Publications
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A list of all my publications can be found here.
2002
·
Enhancing Energy Efficient TCP by
Partial Reliability
Donckers L., Havinga P.J.M., Smit G.J.M, Smit L.T., 13th IEEE
International Symposium on Personal, indoor and mobile radio communications
(PIMRC'2002), Lisboa, Portugal, September 15-18, 2002.
·
Dynamic Reconfiguration in Mobile
Systems
Smit G.J.M., Havinga P.J.M., Smit L.T., Heysters P.M., Rosien M.,
12th International Conference on Field Programmable Logic and Application,
Montpellier, September 2002.
·
Max-Log-MAP Mapping on an FPFA
Heysters P.M., Smit L.T., Smit G.J.M., Havinga P.J.M., Proceedings of
International Conference on Engineering of Reconfigurable Systems and
Algorithms (ERSA '02) Las Vegas, June 2002
·
Influences of Rake receiver/Turbo
decoder parameters on energy consumption and Quality
Smit L.T., Smit G.J.M., Havinga P.J.M., Hurink J.L., Broersma H.,
Proceedings World Wireless Congress, San Francisco, Delson group Inc. ISBN
1529-2592, pp 175-181, May 2002.
·
A reconfigurable function array
architecture for 3G and 4G wireless terminals
Heysters P.M., Bouma H., Smit J., Smit G.J.M., Havinga P.J.M., Proceedings
World Wireless Congress, San Francisco, Delson group Inc. ISBN 1529-2592, pp
399-405, May 2002.
·
Energy Efficient TCP
Donckers L., Havinga P.J.M., Smit G.J.M., Smit L.T., Proceedings 2nd
Asian International Mobile Computing conference (AMOC2002), Malaysia, ACM
Sigmobile, ISBN 983-40633-1-8, pp 18-28, May 2002.
·
WCRP – A WAP based multi-vehicle
Personal Navigation Service
Gorter J., Gorter O., de Keijzer A., Speekenbrink D.G., Havinga
P.J.M., Smit G.J.M., Heysters P.M., Proceedings 2nd Asian International
Mobile Computing conference (AMOC2002), Malaysia, ACM Sigmobile, ISBN
983-40633-1-8, pp 69-75, May 2002.
·
MIRAI Architecture
for Heterogeneous Network
G.
Wu, P. Havinga, and M. Mizuno
IEEE
Communications Magazine, ISBN 0163-6804, pp. 126-134, February 2002.
One
of the keywords that describe next-generation wireless communications is
“seamless.” As part of the e-Japan Plan promoted by the Japanese Government,
the Multimedia Integrated Network by Radio Access Innovation project has as
its goal the development of new technologies to enable seamless integration
of various wireless access systems for practical use by 2005. This article
describes a heterogeneous network architecture including a common tool, a
common platform, and a common access. In particular, software-defined radio
technologies are used to develop a multiservice user terminal to access
different wireless networks. The common platform for various wireless
networks is based on a wireless-supporting IPv6 network. A basic access
network, separated from other wireless access networks, is used as a means
for wireless system discovery, signaling, and paging. A proof-of-concept
experimental demonstration system will be available in March 2002 for users
in overlaid service areas. The seamless integration of heterogeneous wireless
systems will bring about a revolution in the wireless communications industry
that will affect vendors, service/application/context providers, policy
makers, and users. With the adoption of IMT-2000 in Japan, researchers in
both academia and industry have begun to show more and more interest in
new-generation wireless communication networks. Japanese government adopted
the so-called e-Japan Strategy in early 2001, including an explicit goal for
wireless communications: to create an IPv6-based high-speed wireless Internet
access environment and to enable seamless mobile communication services. The
e-Japan Plan to achieve this goal requires developing fourth-generation
mobile communication systems that will support a data rate as high as 100
Mb/s in a vehicular environment by 2010.
2001
·
Architectures
for Ubiquitous Computing
G.J.M. Smit, P.J.M. Havinga, J. Scholten: PT Embedded Systems, Vol.3 dossier
2002, pp. 8-11, Ten Hagen & Stam Uitgevers, ISSN 1389-1905, December 2001
·
Parameter Selection At
Run-Time To Optimize Energy Efficiency
Lodewijk
T. Smit, Gerard J.M. Smit, Paul J.M. Havinga
PROGRESS
2001, proceedings 2nd workshop on Embedded Systems, pp. 227-236, ISBN
90-73461-27-X, Veldhoven, the Netherlands, October 2001.
Energy
efficiency is vital for a mobile terminal. In this paper we investigate how
to choose the right parameter settings at run-time so that the energy
consumption is minimized while satisfying the required level of service. To
use a real world example, the energy consumption of a third generation
telephone WCDMA downlink receiver with turbo decoding forward error
correction is considered. A trade-off is made between the number of fingers
of a rake receiver and the number of iterations of the turbo decoder. A
simulation environment is constructed to simulate the system. In this paper
we present graphs, with which the trade-off can be easily made.
·
Wireless Internet over Heterogeneous
Wireless Networks
G.
Wu, P. Havinga, and M. Mizuno
IEEE
GLOBECOM’01, pp. 1759-1765, San Antonio, Nov. 2001, ISBN 0-7803-7208-5
One
of the two keywords for the next generation wireless communications is
seamless. Being involved in the essential e-Japan Plan promoted by the
Japanese Government, MIRAI (Multimedia Integrated network by Radio Access
Innovation) project is responsible for the research and development on the
seamless integration of various wireless access systems for the practical use
by the year 2005. A heterogeneous network architecture including a common
tool, a common platform, and a common access is proposed in this paper.
