we provide personnel with AR services using data from an ultrasonic tracking system, called the Bat system, which has been deployed building-wide.

We have approached the challenge of implementing a wide-area, in-building AR system in two different ways. The first uses a head-mounted display connected to a laptop, which combines sparse position measurements from the Bat system with more frequent rotational information from an inertial tracker to render annotations and virtual objects that relate to or coexist with the real world. The second uses a PDA to provide a convenient portal with which the user can quickly view the augmented world. These systems can be used to annotate the world in a more-or-less seamless way, allowing a richer interaction with both real and virtual objects.

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.2.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.2.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Chris Town
, David Sinclair
Title:
Ontological Query Language for Content Based Image Retrieval
Abstract:
This paper discusses the design and implementation of the oquel query language for content based image retrieval. The retrieval process takes place entirely within the ontological domain defined by the syntax and semantics of the user query. Since the system does not rely on the pre-annotation of images with sentences in the language, the format of text queries is highly flexible. The language is also extensible to allow for the definition of higher level terms such as ``cars'', ``people'', ``buildings'', etc. on the basis of existing language constructs. Images are retrieved by deriving an abstract syntax tree from of a textual user query and probabilistically evaluating it by comparing the composition and perceptual properties of salient image regions in light of the query. The matching process utilises automatically extracted image segmentation and classification information and can incorporate any other feature detection mechanisms (such as face recognisers) or context-dependent knowledge available at the time the query is processed.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.1.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2001.1.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Tim Edmonds, Antony Rowstron,
Andy Hopper
Title:
Using Time Encoded Terrain Maps for Cooperation Planning
Abstract:
This paper describes a novel adaptation and use of Terrain Mapping and Optimal Path Planning to fuse large and diverse time varying data sets into a common structure used for path extraction. The method described uses a system of map distortion and manipulation to encode anticipated future states of the environment into a single map. By doing so, it effectively encodes time into the map, allowing paths to be planned incorporating short term accuracy and an approximate long term path which accounts for anticipated movement of obstacles in the environment. The path is refined with recalculation as progress is made along the path. An application of the technique in cooperation planning for multiple physical agents is presented in the context of the RoboCup Robot Football Competition.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.16.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Alan Jones
, Andy Hopper
Title:
The Prototype Embedded Network (PEN)
Abstract:
This paper describes a prototype low-power wireless link designed for embedding into everyday objects. After a brief description of the hardware platform, we discuss protocols for discovery and long-term rendezvous, contrasting our approach with master based approaches. The protocols are presented as examples drawn from a larger family of interoperable protocols which may be important to cover the broad range of applications for this sort of network. We then describe some of the applications built using PEN, and add some observations on spectrum costs, and future designs.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.15.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Chris Town
, David Sinclair
Title:
Content Based Image Retrieval using Semantic Visual Categories
Abstract:
This paper demonstrates an approach to content based image retrieval founded on the semantically meaningful labelling of images by high level visual categories. The image labelling is achieved by means of a set of trained neural network classifiers which map segmented image region descriptors onto semantic class membership terms. It is argued that the semantic terms give a good estimate of the salient features which are important for discrimination in image retrieval. Furthermore, it is shown that the choice of visual categories such as grass or sky which mirror high level human perception allows the implementation of intuitive and versatile query composition interfaces and a variety of image similarity metrics for content based retrieval.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.14.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.14.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Gray Girling
, Jennifer Li Kam Wa, Paul Osborn, Radina Stefanova
Title:
The Design and Implementation of a Low Power Ad Hoc Protocol Stack
Abstract:
Low power consumption is a key design metric for wireless network devices that have limited battery energy. The problem of reducing power consumption needs to be addressed at every level of system design. This paper investigates the issues of designing low power protocols in the context of the PEN system, a mobile ad hoc network developed at AT&T Laboratories Cambridge. It describes the ad hoc protocols that have been implemented, outlining both the design of individual protocols and the structure of the overall stack. The power-relevant mechanisms from the various protocols are collated in a summary.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.13.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Gray Girling
, Jennifer Li Kam Wa, Paul Osborn, Radina Stefanova
Title:
The PEN Low Power Protocol Stack
Abstract:
Low power consumption is a key design metric for wireless network devices that have limited battery energy. The problem of reducing power consumption needs to be addressed at every level of system design. This paper investigates the issues of designing low power protocols in the context of the PEN system, a mobile ad hoc network developed at the AT&T Laboratories Cambridge. It describes the ad hoc protocols that have been implemented, outlining both the design of individual protocols and the structure of the overall stack. A summary of the lessons in low power design that were learnt is provided
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.12.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
J.N. Weatherall
Title:
The R2 Low-Power Messaging and Rendezvous Layer
Abstract:
Recent advances in microprocessor and wireless technologies have created scope for a new class of device - the tetherless computer. Tetherless computers encompass not only those devices traditionally regarded as computers but also other electronic household devices. Tetherless computing may even extend, as will be illustrated, to networking non-electronic home items. The R2-Layer provides a simple yet flexible low-power rendezvous and messaging interface suitable for tetherless devices.
Reference:
  • Proceedings of SIGOPS European Workshop, September 2000
  • Technical Report 2000.11
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.11.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Timothy J. Mills
, David Pye, David Sinclair, Kenneth R. Wood
Title:
Shoebox: A Digital Photo Management System
Abstract:
This paper reports recent work at AT&T to develop a system for the management of personal digital photograph collections. Shoebox, the resulting software package, provides a range of browsing and searching facilities, utilising spoken annotations and image content to enable both semantically similar and visually similar images to be retrieved. We report on the design of the system, the construction of a test collection, and the evaluation of its searching facilities. The results show that audio annotation is an effective means of retrieval for photographs, which significantly out-performs image content-based techniques.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.10.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.10.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
James Scott, Frank Hoffman,
Mike Addlesee
, Glenford Mapp, Andy Hopper
Title:
Networked Surfaces: A New Concept in Mobile Networking
Abstract:
Networked Surfaces are surfaces which provide network connectivity to specially augmented objects, when these objects are physically placed on top of the surface. When an object (e.g. a notebook computer) connects, a handshaking protocol assigns functions such as data or power transmission to the various conducting paths that are established. This paper describes the position occupied by this concept in the world of networking, presents an overview of the technology used in its realisation, describes the current prototype implementation, and outlines the potential implications of its introduction.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.9.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.9.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano, Ross Anderson
Title:
The Grenade Timer: Fortifying the Watchdog Timer Against Malicious Mobile Code
Abstract:
Systems accepting mobile code need protection from denial of service attacks staged by the guest program. While protected mode is the most general solution, it is not available to the very low-cost microcontrollers that are common in embedded systems.

