Adaptive secure data transmission method for OSI level 1

Adaptive Secure Data
Transmission Method for OSI
Level 1

PAULI LALLO

Tallinn University of Technology
Faculty of Information Technology

Dissertation was accepted for the defense of the degree of Doctor of
Philosophy in Engineering at Tallinn University of Technology in
August 2005.

Supervisor:

Opponents:

Prof. Kalju Meigas, Ph.D., Biomedical Engineering
Centre, Tallinn University of Technology, Estonia

Prof. Ants Meister, Ph.D., Department of Radio and
Communication Engineering, Tallinn University of
Technology, Estonia

Dr. Frank Böhnke, Ph.D., Department of
Otorhinolaryngology, Technical University Munich,
Germany

Commencement: September 15, 2005

Declaration: I declare that this thesis is my original unaided work.
It is being submitted for the degree of Doctor of
Philosophy in Engineering at Tallinn University of
Technology. It has not been submitted before for any
degree at any other university.

Pauli Lallo

Copyright Pauli Lallo 2005

ISSN 1406-4731

ISBN 9985-59-560-2

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Contents

A_BSTRACT .................................................................................................... 5

K_OKKUVÕTE .................................................................................................6

A_{CKNOWLEDGEMENTS} ................................................................................7

A^BBREVIATIONS ...........................................................................................8

C_HAPTER I ..................................................................................................11
1. Introduction................................................................................................... 11
1.1. Background..................................................................................................11
1.2. Motivation of the Work ...............................................................................12
1.3. Evolution of Telecommunications...............................................................13
1.3.1. Studies of Telecommunication ...............................................................13
1.3.2. Evolution to Adaptive Communications ................................................ 18
1.3.3. Discussion of Broadband Evolution .......................................................20
1.3.4. Discussion of Some Communication Problems .....................................20
1.4. Objectives of the Thesis...............................................................................21
1.5. Outline of the Work .....................................................................................21

C_HAPTER II.................................................................................................23
2. Biomedical Data Processing and Transmission ......................................... 23
2.1. Biomedical Information Systems ................................................................ 23
2.2. Standards...................................................................................................... 27
2.3. Conclusions..................................................................................................28

C_HAPTER III ...............................................................................................29
3. Analysis and Measurements ........................................................................ 29
3.1. Definition of Measurement Objects.............................................................29
3.2. Measurements .............................................................................................. 30
3.3. Measurement Results and Analysis .............................................................33
3.3.1. Discussion of Measurement Results......................................................... 35
3.3.2 Analysis of Packet Switching ................................................................... 36

C_HAPTER IV ...............................................................................................41
4. Data Transmission in Channels and Networks - A Simulation Study.....41
4.1. Worksheet Simulator ................................................................................... 41
4.2 Modeling of Data Transmission ..................................................................43
4.3. Adaptive Delta Modulation and Granular Channel .....................................46
4.3.1. Distortion of Signals in Granular Channel ...............................................54
4.3.2. Simulation Results of Analog Data Transmission.................................... 56
4.4. Simulations of Biomedical Data Networks ................................................. 63
4.5. Summary...................................................................................................... 65

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C_HAPTER V .................................................................................................66
5. A DFT-Based Approach to Adaptive Data Communications................... 66
5.1. Basic theory ................................................................................................. 66
5.2. Adaptive Modem ......................................................................................... 70
5.3. Generation of Symbol Waveforms .............................................................. 72
5.4. Soft Detection of Symbol Waveforms......................................................... 77
5.5. Implementation and Test Results of Adaptive Modem ...............................80
5.5.1. Simulated Waveforms .............................................................................. 80
5.5.2 Field Tests................................................................................................. 80
5.6. Discussion of Fourier Theory, Limitations and Applications .....................85
5.7. Adaptive Multi-Carrier Data Communications ........................................... 88
5.8 Adaptive Selection of Modulation Method ................................................. 89
5.8. Adaptive Secure Data Transmission Method for OSI Level 1 .................... 93
5.9. Sensitivity Analysis of Adaptive Data Communications ............................ 97
5.9.1. Sensitivity of the Soft DFT Detection in AWGN-Channel...................... 97
5.9.2. Sensitivity of the Signal Detection in Granular Channel..........................98
5.9.3. Frequency Deviation Sensitivity of the Soft Signal Detection................. 99
5.9.4. Frequency Deviation Sensitivity of the Soft DFT Detection in ADM –