Concretely, software-defined-radio technologies are used to develop a
multi-service user terminal to be used for access to different wireless
networks. The common platform for various wireless networks is based on a
wireless supporting IPv6 network. A basic access network, separated from
other wireless access networks, is used as a means for wireless system
discovery, signaling and paging. A proof-concept experimental demonstration
system will be available in March 2002.
·
Reconfigurable System Design: The Control Part
Paul
M. Heysters, Henri Bouma, Jaap Smit, Gerard J.M. Smit, Paul J.M. Havinga
PROGRESS
2001, proceedings 2nd workshop on Embedded Systems, pp. 89-94, ISBN
90-73461-27-X, Veldhoven, the Netherlands, October 2001.
Advancement
in low-power hand-held multimedia systems requires exploration of novel
system architectures. In conventional computer architectures, an increase in
processing power also implies an increase in energy consumption. In a mobile
system this results in a shorter operating-time. Limiting the generality of
an architecture can improve its energy efficiency. However, application
specific architectures have a number of drawbacks and are too restricted.
Therefore, an application domain specific architecture is proposed. As part
of an application domain specific architecture for the digital
signal-processing domain, the Field Programmable Function Array (FPFA) was
conceived. The FPFA is a reconfigurable device with a data-path that can be
configured to implement a number of DSP algorithms energy efficiently. The
flexibility in the FPFA results in a data-path that requires many control
signals. To reduce the vast amount of control signals, the FPFA control-path
uses a combination of configuration registers and vertical microprogramming.
·
Micro Scanning Probe Array Memory (μSPAM)
Mathieu
Bolks, Ferdy Hanssen, Leon Abelmann, Paul Havinga, Pieter Hartel, Pierre
Jansen, Cock Lodder, Gerard Smit
PROGRESS
2001, proceedings 2nd workshop on Embedded Systems, pp. 17-26, ISBN
90-73461-27-X, Veldhoven, the Netherlands, October 2001.
The
design for a new type of non-volatile mass storage memory is discussed. This
new design, based on scanning probe techniques, combines the low volume and
power consumption of the FlashRAM, with the high capacity of the hard disk.
The small form factor of the device makes it an excellent candidate for mass
storage in handheld embedded systems. Its hierarchical architecture allows us
to make a trade-off between data-rate, access time and power consumption. The
power consumption scales linearly with the desired data-rate, and is expected
to be lower than what can be achieved with competing technologies.
·
Resource
Management for Seamless Mobile Services
Havinga P.J.M., Smit G.J.M, Wu G., Vognild L.
The fourth international symposium on wireless personal multimedia
communications (WPMC), September 2001
The seamless provisioning
of services and applications across heterogeneous wireless systems will play
a key role in future communication systems. While each individual enabling
wireless technology is advanced and stable, or is expected to become mature
in the near future, a framework for enabling the management of this
heterogeneous infrastructure efficiently and user-friendly, does not exist
yet. We address these challenges within the SMART project with the invention
of a novel architecture for seamless provision of mobile services over
heterogeneous wireless networks. The SMART architecture is scalable, is able
to use the available resources efficiently (like network, energy, and money),
and makes the heterogeneous network transparent to, but nevertheless under
control of the user. User-friendliness, security, and efficiency are the key
goals of the architecture. In SMART all these issues are being dealt with in
an integrated, coherent way.
·
Mobile Multimedia Systems
P.J.M. Havinga, G.J.M. Smit
Chapter 15 of “Electronic Business and Education, Recent Advances in Internet
Infrastructures” (edited by Wendy Chin,
Frédéric Patricelli, Veljko Milutinovic), Kluwer Academic Publishers, Boston,
ISBN 0-7923-7508-4, August 2001.
·
The SMART
project: Exploiting the Heterogeneous Mobile World
Havinga P.J.M., Smit G.J.M, Wu G., Vognild L.
session on "Wireless Internet: Protocols and Applications" as
part of the 2nd International Conference on Internet Computing, (invited),
Las Vegas, USA, June 2001.
·
Energy
management for dynamically reconfigurable heterogeneous mobile systems
Havinga P.J.M., Smit L.T., Smit G.J.M., Bos M., Heysters P.M.
10th Heterogeneous Computing Workshop, San Francisco, USA, April 2001
Dynamically reconfigurable systems offer the potential for realising
efficient systems as well as providing adaptability to changing system
requirements. Such systems are suitable for future mobile multimedia systems
that have limited battery resources, must handle diverse data types, and must
operate in dynamic application and communication environments. We propose an
approach in which reconfiguration is applied dynamically at various levels of
a mobile system, whereas traditionally, reconfigurable systems mainly focus
at the gate level only. The research performed in the CHAMELEON project aims
at designing such a heterogeneous reconfigurable mobile system. The two main
motivations for the system are 1) to have an energy-efficient system, while
2) achieving an adequate Quality of Service for applications.
·
QoS
scheduling for energy-efficient wireless communication
Havinga P.J.M., Smit G.J.M.
International Conference on Information Technology: Coding and Computing
(ITCC2001), special session on recent advances in wireless networking and
communications (invited), Las Vegas, USA, April 2-4, 2001
In this paper we present a QoS scheduler that assigns the bandwidth over the
wireless channel such that the amount of energy spend by the mobile is
minimized, while maintaining the Quality of Service of the connections.
Energy efficiency is an important issue for mobile computers since they must
rely on their batteries. We have designed and implemented an energy-efficient
architecture and MAC protocol for wireless multimedia traffic. The scheduling
is based on two mechanisms, 1) a short term transmission frame scheduling
that concatenates uplink and downlink traffic of one mobile, and 2) a
long-term scheduling, that tries to collect traffic as much as possible
within the QoS requirements of the connections. The result is that the
transceiver can be in a low-power operating mode for an extended period of
time and that the number of operating mode transitions is reduced.