In this paper we introduce the grenade timer, an evolution of the watchdog timer that can place a hard upper bound on the amount of processor time that guest code may consume. Unlike its predecessor, it is resistant to malicious attacks from the software it controls; but its structure remains extremely simple and maps to very frugal hardware resources.

Reference:
  • Proceedings of 7th International Workshop on Mobile Multimedia Communications (MoMuC 2000), Waseda, Tokyo, Japan, 23-26 October 2000.
  • Technical Report 2000.8
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.8.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
David Riddoch,
Steve Pope
, Derek Roberts, Glenford Mapp, David Clarke, David Ingram, Kieran Mansley, Andy Hopper
Title:
Tripwire: A Synchronisation Primitive for Virtual Memory Mapped Communication
Abstract:
Existing user-level network interfaces deliver high bandwidth, low latency performance to applications, but are typically unable to support diverse styles of communication and are unsuitable for use in multiprogrammed environments. Often this is because the network abstraction is presented at too high a level, and support for synchronisation is inflexible.

In this paper we present a new primitive for in-band synchronisation: the Tripwire. Tripwires provide a flexible, efficient and scalable means for synchronisation that is orthogonal to data transfer.

We describe the implementation of a non-coherent distributed shared memory network interface, with Tripwires for synchronisation. This interface provides a low-level communications model with gigabit class bandwidth and very low overhead and latency. We show how it supports a variety of communication styles, including remote procedure call, message passing and streaming.

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.7.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.7.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Alan Mycroft, Richard Sharp
Title:
The FLaSH Project: Resource Aware Synthesis of Declarative Specifications
Abstract:
The FLaSH project concerns the development of a hardware synthesis system based around the idea of mapping a high-level functional specification language, SAFL, into hardware using sophisticated compiler technology.

The system has two phases: first we transform SAFL programs using meaning-preserving transformations to choose the area-time position (e.g. by resource duplication/sharing, specialisation, pipelining) while remaining a high-level specification. After this the FLaSH compiler maps the resultant SAFL program into hardware in a resource-aware manner, that is we map separate functions into separate functional units; functions which are called twice now become shared functional units - accessed by multiplexers and possibly arbiters. The current compiler outputs hierarchical RTL Verilog.

The first phase is user-guided. The second is completely automatic - it uses optimising compiler technology to insert arbiters for shared functional units and to insert intermediate registers (both on an `only when needed' basis). We justify SAFL as both amenable to transformation and facilitating an efficient translation to hardware.

The current compiler has been used to implement a small commercial processor; we achieve similar gatecounts to two previous RTL and netlist specifications but with around one tenth the source code.

Reference:
  • Technical Report 2000.6
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.6.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano
Title:
Il falsario contro il crittologo: sicurezza per la lotteria informatizzata (The Forger vs. the Cryptologist: Security Issues for the Computerised Lottery)
Abstract:
We present the main security issues for a lottery system using a hypothetical sequence of attacks, defenses and counterattacks. Cryptologic techniques are introduced where appropriate and the case of a fully digital lottery scenario is also examined.
Reference:
  • Proceedings of the 40th conference of the Italian Statistical Society, Florence, Italy, April 2000. Invited paper
  • Technical Report 2000.5
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.5.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.5.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano
Title:
The Resurrecting Duckling -- What Next?
Abstract:
In the context of the security of wireless ad hoc networks, we previously explored the problem of secure transient association between a master and a slave device in the absence of an online authentication server. We introduced the Resurrecting Duckling security policy model to address this problem. Master-slave relationships, however, do not exhaust the range of interesting interactions. We therefore extend the Duckling model to also cover relationships between peers.
Reference:
  • Proceedings of the 8th International Workshop on Security protocols, Cambridge, UK, April 2000,
  • To be published in the Lecture Notes in Computer Science series, Springer-Verlag
  • Technical Report 2000.4
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.4.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.4.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Richard Sharp, Alan Mycroft
Title:
The FLaSH Compiler: Efficient Circuits from Functional Specifications
Abstract:
In previous work we have outlined the design of a functional language, SAFL, and argued that it is well suited to hardware description and synthesis. Unlike conventional high-level synthesis languages, SAFL specifications capture explicitly resource allocation, variable binding and scheduling. This paper is concerned with the details of the FLaSH compiler: an optimising silicon compiler which translates SAFL specifications to RTL Verilog suitable for simulation or synthesis. We describe a number of high-level optimisation and analysis techniques which find novel application in the field of hardware-synthesis. In particular, we believe our approach to compiling function definitions into shared resources could be applied advantageously in existing industrial silicon compilers.
Reference:
  • Technical Report 2000.3
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.3.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Sheng Feng Li, Mark Spiteri, John Bates,
Andy Hopper
Title:
Capturing and Indexing Computer-based Activities with Virtual Network Computing
Abstract:
In this paper, we present a new technique to capture and index computer-based activities, without hindering natural human-computer interactions. This technique is based on the Virtual Network Computing (VNC) technology, which is an ultra-thin-client/server computing model that separates the display interface from the application logic in windowing systems. The server executes all the applications and the client simply presents the frame buffer updates to the user and accepts user input. We record the frame buffer updates for work review, and store the user and system events as potential indices into the recording.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.2.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.2.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Sheng Feng Li,
Quentin Stafford-Fraser
, Andy Hopper
Title:
Integrating Synchronous and Asynchronous Collaboration with Virtual Networking Computing
Abstract:
The trend in computing models has changed from thin-client (text terminals) to thick-client (graphics terminals) to standalone personal computing (PCs), and then back to thick-client (client/server applications) and thin-client (Web-based applications) again. This trend is now leading us to the so-called stateless-client computing, which is an ultra-thin-client model that frees the client completely from preserving any application state. This paper explains how we integrate synchronous and asynchronous sharing of workspace with VirtualNetwork Computing, a stateless-client computing technology developed at the AT&T Laboratories Cambridge. Experiments and applications have demonstrated that our collaborative system is feasible for operation in current and future computing environment.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.1.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.2000.1.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Tim Edmonds,
Steve Hodges
, Andy Hopper
Title:
An Adaptive Thin-Client Robot Control Architecture
Abstract:
This paper describes an architecture and runtime system to implement distributed control and data processing applications in a thin-client manner, suitable for implementing a thin-client mobile robotics system. The system varies control fidelity and locality to adapt a control application to changes in Quality of Service availability and processing resources using a cost benefit model. An example application is presented in which the architecture is used to implement the distributed control of an inverted pendulum over a shared network. Performance results are compared with non-adaptive distributed control approaches.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.13.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Andy Hopper
Title:
The Royal Society Clifford Paterson Lecture, 1999, Sentient Computing
Abstract:
Sentient computing is the proposition that applications can be made more responsive and useful by observing and reacting to the physical world. It is particularly attractive in a world of mobile users and computers.