Channel ................................................................................................... 100
5.9.5. Sensitivity of the Soft DFT Detection in Granular Noisy Channel

(ADM-channel)....................................................................................... 101
5.9.6. Sensitivity of the Soft DFT Detection in Multi-Path Noisy Channel.....102
5.9.7. Orthogonal Signal Space ........................................................................ 103

C_HAPTER VI .............................................................................................104
6. Summary .....................................................................................................104

L_{IST OF} O_RIGINAL P_APERS......................................................................105

R^EFERENCES.............................................................................................106

A_PPENDIX 1:
^MATHEMATICAL BACKGROUND OF SOME TRANSFORMS ^{......................111}

A_PPENDIX 2:

^A HIGH^-LEVEL BLOCK DIAGRAM OF A DMT^/OFDM SYSTEM^{..................114}

A_PPENDIX 3:

^XDSL C^{APACITY VERSUS} D^ISTANCE ......................................................115

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Adaptive secure data transmission method for OSI level 1

Abstract

This thesis discusses the problems of physical level data transmission of biomedical
information systems over different channels in telecommunication networks. Existing standards
of band-limited data transmission (modem standards) are based on hardware technology and
defined for fixed not varying channels characteristics (bandwidth, signal-to-noise ratio etc). The
methods recommended are not adaptive and thus modems do not show high performance used
over different channels. On the other hand software based modulation systems use Fourier theory
and algorithms in generation and detection of complex multi-carrier waveforms, which
gives the possibility to obtain a higher performance than traditionally. Adaptive data communication
based on software algorithms is used increasingly in modern wired and wireless communication
networks as a result of technology development. These adaptive data communication
methods give security and near optimal performance (bit rate, bit error rate etc) in different
cases. These systems are investigated in this thesis and applied to the biomedical data transmission
needs of the future.

The research methods are:
- Literary research is used in problem formulation and review of studies.
- Measurement of data communication in digital network is an approach to investigate data

transmission problems.
- A robust tool (worksheet modeling and simulation) was developed for evaluation of voice

coding, Gaussian or granular noise channels, and legacy and adaptive modulation methods.
Simulations with this worksheet method help in investigating new modulation methods
(waveforms).
- Discrete Fourier transform is used as the main mathematical method throughout this thesis

in the design of modulation methods and modeling of waveforms.

Results are verified as:
- Simulation results are verified with standard data modem measurements and literature.
- A prototype adaptive modem is designed based on the simulation research results.
- Research results are verified with field tests using adaptive modem prototypes.
- Error performance and sensitivity study of the modeled communication system is made

with data transmission simulations using band-limited adaptive multi-carrier data transmission
waveforms over different channels.

The results are: traffic analysis of a biomedical data system, design of a robust worksheet
simulation system, formulation and analysis of the adaptive band-limited data transmission for
Gaussian and granular channels, and an adaptive data modem prototype based on discrete Fourier
transform (DFT) approach. The main contribution of the thesis is: formulation of the adaptive
secure data communication method for OSI level one (physical), its potential application
(a proposal) and new knowledge of the use of DFT in generation and detection of waveforms.

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Adaptiivne turvaline infovahetuse meetod OSI tasemele 1

Kokkuvõte

Käesolevas väitekirjas käsitletakse probleeme, mis on seotud biomeditsiinilise info vahetusega
telekommunikatsioonivõrkudes, kasutades erinevaid infokanaleid. Olemasolevad, piiratud riba
korral kehtivad, infovahetusstandardid (modemi standardid) baseeruvad riistvaralisel tehnoloogial
ja kehtivad fikseeritud, mitte muutuvate infokanali parameetrite korral (ribalaius, signaal-müra
suhe jne). Soovitatud meetodid ei ole adaptiivsed ja sellised modemid ei saavuta
kõrgeid tehnilisi näitajaid muutuvate infokanalite korral. Samal ajal tarkvaral baseeruvad modulatsioonisüsteemid
kasutavad Fourier teisendust ning algoritme nii komplekssete multikandesageduslike
signaalide genereerimisel kui detekteerimisel, mis annab võimaluse saavutada
paremaid tehnilisi näitajaid kui eespoolnimetatud traditsiooniliste süsteemide abil. Tehnoloogilise
arengu tulemusena leiab
kaasaegsetes nii traat- kui ka traadita sidevõrkudes üha laiemat kasutamist adaptiivne
andmevahetus, mis baseerub vastavatele tarkvaralistele algoritmidele. Sellised adaptiivsed
infovahetusmeetodid kindlustavad parema turvalisuse ja optimaalsele lähedased tehnilised
parameetrid (ülekandekiirus, vigade arv jne) väga erinevates olukordades. Käesolev väitekiri
ongi pühendatud adaptiivsete süsteemide uurimisele, samuti nende praktilise kasutamise võimalustele
tulevikus erinevates biomeditsiinilistes infosüsteemides.

Töös kasutatud uurimismeetodid:
^• Kirjanduslikku uurimist on kasutatud probleemi formuleerimisel ja ülevaatelises osas.
^• Infovahetuse parameetrite mõõtmist digitaalses võrgus on kasutatud vastavate

andmevahetuse probleemide uurimisel.
^• On välja töötatud lihtne töövahend (probleemi modelleerimiseks ja simuleerimiseks),

mille abil on uuritud kõne kodeerimist, Gaussi ja digitaalseid mürakanaleid ning
fikseeritud ja adaptiivseid modulatsioonimeetodeid. Selle väljatöötatud meetodiga
simuleerimine võimaldas uurida erinevaid modulatsioonimeetodeid ja signaalikujusid.

^• Põhilise matemaatilise meetodina on selles väitekirjas kasutatud diskreetset Fourier
teisendust nii erinevate modulatsiooniviiside väljatöötamisel kui ka signaalikujude
modelleerimisel.

Saadud tulemusi on kontrollitud, kasutades:
^• Simulatsioonide tulemusi on võrreldud nii standardsete modemite mõõtetulemustega

kui ka kirjanduse põhjal.
^• Adaptiivse modemi prototüüp on välja töötatud kasutades simulatsioonidel saadud

tulemusi.
^• Saadud uuringutulemusi on võrreldud erinevate adaptiivsete modemite prototüüpidele

korraldatud testidega.
^• Modelleeritud infovahetussüsteemi vigade analüüsi ja tundlikkuse uurimisel on kasutatud
piiratud sagedusribaga adaptiivse multikandesagedusliku signaaliga infovahetuse
simuleerimist üle muutuvate kanalite.

Töö käigus on saadud järgmised tulemused: biomeditsiinilise andmevahetussüsteemi info
liikumise analüüs, lihtsa simulatsioonisüsteemi väljatöötamine, adaptiivse piiratud sagedusribaga
infovahetuse formuleering ja analüüs nii Gaussi kui digitaalsete kanalite jaoks ning diskreetsel
Fourier teisendusel (DFT) baseeruva adaptiivse modemi prototüübi väljatöötamine.
Väitekirja põhiliseks panuseks on: adaptiivse turvalise infovahetuse meetodi OSI tasemele 1
formuleerimine, selle potentsiaalne kasutamine (ettepanekuna) ja uued teadmised DFT
kasutamisest signaalide genereerimisel ja detekteerimisel.

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Acknowledgements

First of all, I thank my supervisor Professor Kalju Meigas accepting me as his student in
Tallinn and helping me in starting and finding practical solutions during the research
process.

I express my gratitude to many people in Helsinki University of Technology (HUT) for their
excellent contacts to Tallinn University of Technology. Without their knowledge I would
never have started my research in Tallinn. I express my gratitude to Professor Seppo J.
Halme, the former chief of the Communications Laboratory at HUT, who was my instructor
in simulation research and modem prototype development.

Special thanks to Mr. Lloyd Bethell.

I acknowledge the funding of the Foundation of Technology, the Finnish Society of Electronics
Engineers, the Scientific Advisory Board for Defence, the National Technology
Fund, and the Foundation for Finnish Inventions.

My family, especially my father, my wife Raili and our children have supported me - I
would never have finished my PhD research without their encouragement.

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