·
Wireless
Internet on Heterogeneous Networks
Havinga P.J.M., Wu G.
workshop on Mobile Communications in Perspective, Enschede, the
Netherlands, February 2001.
The wide proliferation of wireless systems and the use of software radio
technologies enable the employment of a heterogeneous network. In this
concept services are delivered via the network that is most efficient for
that service. The solution is based on a common core network that
interconnects access points of various wireless access points. A mobile host
can apply multiple different access networks simultaneously to increase
capacity or efficiency. A basic access network, separated from other wireless
access networks, is used as a means for wireless system discovery, signalling
and paging. Quality of Service is of prominent importance due to the
heterogeneous environment and the characteristics of the wireless channel.
This paper describes the concepts of our architecture, and presents an
overview of the architecture.
·
Energy-efficient
wireless networking for multimedia applications
Havinga P.J.M., Smit G.J.M.
Wireless Communications and Mobile Computing, Wiley, 2001.
In this paper we identify the most prominent problems of wireless multimedia
networking and present several state-of-the-art solutions with a focus on
energy efficiency. Three key problems in networked wireless multimedia
systems are 1) the need to maintain a minimum quality of service over
time-varying channels, 2) to operate with limited energy resources, and 3) to
operate in a heterogeneous environment. We identify two main principles to
solve these problems. The first principle is that energy efficiency should
involve all layers of the system. Second, Quality of Service is an essential
mechanism for mobile multimedia systems not only to give users an adequate
level of service, but also as a tool to achieve an energy-efficient system.
Due to the dynamic wireless environment, adaptability of the system will be a
key issue in achieving this.
2000
·
Energy-efficient
TDMA medium access control protocol scheduling
Havinga P.J.M., Smit G.J.M.
proceedings Asian International Mobile Computing Conference (AMOC 2000),
Nov. 2000.
In this paper we study the energy efficiency and channel efficiency of TDMA
MAC protocol scheduling mechanisms. Most MAC protocols are based on phase
grouping that basically has three phases in a frame: uplink, downlink and
reservation. We propose a new mechanism in which we have multiple uplink and
downlink phases. These phases are grouped per mobile in a frame. Although
this has a negative effect on the capacity of the channel, it allows the
mobile to turn the power off from the wireless interface for a longer period.
We made this choice since in a mobile multimedia environment it is more
important that connections have a certain QoS, than highest possible
bandwidth. We present an analysis in which these two basic mechanisms are
compared in respect to bandwidth efficiency and energy efficiency. We have
developed and implemented a novel MAC protocol based on mobile grouping that
provides Quality of Service (QoS) support for diverse traffic types.
·
Mapping
the SISO Module of the Turbo Decoder to a FPFA
G. Smit, P. Heysters, P. Havinga, L. Smit, J. Dilessen, J. Huisken
proceedings Second International Symposium on Mobile Multimedia Systems
& Applications (MMSA2000), November 2000.
In the CHAMELEON project a reconfigurable systems-architecture, the Field
Programmable Function Array (FPFA) is introduced. FPFAs are reminiscent to
FPGAs, but have a matrix of ALUs and lookup tables instead of Configurable
Logic Blocks (CLBs). The FPFA can be regarded as a low power reconfigurable
accelerator for an application specific domain. In this paper we show how the
SISO (Soft Input Soft Output) module of the Turbo decoding algorithm can be
mapped on the reconfigurable FPFA.
·
Exploring
Energy-Efficient Reconfigurable Architectures for DSP Algorithms
Heysters P.M., Smit J., Smit G.J.M., Havinga P.J.M.
proceedings PROGRESS 2000 workshop, pp. 37-46, ISBN 90-73461-22-7, Oct.
2000.
Future hand-held multimedia terminals require a very high performance on a
very small energy budged. Such devices can only be realized if their entire
syste is energy cognisant. In this paper a reconfigurable
systems-architecture for mobile multimedia systems is introduced. The Field
Programmable Function Array (FPFA) is discussed in detail. Several digital
signal processing algorithms are discussed and applied on the FPFA. Also, the
power radius theory about low-power design is introduced.
·
Run-time
Energy Management for Mobiles
Smit L.T., Smit G.J.M. and Havinga P.J.M.
proceedings PROGRESS 2000 workshop, pp. 107-112, ISBN 90-73461-22-7, Oct.
2000.
Due to limited energy resources, mobile computing requires an energy
efficient architecture. The dynamic nature of a mobile environment demands an
architecture that allows adapting to (quickly changing conditions. The mobile
has to adapt dynamically to new circumstances in the best suitable manner.
The hardware and software architecture should be able to support such
adaptability and minimize the energy consumption by making resource
allocation decisions at run-time. To make these decisions effective, a trade-off
has to be made between computation, communication and initialisation costs
(both time and energy). This paper describes our approach to construct a
model that supports taking such decisions.
·
Channel
Communication and Reconfigurable Hardware
Bos M., Havinga P.J.M., Smit G.J.M.
proceedings PROGRESS 2000 workshop, pp. 11-14, ISBN 90-73461-22-7, Oct.
2000.
Many applications can be structured as a set of processes or threads that
communicate via channels. These threads can be executed on various platforms
(e.g. general purpose CPU, DSP, FPGA, etc). In our research we apply channels
as a basic communication mechanism between threads in a reconfigurable
system. The research involves providing system level functions to describe
the setup of communicating threads, which may now either run timeshared on a
general CPU or in dynamically-setup special purpose logic that runs on
reconfigurable hardware. The use of channels and threads running in both
software and hardware, will be made transparent for the application level
programmers by the system level functions. By first describing the threads
and how they are connected and then letting the operating system decide on
’geographical’ placement of the threads and buffers, multiprogramming will be
supported and programs will be able to run on different setups of hardware
(i.e. different amount of CPUs or available programmable logic). This is an
ongoing work, the paper is a collection of thoughts, which lead to a first
setup of rudimentary support functions in the operating system.