The paper presents a classification and quantification of sensor information together with a description of a method for altering the behaviour of arbitrary terminal devices. It also presents a framework for ``programming with space'' which can associate space-related events with actions. Consideration is given to the applications made possible by such systems.

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.12.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.12.ps.gz
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.12.doc
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Rupert Curwen
, Andy Hopper, Pete Steggles, Andy Ward
Title:
Sentient Computing
Abstract:
The integration of Active Bats and other sensors is made possible by using an object model of the environment. Together with an API for programming with spatial relationships, they enable a style of programming called sentient computing.
Reference:
Video:
ftp.uk.research.att.com/pub/videos/qsif-200/spirit-qsif-200.mpg
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Raymond Liao,
Martin Brown
, Glenford Mapp, Ian Wassell
Title:
The Cambridge Wireless Broadband Trial
Abstract:
In this paper, we present a system overview of the Cambridge Wireless Broadband Trial which is being deployed in the Cambridge City area in the UK. The trial network is intended to serve as a testbed for research into new paradigms for wireless communications, and will provide an infrastructure for research on home networks. After a brief discussion of the network provisioning methods required to make the network operational, we present some preliminary measurement results. We then identify potential performance issues and propose some possible solutions as future work.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.11.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano
Title:
Python in Education: Raising a Generation of Native Speakers
Abstract:
Primarily because of its young age, Python is still a language that people only discover after having digested a few others: while many of its users love it enthusiastically, almost nobody is a native speaker of it, in the sense of having been exposed to it before any other.

As computer literacy evolves from desirable to necessary for people from all backgrounds, computer professionals and academics are responsible for taking a long-term view on how best to educate the next few generations of computer users. Form shapes contents, so the influence of a clean yet expressive first language in establishing good mental models and programming habits should not be underestimated.

This paper discusses how Python, with its high level of abstraction and judicious balance of simplicity, conciseness and versatility, is an excellent choice to introduce the fundamental ideas of the art of programming.

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.10.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.10.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Steve Hodges
, Dave Crosby, Antony Rowstron, Ben Bradshaw, Tim Edmonds, Andy Hopper, Steve Lloyd, Jian Wang
Title:
Building and integrating a goalkeeper robot for the small-size RoboCup competition
Abstract:
This paper details the design and development of a highly specialised goalkeeping robot for use in the RoboCup small-size league, and its integration into the Cambridge University Robot Football Team (RFT). The goalkeeper described is novel in its shape, in its use of CO2 as a power source, and in its ability to actually catch the ball and subsequently 'kick' it out at high speed. The last of these attributes also means that the goalkeeper has to coordinate with the rest of the team much more than it would otherwise have to.

The Cambridge RFT came top of their group and subsequently fourth overall in the Paris 1998 RoboCup small-size league. In the later stages of the competition the goalkeeper proved highly valuable, and enabled extended periods of play. Although it is difficult to provide empirical data to show the skill of a given team, or the effectiveness of its individual players, descriptions of the goalkeeper in use in a penalty shoot-out, and whilst in play against the CMU '98 team in the semi-final are provided.

