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Research topics
Chronological on-line publications can be found here.
Reconfigurable systems
·
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.
·
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.
·
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.
- 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.
- 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.
- 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 system 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 chan in
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 tradeoff has to be made between computation,
communication and initialization 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 ’geograph-ical’
placement of the threads and buffers, multiprogram-ming 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.
- 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.
- 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.
- 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.
- 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.
System architecture of
mobile computers
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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: minimizing 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 networks.
- 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
inves-tigated.
- 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.
- 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.
- 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.
- 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 networks.
Energy-efficient wireless communication
·
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.
·
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.
- Energy
efficient TCP
Donckers L.
Master’s thesis University of Twente, department of Computer Science,
May 2001
This thesis describes the design of an energy-efficient transport
protocol for mobile wireless communication. We first describe the
metrics used to measure the energy efficiency of transport protocols.
These metrics were used to study the performance of TCP/IP on wireless
links carefully. Four problem areas are defined that prevent TCP/IP from
reaching high levels of energy efficiency. For these problem areas,
solutions are proposed and their feasibility is examined. The results of
this study were used to design E2TCP. A simulation model of
this proposed energy-efficient transport protocol has been implemented
and was subject to a thorough evaluation. The results show that E2TCP
not only has a higher energy efficiency than TCP/IP, but it also manages
to outperform TCP/IP on more traditional performance metrics: throughput
and latency.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- A
Power Dissipation Comparison of the R-TDMA and the Slotted-Aloha
Wireless MAC Protocols
G.R.J. Linnenbank
In this paper two wireless multiple-access
protocols are compared by their power dissipation for the uplink traffic
of a wireless networks. After briefly discussing the behaviour of the
Slotted Aloha protocol and the R-TDMA protocol, we estimate the energy
that is dissipated by the protocols to transmit a packet. We will show
that for general loads, the power dissipation of the R-TDMA protocol is
far less than that of the Slotted Aloha protocol.
- 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.
- 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 can not 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.
Efficient architectures for seamless services on heterogeneous
wireless networks
- MIRAI Architecture for Heterogeneous Network
G.
Wu, P. Havinga, and M. Mizuno, IEEE Communications Magazine, February
2002
- Wireless Internet over
Heterogeneous Wireless Networks
G.
Wu, P. Havinga, and M. Mizuno, IEEE GLOBECOM’01, pp. 1759-1765, San
Antonio, Nov. 2001.
- Resource
Management for Seamless Mobile Services
Havinga P.J.M., Vognild L., Smit G.J.M, Wu
G.
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.
- 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.
- 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 enables 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, signaling 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.
Security
- 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.
- 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.
Moby Dick LTR 20422 -
Project programme and deliverables
- Moby
Dick, The Mobile Digital Companion, LTR 20422, Annex I - Project
Programme
Sape J. Mullender, Paolo Corsini, Gunnar Hartvigsen
An exiting prospect for the next decade is the deployment of a new
generation of hand-held computers. Wireless computing greatly enhances
the usability of these portable computing devices.
The Moby Dick project has been a joint european project (Esprit Long
Term Research 20422) to develop and define the architecture of a new
generation of mobile handheld computers. Currently the research themes
have focussed on: systems architecture of mobile computers,
reconfigurable computing, energy efficient multimedia communication, and
QoS over wireless access networks. The design challenges lie primarily
in the creation of a single architecture that allows the
integration of security functions (e.g. payment), externally offered
services (e.g. airline ticket reservation), personality (i.e. these
devices know what their owners want), and communication.
- 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.
- Systems
support for hybrid networks (deliverable II.3.2)
Gunnar Hartvigsen, Dag Brattli, Tage Stabell-Kulø, Luigi Rizzo
One objective of the Moby Dick project is to find out whether it is
possible to switch seamless between radically different networking
technologies with a resource poor machine like the Pocket Companion.
This chapter will show that it's indeed feasible to utilize more than
one network. We present a detailed technical documentation of the
Software Network, which enables multihomed mobile computers to dynamic
and seamless switch from one network to another. This means that all
applications can keep their connections, while the computer switches
from one network to another. The basic idea is to put the router into a
mobile computer, enabling the computer to switch uninterrupted from one
network to another. The Software Network protects applications from
unwanted connectivity interrupts since connections are simply routed
according to the quality of service of the mobile hosts network
interfaces.
- Digital
cheque-book (deliverable II.3.3)
Tage Stabell-Kulø, Arne Helme
In this paper we will describe the overall design of the demonstrator
and the technical details of its implementation. We start out by
presenting an overview of the demonstrator as to what will be
demonstrated and why this is relevant. Then we will embark on a
technical description of the solution.
- Distributed
diary (deliverable II.3.4)
Alberto Bartoli, Gianluca Dini, Marco Avvenuti
The diary application allows a set of users, each equipped with his/her
own handheld, to arrange for meetings. This application is an example of
coordination among a set of mobile users and it is structured to take
into account aspects peculiar of mobile computing.
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