·
Reconfiguration
in mobile multimedia systems
Smit G.J.M., Havinga P.J.M., Bos M., Smit L.T., Heysters P.M.
proceedings PROGRESS 2000 workshop, pp. 95-106, ISBN 90-73461-22-7, Oct.
2000.
Dynamically reconfigurable systems offer the potential for realising
efficient systems as well as providing adaptability to changing system requirements.
Such systems are suitable for future mobile multimedia systems that have
limited battery resources, must handle diverse data types, and must operate
in dynamic application and communication environments. We propose an approach
in which reconfiguration is applied dynamically at various levels of a mobile
system, whereas traditionally, reconfigurable systems mainly focus at the
gate level only. The research performed in the CHAMELEON project aims at
designing such a heterogeneous reconfigurable mobile system. The two main
motivations for the system are 1) to have an energy-efficient system, while
2) achieving an adequate Quality of Service for applications.
·
Lessons
learned from the design of a mobile multimedia system in the MOBY DICK
project
G.J.M. Smit, P.J.M. Havinga
HUC2k, Bristol, UK, September 2000
The research performed in the MOBY DICK project is about designing a mobile multimedia
system. This paper discusses the approach made in the MOBY DICK project to
solve some of the problems involved, discusses its contributions, and
accesses what was learned from the project.
·
Mapping of
DSP Algorithms on Field Programmable Function Arrays
Paul M. Heysters, Jaap Smit, Gerard J.M. Smit, Paul J.M. Havinga
FPL2000, August 2000
This position paper discusses reconfigurability issues in low-power hand-held
multimedia systems. A reconfigurable systems-architecture is introduced, with
a focus on a Field Programmable Function Array (FPFA). Application domain
specific algorithms determine the granularity of FPFA processor tiles.
Several algorithms are discussed and mapped onto a FPFA processor tile.
·
Moby
Dick, on the design of a Swiss army knife of computing
P.J.M. Havinga, G.J.M. Smit
International Conference on Advances in infrastructure for Electronic
Business, Science, and Education on the internet (SSGRR 2000), L'Aquila,
Italy, August, 2000
Recent advances in wireless networking technology and the exponential
development of semiconductor technology have engendered a new paradigm of computing,
called personal mobile computing or ubiquitous computing. This offers a
vision of the future with a much richer and more exciting set of architecture
research challenges than extrapolations of the current desktop architectures.
In particular, these devices will have limited battery resources, will handle
diverse data types, and will operate in environments that are insecure,
dynamic and which vary significantly in time and location. The research
performed in the MOBY DICK project is about designing such a mobile
multimedia system. This paper discusses the approach made in the MOBY DICK
project to solve some of these problems, discusses its contributions, and
accesses what was learned from the project.
·
Energy
efficient adaptive wireless network design
P.J.M. Havinga, G.J.M. Smit, Martinus Bos
The Fifth Symposium on Computers and Communications (ISCC'00), Antibes,
France, July 3-7, 2000
Energy efficiency is an important issue for mobile computers since they must
rely on their batteries. We present an energy-efficient highly adaptive
architecture of a network interface and novel data link layer protocol for
wireless networks that provides Quality of Service (QoS) support for diverse
traffic types. Due to the dynamic nature of wireless networks, adaptations
are necessary to achieve energy efficiency and an acceptable quality of
service. The paper provides a review of ideas and techniques relevant to the
design of an energy efficient adaptive wireless network. In our approach we
apply adaptability through all layers of the protocol stack, and provide
feedback to the applications. In this way the applications can adapt the data
streams, and the network protocols can adapt the communication parameters. We
present an overview of the techniques we have applied for our wireless
system.
·
Mobile
Multimedia Systems
P.J.M. Havinga
Ph.D. thesis University of Twente, February 2000, ISBN 90-365-1406-1
The research presented in this thesis addresses the design of an architecture
for a mobile multimedia handheld computer. Energy efficiency and Quality of
Service is important for these systems. We show that the key to energy
efficiency will be achieved in the design of the higher layers of the system,
its system architecture, its operating system, and the entire network. Of
special importance in this are the communication channels. Quality of Service
is used not only to give users an adequate level of service, but also as a
tool to achieve an energy efficient system.
Specific contributions of the research described in this thesis are the
design of an energy-efficient architecture for mobile multimedia systems and
a reconfigurable connection switch, as well as the design of crucial wireless
network functions (i.e. MAC protocol, adaptable network interface, and a
model for adaptable error-correction) that are energy efficient and can
support multimedia traffic.
·
Moby Dick, het ontwerp van een Digitale
Kameraad (in
Dutch)
P.J.M. Havinga, G.J.M. Smit
I/O Vivat, May 2000, Vol. 16-3, ISSN 1389-0468.
Zullen de zaktelefoon en de mobiele computer uitgroeien tot een Digitale
Kameraad waarmee je betaalt, de voordeur opent, jezelf identificeert en
luistert naar muziek tijdens het joggen? Dit is een vraag waar het MOBY DICK
project zich mee bezig houdt. In het MOBY DICK project van het cluster
Embedded Systemen wordt onderzoek gedaan aan dergelijke systemen.