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.9.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Dave Crosby, Steve Greaves,
Andy Hopper
Title:
A Theoretical Analysis of Multiple Diffraction in Urban Environments for Wireless Local Loop Systems
Abstract:
The simulation technique of Walfisch is used to examine multiple diffraction in wireless local loop systems. The simulations results show that the average propagation characteristic is described by a two slope model. In the immediate vicinity of the basestation the propagation loss is found to have a distance dependence of 20 dB per decade. At greater distances the slope increases to approximately 40 dB per decade. The distance at which the slope changes value is derived by considering the probability of Fresnel zone blockage.
Reference:
Text:
Not currently available in electronic form
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Andy Harter
, Andy Hopper, Pete Steggles, Andy Ward, Paul Webster
Title:
The Anatomy of a Context-Aware Application
Abstract:
We describe a platform for context-aware computing which enables applications to follow mobile users as they move around a building. The platform is particularly suitable for richly equipped, networked environments. The only item a user is required to carry is a small sensor tag, which identifies them to the system and locates them accurately in three dimensions. The platform builds a dynamic model of the environment using these location sensors and resource information gathered by telemetry software, and presents it in a form suitable for application programmers. Use of the platform is illustrated through a practical example, which allows a user's current working desktop to follow them as they move around the environment.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.7.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.7.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Sheng Feng Li,
Quentin Stafford-Fraser
, Andy Hopper
Title:
Frame-buffer on Demand: Applications of Stateless Client Systems in Web-based Learning
Abstract:
The growth of the Internet and the World Wide Web has changed the way people areeducated, and distance learning is amongst the most promising fields of new Webapplications built from existing services with supporting infrastructures. Inthis paper, we introduce a number of new applications built from StatelessClient Systems to assist the learning of computer-based activities. StatelessClient Systems separate the display interface from the application logic inwindowing systems. They embed a client/server architecture, where the serverexecutes all the applications and the client simply presents the frame buffersor screen images to the user and accepts user input. We seamlessly introduce aproxy server into the client/server architecture and create tools that enableteachers and students to record, replay, operate and share computer-based worksessions. The concepts and the systems for distance learning can be easilyextended to generic collaborative work.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.6.ps.gz
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.6.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
James Weatherall,
Andy Hopper
Title:
Predator: A Distributed Location Service and Example Applications
Abstract:
This paper introduces a simple distributed location service, suitable for deployment on a wide variety of heterogeneous platforms and which is scalable to cope with location forwarding on a global scale. Also described are two existing applications of the Predator location service, in particular to support of a wireless-via-wired routing service for low-power mobile devices, suitable for deployment both in-building and over a wide area.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.5.ps.gz
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.5.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano, Ross Anderson
Title:
The Cocaine Auction Protocol: On The Power of Anonymous Broadcast
Abstract:
Traditionally, cryptographic protocols are described as a sequence of steps, in each of which one principal sends a message to another. It is assumed that the fundamental communication primitive is necessarily one-to-one, so protocols addressing anonymity tend to resort to the composition of multiple elementary transmissions in order to frustrate traffic analysis.

This paper builds on a case study, of an anonymous auction between mistrustful principals with no trusted arbitrator, to introduce ``anonymous broadcast'' as a new protocol building block. This primitive is, in many interesting cases, a more accurate model of what actually happens during transmission. With certain restrictions it can give a particularly efficient implementation technique for many anonymity-related protocols.

Reference:
  • To appear in A. Pfitzmann, Proceedings of Information Hiding Workshop 1999, Springer-Verlag Lecture Notes in Computer Science.
  • ©Springer-Verlag
  • Technical Report 1999.4
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.4.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.4.ps.gz
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
David Sinclair
Title:
Voronoi seeded colour image segmentation
Abstract:
The goal of the segmentation scheme presented is to combine edge and region information to achieve a stable segmentation. The segmentation scheme presented is designed to operate on general home and stock photographs, it returns a comprehensive region-based description of the visual content of an image (including a distinction between smooth and textured regions and a description of the internal properties of the later).

A colour edge detector is presented, where hue difference is weighted more heavily than brightness difference. Seed points for region growing are derived from the colour edge image as the peaks in the associated Voronoi image. Regions are grown using gates on pixel colour relative to region central colour and region edge pixel colour. This permits regions to encompass shading gradients. Image edges act as hard barriers during region growing. A discrete feature based texture model is derived and then used to unify groups of smaller regions into extended textured regions.

The segmentation scheme is designed to facilitate image retrieval and has been tested on a corpus of over 40000 images and has been found to be robust.

Keywords: image segmentation, colour edge detection, textured region properties, region based image retrieval.

Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.3.ps.gz
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.3.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano, Ross Anderson
Title:
The Resurrecting Duckling: Security Issues for Ad-hoc Wireless Networks
Abstract:
In the near future, many personal electronic devices will be able to communicate with each other over a short range wireless channel. We investigate the principal security issues for such an environment. Our discussion is based on the concrete example of a thermometer that makes its readings available to other nodes over the air. Some lessons learned from this example appear to be quite general to ad-hoc networks, and rather different from what we have come to expect in more conventional systems: denial of service, the goals of authentication, and the problems of naming all need re-examination. We present the resurrecting duckling security policy model, which describes secure transient association of a device with multiple serialised owners.
Reference:
  • To appear in B. Christianson, B. Crispo and M. Roe (Eds.) Security Protocols. 7th International Workshop Proceedings, Lecture Notes in Computer Science, Springer-Verlag, 1999.
  • ©Springer-Verlag.
  • A revised version (tr.1999.2b) appears in the proceedings of the 3rd AT&T Software Symposium (20th October 1999, Middletown, NJ, USA).
  • Technical Report 1999.2
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.2.pdf,
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.2.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.2b.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.2b.ps.Z
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Sheng Feng Li,
Quentin Stafford-Fraser
, Andy Hopper
Title:
Applications of Stateless Client Systems in Collaborative Enterprises
Abstract:
We exploit and extend the so-called stateless client systems to support individuals in cooperative work. Stateless client systems are the software tools that separate the display interface from the application logic in windowing systems. They embed a client/server architecture, where the server executes all applications and the client simply presents the frame buffers or screen images to the user and accepts user input. By providing these stateless clients with suitable coordination mechanism, we enable geographically separated users to share workspaces and applications in a work session. And by recording the messages flowing between the client and the server, we enable temporally separated users to search for and playback previous work sessions to share knowledge and experience.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.1.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1999.1.ps.Z
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Andy Hopper
Title:
DART Shoebox
Abstract:
The DART project builds systems which allow indexing and retrieval of multimedia from large archives. In this example application we applied DART technology to the problem of the storing and finding pictures in personal photographic collections. Speech annotations are attached to the photos. The speech is then automatically recognised so that photos can be searched for and retrieved using keywords. Image content can also be used to retrieve photos from the archive.
Reference:
Video:
ftp.uk.research.att.com/pub/videos/qsif-200/shoebox-qsif-200.mpg
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Andy Ward
Title:
Ultrasonic Location Sensing
Abstract:
Small, wearable devices known as Active Bats and ceiling-mounted ultrasonic sensors are used to follow the time-varying 3D position of people and objects in a building.
Reference:
Video:
ftp.uk.research.att.com/pub/videos/qsif-200/bat-qsif-200.mpg
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Tristan Richardson
, Quentin Stafford-Fraser
Title:
Virtual Network Computing
Abstract:
VNC is a remote display system which allows you to view a computing 'desktop' environment not only on the machine where it is running, but from anywhere on the Internet and from a wide variety of machine architectures.
Reference:
Video:
ftp.uk.research.att.com/pub/videos/qsif-200/vnc-qsif-200.mpg
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
D. Pye,
N. Hollinghurst
, T. Mills, K. Wood
Title:
Audio Visual segmentation for content based retrieval
Abstract:
This paper reports recent work at ORL on segmentation of digital audio/video recordings. Firstly, we described an audio segmentation algorithm that partitions a soundtrack into manageably sized segments for speech recognition. Secondly, we present an algorithm for detecting camera shotbreak locations in the video. The output of these two algorithms is combined to produce a semantically meaningful segmentation of audio/video content, appropriate for information retrieval. We report the success of the algorithms in the context of television news retrieval.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.15.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
M. V. Wilkes
Title:
CMOS Workstations and Servers---How Far Can Evolution and Innovation Take Us?
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.14.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.14.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
S. F. Li,
Andy Hopper
Title:
What You See Is What I Saw: Applications of Stateless-Client Systems in Asynchronous CSCW
Abstract:
In stateless-client systems, the application processing takes place in the server, only changes to the user interface are sent to the client. Our paper will focus on how we make use of the stateless-client systems to support asynchronous CSCW on the World-wide Web by recording the changes to the user interface during a work session and replaying the session for any collaborative participant who is temporally separated. The recorded medium is a stream of rectangles containing pixel data of the user interface. Experiments show that the new lossless medium in general consumes less storage space than required by an equivalent lossy MPEG video.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.13.ps.gz
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.13.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
S. F. Li,
Andy Hopper
Title:
A Framework to Integrate Synchronous and Asynchronous Collaboration
Abstract:
In this research paper, we describe a framework for asynchronous as well as synchronous collaboration by extending ORL's Virtual Network Computing system. The framework provides facilities to transfer screen images or frame buffers of the on going CSCW session to remote users, allowing the available participants to share the view and the control of the session simultaneously, and to record the screen images or frame buffers for the absent participants to retrieve and playback the seesion at a later stage, with VCR-like controls.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.12.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.12.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
M.P. Sellars, S.D. Greaves, J. Porter,
Andy Hopper
, W.J. Fitzgerald
Title:
Fast Start-up Equalizer for Radio ATM
Abstract:
High speed TDMA wireless networks require high data rate efficiency and fast turnaround times. In dispersive multipath channels, an equalizer is needed to remove ISI from the signal. The equalizer may be trained more quickly if its taps are preloaded with initial values. This paper describes a power ratio approximation method which produces estimates for the initial tap values. Simulation results demonstrate that these estimates are sufficiently accurate to considerably reduce the equalizer settling time. The performance and complexity of the method is compared with existing methods for calculating the initial tap values, and shown to offer advantages for high speed systems.
Reference:
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
John Naylon, Damian Gilmurray, John Porter,
Andy Hopper
Title:
Low Latency Handover in a Wireless ATM LAN
Abstract:
The micro- and pico-cellular architectures proposed for wireless ATM LANs lead to wireless terminals frequently changing their point of attachment to the network. Because ATM connections have QoS guarantees which must be maintained, handover must be as seamless as possible. We present a novel architecture and protocol which primarily aims to keep the interruption period due to handover low, rather than seeking to keep the process entirely lossless. We compare the trade-offs made with those in other schemes from the literature and give quantitative results from an implementation of our scheme on a 10Mbps prototype wireless ATM LAN.
Reference:
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano
Title:
The SMS server, or why I switched from Tcl to Python
Abstract:
The SMS server is a system that allows mobile users to access information on their fixed computer facilities through the short message facility of GSM cellphones. Writing a versatile and extensible SMS server in Python, with interfaces to the cellphone on one side and to the Internet on the other, has been an interesting and enjoyable experience. This paper examines some Python programming issues and techniques used in implementing the server and distils some experience-based insights about the relative strengths and weaknesses of this remarkable programming environment when compared to the author's previous weapon of choice in the realm of scripting.
Reference:
  • Proceedings of the 7th International Python Conference, Houston, Texas, USA, November 1998.
  • Technical Report 1998.9
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.9.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.9.pdf
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.1998.9.html/index.html
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
P J Steggles
, P M Webster, A C Harter
Title:
The Implementation of a Distributed Framework to support 'Follow Me' Applications
Abstract:
This paper describes a framework for supporting `Follow Me' applications; that is, applications that adapt their behaviour to best serve a mobile user. The framework is based around a 3-tier architecture comprising a centralised database, a middle layer of parallel object servers and a collection of distributed clients. Some clients gather information from the environment, and are long running. Other clients are the mobile applications, which must respond rapidly to environmental changes. As all these applications are in daily use, robustness and availability are key requirements. The framework uses on-demand loading of CORBA objects and is sufficiently flexible and scalable to be applied to a wide variety of other application areas.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.8.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.8.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
S J Hodges
, S Pope, D E Roberts, G E Mapp, Andy Hopper
Title:
Remoting Peripherals using Memory-Mapped Networks
Abstract:
Memory-mapped networks such as Scalable Coherent Interconnect (SCI) and Memory Channel offer a new method for constructing network peripherals by remoting a host's IO bus. This paper details our experiences from building such an endpoint, and examines how greater support may be provided.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.7.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.7.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
S. Pope
, S. J. Hodges, G. E. Mapp, D. E. Roberts, Andy Hopper
Title:
Enhancing Distributed Systems with Low-Latency Networking
Abstract:
Recently several network technologies which support user-level communication between processes using a shared-memory interface have become available. These technologies offer very low latency, high bandwidth communication by eliminating the need for software protocol stacks. Whilst there has been much research on the use of such networks in the context of parallel computing, relatively little work has been done on their suitability for distributed applications. This paper describes the work undertaken to integrate the Scalable Coherent Interface (SCI) interconnect with the standard NFS server and a CORBA 2.0 compliant ORB over Linux. It is shown that impressive performance increases can be achieved without modification to either the operating system or the distributed application.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.6.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.6.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
S Pope
, S Lo
Title:
The Implementation of a Native ATM Transport for a High Performance ORB
Abstract:
The paper describes the design and implementation of omniTransport, a lightweight, user level transport protocol which has been tailored for the asymmetric communication requirements of a CORBA 2.0 compliant ORB, omniORB2. The protocol is shown to interwork with omniORB2 and has outperformed a leading in-kernel TCP implementation.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.5.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.5.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
S Lo,
S Pope
Title:
The Implementation of a High Performance ORB over Multiple Network Transports
Abstract:
This paper describes the implementation of a high performance Object Request Broker (ORB)-- omniORB2. The discussion focuses on the experience in achieving high performance by exploiting the protocol and other characteristics of the CORBA 2.0 specification. The design is also highly adaptable to a variety of network transports. The results of running the ORB over TCP/IP, shared memory, Scalable Coherent Interface (SCI) and ATM Adaptation Layer 5 (AAL5) are presented. In both null calls and bulk data transfers, the performance of omniORB2 is significantly better than other commercial ORBs.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.4.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.4.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano,
Alan Jones
Title:
The Thinnest Of Clients: Controlling It All Via Cellphone
Abstract:
The "thin client" paradigm aims to give users access to central resources through inexpensive and easily deployed computing systems. But, however 'thin' the client hardware, mobile users in the field still have the burden of carrying it. To alleviate this problem, we decided to adopt as our client a piece of hardware that many mobile users already carry with them anyway: the cellphone. This paper presents our experience in researching, implementing, deploying and using a system whereby users, wherever they are, can query and control their personalised computing resources and services by typing short messages on the keypad of their cellphone. Our system has been deployed and in use for over a year and has given us valuable insights on how to design and build a personal information service.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.3.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.3.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano
Title:
A Gentle Introduction to Relational and Object-Oriented Databases
Reference:
  • Technical Report 98.2
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.2.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.2.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Tristan Richardson
, Quentin Stafford-Fraser, Kenneth R. Wood, Andy Hopper
Title:
Virtual Network Computing
Abstract:
VNC is an ultra-thin client system based on a simple, open, platform-independent display protocol. It achieves mobile computing without requiring the user to carry any hardware
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.98.1.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Michael D. Addlesee
, Alan Jones, Finnbar Livesey, Ferdinando Samaria
Title:
The ORL Active Floor
Abstract:
In this article a novel type of sensor system called the Active Floor is presented that allows the time varying spatial weight distribution of the active office environment to be captured. The properties of the Active Floor are described, showing that it differs substantially from other commonly encountered sensor systems. Furthermore, classification of the footstep signature of a number of individuals is attempted by application of the hidden Markov model technique.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.11.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.11.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Andy Ward
, Alan Jones, Andy Hopper
Title:
A New Location Technique for the Active Office
Abstract:
Configuration of the computing and communications systems found at home and in the workplace is a complex task that currently requires the attention of the user. Recently, researchers have begun to examine computers that would autonomously change their functionality based on observations of who or what was around them. By determining their context, using input from sensor systems distributed throughout the environment, computing devices could personalize themselves to their current user, adapt their behaviour according to their location, or react to their surroundings. The authors present a novel sensor system, suitable for large scale deployment in indoor environments, which allows the locations of people and equipment to be accurately determined. We also describe some of the context-aware applications which might make use of this fine-grain location information.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.10.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.10.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frazer Bennett,