·
Energy
efficient wireless ATM design
P.J.M. Havinga, G.J.M. Smit, Martinus Bos
ACM/Baltzer Journal on Mobile Networks and Applications (MONET), Special
issue on Wireless Mobile ATM technologies, Vol. 5, No 2., 2000
We present an architecture for wireless ATM and a novel MAC protocol that
achieves a good energy efficiency of the wireless interface of the mobile and
provides QoS support for diverse traffic types. The scheduler of the base
station is responsible for providing the required QoS to connections on the
wireless link and to minimise the amount of energy spent by the mobile. The
main principles used are to avoid unsuccessful actions, to minimise the
number of transitions, and to synchronise the mobile and the base-station. We
will show that considerable amounts of energy can be saved using these
principles. In the protocol the actions of the mobile are minimised. The base-station
with plenty of energy performs actions in courtesy of the mobile. We have
paid much attention in reducing the cost for a mobile of just being
connected. The protocol is able to provide near-optimal energy efficiency
(i.e. energy is spent for the actual transfer only) for a mobile within the
constraints of the QoS of all connections in a cell, and only requires a
small overhead.
·
Design
techniques for low-power systems
P.J.M. Havinga, G.J.M. Smit
(Journal of Systems Architecture, Vol. 46, Iss. 1, 2000)
Portable products are being used increasingly. Because these systems are
battery powered, reducing power consumption is vital. In this report we give
the properties of low power design and techniques to exploit them on the
architecture of the system. We focus on: min imizing capacitance, avoiding
unnecessary and wasteful activity, and reducing voltage and frequency. We
review energy reduction techniques in the architecture and design of a
hand-held computer and the wireless communication system, including error
control, sys tem decomposition, communication and MAC protocols, and low
power short range net works.
1999
·
Reconfigurable
Mobile Multimedia Systems
G.J.M. Smit, Martinus Bos, Paul J.M. Havinga, Jaap Smit
(ProRISC workshop on Circuits, Systems and Signal Processing, ProRISC'99,
pp. 431-436, November 1999)
This paper discusses reconfigurability issues in low-power hand-held
multimedia systems, with particular emphasis on energy conservation. We claim
that a radical new approach has to be taken in order to fulfill the
requirements - in terms of processing power and energy consumption - of
future mobile applications. A reconfigurable systems-architecture in
combination with a QoS driven operating system is introduced that can deal
with the inherent dynamics of a mobile system. We present the preliminary results
of studies we have done on reconfiguration in hand-held mobile computers: by
having reconfigurable media streams, by using reconfigurable processing
modules and by migrating functions.
·
Single
shared memory space architecture for less power
M. Bos, Paul J.M. Havinga, G.J.M. Smit
(ProRISC workshop on Circuits, Systems and Signal Processing, ProRISC'99,
pp. 43-48, November 1999)
Virtual Memory and Hardware Memory Pro-tection are so common now that they
are even used in hand-held devices that do not include any secondary storage
to swap to. As most handhelds depend on batteries for their power supply, it
seems worth investigating an architecture without these expensive pieces of hardware.
New type safe languages may allow dropping the memory protection hard-ware as
well. This paper describes the first investigations done in this direction.
Both benefits and drawbacks are described and ways to minimize the drawbacks
are investigated.
·
Octopus
- an energy-efficient architecture for wireless multimedia systems
P.J.M. Havinga, G.J.M. Smit
(ProRISC workshop on Circuits, Systems and Signal Processing, ProRISC'99,
pp. 185-192, November 1999)
Multimedia computing and mobile computing are two trends that will lead to a
new application domain in the near future. However, the technological
challenges to establishing this paradigm of computing are non-trivial.
Personal mobile computing offers a vision of the future with a much richer
and more exciting set of architecture research challenges than extrapolations
of the current desktop architectures. In particular, these devices will have
limited battery resources, will handle diverse data types, and will operate
in environments that are insecure, dynamic and which vary significantly in
time and location. The approach we made to achieve such a system is to use
autonomous, adaptable modules, interconnected by a switch rather than by a
bus, and to offload as much as work as possible from the CPU to programmable
modules that is placed in the data streams. A reconfigurable internal
communication network switch called Octopus exploits locality of reference
and eliminates wasteful data copies.
·
Chameleon -
reconfigurability in hand-held multimedia computers
Gerard J.M. Smit, Martinus Bos, Paul J.M. Havinga, Sape J. Mullender,
Jaap Smit
(Handheld and Ubiquitous Computing, HUC'99, September 1999)
In this paper a reconfigurable systems-architecture in combination with a QoS
driven operating system is introduced that can deal with the inherent
dynamics of future mobile systems. We claim that a radical new approach has
to be taken in order to fulfill the requirements - in terms of processing
power and energy consumption - of future mobile applications.
·
Octopus:
embracing the energy efficiency of handheld multimedia computers
Paul J.M. Havinga, Gerard J.M. Smit
(ACM/IEEE Mobicom, August 1999)
In the MOBY DICK project we develop and define the architecture of a new
generation of mobile hand-held computers called Mobile Digital Companions.
The Companion has an unconventional architecture that saves energy by using
system decomposition at different levels of the architecture and exploits
locality of reference with dedicated, optimised modules. A reconfigurable
internal communication network switch called Octopus exploits locality of
reference and eliminates wasteful data copies. The switch is implemented as a
simplified ATM switch and provides Quality of Service guarantees and enough
bandwidth for multimedia applications. We have built a testbed of the
architecture, of which we will present performance and energy consumption
characteristics.
·
Energy
efficiency of error correction on wireless systems
Paul J.M. Havinga
(IEEE Wireless Communications and Networking Conference, September 1999)
Since high error rates are inevitable to the wireless environment, energy
efficient error control is an important issue for mobile computing systems.
We have studied the energy efficiency of two different error correction
mechanisms and have measured the efficiency of an implementation in software.
We will show that it is not sufficient to concentrate on the energy
efficiency of error control mechanisms only, but the required extra energy
consumed by the wireless interface should be incorporated as well. A model is
presented that can be used to determine an energy efficient error correction
scheme of a minimal system consisting of a general-purpose processor and a wireless
interface. This model can be used to adapt the error correction parameters,
such that the system is energy efficient. As an example we have determined
these error correction parameters on two systems with a WaveLAN interface.
·
Energy
efficient wireless ATM design
P.J.M. Havinga, G.J.M. Smit, Martinus Bos
(wmATM'99, June 2-4 1999)
We present an architecture for wireless ATM and a novel MAC protocol that
achieves a good energy efficiency of the wireless interface of the mobile and
provides QoS support for diverse traffic types. The scheduler of the base
station is responsible for providing the required QoS to connections on the
wireless link and to minimise the amount of energy spent by the mobile. The
main principles used are to avoid unsuccessful actions, to minimise the
number of transitions, and to synchronise the mobile and the base-station. We
will show that considerable amounts of energy can be saved using these
principles. In the protocol the actions of the mobile are minimised. The
base-station with plenty of energy performs actions in courtesy of the
mobile. We have paid much attention in reducing the cost for a mobile of just
being connected. The protocol is able to provide near-optimal energy
efficiency (i.e. energy is spent for the actual transfer only) for a mobile
within the constraints of the QoS of all connections in a cell, and only
requires a small overhead.
·
Implementation
of a wireless ATM transceiver using reconfigurable logic
G.J.M. Smit, P.J.M. Havinga, Marcel van Opzeeland, Remco Poortinga
(wmATM'99, June 2-4 1999)
In this paper we present the design, implementation and realization of a
receiver for a wireless nano-cellular ATM network using a small Field
Programmable Gate Array. The network is designed for an office environment.
The method used for transmitting data, at the rate of 1Mbps, is Differential
Phase Shift Keying (DPSK) on a 3 MHz carrier using near-field RF. It uses
differential coherent detection to demodulate the received signal. A matched
filter combined with a notch filter reduces the bit error rate. A MAC
protocol for this network that is suitable for multimedia traffic is
implemented in a micro-controller. The system has been demonstrated in a
setup where uncompressed video frames (320x200x6) were transmitted at a rate
of 4 frames per second.
·
Low cost
& fast turnaround: reconfigurable graph-based execution units
J. Smit, M. Stekelenburg, C.E. Klaassen, S. Mullender, G. Smit, P.
Havinga
(7th BELSIGN workshop, 1998)
New devices with the efficiency of full-custom designs and the
programmability of FPGAs will ease many aspects of the design of complex
systems, without the high cost of mask production. The possibility of
in-circuit programming and even dynamic reconfiguration offers great
advantages over the traditional design approach. One instance of a fully
programmable architecture, which offers a platform for rapid prototyping,
quick market and application evaluation, is introduced in the form of a field
programmable function array (FPFA). The design of such a device is extremely
challenging as the aspects of physical design for speed and low-power, the
construction of an ALU which is optimal for as many applications as possible,
as well as highly efficient mappings of algorithms, are extremely important
for a successful device which suits many applications. This paper introduces
the reader with the concept of reprogrammable devices with graph-based
execution of arithmetic expressions, the corresponding principles of
operation, the aspects of low-power operation of the proposed design, the
corresponding physical design of the ALU, algorithmic mappings of systems on
a chip and the performance aspects compared to other architectures and
implementations.
1998
·
Energy
efficiency of error correcting mechanisms for wireless communication
P.J.M. Havinga
(CTIT Technical Reports 1998, TR-CTIT 98-19, September 1998)
We consider the energy efficiency of error control mechanisms for wireless
communication. Since high error rates are inevitable to the wireless
environment, energy efficient error control is an important issue for mobile
computing systems. Although good designed retransmission schemes can be
optimal with respect to energy efficiency, they can introduce problems to
fulfill the required QoS of an application. Since the channel conditions and
the requirements vary dynamically, we concentrate on adaptive implementations
of error correction mechanisms. Error correction mechanisms traditionally
optimize the performance and provide an optimal solution to withstand all
possible errors. In the context of energy consumption we have studied the
energy efficiency of three different error correction mechanisms and have
implemented these in software. We show that the energy efficiency trade-off
between error correction and communication can have a great impact on the
energy efficiency of a system. It will be shown that from energy efficiency
perspective it is not always profitable to minimize the number of bits transmitted
over the air. A general strategy will be provided that can be used to
determine an energy efficient error correction scheme of a minimal system
consisting of a general-purpose processor and a wireless interface. As an
example we have investigated a system with a WaveLAN card as wireless
interface.
·
E2MaC: an energy efficient MAC protocol for
multimedia traffic
P.J.M. Havinga, G.J.M. Smit
(Moby Dick technical report 1998)
Energy efficiency is an important issue for mobile computers since they must
rely on their batteries. We present a novel MAC protocol that achieves a good
energy efficiency of wireless interface of the mobile and provides support
for diverse traffic types and QoS. The scheduler of the base station is
responsible to provide the required QoS to connections on the wireless link
and to minimise the amount of energy spend by the mobile. The main principles
of the E2MaC protocol are to avoid unsuccessful actions, minimise the number
of transitions, and synchronise the mobile and the base-station. We will show
that considerable amounts of energy can be saved using these principles. In
the protocol the actions of the mobile are minimised. The base-station with
plenty of energy performs actions in courtesy of the mobile. We have paid
much attention in reducing the cost of a mobile for just being connected. The
protocol is able to provide near-optimal energy efficiency (i.e. energy is
only spent for the actual transfer) for a mobile within the constraints of the
QoS of all connections in a cell, and only requires a small overhead.
·
Battery-powered
Distributed Systems
P.J.M. Havinga, A. Helme, S.J. Mullender, G.J.M. Smit, J. Smit
(eighth ACM SIGOPS European Workshop on Support for Composing Distributed
Applications, 7-10 September 1998, Sintra, Portugal,
http://www.acm.org/sigops/EW98/papers.html)
Mobile personal computers will be a vital technology for making electronic
information processing available to people on the move. This paper reports
ongoing work on Moby Dick, a research project that addresses fundamental
issues in the architecture, design and implementation of low-power hand-held
computers, with particular emphases on energy conservation and security.
·
Overview of
the Moby Dick project
(1st Euromicro summer school on mobile computing, August 1998)
The Moby Dick project focuses on developing theories, architectures and
applications for a new generation of hand-held computers. The combination of
an intelligent information system and a location system enables many new
types of applications, such as admission control, digital chequebook, paging,
and an automatic diary that keeps track of where you were and with whom. The
design challenges lie primarily in the creation of a single architecture that
allows the integration of security functions, externally offered services,
personality, and communication. In the architecture, Quality of Service (QoS)
is no longer a networking issue alone, but a framework to model integration
and integrated management of all the system services and applications in the
Pocket Companion.
·
The Pocket
Companion's architecture
P.J.M. Havinga, G.J.M. Smit
(1st Euromicro summer school on mobile computing, August 1998)
The Pocket Companion is a small personal portable computer with wireless
communication facilities. The typical use of the Pocket Companion induces a
number of requirements concerning security, performance, energy consumption,
communication and size. The energy consumption due to the increasing demand
for performance and functionality will be the limiting factor for its
capabilities. Therefore reducing energy consumption plays a crucial role in
the architecture. Communication, and particularly wireless communication, is
essential for the system to support electronic transactions. Such a system
requires a good security infrastructure not only for safeguarding personal
data, but also to allow safe transactions.
1997
·
Low
power system design techniques for mobile computers
P.J.M. Havinga, G.J.M. Smit
(CTIT Technical report, No. 97-32, Enschede, the Netherlands, ISSN
1381-3625)
Portable products are being used increasingly. Because these systems are
battery powered, reducing power consumption is vital. In this report we give the
properties of low power design and techniques to exploit them on the
architecture of the system. We focus on: min imizing capacitance, avoiding
unnecessary and wasteful activity, and reducing voltage and frequency. We
review energy reduction techniques in the architecture and design of a
hand-held computer and the wireless communication system, including error
control, sys tem decomposition, communication and MAC protocols, and low
power short range net works.
·
A request-TDMA
multiple-access scheme for wireless multimedia networks
G.R.J. Linnenbank, P. Venkataram, P.J.M. Havinga, S.J. Mullender, G.J.M.
Smit
(in Proceedings MoMuC-3, 1996 and in Mobile Multimedia Communications,
(D. Goodman, D. Raychaudhuri, Eds.), pp. 173-180, 1997)
This paper describes a cellular multiple-access scheme based on TDMA for
multimedia communication networks. The scheme proposes an admission control
of two different multimedia application stream types: real-time and
non-real-time. We do not consider interference between cells. The proposed
protocol, that is based on TDMA, exploits the available bandwidth fully. The
throughput per mobile station is higher compared to other multiple-access
protocols, it offers low latency for both real-time and non-real-time
communication and the unused reserved bandwidth is reallocated for
non-real-time communication. Furthermore, the throughput and latency remain
stable under high loads.
·
A survey of
energy saving techniques for mobile computers
G.J.M. Smit, P.J.M. Havinga
(Moby Dick technical report, 1997)
Portable products such as pagers, cordless and digital cellular telephones,
personal audio equipment, and laptop computers are increasingly being used.
Because these applications are battery powered, reducing power consumption is
vital. In this report we first give a survey of techniques for accomplishing
energy reduction on the hardware level such as: low voltage components, use
of sleep or idle modes, dynamic control of the processor clock frequency,
clocking regions, and disabling unused peripherals. System- design techniques
include minimizing external accesses, minimizing logic state transitions, and
system partitioning using application-specific coprocessors. Then we review
energy reduction techniques in the design of operating systems, including
communication protocols, caching, scheduling and QoS management. Finally, we
give an overview of policies to optimize the code of the application for
energy consumption and make it aware of power management functions.
Applications play a critical role in the user's experience of a power-managed
system. Therefore, the application and the operating system must allow a user
to control the power management. Remarkably, it appears that some energy
preserving techniques not only lead to a reduced energy consumption, but also
to more performance.
·
Minimizing
energy consumption for handheld computers in Moby Dick
P.J.M. Havinga, G.J.M. Smit
(Proceedings Euromicro 97, pp. 196-201, September 1997)
In this report we propose a number of techniques to reduce energy consumption
for mobile computers. We use extra dedicated low-power modules to cut on
processor cycles of the main CPU, i.e. hardware and software decomposition.
These modules are autonomous and can be powered down individually.
Furthermore, as networking consumes a large part of a mobile system's battery
resources much effort is put in reducing energy consumption in this part. We
use intelligent network interfaces with a power aware network protocol, and a
MAC protocol that minimizes the `on-time' of network interfaces to reduce energy.
There is a direct link between QoS and energy consumption. Therefore we move
power management into the QoS domain.
·
The Harpoon
Security System for Helper Programs on a Pocket Companion
G.J.M. Smit, P.J.M. Havinga, D. van Os
(Proceedings Euromicro 97, September 1997, pp 231-238)
In this paper we present a security framework for executing foreign programs,
called helpers, on a Pocket Companion: a wireless hand-held computer. A helper
program as proposed in this paper, is a service program that can migrate once
from a server to a Pocket Companion or vice-versa. A helper program is
convenient, provides environment awareness and allows asynchronous
interaction. Moreover, helpers can be used to save processing power and to
reduce communication. By migrating to the location of a resource, a helper
can access the resource more efficiently. This is particularly attractive for
mobile computing, where the network conditions can be poor and unreliable,
and because it does not require a permanent connectivity. Security is a
significant concern for helpers, as the user of a Pocket Companion receiving
a piece of code for execution may require strong assurances about the
helper's behaviour. The best way to achieve a high security is to use a
combination of several methods. We are designing a prototype of a helper
system, called Harpoon, on top of the Inferno operating system.
·
An
Event-Driven Wireless MAC Protocol Simulator
George R.J. Linnenbank, Paul J.M. Havinga
(Proceedings ICPWC 97, December 1997)
Recently, many multiple-access (MAC) protocols
have been or are being proposed for wireless networks. As most of these multiple-access
protocols are designed for specific applications (such as telephony) and
analyzed accordingly, the analysis results cannot always be adapted to
situations where each user has a different behavior. Wireless MAC protocols
for data communication are not straightforward to analyse. To quickly make a
reliable judgement of the usability of a MAC protocol for specific
situations, we designed a simulator that makes it simple to implement the
protocol and test it in different configurations and with differently
behaving users. Our simulator generates a large amount of quantitative
performance information that can be processed with standard graph drawing
tools and an integrated trace analyzer.
·
Minimizing
energy consumption for wireless computers in Moby Dick
Paul J.M. Havinga, Gerard J.M. Smit
(proceedings ICPWC 97, December 1997)
Portable and hand-held computers must be careful
not to waste the scarce energy resources in their batteries. More extensive
and continuous use of network services will only aggravate this problem since
communication consumes relatively much energy. The Pocket Companion is a
hand-held device that is resource-poor, i.e. small amount of memory, limited
battery life, low processing power, and connected with the environment via a
network with variable connectivity. Because battery life is limited and
battery weight is an important factor for the size and the weight of the
Pocket Companion, energy management plays a crucial role in the architecture.
In our architecture we apply several supplementary power reduction techniques
on all levels of the system, including the operating system and applications.
The two main themes are 1) to avoid wasteful activity, and 2) to exploit
locality of reference.
We put considerable effort in reducing energy consumption of communication
interfaces. There are several ways to reduce energy consumption: e.g. by
system decomposition, using hybrid networking, and by applying power aware
MAC protocols.
·
Moby Dick Final Report
Section I: Results of the first phase
This paper is section I of the final report of phase I. It shows the results achieved
with regard to the project objectives. The design challenges of the Moby Dick
project lie primarily in the creation of a single architecture that allows
the integration of security functions, externally offered services,
personality, and communication.
·
The Moby
Dick architecture (deliverable II.3.1)
Sape J. Mullender, Gerard J.M. Smit, Paul J.M. Havinga, Arne Helme,
Gunnar Hartvigsen, Terje Fallmyr, Tage Stabell-Kulø, Alberto Bartoli,
Gianluca Dini, Luigi Rizzo, Marco Avvenuti
This document is deliverable II.3.1, and presents the Moby Dick architecture.
The introduction outlines the main areas of use and the main characteristics
of the Pocket Companion, and ends up with the overall demands we put on the
architecture. In chapter 2 Quality of Service (QoS) as we use it in Moby Dick
QoS is presented. It gives the foundation the adaptability used in the
chapters to follow. In chapter 3 an overview of the software architecture of
the Pocket Companion is presented. The security architecture of the Pocket
Companion is presented in chapter 4, and the consistency architecture is
presented in chapter 5. In chapter 6, the system architecture of the Pocket
Companion is outlined.
1996
·
Survey of
electronic payment methods and systems
Paul J.M. Havinga, Gerard J.M. Smit, Arne Helme
(Proceedings Euromedia '96, pp 180-187)
In this paper an overview of electronic payment methods and systems is given.
Electronic payment systems can be grouped into three broad classes:
traditional money transactions, digital currency and credit-debit payments.
Such payment systems have a number of requirements: security, acceptability, convenience,
cost, privacy, durability, control, traceability, legal framework and control
of encryption methods. Some requirements appear contradictory and trade-offs
have to be made:
- traceability versus anonymity,
- on-line versus off-line,
- dedicated tamper-resistance hardware versus only software.
We further present an introduction to the basics of electronic money:
encryption, digital signatures, anonymity, and solutions to the double
spending problem for digital cash. We give a survey of payment mechanisms,
that are either commercially or in a pilot version available today or have
been published recently.
·
Audio Source Location for a Digital
TV-director
F.W. Dillema, P.J.M. Havinga, P. Sijben, G.J.M. Smit
(in Proceedings Euromedia 96, pp. 103-110, London, December 1996)
Three algorithms are presented for location of audio sources using standard
workstations and a minimal amount of resources. The audio source location is
based on time-delay estimation. The algorithms use general human speech
properties and straightforward heuristics on human speaker behaviour to
acquire accurate and efficient estimation of delays.
Even older…
·
Rattlesnake ATM switch (86k ps.gz).
The Rattlesnake ATM switch is a switch for building a cost effective
switching system that meets multimedia requirements. The main goal of this
project is to design a complete network system that uses only one chip per
external data link. In the architecture of an ATM switching system there are
a number of closely related issues involved such as buffering, link protocol,
buffer scheduling, routing and network topology. The switch uses input
buffering. Buffers are small and organized in a parallel fashion. To make
optimal use of the scarce resources we use the buffers in combination with
virtual lanes, iterative scheduling and a backpressure link protocol. Owing
to this the bandwidth of the switching system's internal data links is used
efficiently. We use a Kautz graph as the interconnection topology of the
switching fabric. It makes our switching system modular extensible and fault
tolerant. The fixed degree allows us to implement a node in one chip. A Kautz
graph also provides a simple routing mechanism.
·
Multicast
and broadcast (46k ps.gz) is
implemented efficiently.
This switch was build as part of the Pegasus
project.
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