David Clarke
, Joseph B. Evans, Andy Hopper, Alan Jones, David Leask
Title:
Piconet - Embedded Mobile Networking
Abstract:
Piconet is a general purpose, low powered, ad-hoc radio network. It provides a base level of connectivity to even the simplest of sensing and computing objects. It is our intention that a full range of portable and embedded devices may make use of this connectivity. This paper outlines the Piconet system, under development at the AT&T Laboratories Cambridge (ORL). We discuss the motivation for providing this low-level 'embedded networking', and describe our experiences of building such a system. We conclude with a commentary of some of the implications that power-saving, and other considerations central to Piconet, have on the design of the system.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.9.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.9.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Glenford Mapp
, Steve Pope, Andy Hopper
Title:
The Design and Implementation of a High-Speed User-Space Transport Protocol
Abstract:
Audio and video are fast becoming an integral part of new computing environments. These media have transport requirements which differ from the normal bursty computer traffic. There is therefore a need to explore transport protocols that can provide different qualities of service. User-space implementations of such protocols are particularly interesting because they can be easily tested and refined. This paper discusses the design and implementation of a high-speed user-space protocol called A1. Its preliminary performance in an ATM environment is presented and compared with an efficient kernel implementation of TCP/IP.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.97.8.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.97.8.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Subir Biswas,
Andy Hopper
Title:
An Agent-Based Signaling Architecture for Supporting Mobility in Radio ATM Networks
Abstract:
The paper presents a signaling architecture for supporting mobility in radio asynchronous transfer mode (ATM) networks. A new concept of mobile software agent, known as 'representative', is used for insulating fixed network entities from the effects of user mobility. It is shown that, depending on the physical locations of the mobile terminals, their representatives can be used for distributing the mobility management load within the fixed backbone network. This paper describes a location and a representative management scheme followed by a novel connection caching strategy which is used for implementing a family of low-latency and scalable ATM connection handovers. A prototype implementation of the proposed architecture and the associated experimental results are also presented to demonstrate the feasibility and performance of this agent-based signaling scheme.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.97.7.ps.Z
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Steve Young, Jonathan Foote, Gareth Jones, Karen Sparck-Jones,
Martin Brown
Title:
Acoustic Indexing for Multimedia Retrieval and Browsing
Abstract:
This paper reviews the Video Mail Retrieval (VMR) project at Cambridge University and ORL. The VMR project began in September 1993 with the aim of developing methods for retrieving video documents by scanning the audio soundtrack for keywords. The project has shown, both experimentally and through the construction of a working prototype, that speech recognition can be combined with information retrieval methods to locate multimedia documents by content. The final version of the VMR system uses pre-computed phone lattices to allow extremely rapid word spotting and audio indexing, and statistical information retrieval (IR) methods to mitigate the effects of spotting errors. The net result is a retrieval system that is open-vocabulary and speaker-independent, and which can search audio orders of magnitude faster than real time.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.97.6.ps.Z
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Maurice V. Wilkes
, Andy Hopper
Title:
The Collapsed LAN: a Solution to a Bandwidth Problem?
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.5.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.5.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
David Sinclair
Title:
Image parsing for image retrieval from large image data bases: from coloured image to coloured regions
Abstract:
This paper gives details of a series of low level image processing routines which successfully break an image into a set of coloured regions. The first stage in the process is multi-scale edge detection. A fixed set of different sized kernels are used with the results being put into a single 'edgeness' image. A fixed lower threshold is applied to the edgeness image. A non-maximum suppression step is then applied. The histogram of edge strength in the non-max-suppressed image is used to set the high threshold for a hysteresis edge tracking routine. Points in the non-max-suppressed image above the high threshold are used as seed points to grow edges with the full edgeness image being used as the search domain. The edge growing algorithm therefore suffers less from the topological damage resulting from non-maximum suppression. A saliency filter is used to reject short crinkled edge chains. The second stage in the process uses the edge image to generate a series of Voronoi peaks. These are used as seed points for dilation type region growing. As the regions are grown the edgeness image is used to give a simple integrated measure of distance from a Voronoi centre. Pixels are then assigned membership in the 'nearest' centre. Regions are not permitted to grow through edges in the edge image. A merging step is then applied to amalgamate regions with large non-edge shared boundary. The mean colour of each region is evaluated and the regions then form nodes in a graph.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.4.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.97.4.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Glenford Mapp
, Steve J Hodges
Title:
Qos-Based Transport
Abstract:
This paper looks at transport services required by applications and proposes using a QoS vector to specify all transport requirements. These ideas have been pursued in the design and development of a new transport protocol called A1. Preliminary performance results for A1 over ATM are presented and compared with an efficient kernel implementation of TCP/IP.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.97.3.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.97.3.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Noha Adly,
Pete Steggles
, Andy Harter
Title:
SPIRIT: a Resource Database for Mobile Users
Abstract:
Users of computer systems need continuous access to information and services, but, as they move around in a richly equipped, networked environment, the available hardware resources change; software systems must adapt to these changes, offering location-aware personalisation and control. The SPIRIT project (SPatially Indexed Resource Identification and Tracking) is building a resource database which integrates the configuration data for heterogeneous networked hardware and software with fine-grained location data for users and equipment, allowing software to dynamically configure and reconfigure itself as users move around the networked environment. The ultimate goal of the project is to make it seem to users as though an application knows as much about the physical environment as they do. This paper describes the architecture of the SPIRIT database and provides an overview of some of its client applications.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.97.2.ps.Z
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Frank Stajano, Tom Blackie
Title:
AMIE - Advanced Multimedia Integrated Environment
Abstract:
The objective of the AMIE project was to research, develop and demonstrate an advanced environment for co-operative and distributed multimedia applications which would be integrated into an enterprise wide information technology system. A major design goal was to develop generic sub-system components which could be quickly and easily re-configured and integrated to address many different multimedia application and systems scenarios. The health care arena was chosen as an excellent demonstration for the capabilities of such a system, as it offered a demanding environment with a plethora of data modalities. An application area was identified where specific needs of a group of real users within a cardiology department were addressed. The culmination of the project was a three-month pilot field trial (later extended to four months) where the system was used in an operational role. This richly illustrated CD describes the aims and achievements of the project at various levels of detail, from a general overview of the system to technical papers and highlights of business exploitation opportunities. The documentation is presented as web pages and contains local links to, among other items, multimedia slide shows and MPEG movies showing the system in action.
Reference:
  • Technical Report 97.1 (CD ROM)
CD ROM:
CD-ROM available on request
Text:
http://www.uk.research.att.com/amie/
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Andy Hopper
Title:
Network Computer Architectures
Abstract:
Network computers can present a simpler and more manageable interface to the user. The ATM network computer developed at our lab was a stateless device which combined a pen interface with a network-remoted windowing system. It was also a high-bandwidth networked multimedia display. In contrast a purely software development, the Virtual Network Computer, requires only a Web browser to interact with a windowing system running back at base.
Reference:
Video:
ftp.uk.research.att.com/pub/videos/qsif-200/nca-qsif-200.mpg
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Title:
Video Mail Retrieval
Abstract:
The large collections of video mail which accumulated during the Pandora and later the Medusa projects suggested a difficult retrieval problem. The Video Mail Retrieval project showed that it was practical to use a speech recognition system in combination with traditional text-based techniques to achieve useful retrieval rates. Video.
Reference:
  • Technical Report 96.9 (video)
Video:
ftp.uk.research.att.com/pub/videos/qsif-200/vmr-qsif-200.mpg
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Andy Hopper
Title:
Modular Networked Multimedia
Abstract:
This video features new applications made possible by the Medusa approach of delivering large numbers of ATM multimedia streams to the desktop.
Reference:
Video:
ftp.uk.research.att.com/pub/videos/qsif-200/mnm-qsif-200.mpg
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Martin Brown
Title:
Supporting User Mobility
Abstract:
The availability of wireless network connections to laptop computers and PDA's has created interest in the issues surrounding mobile computing. However, enabling users to be genuinely mobile in their work requires more than a wireless connection. Distributed system services are needed to support the locating of people, equipment and software objects, and, especially for mobile multimedia applications, network transport protocols which can adapt to a wide range of networking conditions must be developed. This paper reviews some important mobility issues, looks at some of the systems requirements raised by user mobility, and describes some practical experiences with mobile applications at AT&T Laboratories Cambridge
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.96.7.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.96.7.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Martin Brown
, Jonathan Foote, Gareth Jones, Karen Sparck-Jones, Steve Young
Title:
Open-Vocabulary Speech Indexing for Voice and Video Mail Retrieval
Abstract:
This paper presents recent work on a multimedia retrieval project at Cambridge University and Olivetti Research Limited (ORL). We present novel techniques that allow extremely rapid audio indexing, at rates approaching several thousand times real time. Unlike other methods, these techniques do not depend on a fixed vocabulary recognition system or on keywords that must be known well in advance. Using statistical methods developed for text, these indexing techniques allow rapid and efficient retrieval and browsing of audio and video documents. This paper presents the project background, the indexing and retrieval techniques, and a video mail retrieval application incorporating content-based audio indexing, retrieval, and browsing.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.96.6.ps.Z
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
John Porter,
Andy Hopper
, Damian Gilmurray, Oliver Mason, John Naylon, Alan Jones
Title:
The ORL Radio ATM System, Architecture and Implementation
Abstract:
This paper presents a solution to the problem of connectivity of portables to an ATM wired network in the in-building environment. The approach to the support of ATM reduces the mobility load on the wired ATM network and is compatible with standard signalling protocols. The system is pico-cellular with a large number of base stations. The base stations are designed to be deployed in large numbers each covering a short range with partially overlapping coverages. This increases the aggregate throughput and reduces some of the problems specific to a radio physical layer. The MAC layer is optimised to provide efficient use of bandwidth and support guarantees for ATM traffic classes. An experimental prototype system based on low-cost fixed ATM switches and software controlled base stations has been developed and is outlined.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.96.5.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/tr.96.5.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Feng Shi,
Andy Hopper
Title:
A Network Striped Storage System for Video on Demand
Abstract:
This research advocates the architecture of using the switched network as the interconnect among the loosely coupled storage devices for large scale video on demand(VOD) servers. The article proposes a flexible and scalable network striped distributed storage system framework to exploit the above architecture. Quality of Service(QoS) and implementation issues are also discussed in the end.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.96.4.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.96.4.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Brendan Murphy,
Glenford Mapp
Title:
Integrating Multimedia Streams into a Distributed Computing System
Abstract:
Continuous media, such as audio and video, are quickly becoming an integral part of distributed computing environments. A shortcoming of such environments is their lack of support for continuous flows of information. What is missing is the notion of an on-going communication activity with an associated quality of service. This paper describes a model for integrating multimedia flows into a distributed computing system. The model permits explicit bindings to be established between type-checked stream interfaces. The stream binding is represented in the computational model as a first-class object which encapsulates configuration rules and QoS attributes. An operational interface supplied by the binding object allows other objects within the system to manage the binding, to renegotiate QoS parameters, to control the flows across the binding, and to register interest in stream events such as flow reports and communication errors. The in-band stream interface is an abstract C++ wrapper around transport mechanisms that include intra-host IPC and network transport protocols such as TCP and XTP. A prototype implementation of this model is described using the Common Object Request Broker Architecture (CORBA). The implementation environment comprises a local area ATM network with directly attached multimedia peripherals and general purpose workstations.
Reference:
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.96.3.ps.Z
Text:
ftp.uk.research.att.com:/pub/docs/att/paper.96.3.pdf
Contact:
AT&T Laboratories Cambridge, 24a Trumpington Street, Cambridge CB2 1QA, England

Author:
Kenneth R. Wood
, Tristan Richardson, Frazer Bennett, Andy Harter, Andy Hopper
Title:
Global Teleporting with Java: Towards Ubiquitous Personalised Computing
Abstract:
Previous work has described Teleporting, an approach to mobile computing in which it is the user's personal application environment which is mobile rather than the hardware on which the applications run. In this paper we describe an extended teleporting system which makes the user's environment available on any machine in the world running a Java-compliant web browser. We present some preliminary experimental results together with discussions of security and performance issues.
Reference:
Reference: