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Helsinki University of Technology Signal Processing Laboratory Teknillinen korkeakoulu Signaalinkäsittelytekniikan laboratorio Espoo 2005 Report 52
BIANNUAL REPORT 2003 - 2004
Anne Jääskeläinen (editor)
This report describes the activities of Signal Processing Laboratory
in 2003 and 2004.
Helsinki University of Technology Department of Electrical and Communications Engineering Signal Processing Laboratory Teknillinen korkeakoulu Sähkö- ja tietoliikennetekniikan osasto Signaalinkäsittelytekniikan laboratorio
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Distribution: Helsinki University of Technology Signal Processing Laboratory P.O. Box 3000 FIN-02015 HUT Tel. +358-9-451 2486 Fax. +358-9-452 3614 E-mail: [email protected] http://wooster.hut.fi/ ISSN 1458-6401 Otamedia Oy Espoo 2005
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Table of contents 1. INTRODUCTION ......................................................................................... 5 2. PERSONNEL ................................................................................................. 8 3. TEACHING .................................................................................................. 11 4. THESES ........................................................................................................ 13
4.1 Doctor of Science in Technology.............................................................................13 4.2 Licentiate of Science in Technology........................................................................13 4.3 Master of Science in Technology .............................................................................14
5. STATISTICAL AND ARRAY SIGNAL PROCESSING IN
COMMUNICATIONS RESEARCH GROUP LEADER PROFESSOR VISA KOIVUNEN ............................... 16
5.1 Signal Processing for Spread Spectrum Systems ......................................................16 5.2 Multicarrier and MIMO Systems .............................................................................17 5.3 Fundamentals of Statistical and Array Signal Processing .........................................18 5.4 Radio Channel Propagation Parameter Estimation .................................................19
6. SPITRES - THE SIGNAL PROCESSING IN TELECOMMUNICATION S
RESEARCH GROUP LEADER PROFESSOR TIMO LAAKSO.................................... 21
6.1 Data Selective Adaptive Filtering Algorithms...........................................................21 6.2 Analysis of Partial-Update Adaptive Filters ...............................................................22 6.3 Linearly Constrained Adaptive Filters ......................................................................22 6.4 Fast Adaptive Filtering Algorithms for APLAC System Simulator...........................23 6.5 Adaptive Multiple-Notch Filters ...............................................................................23 6.6 Measurement and Analysis of Nonlinearities of Power Amplifiers for Wireless
Communications ......................................................................................................24 6.7 Modelling of High-Power Amplifier Nonlinearities for Wireless Communications ......................................................................................................25 6.8 Adaptive Digital Predistortion for Broadband Power Amplifiers..............................25 6.9 Amplifier Nonlinearities in Multiple-Antenna Systems ...........................................26 6.10 Fast Multichannel QRD-RLS Algorithms for Efficient Nonlinear Filtering...........27 6.11 Synchronization in Communication Systems..........................................................27 6.12 Joint Transmit and Receive Filter Design for Wireline Channels...........................27
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7. RAID - RECONFIGURABILITY IN ALGORITHM IMPLEMENTATION AND DESIGN RESEARCH GROUP LEADER PROFESSOR JORMA SKYTTÄ.................................. 28
7.1 Hardware Description Language Generator for Elliptic Curve Point Multiplication ...........................................................................................................28 7.2 Reconfigurable Computing Platform .......................................................................28 7.3 FPGA-based Education Platform Using System-on-Chip (SoC) Technology.........29 7.4 Potential of a Hardware Assisted Attack on A5/1 security .........................................30 7.5 Implementation of Neural Networks on Reprogrammable Hardware.....................31
8. WIRELESS SIGNAL PROCESSING GROUP LEADER PROFESSOR RISTO WICHMAN............................. 31
8.1 MIMO Channel Modeling.......................................................................................31 8.2 Multiuser Diversity....................................................................................................32 8.3 MIMO Macrodiversity ..............................................................................................32 8.4 Multiantenna Solutions for 3G WCDMA ...............................................................32 8.5 Sphere Decoders for MIMO Channels ....................................................................33 8.6 Performance of Multiantenna Transceivers with Partial Channel State Information ......................................................................................................33
9. ACTIVITIES ................................................................................................. 34
9.1 International Conferences and Meetings .................................................................34 9.2 Foreign Visitors .........................................................................................................38 9.3 Visits abroad ..............................................................................................................39
10. PARTICIPATION IN BOARDS AND COMMITTEES............................ 40
10.1 University Boards and Committees...........................................................................40 10.2 Other Boards and Committees .................................................................................40 10.3 Referee Activities .......................................................................................................41
11. PUBLICATIONS 2003 ................................................................................. 43
11.1 Books and Chapters in Books....................................................................................43 11.2 Refereed Journal Articles ..........................................................................................43 11.3 Published Proceedings of International Conferences ..............................................44 11.4 Other Published Presentations at Scientific Meetings .............................................47 11.5 Nonrefereed Articles and Reports .............................................................................48 11.6 Patents .......................................................................................................................48
12. PUBLICATIONS 2004 ................................................................................. 49
12.1 Books and Chapters in Books....................................................................................49 12.2 Refereed Journal Articles ..........................................................................................49 12.3 Published Proceedings of International Conferences ..............................................50 12.4 Nonrefereed Articles and Reports .............................................................................53 12.5 Patents .......................................................................................................................53
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1. INTRODUCTION
Signal Processing laboratory teaches and carries out research work in the areas of digital signal processing and digital circuit technology. Undergraduate education consists of computer technology, system level concepts of modern digital hardware design and optimization and implementation of digital signal processing algorithms. The areas of research are: • Statistical and Array Signal Processing • Implementation of Signal Processing Systems • Signal Processing for Telecommunications • Multiantenna Communications The laboratory is active in the following research projects: • Blind and Semi-blind Receiver Structures • Blind Signal Separation • Antenna Array Signal Processing, Smart Antennas • MIMO Systems, Multicarrier Systems • Estimation Theory • Signal Processing Implementations for Channel Models • Implementation of Neural Networks for Signal Processing • Parallel Simulation Architectures • Adaptive Filtering Algorithms of Communications • Interpolation for Synchronization in Communications • Mobile Radio Propagation Parameter Estimation and Modeling The projects are funded by Nokia, Sonera, Finnish Defence Forces, Digita, Elisa Communications, Yleisradio, National Technology Agency of Finland (TEKES) and Academy of Finland. The Laboratory is a part of the SMARAD (Smart and Novel Radios Research Unit) Center of Excellence in research, nominated by the Academy of Finland for 2002-2007. In Signal Processing Laboratory, there were 4 GETA post graduate positions and 1 post doctoral position in 2003 and in year 2004 5 GETA post graduate positions were held by researchers of the Laboratory. In 2004 one post graduate position in the Electrical and Communications Engineering Department was received. The laboratory is also part of the Institute of Digital Communications, IDC.
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SMARAD - Center of Excellence in research The Radio Laboratory and the Signal Processing Laboratory of Department of Electrical and Communications Engineering (ECE), Helsinki University of Technology have formed a research unit aiming at world-class research in radio engineering and related signal processing in radio transceivers. The leader of the research unit is Prof. Antti Räisänen (Fellow of the IEEE) from the Radio Laboratory. Prof. Pertti Vainikainen and Prof. Sergei Tretyakov from the Radio Laboratory as well as Prof. Timo Laakso and Prof. Visa Koivunen from the Signal Processing Laboratory are the other principal investigators in SMARAD. The total number of employees within the research unit is about 60 including about 30 graduate students and several undergraduate students working on their Master’s thesis. All the involved faculty are active members of the IDC (Institute of Digital Communications) and are co-operating in radio and communications engineering related projects. IDC is a joint institute of several laboratories in the ECE and Department of Information Technology at HUT that coordinates both basic and applied research projects. In the education sector, the participating faculty provides curricula in radio engineering and signal processing in communications.
SMARAD provides world-class RF, microwave and millimeter wave as well as communications signal processing research and education. In microwave and millimeter wave engineering it is also the only research unit in Finland. SMARAD has an important mission to provide the Finnish industry and public organizations with experts of radio engineering and communications signal processing at both basic degree and postgraduate degree levels. This is possible only if the unit conducts high quality basic research but at the same time maintains good connections to industry. SMARAD has expertise at the highest level in millimeter wave techniques and novel industrial microwave sensors. Research into RF techniques for wireless communications (including wideband propagation in mobile systems), radio channel modeling and measuring, smart (adaptive) antennas, receiver structures and architectures and communication signal processing meet the highest international research standards as well. The scope of the signal processing research is in developing theory and algorithms for smart, adaptive antenna systems and designing advanced and flexible transceiver structures for the future wireless communication systems. Fully novel approach is taken, e.g., in antenna measurements: a radio hologram is used as collimating element in order to form the necessary planar wave front in an compact antenna test range (CATR). Novel ideas are also applied in design of new antenna structures resulting in several patents and patent applications. Through the expertise described above, SMARAD also supports the telecommunications industry by bringing new state-of-the-art results to it.
SMARAD has a well-established network of co-operating partners in industry, research institutes and academia worldwide. Its funding sources are also diverse including the Academy of Finland, TEKES and industry. IDC serves as an umbrella organization for most of the telecommunication projects. In addition, the Radio Laboratory is the initiator and a contributor to MilliLab, ESA External Laboratory (a joint institute between VTT and HUT). As a by-product of this research the SMARAD provides highest-level education and supervision to graduate students in the areas of radio engineering and communications through HUT and Finnish graduate schools such as GETA.
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GETA - Graduate School in Electronics, Telecommunications and Automation Director: professor Iiro Hartimo, HUT Coordinator: Marja Leppäharju, HUT GETA is the largest graduate school in Finland. GETA offers postgraduate programs in electronics, telecommunications and automation. The office of the school is in the department. The activity of GETA is primarily based on the grants (71) that it supplies for selected research students and for post docs. About 20 % of the GETA research students are foreigners. GETA also organizes high quality courses inviting lecturers from top foreign universities and companies. The courses are also open to other postgraduate students in addition to the granted students. There are almost 200 associated researchers on the GETA e-mail list being informed of the school´s courses and activities. The 35 participating departments and laboratories have over 120 professors, over 75 postdoctoral instructors and several docents from the universities: Helsinki University of Technology, Tampere University of Technology, University of Oulu, University of Turku and University of Jyväskylä. Part-time professors from industry and foreign visiting professors also participate in the activities of the school. 6th Nordic Signal Processing Symposium – NORSIG 2004 In 2004, June 9-11 our laboratory acted as the main organisator of the 6th Nordic Signal Processing Symposium. Iiro Hartimo acted as a organizing Committee member, Anne Jääskeläinen and Marja Leppäharju acted as organizing chairs. The Symposium gathered about 120 researchers from 25 countries. Nearly 90 high quality research papers were presented. The conference venue was Meripuisto Convention Center in Espoo.
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2. PERSONNEL
Iiro Hartimo D.Sc. (Tech), professor, head of the laboratory Visa Koivunen D.Sc. (Tech), professor Timo Laakso D.Sc. (Tech), professor Jorma Skyttä D.Sc. (Tech), professor Risto Wichman D.Sc. (Tech), professor José Apolinario PhD, visiting professor 3.11.2004-31.1.2005 Juan Cousseau PhD, visiting professor 1.2.-31.5.2004 Anne Jääskeläinen Department secretary Mirja Lemetyinen Laboratory secretary Marja Leppäharju GETA Coordinator Aarne Mämmelä D.Sc. (Tech), docent, professor Jukka Saarinen D.Sc. (Tech), docent, professor Paulo S. R. Diniz PhD., docent, professor Traian Abrudan M.Sc., research scientist Tuomas Aittomäki Mr, research assistant from 1.6.2003 Fabio Belloni M.Sc., research scientist Mei Yen Cheong M.Sc, research scientist from 17.2.2003 Eugenio Delfino Mr, research assistant 9.6.2003- 30.9.2004 Pyry Ekholm Mr, computer administrator from 17.5.2004 Mihai Enescu D.Sc (Tech), research scientist Jan Eriksson D.Sc. (Tech), research scientist Alessandro Ferrante Mr, research assistant until 31.5.2003 Juha Forstén M.Sc, research scientist Gilda Gamez M.Sc, research scientist 1.4.2003-31.12.2004 Fernando Gregorio M.Sc. research scientist from 9.10.2003 Mikko Grönroos Mr, computer administrator until 31.7.2004 Are Hjörungnes D.Sc. (Tech), research scientist until 31.8.2003 Antti Hämäläinen M.Sc., research scientist Jyri Hämäläinen Ph.D., research scientist Peter Jantunen M.Sc, research scientist 1.2.2003-31.8.2004 Pekka Jänis Mr, research assistant from 1.8.2004 Jussi Järvinen M.Sc., research scientist until 31.12.2003 Kimmo Järvinen M.Sc., research scientist Jaakko Kairus Mr, research assistant Juha Karvanen D.Sc. (Tech), research scientist until 9.9.2003 Tommi Koivisto M.Sc. research scientist from 1.6.2003 Esa Korpela M.Sc., research scientist Markus Lehtonen M.Sc., research scientist 1.6.2003-31.10.2004 Mikko Lehtonen M.Sc. research scientist 5.7.-5.9.2004
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Yaohui Liu Lic.Sc., research scientist until 30.6.2004 Jarmo Lundén M.Sc., research scientist from 1.6.2003 Martin Makundi M.Sc., research scientist Tiina Manner Ms, Trainee 1.-31.1.2003 Jarno Martikainen M.Sc., research scientist until 31.12.2003 Julian Martin Martinez M.Sc., research scientist 26.5.2003-31.5.2004 Kerttu Marttila Ms, trainee 1.1.-29.2.2004 Maarit Melvasalo Lic.Sc., research scientist Nikolai Nefedov D.Sc. (Tech), research scientist 11.2.2003-31.1.2004 Tuomas Nyblom M.Sc., research scientist 19.5.2003-31.12.2004 Eino Oja Mr, research assistant 1.1.-30.4.2003 Sampo Ojala M.Sc., research scientist Esa Ollila Ph.D., research scientist from 17.4.2003 Aura Paloheimo M.Sc, research scientist 20.1.2003-31.3.2004 Keijo Pölönen M.Sc., research scientist from 19.5.2003 Enrique Ramirez M.Sc. research scientist 11.2.2003-30.1.2004 Cassio Ribeiro M.Sc. research scientist from 4.9.2003 Andreas Richter Dr.Ing., research scientist from 6.9.2004 Matti Rintamäki Lic.Sc., research scientist until 31.12.2004 Timo Roman M.Sc., research scientist Anne-Mari Seppola Ms, research assistant from 1.5.2004 Mobien Shoaib Mr, research assistant from 17.5.2004 Marius Sirbu D.Sc. (Tech), research scientist until 30.4.2004 Kati Tenhonen M.Sc., research scientist Matti Tommiska Lic.Sc. (Tech), research scientist until 31.12.2004 Mikko Valkama D.Sc. (Tech), part time research scientist 1.-30.11.2004 Juha Venäläinen M.Sc., research scientist until 31.10.2004 Samuli Visuri D.Sc. (Tech), research scientist 1.1.-30.4.2004 Stefan Werner D.Sc. (Tech), research scientist Matias With M.Sc., research scientist Hai Xu Mr, research assistantuntil 31.8.2003 Eduardo Zacarías M.Sc., research scientist from 1.7.2003 Xiaojing Zhang M.Sc, research scientist from 1.11.2003 Periodical lecturers Allan Davidson M.Sc. (Tech) Juha Heiskala M.Sc. (Tech) Jori Johansson M.Sc. (Tech) Kimmo Järvinen M.Sc. (Tech) Vesa Koskela M.Sc. (Tech) Jaakko Tölli M.Sc. (Tech)
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Guest lecturers Reiner Creutzburg Ph.D. Marcello de Campos Ph.D. Paulo S. R. Diniz Ph.D. David Gesbert Ph.D. Faroh Marvasti Ph.D. Andreas Richter Dr.Ing. Course assistants Traian Abrudan Mei Yen Cheong Jan Eriksson Juha Forstén Jori Johansson Jaakko Kairus Tommi Koivisto Esa Korpela Antti Leskelä Yaohui Liu Sampo Ojala Antti Ojapelto Aura Paloheimo Enrique Ramirez Jari Ranta Matti Rintamäki Timo Roman Mobien Shoaib Marius Sirbu Kati Tenhonen Matti Tommiska Jaakko Tölli Kurt Ugur Tapio Valli Stefan Werner Hai Xu
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3. TEACHING
The following courses were given year 2003: S-88.105 Digital Signal Processing Systems (Teacher: Hartimo) S-88.110 Digital and Computer Technology, basic course (Teachers: Hartimo, Skyttä Assistants: Leskelä, Ojala, Ojapelto, Paloheimo) S-88.132 Design of VLSI Circuits (Teacher: Skyttä, Assistant: Korpela) S-88.133 Digital Design with Hardware Description Lanquages S-88.134 Design of ASIC Circuits (Teacher: Skyttä, Assistants: Paloheimo, Valli) S-88.144 Seminar on Information Technology (Teacher: Skyttä) S-88.145 Stochastic Processes in Communications (Teacher: Koivunen, Assistant: Eriksson) S-88.150 (Assistants: Forstén, Kairus) S-88.155 Signal Processing, Special assignment (Teachers: Hartimo, Koivunen, Skyttä) S-88.168 Adaptive Signal Processing Systems (Teacher: Wichman, Assistant: Rintamäki) S-88.175 Signal Processing in Wireless Communications (Teacher: Wichman, Assistant: Roman) S-88.190 Individual Course in Information Technology S-88.200 Statistical Signal Processing (Teacher: Koivunen, Assistant:) S-88.205 Processing of Video Signals (Teacher: Koivunen, Assistant: Eriksson) S-88.211 Signal Processing in Telecommunications I (Teacher: Laakso, Assistant: Makundi) S-88.212 Signal Processing in Telecommunications II (Teacher: Laakso, Assistant: Xu) S-88.221 Postgraduate Seminar on Signal Processing 1 (Teachers: Koivunen, Wichman) S-88.224 Postgraduate Seminar on Signal Processing 4 (Teacher: Laakso, Assistant: Xu)
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The following courses were given year 2004: S-88.106 Digitaaliset signaalinkäsittelyjärjestelmät (Teacher: Hartimo, Assistant:
Rintamäki) S-88.110 Digital and Computer Technology, basic course (Teachers: Hartimo, Skyttä Assistants: Leskelä, Ojala, Ojapelto, Paloheimo) S-88.132 Design of VLSI Circuits (Teacher: Skyttä, Assistant: Korpela) S-88.133 Digital Design with Hardware Description Languages S-88.134 Design of ASIC Circuits (Teacher: Skyttä, Assistant: Järvinen) S-88.144 Seminar on Information Technology (Teacher: Skyttä) S-88.145 Stochastic Processes in Communications (Teacher: Koivunen, Assistants: Eriksson, Koivisto) S-88.150 (Teachers: Hartimo, Skyttä, Assistants: Forstén, Kairus) S-88.155 Signal Processing, Special assignment (Teachers: Hartimo, Koivunen, Laakso,
Skyttä, Wichman) S-88.175 Signal Processing in Wireless Communications (Teacher: Wichman, Assistant: Roman) S-88.190 Individual Course in Information Technology S-88.200 Statistical Signal Processing (Teacher: Koivunen, Assistant: Abrudan) S-88.205 Processing of Video Signals (Teacher: Hartimo, Assistant: Tenhonen) S-88.211 Signal Processing in Telecommunications I (Teacher: Laakso, Assistant: Shoaib, Ramirez) S-88.212 Signal Processing in Telecommunications II (Teacher: Laakso, Assistant: Ramirez, Ugur) S-88.221 Postgraduate Seminar on Signal Processing 1 (Teacher: Laakso, Assistant: Shoaib) S-88.224 Postgraduate Seminar on Signal Processing 4 (Teacher: Skyttä, Assistant: Forstén) More information: Study Programme, Helsinki University of Technology.
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4. THESES 4.1 Doctor of Science in Technology Year 2003 Kimmo Kettunen: “Soft Detection and Decoding in Wideband CDMA Systems” Thesis defence: March 14, 2003
Supervisor: prof. T. Laakso Opponents: Prof. B. Aazhang (Rice University, Houston, Texas, USA) and prof. M. Latva-aho (University of Oulu, Finland) Research done at: HUT/SMARAD, Signal Processing Laboratory
Markku Pukkila: “Iterative Receivers and Multichannel Equalisation for Time Division Multiple Access Systems”
Thesis defence: October 10, 2003 Supervisor: prof. T. Laakso Opponent: Prof. Markku Renfors (Tampere University of Technology,
Finland) Research done at: HUT/SMARAD, Signal Processing Laboratory
Marius Sirbu: “Channel and Delay Estimation Algorithms for Wireless Communication Systems” Thesis defence: December 4, 2003 Supervisor: prof. V. Koivunen Opponents: Prof. Erik Ström, (Chalmers Technical University, Sweden) and Dr. Kari Pehkonen (Nokia Mobile Phones, Finland). Research done at: HUT/SMARAD, Signal Processing Laboratory
Year 2004 Jan Eriksson: “Contributions to Theory and Algorithms of Independent Component
Analysis and Signal Separation” Thesis defence: August 20, 2004 Supervisor: prof. V. Koivunen Opponents: Prof. Douglas C. Scott, (Southern Methodist University, Dallas, USA) and prof. Christian Jutten (University of Grenoble, France) Research done at: HUT/SMARAD, Signal Processing Laboratory
4.2 Licentiate of Science in Technology Year 2003 Matti Rintamäki: “Adaptive Power Control in CDMA Cellular Communication
Systems” Supervisor: Prof. Iiro Hartimo Year 2004 Juha Venäläinen: “Modulation Recognition in Dispersive Communication Channels” Supervisor: Prof. Visa Koivunen
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4.3 Master of Science in Technology Year 2003 Fabio Belloni: “Direction of Arrival Estimation Algorithms for Linear and Circular
Arrays” Supervisor: Prof. Visa Koivunen Benoit Hebrard: “Optimizations for 8-PSK EDGE Equalizer: Channel Impulse
Response And Bit Error Probability Estimation” Supervisor: Prof. Timo Laakso Antti Hämäläinen: “Implementation and Training of Neural Networks on
Reprogrammable Hardware” Supervisor: Prof. Jorma Skyttä Kimmo Järvinen: “Hardware Description Language Generator for Elliptic Curve Point
Multiplication” Supervisor: Prof. Jorma Skyttä Jori Johanssoni: “Clock Domain Crossings and Metastability in ASIC Design” Supervisor: Prof. Jorma Skyttä Martin Makundi: “Efficient Implementation of Variable Thiran Allpass Fractional Delay
Filters for Synchronization in Communications” Supervisor: Prof. Timo Laakso Jarno Martikainen: “Feasibility Study of a Link Level UMTS System Simulator Using
Parallel Computing” Supervisor: Prof. Iiro Hartimo Topi Rantalainen: “Medium Access Control protocol implementation in 3G Radio
Network Controller” Supervisor: Prof. Jorma Skyttä Mikko Ruotsalainen: “Adaptaton of Circuit Switched Services in 3G Media Gateway” Supervisor: Prof. Jorma Skyttä Aki Suihkonen: “Signal Processing for Wireless Communication on Reconfigurable
Hardware” Supervisor: Prof. Jorma Skyttä Carl Wallén: “Component-Based Real-Time Software Environment for Digital
Signal Processors” Supervisor: Prof. Jorma Skyttä Hai Xu: “Joint Transmit and Receive Filter Design for Wireline Channels” Supervisor: Prof. Timo Laakso
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Year 2004 Eugenio Delfino: “Novel Acquisition and Tracking Methods for Long-Code Satellite
Navigation Receivers” Supervisor: Prof. Visa Koivunen Juha Forstén: “Enhancing Priority IP-Packet Forwarding with Hardware
Acceleration Using Reprogrammable Logic” Supervisor: Prof. Jorma Skyttä Gilda Gamez Gonzales:
“Measurements for Modelling of Wideband Nonlinear Power Amplifiers for Wireless Communications” Supervisor: Prof. Timo Laakso
Peter Jantunen: “Modelling of Nonlinear Power Amplifiers for Wireless Communications”
Supervisor: Prof. Timo Laakso Anssi Juvonen: ”Digitaalinen piiriarkkitehtuuri hyvin suuren signaalimäärän ohjaa-
miseen” Supervisor: Prof. Jorma Skyttä Tuomo Kaikkonen: ”Varmistetun tehonsyöttölaitteen käyttöliittymäohjelmiston suunnit-
telu ja toteutus” Supervisor: Prof. Jorma Skyttä Esa Korpela: ”Design of a Generic Reconfigurable Computing Platform” Supervisor: Prof. Jorma Skyttä Markus Lehtonen: ”Interference in Satellite Navigation Systems” Supervisor: Prof. Visa Koivunen Julian Martin Martinez:
“Fast Adaptive algorithms for APLAC System Simulator” Supervisor: Prof. Timo Laakso
Manuel Enrique Ramirez Montalvo: "Sub-Optimal Non-Linear Detection Methods for High Data Rate Systems Using Multiple Antennas" Supervisor: Prof. Risto Wichman
Veli-Pekka Salo: ”Impact of the New Global Navigation Satellite Systems on Receiver Architectures”
Supervisor: Prof. Jorma Skyttä Antti Virolainen: ”Magneettikuvauslaitteen vastaanottokelojen tuotantotestaus-
järjestelmä” Supervisor: Prof. Jorma Skyttä Matias With: “Space-Time Anti-Jamming Receiver Structures for Satellite
Navigation Systems” Supervisor: Prof. Visa Koivunen
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5. STATISTICAL AND ARRAY SIGNAL PROCESSING IN COMMUNICATIONS RESEARCH GROUP LEADER PROFESSOR VISA KOIVUNEN
The group is a part of the SMARAD CoE nominated by the Academy of Finland. The principal investigator of the group is professor Visa Koivunen. There are 4 post-doctoral fellwos in the group and 8 doctoral students. Moreover, a number of M.Sc. students are working on their master theses in the group. The main funding sources are the Academy of Finland, TEKES, EU, industry and defence forces.
5.1 Signal Processing for Spread Spectrum Systems Maarit Melvasalo, Tommi Koivisto, Markus Lehtonen, Keijo Pölönen, Matias With, Visa Koivunen In this project, transceiver structures for spread spectrum systems are developed. In particular, WCDMA system and its future extensions and satellite navigation systems such as GPS and Galileo are considered. In case of WCDMA systems, the goal of the research is to increase effective data rates and spectral efficiency of the system as well as the improve the quality of the radio link. Novel receiver structures are derived and their performance is studied. In particular, so-called HSDPA system used to provide high datarates to a user. Multicode transmission where more than one spreading-code is dedicated is to one user. Moreover, the amount of control signalling may be reduced by emplying blind and semi-blind receiver structures. Then more informations symbols may be transmitted. Blind receivers allow for using the information symbols for refining the channel estimates or equalizer. This is of particular interest in fast-fading channels. Semi-blind receiver employ both the pilot and the information symbols. Hence, maximal sample support is achieved which leads to reduced variance in estimating the channel parameters. Multiantenna transmission, i.e. MIMO-systems may be used to improve the spectral efficiency of the spread spectrum systems, cancel interferences as well as improve the quality of the radio link. In this project, multiantenna receiver algorithms for future evolution WCDMA system are developed. Their performance is studied in simulation using realistic channel models and mobile user scenarios. In the area of navigation systems, antijamming receivers are developed. Smart antennas emplying space-time processing allow cancelling multiple broadband and narrowband jammers as well as unintentional interference simultaneously. The developed methods stemming from multi-stage Wiener filtering are exploiting the low-rank structures of the signal model. Computationally efficient and numerically stable Householder transformations are employed in the methods. The performance of such anti-jamming processors is studied under highly demanding jamming scenarios and in the face of multipath. The co-existence of navigation systems and other wideband systems is also studied.
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Figure 1: Response of a space-time antijamming navigation receiver in the face of several broadband and narrow band jammers
The problem of direction finding is spread spectrum systems is addressed as well. Direction finding and emitter localization are needed in beamforming as well as in other applications where the location of the user is of interest. Such applications include safety-of-life and different spectrum management and surveillance applications. The SNR's of spread spectrum signals are very low. Hence, the direction finding is highly challensging problem. In particular, the problem of blind despreading, i.e. obtaining the processing gain without explicit knowledge of the spreading codes is addressed. This allows of high-resolution angle of arrival estimation of transmitters where spreading codes are not known. 5.2 Multicarrier and MIMO Systems Timo Roman, Traian Abrudan, Mihai Enescu, Maarit Melvasalo, Visa Koivunen In this project transceiver structures for Multiple-Input Multiple-Output systems are developed. Such systems allow linear increase in spectral efficiency as a function of number of antennas in transmitter or receiver. Moreover, the radio link quality may be improved so that ADLS quality radio link is experienced in a wireless system. Multicarrier modulation schemes are of special interest in this research. Multicarrier systems turn a broadband frequency selective channels into number of narrowband channels. This makes the receiver design particularly simple. Multicarrier communications and MIMO systems together are the key tehnologies in future high data rate wireless communication systems as well as in wireless LAN's and broadcast systems. In this work channel estimation and synchronization methods are developed for MIMO-OFDM systems. The carrier frequency compensation problem caused by mobility, oscillator inaccuracies and rich scattering environments is important because the offset degrades the desirable properties of the multicarrier transmission. Also time synchronization and estimation of time-frequency-space selective radio channel is studied.
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Adaptive receiver structures operating both on time-and frequency domain are derived. Also low complexity receivers are developed that exploit the special structure of the matrices used in the MIMO-OFDM model. Blind and semi-blind receiver structures are developed in order to improve effective data rates. Both statistical and structural properties of multicarrier signals are exploited.
Figure 2: Typical MIMO-OFDM system configuration
5.3 Fundamentals of Statistical and Array Signal Processing Jan Eriksson, Esa Ollila, Mihai Enescu, Cassio Ribeiro, Fabio Belloni, Andreas Richter, Traian Abrudan, Timo Roman, Jarmo Lundén, Anne-Mari Seppola, Tuomas Aittomäki, Visa Koivunen
In this research new statistical methods and models for different signal processing applications are developed. This research stems from estimation theory and applied mathematics. Optimal and suboptimal statistical procedures are derived. The properties of the new methods are established using large sample analysis (asymptotics) and matrix theory.
The specific research problems include complex random vectors and processes and their statistical models and estimation procedures, optimization under unitary matrix constraints using Riemannian geometry, linear and nonlinear state-space models, estimation methods for angular distribution models, robust estimation theory, subspace analysis and signal separation and independent component analysis. The fundamental results obtained in this research have applications in communications, sensor networks, biomedicine and data analysis in general. Different statistical pattern recognition problems especially in the context of wireless communications and radar are investigated as well. The applications include spectrum management and electronic warfare.
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Figure 3: Blind signal separation problem
Also methods for smart antennas for different antenna configurations are developed. Small antenna arrays that may be used for example in mobile terminals are of interest. Particular examples include uniform circular arrays and dual-polarized antenna systems. Computationally efficient high-resolution methods are developed considering also practical antenna gain patterns. This requires deriving beamspace transforms and procedures for reducing possible bias and excess variance from the estimates.
5.4 Radio Channel Propagation Parameter Estimation Cassio Ribeiro, Andreas Richter, Fabio Belloni, Esa Ollila, Jussi Salmi, Visa Koivunen The interest in the multidimensional structure of the mobile radio channel is growing rapidly. This is mainly due to the fact that future beyond 3G wireless systems will employ multi-antenna transceivers in order to improve spectral efficiency and radio link quality. Consequently, realistic channel models that are verified by real-world measurement campaigns are needed especially for transceiver design and network planning purposes.
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Figure 4: Tracking time-delay of arrival propagation parameter using extended Kalman filter Channel sounding and related propagation parameter estimation are key tasks in creating such channel models. In particular, the double-directional modeling of the radio channel has attracted a lot of interest because it gives a better physical insight into the wave propagation mechanism in real radio environments and it has the ability to remove the measurement antenna influence from the channel observation. Moreover, studying and comparing the performance of various MIMO (multiple-input-multiple-output) transceiver structures requires such advanced channel models as well. In the research we address the problem of parametric channel estimation in channel sounding. Propagation parameter estimation is crucial in creating realistic channel models that may be used to study the performance of multi-antenna (MIMO) transceivers as well as in network planning. Novel optimal and sub-optimal estimation procedures are developed and their asymptotic properties are established. Special emphasis is put on using appropriate angular distribution models for parameters that are defined in angular domain, modeling both the specular and diffuse component of the propagations, tracking time-varying propagation parameters in mobile radio channels and well as developing models that allow describing arbitrary scattering environments. This part is done in co-operation with prof. Pertti Vainikainen from Radio Laboratory and SMARAD CoE of Helsinki University of Tecnology.
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6. SPITRES – THE SIGNAL PROCESSING IN TELECOMMUNICATION RESEARCH GROUP LEADER PROFESSOR TIMO LAAKSO
Current research of the Signal Processing in Telecommunication Research (SPITRES) group focuses on design and implementation of receiver algorithms for diverse communications systems, including both wireline and wireless systems. Topics include efficient adaptive filter algorithms, adaptive estimation and equalization of nonlinearities, adaptive notch filters, synchronization algorithms, tunable fractional delay filter structures, and power amplifier nonlinearities in multiple-antenna systems. The group is part of the Smart and Novel Radios Research Group, which was selected as a Center of Excellence by the Academy of Finland for the period 2002-2007. 6.1 Data Selective Adaptive Filtering Algorithms Stefan Werner, Timo I. Laakso, Paulo S. R. Diniz and Jose A. Apolinário
Figure 5. Block diagram of set-membership filtering This research investigates new data selective adaptive filtering algorithms using the framework of set-membership filtering (SMF). These algorithms combine a bounded error specification on the adaptive filter with the concepts of proportionate adaptation and data reusing in order to obtain efficient algorithms for both sparse and dispersive systems. The resulting algorithms have low average computational complexity because coefficient update is not performed each iteration. The adaptation algorithms can be adjusted to achieve a desired computational complexity by allowing a variable number of data-reuses for the filter update.
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6.2 Analysis of Partial-Update Adaptive Filters Stefan Werner, Marcello L. R. de Campos and Paulo S. R. Diniz
Figure 6. Convergence of partial-update adaptive filters This research analyzes partial-update normalized adaptive filters. Partial-update adaptive filtering is a technique suitable for applications where the order of the adaptive filter is so high that it may impair even the implementation of low computational complexity algorithms, such as the NLMS algorithm. Partial-update adaptive filters reduce the algorithm complexity by properly decreasing the number of filter coefficients that is updated each iteration so that the filter order may be kept fixed. Order statistics is used to analyze the mean-squared error of the adaptive filter output. 6.3 Linearly Constrained Adaptive Filters Stefan Werner, Marcello L. R. de Campos and Jose A. Apolinário
Figure 7. Illustration of linearly constrained adaptive filtering
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Adaptation algorithms that satisfy linear constraints find applications in various areas of communications, e.g., in antenna array processing and multiuser detection. In this project, new linearly constrained adaptive filtering (LCAF) algorithms are derived and analyzed, which are tailored to specific applications and have advantageous performance regarding convergence and robustness. Reduced complexity adaptive filtering algorithms are developed through input-signal transformation, set-membership filtering, and data-reusing. In addition, efficient implementations of the multistage Wiener filter structure are considered. 6.4 Fast Adaptive Filtering Algorithms for APLAC System Simulator Julián Martín Martínez, Stefan Werner, Timo I. Laakso, This project provides an insight into adaptive filtering algorithms, ranging from the simplest to the more sophisticated algorithms. A testbench is designed for the algorithms in order to measure their performances for two applications; channel equalization and system identification. The goal of the project is to provide a systematic approach on how to choose a suitable algorithm given a set of application requirements. The approach assumes only little knowledge of the underlying theory of the algorithms and targets engineers with no expertise in the field. Finally, this thesis project provides C code implementations of the recent algorithms for implementation in the APLAC System Simulator. 6.5 Adaptive Multiple-Notch Filters Yaohui Liu, Paulo S. R. Diniz, Juan Cousseau, Timo I. Laakso
Figure 8. Adaptive multiple-notch filters This research investigates IIR realization of adaptive notch filters. We focus on the multiple notch case. We study a new family of IIR adaptive notch filters which is based on a second-order factorization of the all-pass transfer function that forms the multiple notch filter. Compared to the previous research done on this topic, these realizations avoid finding a
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high-order polynomial root to obtain the unknown frequencies of interest. For the case of low SNR, a smaller bias can be achieved using the new realizations as compared with previous realizations available in the literature. This property is particularly attractive for multiple sinusoids estimation and tracking. Furthermore, we derive several updating algorithms dealing with multiple notches. Algorithms used include gradient descent and Steiglitz-McBride algorithms. This research also includes analysis of the convergence properties, analysis of the relationship of the frequency estimation errors, analysis of the signal to noise ratios, and characterisation of the stationary points. 6.6 Measurement and Analysis of Nonlinearities of Power Amplifiers for Wireless Communications Gilda Gamez, Timo I. Laakso Figure 9. Measurement of power amplifiers In this project, single-tone and multi-tone input signals are applied to high-power amplifiers and the output of the device is measured in order to obtain enough data to characterize their nonlinearities. The results of this research are further used for amplifier modelling and predistorter design. Memoryless distortions can be represented by the measured AM-AM and AM-PM characteristics, which show how the amplitude and phase of the output changes with the input power level. Nonlinear distortions may depend on thermal, biasing or supply conditions, which can appeared as mixed (in form of noise) with the basic AM-AM/AM-PM characteristics. In this case and in systems with memory, the normal AM-AM and AM-PM measurements are not enough to characterize the nonlinearity of the devices, so a Two-Tone transfer characteristics measurement may be done.
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6.7 Modelling of High-Power Amplifier Nonlinearities for Wireless Communications Peter Jantunen, Timo I. Laakso
Figure 10. Frequency response of the linear part of the amplifier model This research investigates identification techniques for nonlinear systems. The goal is to find a suitable model for a power amplifier that can be utilized in the design of linearization techniques that can alleviate the distortion generated by the power amplifier. Narrowband amplifiers can usually be estimated using frequency-independent models, whilst wideband amplifiers require frequency-dependent models. In this project a Hammerstein model is proposed for frequency-dependent estimation of power amplifier nonlinearities. The static nonlinearity has been implemented as polynomial model and the linear dynamic block as an FIR filter. A simplified parameter estimation technique based on the measured AM/AM and AM/PM characteristics using linear least-squares estimation was developed. In order to determine the filter coefficients, a weighted least-squares FIR approximation technique for use on a discrete frequency grid has been derived. Very good results were obtained for single-tone inputs. The next challenge is to verify applicability of the model for practical input signals, i.e., QAM or OFDM signals. 6.8 Adaptive Digital Predistortion for Broadband Power Amplifiers Mei Yen Cheong, Stefan Werner, Juan Cousseau, Timo I. Laakso This project aims at developing an adaptive digital predistorter that compensates nonlinearity with memory (NLWM) caused by the power amplifier (PA) in broadband wireless communication systems. The logical way to develop a pre-distorter (PD) is to find the inverse characteristic of the PA such that the cascaded system of PD-PA produces a linear output. Volterra series is a classical model for nonlinearity with memory effect.
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However, a Volterra model based predistorter may suffer from a prohibitive computational complexity as well as ill-conditioned kernels for a high-order series expansion. This project considers models based on the Wiener-Hammerstein structure that separates the NLWM into a nonlinear static system and linear dynamic system. Piecewise linear functions are considered for modelling the static nonlinearity. The models of the PA and PD are extracted from measurement data of the Mini-Circuits ZVE-8G amplifier made within the group. 6.9 Amplifier Nonlinearities in Multiple-Antenna Systems Fernando H. Gregorio, Timo I. Laakso, Risto Wichman
Figure 11. Multiple-antenna systems In this project, design techniques and algorithms for switched-beam antenna systems and adaptive beamforming arrays are evaluated with the objective to reduce the nonlinear effects in cellular system. Antenna array systems are used with Multicarrier Power Amplifier (MCPA) in order to reduce the number of amplifiers placed in the base-station. The combination of different signals with different phase and frequency give a large Peak-to-Average ratio, which results in severe clipping effects if the composite signal is amplified by a MCPA with nonlinear transfer function. The nonlinear amplifier distortion can seriously degrade the transmit beamforming performance. First, the directions of the nulls and the main beam will change, increasing the interference level for mobiles using the same frequency channel. On the other hand, intermodulation beams are created that radiate the intermodulation products in different directions. Hence, multiple-antenna systems employing nonlinear amplifiers should be designed with special care, and DSP-based linearisation techniques may turn useful.
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6.10 Fast Multichannel QRD-RLS Algorithms for Efficient Nonlinear Filtering Mobien Shoaib, Stefan Werner, Jose A. Apolinário, Timo I. Laakso This project studies the application of multichannel fast QRD-RLS algorithms for the identification equalization of nonlinear systems that can be modelled by a Volterra series. Of particular interest is the design of predistorters for broadband power amplifiers, where the use of fast QRD-RLS algorithms provides a numerically robust solution of reduced computational complexity. 6.11 Synchronization in Communication Systems Martin Makundi, Xiaojing Zhang, Timo I. Laakso, Are Hjörungnes This research investigates efficient algorithms and implementation structures for the purpose of timing synchronization in communication systems. The more efficient algorithms and implementation structures aim to lower the complexity and cost of the communication devices while improving their performance. We developed an efficient generalized scheme for synchronization using Figure 12. Variable filter implementation structure
synchronous sampling and arbitrary oversampling ratios. We have also developed a closed-form design method for tunable fractional delay (FD) approximation when constraining the magnitude response to be constant for different delays. Recently we have studied FD-based efficient interpolation techniques for carrier frequency offset correction in OFDM systems. 6.12 Joint Transmit and Receive Filter Design for Wireline Channels Hai Xu, Timo I. Laakso This project investigated efficient joint transmit and receive filter algorithms and implementation structure for wireline channels. The algorithms were derived by simultaneous Nyquist and matched filter criteria with transmit power constraints. The main idea is to reduce the complexity of the decision-feedback (DFE) equalizer at the receiver. Figure 13. Wireline channel model
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7. RAID - RECONFIGURABILITY IN ALGORITHM IMPLEMENTATION AND DESIGN RESEARCH GROUP LEADER PROFESSOR JORMA SKYTTÄ
7.1 Hardware Description Language Generator for Elliptic Curve Point Multiplication Kimmo Järvinen, Matti Tommiska, Jorma Skyttä Elliptic curve cryptography (ECC) has been of much interest in the recent years, because considerably shorter keys and lower computational complexity compared to other public-key methods, e.g. RSA, is required for high level of security. Thus, ECC is an attractive alternative, especially, in applications where bandwidths or memory resources are limited. In ECC, an operation called elliptic curve point multiplication is defined on an elliptic curve over Galois fields. The point multiplication is the basic operation of any elliptic curve cryptosystem and, therefore, efficient implementation of the point multiplication is essential for high performance elliptic curve cryptosystems. There is a large variety of different recommended or standardized elliptic curves, which can be used for elliptic curve point multiplication. It would be too laborious to implement all these by hand and, therefore, a VHDL generator called SIG-ECPM was designed. Parameters of the used elliptic curve are given for SIG-ECPM and it generates fully synthesizable and device independent VHDL code implementing an elliptic curve point multiplication on the given curve. SIG-ECPM uses a novel flexible Galois field multiplier structure which allows fast elliptic curve point multiplications. SIG-ECPM creates designs optimized especially for FPGA devices but they can be used for ASICs as well. World-class results in point multiplication performance are achieved with SIG-ECPM designs on FPGAs. The achieved point multiplication times are the fastest published times on FPGAs for certain curves. 7.2 Reconfigurable Computing Platform Esa Korpela, Matti Tommiska, Jorma Skyttä Most computing nowadays is done on processors. However, many personal computers have separate enhancement cards e.g. for graphics and video stream compression or decompression. The enhancement could be done with an ASIC or an FPGA chip. These can be much faster in parallel tasks than a sequential code processor. A generic board implies that a programmable FPGA must be used which is much cheaper choice in prototyping compared to ASICs. With new technologies, faster chips come to market. Especially FPGAs change rapidly. A year old device may well now be old in some sense. This is why new computing cards must be built to keep up with the technology. Algorithm testing and prototyping needs rather much logic if the board has to be generic. A thing found also in this project. The computing board made is of an enhancement type. The card was designed for any type of tasks. The board itself may be used stand-alone but intended to be used alongside with a computer. On the board, there is a USB 2.0 serial connection to a computer and connectors for external cards.
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The challenges are in designing for manufacturing and the card to be generic. There are many notable things when working with professional companies compared to hand soldering. There was no previous knowledge of this and time was spend to find answers.
Figure 14. SIG-USB2 FPGA card 7.3 FPGA-based education platform using System-on-Chip (SoC) technology Jaakko Kairus, Juha Forsten, Matti Tommiska, Jorma Skyttä System-on-Chip (SoC) technology is currently the primary interest of the digital design community. SoC can be defined as a programmable platform integrating most of the functions of the end product in a single chip. It incorporates at least one processing element (microprocessor, DSP, etc.) that runs the embedded software. As the growing popularity of SoC/SoPC designs is coupled with the increasing importance of programmable logic as the implementation platform, the educational system must cater to the needs of both Computer Science and Electrical Engineering students at the undergraduate level. The goal should be to bridge the gap in the way software and hardware engineers think. The hardware environment contains two distinct modules, an FPGA (Field Programmable Gate Array) development board supplied by Altera and a peripheral custom-designed expansion board. The Nios embedded softcore processor provides a flexible platform for all SoPC designs in the student exercises. As the Nios processor requires only a third of the FPGA resources, the rest is available for custom logic. Altera's Nios Development Kit supports C and VHDL programming languages and they both are used in the exercises. The custom-made expansion board has a wide selection of auxiliary equipment that can be controlled by either the Nios processor or by custom logic. Peripherals like a program-mable sound generator, MIDI (Musical Instrument Digital Interface), A/D and D/A converters, a temperature measurement unit, a wireless data transfer unit, servomotors and a LED display make the learning process practical and even entertaining.
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Figure 15. FPGA-based education platform
7.4 Potential of a Hardware Assisted Attack on A5/1 security Jaakko Kairus, Matti Tommiska, Jorma Skyttä The GSM (Groupe Spéciale Mobile) mobile phone standard is designed to be secure against eavesdropping and user identity spoofing. Over-the-air transmissions are encrypted with 64-bit encryption, and each subscriber has a unique key stored to a SIM (Subscriber Identification Module) card that authenticates the caller. The encryption and key generation algorithms were developed in secrecy and meant to remain unpublished. However, the specifications have leaked out and been studied by cryptanalysts over the world. There have been found severe flaws in the algorithms, thus weakening the effective key length to around 40-54 bits. With present computation power, the over-the-air encryption might be possible to break. There are also many more ways to eavesdrop GSM phones, which may be even more realistic, including SIM card cloning and listening the signal between base stations and backbone network. Anyway it seems that one should not rely on the standard GSM encryption alone if the conversation is meant to be secret.
Figure 16. A5/1 algorithm description
Illustration 1Schematic description of A5/1
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7.5 Implementation of Neural Networks on Reprogrammable Hardware Antti Hämäläinen, Matti Tommiska, Jorma Skyttä Neural network implementations using special hardware platforms, such as FPGAs, are essential in certain real-time applications, where software-based networks are not efficient enough. However, the design of a hardware-based network is more complicated and requires special attention.
The research on the neural networks was continued focusing on the effects a fixed-point arithmetic. The use of fixed-point arithmetic is usually required in hardware designs as it offers better performance and smaller logic area consumption than floating point structures. Fixed-point implementations can achieve the same accuracy as the floating-point software networks when the structure of the hardware is properly designed. The best way to design a neural network on a hardware platform is to use fixed-point arithmetic already in the training phase.
The logic area of the hardware devices is always limited and the final design is always a compromise between the accuracy of the network and area consumption of the device. However, the logic area of new FPGAs is expanding and makes possible to implement high performance fully connected neural networks on a single device.
8. WIRELESS SIGNAL PROCESSING GROUP LEADER PROFESSOR RISTO WICHMAN
The group concentrates in developing and analyzing multiantenna transceiver schemes in modern wireless communication systems, mainly on the physical layer but also on higher layers of the protocol stack. One vision for future wireless system is the convergence and integration of the existing systems instead of developing a totally new air interface and backbone network. This calls for cross-layer design of wireless networks, where the knowledge on the physical layer only is not enough. In order to better validate different adaptive multiantenna algorithms within wireless propagation environment, the group is also familiarizing with spatio-temporal channel modeling. Furthermore, we are interested in viability on multiantenna transceiver algorithms and aim to develop schemes that can be used in practice. 8.1 MIMO Channel Modeling Jyri Hämäläinen, Risto Wichman The project concentrates in mathematical modeling of MIMO wireless channels and refining the model based on the assumption that the spatial correlations between transmit and receive antenna arrays can be modeled separately. The project has developed a model for spatially separated cross polarized antennas as a function of the distribution of the angle of arrival of the signal and the characteristics of the transmit and receive antenna arrays. Due to its compactness and cost, this kind of antenna construction is popular in base
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stations instead of spatially separated co-polarized antenna array. Furthermore, we have been developing an efficient numerical method to calculate the density of scatterers in radio channel based on the measured angle of arrival and delay profile. We hope to be able to validate the models with channel measurements in the future. 8.2 Multiuser Diversity Jyri Hämäläinen, Risto Wichman It is expected that in future wireless systems, the proportion of non-realtime data traffic is increasing. Examples of such a traffic are web browsing sessions or downloading of music files. Allowing larger delays for services opens up new possibilities for the design of multiantenna transceiver algorithms, and it can be shown, for example, that space-time codes that are useful with delay-constrained traffic do not work so well any more. Multiuser diversity exploits efficiently the relaxed delay constraints by monitoring the channel conditions and transmitting only to users whose connections are good. This requires feedback signaling from the active users to the scheduler, which may generate a lot of overhead in control channels. Recently, we developed a multiuser MISO concept that can be implemented without modifications to existing WCDMA specification and whose performance is comparable to that of MIMO. However, the complexity of the implementation in the receiver end is substantially smaller than with MIMO. 8.3 MIMO Macrodiversity Jyri Hämäläinen, Risto Wichman The most common system scenario for MIMO studies is the one where the multiple antennas are located in the same antenna mast or device. However, also macrodiversity scenarios, where the antennas are located, e.g., in different base stations, is relevant in wireless cellular systems. In this case, instantaneous signaling between different transmit or receive branches is not feasible, but the information can only be exchanged on long-term basis, which should be taken into account in the design and analysis of multiantenna transceiver algorithms. So far, the project has analyzed the performance of site selection diversity transmission concept, which is a part of WCDMA specification. 8.4 Multiantenna Solutions for 3G WCDMA Jyri Hämäläinen, Risto Wichman Multiantenna techniques have received a lot of interest due to their celebrated capacity enhancement. However, in practical cellular systems, boundary conditions may eat up most of the projected gains of MIMO: Signal-to-noise ratios are modest in practice due to multiaccess interference and because intercell interference must be kept in reasonable levels in network design. Furthermore, channels are seldom independently fading as in a large body of studied on MIMO capacities. In this project, we evalute practical multiantenna transceiver techniques for 3G.. For example, we have shown that transmit diversity is of limited use in WCDMA uplink, because of fast transmit power control characteristic to CDMA systems.
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8.5 Sphere Decoders for MIMO Channels Enrique Ramírez, Nikolai Nefedov The project focuses on the development of suboptimal hard and soft detection algorithms for MIMO systems. The research started with the creation of sphere detector for MPSK modulation, mixed modulation scenarios (different modulation in different data streams), and for asymmetric MIMO channels, where the number of transmit antennas is larger than the number of receive antennas. The research then continued with the implementation of soft output sphere detectors, instrumental in wireless channels, which require forward error correcting codes, and sphere detectors for multipath fading channels. 8.6 Performance of Multiantenna Transceivers with Partial Channel State Information Eduardo Zacarías, Risto Wichman The project develops and analyzes feedback algorithms providing partial channel state information to the transmitter taking into account the boundary conditions of realistic wireless communication systems. Imperfections of feedback information in practical systems include, e.g., limited feedback capacity, feedback latency, feedback errors, and errors in channel estimation.
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9. ACTIVITIES
9.1 International Conferences and Meetings Year 2003 11th Euromicro Conference on Parallel Distributed and Network based Processing, Genova, Italy, February 4-9. (Iiro Hartimo) ACM/SIGDA 11th ACM International Symposium on Field Programmable Gate Arrays, Monterey, USA, February 26-27. (Kimmo Järvinen, Jorma Skyttä, Matti Tommiska) ICA2003 - Fourth International Symposium on Independent Component Analysis and Blind Signal Separation, Nara, Japan, April 1-4. (Jan Eriksson, Visa Koivunen) IST/SET Symposium on Smart Antennas, Manchester, United Kingdom, April 7-9. (Eino Oja) VTC2003-spring, IEEE Seminannual Vehicular Technology Conference, Jeju, South-Korea, April 22-25. (Timo Roman) International Conference on Robust Statistics, Belgium, May 2003. (Esa Ollila) ICC – IEEE International Conference on Communications, Anchorage, Alaska, May 11-16. (Risto Wichman) 1st International Workshop on Signal Processing for Wireless Communications 2003, Great Britain, May 19-20. (Visa Koivunen) Finsig Symposium, Tampere, Finland, May 19. (Peter Jantunen, Hai Xu) IEEE ISCAS2003 Conference, Bangkok, Thailand, May 24-29. (Are Hjörungnes, Yaohui Liu, Martin Makundi) SPWC - First International Workshop on Signal Processing for Wireless Communications 2003, London, United Kingdom, May 19-20. (Visa Koivunen, Marius Sirbu) IWUWBS – International Workshop on Ultra-Wideband Systems, Oulu, Finland, June 2-3. (Visa Koivunen, Marius Sirbu) SPAWC - IEEE Workshop on Signal Processing Advances in Wireless Communications, Rome, Italy, June 15-18. (Traian Abrudan, Visa Koivunen, Timo Roman, Marius Sirbu) European Summer School on ICA, Berlin, Germany, June 16-18. (Jan Eriksson)
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ICME2003, International Conference on Multimedia and Expo, Baltimore, USA, July 6-9. (Mihai Enescu) ICORS2003, Antwerpen, Belgium, July 12-18. (Esa Ollila) ECCTD´03 European Conference on Circuit Theory and Design, Krakow, Poland, September 1-4. (Timo Laakso) PIMRC2003 – The 14th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, Beijing, China, September 7-10. (Visa Koivunen, Nikolai Nefedov, Risto Wichman) SMMSP2003 - Spectra Methods and Multirate Signal Processing, Barcelona, Spain, September 13-14. (Iiro Hartimo) ICIP2003 - International Conference on Image Processing, Barcelona, Spain, September 14-17. (Iiro Hartimo) COST 273 meeting, Prague, Czeck Republic, September 23-27. (Mihai Enescu) SSP - Statistical Signal Processing, St. Louis, USA, September 28-October 1. (Mihai Enescu, Esa Ollila) VTC2003-Fall, IEEE Vehicular Technology Conference, Florida, USA, October 6-9. (Mihai Enescu, Esa Ollila, Matti Rintamäki) WPMC´03 - The 6th International Symposium on Wireless Personal Multimedia Communications, Yokosuka, Kanagawa, Japan, October 19-22. (Matti Rintamäki, Risto Wichman) FIE2003 - Frontiers in Educations Conference, Colorado, USA, November 6-8. (Juha Forstén, Jaakko Kairus) 37th Asilomar Conference on Signals, Systems and Computers, San Francisco, USA, November 9-12. (Traian Abrudan, Mihai Enescu, Visa Koivunen) Globecom 2003 Conference, San Francisco, USA, November 30-4 December. (Cassio Ribeiro, Stefan Werner, Risto Wichman) ISPACS 2003 Conference, Japan, December 7-10. (Eugenio Delfino) ISSPIT 2003 Conference, Darmstadt, Germany, December 15-17. (Fabio Belloni, Visa Koivunen)
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Year 2004 DATE´04 - Design, Automation and Test in Europe, Paris, France, February 17-19. (Jorma Skyttä) IZS - International Zürich Seminar on Communications, Zürich, Switzerland, February 17-22. (Traian Abrudan, Visa Koivunen, Timo Roman, Samuli Visuri) IEEE ICASSP2004 – International Conference on Acoustics, Speech and Signal Processing, Montreal, Canada, May 17-21. (Visa Koivunen, Yaohui Liu, Timo Roman) IWWAN´04 Conference, Oulu, Finland, May 31-June 3. (Matti Rintamäki) NORDSTAT2004 - 20th Nordic Conference on Mathematical Statistics, Jyväskylä, Finland, June 6-7. (Jan Eriksson, Esa Ollila) NORSIG 2004 - 6th Nordic Signal Processing Symposium, Espoo, Finland, June 9-11. (Traian Abrudan, Fabio Belloni, Mei-Yen Cheong, Fernando Gregorio, Iiro Hartimo, Peter Jantunen, Timo Laakso, Enrique Ramirez, Cassio Ribeiro, Matti Rintamäki, Mobien Shoaib, Stefan Werner) IC-AI´04 – The 2004 International Conference on Artificial Intelligence, Las Vegas, Nevada, USA, June 21-24. (Antti Hämäläinen, Matti Tommiska) IEEE SPAWC- Signal Processing for Wireless Communications, Portugal, July 11-14. (Traian Abrudan) SAM 2004- The third IEEE Sensor Array and Multichannel Signal Processing Workshop, Barcelona, Spain, July 18-21. (Esa Ollila, Matias With, Stefan Werner) Nordic Radio Symposium and Finnish Wireless Conference 2004, Oulu, Finland, August 16-18. (Risto Wichman) The thirteenth International Workshop on Matrices and Statistics, Poland, August 18-21. (Esa Ollila) FPL - 14th International Conference on Field Programmable Logic and its Applications, Belgium, August 30-September 1. (Kimmo Järvinen, Jorma Skyttä) IEEE International Symposium on Spread Spectrum Techniques and Applications. Australia, August 28-September 6. (Eugenio Delfino) PIMRC 2004 – 15th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, Barcelona, Spain, September 5-8. (Cassio Ribeiro, Risto Wichman) Eusipco 2004, XII European Signal Processing Conference, Vienna, Austria, September 7-10. (Mihai Enescu, Visa Koivunen, Stefan Werner)
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IEEE 1st International Symposium on Wireless Communications Systems, Mauritius, September 17-23. (Martin Makundi) ICA2004 Conference, Granada, Spain, September 20-23. (Jan Eriksson) IEEE VTC ´04Fall – Semiannual Vehicular Technology Fall Conference, Los Angeles, California, USA, September 26-29. (Timo Roman) MLSP Conference, Sao Luis, Brazil, September 28-30. (Jan Eriksson) Nordstat 2004 Conference, Jyväskylä, Finland, October 6. (Jan Eriksson, Samuli Visuri) URSI/IEEE XXIX Convention on Radio Science, Espoo, Finland, November 1-2. (Antti Hämäläinen) 38th Asilomar Conference on Signals, Systems and Computers, San Francisco, USA November 7-11. (Fabio Belloni, Visa Koivunen, Cassio Riberio, Mikko Valkama) SoC 2004 - Symposium on system-On-Chip, Tampere, Finland, November 18-16. (Juha Forstén, Antti Hämäläinen, Kimmo Järvinen, Jaakko Kairus, Esa Korpela, Jorma Skyttä) Field-Programmable Technology Conference, Brisbane, Australia, December 5-12. (Kimmo Järvinen) SPCOM2004, International Conference on Signal Processing and Communications, Bangalore, India, December 11-14. (Risto Wichman) IEEE ISSPIT 2004 Conference. Rome, Italy, December 17-23. (Mihai Enescu)
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9.2 Foreign Visitors The following persons have visited laboratory during the year 2003: • Marcello L. R. de Campos, professor, Federal University of Rio de Janeiro, Brazil • Paulo S. R. Diniz, professor, Federal University of Rio de Janeiro, Brazil • Til Aach, professor, University of Lübeck, Germany • Stefan Petrausch, professor, University of Erlangen-Nuremberg, Germany • Anantrhram Swami, Dr, US Army Research Laboratory, USA • Behnaam Aazhang, professor, Rice University, USA • Tsen Chung Kang, PhD, Director Tecnico, Instituto Nokia de Tecnologia, Brazil • Carlos Geralde de Britto Feitoza, Director Presidente, Instituto Nokia de Tecnologia,
Brazil • Sandro Alves, Grerente de Projetos, Director Presidente, Instituto Nokia de Tecnologia,
Brazil • Akira Sano, professor, Keio University, Japan • Yukitoshi Sabada, Ph.D., Keio University, Japan • Iwao Sasase, Ph.D., Keio University, Japan The following persons have visited laboratory during the year 2004: • José Apolinario, visiting professor, Instituto Militar de Engenharia (IME), Brazil, 2 months • Juan Cousseau, visiting professor, Universidad National del Sur Argentina, Argentina, 4
months • Alfred Fettweis, professor, Germany • Reiner Creutzburg, professor, University of Applied Sciences, Germany • Jar-Ferr Yang, professor, CCE director, National Cheng Kung University, Taiwan • Santosh Venkatesh, PhD, professor, University of Pennsylvania, Philadelphia, USA • Dave Tyler, professor, University of Rutgers, USA • David Gesbert, professor, Eurecom Institute, France • Andreas Richter, Dr.Ing., Technical University of Ilmenau, Germany • Kassam Saleem A., PhD, professor, University of Pennsylvania, Philadelphia, USA • Martin Haardt, professor, Technical University of Ilmenau, Germany • Christian Schneider, Technical University of Ilmanau, Germany • Giovanni Delgaldo, Technical University of Ilmenau, Germany • Christian Jutten, professor, University of Grenoble, France • Douglas C. Scott, professor, Southern Methodist University, Dallas, USA • Rainer Thomae, Dr., Technical University of Ilmenau, Germany • Farokh Marvasti, professor, Sharif University of Technology Teheran, Iran • Graciela Corral, researcher, Universidad Nacional de Cordoba, Argentina, 2 months • Paulo S. R. Diniz, professor, Federal University of Rio de Janeiro, Brazil
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9.3 Visits abroad Year 2003 • Mihai Enescu, visiting researcher, University of Delaware, USA (July 11-13) • Mihai Enescu, visiting researcher, Technische Universität Wien, Austria (one month) • Are Hjörungnes, visiting researcher, Federal University of Rio de Janeiro, Brazil (one
month) • Juha Karvanen, visiting researcher, Riken Research Institute, Japan (4 months) • Visa Koivunen, visiting professor, University of Pennsylvania, USA • Esa Ollila, visiting researcher, University of Bruxelles, Belgium (three weeks) • Esa Ollila, visiting researcher, University of Pennsylvania, USA • Samuli Visuri, visiting researcher, ETH Zentrum, Switzerland (12 months) • Stefan Werner, visiting researcher, Federal University of Rio de Janeiro, Brazil (6
months) Year 2004 • Tuomas Aittomäki, visiting researcher, University of Pennsylvania, USA (4 months) • Mei Yen Cheong, Technische Universität Wien, Austria (3 months) • Mihai Enescu, visiting researcher, Technische Universität Wien, Austria (3 months) • Jan Eriksson, visiting researcher, Universidade Federal do Rio de Janeiro, Brazil • Visa Koivunen, visiting professor, University of Pennsylvania • Visa Koivunen, visiting professor, University of Villanova Pennsylvania • Visa Koivunen, visiting professor, University of Delaware • Timo Roman, visiting researcher, University of Pennsylvania, USA • Timo Roman, visiting researcher, University of Delaware, USA • Risto Wichman, Indian Institute of Science, Department of electrical communication
engineering, Bangalore, India (2 weeks)
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10. PARTICIPATION IN BOARDS AND COMMITTEES
10.1 University Boards and Committees Iiro Hartimo
• director of GETA (Graduate School on Electronics, Telecommunications and Automation), the largest Graduate School in Finland
• chairman of the Doctoral Education Committee of the Department of Electrical and Telecommunication Engineering
Visa Koivunen
• member of the HUT Dissertation Committee • member of 2 faculty search committees
Jorma Skyttä
• chairman of the Course Evaluation Committee of the Department of Electrical and Communications Engineering
10.2 Other Boards and Committees Iiro Hartimo
• chairman of the steering group of the TULE research program funded by Academy of Finland
• chairman of the publications board of the periodical 'Sähkö-Tele' • member of the Science and Technology Committee of the Academy of Finland • chairman and member of the steering group of the ANTARES research program
funded by the Academy of Finland • member of the planning committee of TIEDE’03 program of the Academy of
Finland • member of the steering group of ELMO research program funded by TEKES
(National Technology Agency) • member of the vocabulary group of the Finnish Society of Information
Processing • member of the advisory board of INFOTECH, Oulu • member of the IEEE FS EXCOM • member of the Executive board of LAUREA • member of the Executive board of EVTEK Fund • member of the Advisory board of the Foundation for Finnish Inventions
Visa Koivunen • GETA Graduate course, Course in Wireless Communications, Ruka, Kuusamo,
Organizer (2003 and 2004) • Nokia Leading Science Program, tutoring professor • Member of Technical Program Committee, several conferences
41
Timo Laakso • reviewer for a number of international conferences and journals • member of HUT professors’ orchestra (bass clarinet)
Jorma Skyttä • chairman of the HUT section of Association of the University Professors in
Finland Risto Wichman
• member of program committee in Finnish Wireless Communications Workshop
10.3 Referee Activities Iiro Hartimo
• Reviewer of several international periodicals and conferences • Reviewer for the Finnish Academy • External evaluator for the fulfillment of a professorship in “tietoliikenne-
tekniikka” in University of Turku (2003)
Visa Koivunen • Associate editor for IEEE Signal Processing Letters • Following Journals: IEEE Transactions on Antennas and Propagation, Signal
Processing, IEEE Transactions on Signal Processing, IEEE Transactions on Circuits and Systems II, IEEE Transactions on Neural Networks, IEEE Transactions on Communications, IEEE Signal Processing Magazine, Signal Processing
• Reviewer for a number of international conferences • Opponent in the dissertation of Arto Kantsila at Tampere University of
Technology (2004) • Opponent in the dissertation of Nedeljko Cvejic at University of Oulu (2004) • Expert evaluator for Termed professor position, University of Delaware
Timo Laakso
• Following journals: Electronic Letters, Signal Processing, Applied Signal Processing, IEEE Transactions in Signal Processing, IEEE Transaction on Circuits and Systems II, IEEE Transactions on Instrumentation and Measurement, IEEE Transactions on Communications.
• External evaluator of the Dr. Tech. thesis by Riitta Niemistö, Tampere University of Technology (2003)
• External evaluator of the Dr. Tech. thesis by Konsta Koppinen, Tampere University of Technology (2003)
• External evaluator of the Dr. Tech. thesis by Babic Djordje, Tampere University of Technology (2003)
• Opponent in the dissertation of Riitta Niemistö at Tampere University of Technology (2003)
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• Opponent in the dissertation of Babic Djordje at Tampere University of Technology (2004)
Jorma Skyttä
• External evaluator for the fulfillment of a professorship in “tietotekniikka” in Tampere University of Technology (2003)
• External evaluator for the fulfillment of a professorship in “tietotekniikka” in University of Jyväskylä (2004)
• External evaluator of the Dr. Tech. thesis by Florean Curticapean, Tampere University of Technology (2004)
• External evaluator of the Dr. Tech. thesis by Jari Nikara, Tampere University of Technology (2004)
• Opponent in the dissertation of Juha-Pekka Soininen at University of Oulu (2004)
• Following journal: IEEE Transaction on Computers
Risto Wichman • Following journals: IEEE Signal Processing Letters, IEEE Transactions on
Wireless Communications, IEEE Transactions on Vehicular Technology • External evaluator of the Dr. Tech. thesis by Simona Lohan, Tampere
University of Technology
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11. PUBLICATIONS 2003
11.1 Books and Chapters in Books 1. A. Hottinen, O. Tirkkonen, R. Wichman: Multiantenna Transceiver Techniques for 3G
and Beyond. England 2003, John Wiley & Sons, Ltd. pp.326
2. I. Pietarinen, P. Ahonen, N. Godenhjelm, I. Hartimo, P. Kilpeläinen, T. Kotovirta, S. Mattila, P. Saastamoinen, M. Taskinen: Atk-sanakirja. (12.). Jyväskylä 2003. Gummerus Kirjapaino Oy. 710 pages.
11.2 Refereed Journal Articles 1. J. Eriksson, V. Koivunen: Characteristic-function-based independent component analysis.
Signal Processing, Vol. 83, 2003. PGN: pp.2195-2208. 2. 3. J. Karvanen: The Statistical Basis of Laboratory Data Normalization. Drug Information
Journal, Vol. 37, nro 1, 2003, pp. 101-107. 4. N. Nefedov, M. Pukkila, R. Visoz, A.O. Berthet: Transmission Systems Iterative receiver
concept for TDMA packet data systems. European Transactions on Telecommunications, Vol. 14, nro 5, 2003, pp. 457-469.
5. S. Visuri, E. Ollila, V. Koivunen, J. Möttönen, H. Oja: Affine equivariant multivariate
rank methods. Journal of Statistical Planning and Inference, Vol. 114, 2003, pp. 161-185.
6. E. Ollila, H. Oja, V. Koivunen: Estimates of Regression Coefficients Based on Lift Rank
Covariance Matrix. The Journal of the American Statistical Association, Vol. 98, nro 461, 2003, pp. 90-98.
7. M. Sirbu, V. Koivunen: Multichannel Estimation and Equalization Algorithm for
Asynchronous Uplink DS/CDMA*.Wireless Personal Communications, nro 26, 2003, pp. 33-52.
8. S. Werner, M.L.R. de Campos, P.S.R. Diniz: Mean-Squared Analysis of the Partial-
Update NLMS Algorithm. Brazilian Telecommunications Journal - SBT, Vol. 18, nro June 2003, pp. 77-85.
9. S. Werner, J.A. Apolinario Jr., M.L.R. de Campos: On the equivalence of RLS
implementations of LCMV and GSC processors. IEEE Signal Processing Letters, Vol. 10, nro 12, 2003, pp. 356-359.
10. P.S.R. Diniz, S. Werner: Set-membership Binormalized Data Reusing LMS Algorithms.
IEEE Transactions on Signal Processing, Vol. 51, nro Jan 2003, pp. 124-134.
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11. M. Tommiska: Efficient Digital Implementation of the Sigmoid Function for Reprogrammable Logic. IEEE Proceedings - Computers & Digital Techniques, 2003. Vol. 150, nro 6, pp.403-411.
11.3 Published Proceedings of International Conferences 1. T. Abrudan, M. Sirbu, V. Koivunen: Blind Multi-user Receiver for MIMO-OFDM
Systems. IV IEEE Workshop on Signal Processing SPAWC2003, Rome Italy, 15-18 June 2003.
2. F. Belloni, V. Koivunen: High-resolution Direction Finding using Uniform Circular
Array. Signal Processing Advances and Smart Antenna Systems, Helsinki, 7-8 October 2003.
3. F. Belloni, V. Koivunen: Unitary Root-Music Technique for Uniform Circular Array.
The 2003 International Symposium on Signal Processing and Information Technology, Darmstadt Germany, December 14-17 2003.
4. M. Enescu, T. Roman, Timo, V. Koivunen: Channel estimation and tracking in spatilly
correlated MIMO OFDM system. IEEE Workshop on Statistical Signal Processing, St.Louis MO USA, September 29- October 1 2003.
5. J. Eriksson, V. Koivunen: Identifiability and Separability of Linear Ica Models Revisited.
ICA2003 Fourth International Symposium on Independent Component, Analysis and Blind Signal Separation, Nara, Japan, April 1-4, 2003.
6. A. Hjörungnes, P.S.R. Diniz, M.L.R. de Campos: Jointly Minimum MSE Transmitter
and Receiver FIR MIMO Filters in the Presence of Near-End Crosstalk and Additive Noise. IEEE ISCAS2003, Bangkok Thailand, May 2003 Proceedings of IEEE ISCAS2003, Vol IV.
7. A. Hjörungnes, P.S.R. Diniz: Jointly Minimum Symbol Error Rate FIR MIMO
Transmitter and Receiver Filters for PAM Signal Vectors. IEEE ISCAS 2003, Bangkok Thailand, May 2003, Proceedings of IEEE ISCAS2003, Vol IV.
8. A. Hjörungnes, P.S.R. Diniz.: Minimum MSE Transmitter and Receiver FIR MIMO
Filters Including Decision Feedback and Near-End Crosstalk. 7th International Symposium on Digital Signal Processing and Communication Systems DSPCS´2003 &2ndWorkshop on the Internet, Telecommunications and Signal Processing WITSP´2003, Coolangatta-Gok Coast, Australia, 8-11 December 2003, pp. 264-269.
9. A. Hjörungnes, P.S.R. Diniz: On the Relevancy of the Perfect Reconstruction Property
when Minimizing the Mean Square Error in FIR MIMO Filter Systems. IEEE ISCAS2003, Bangkok Thailand, May 2003, Proceedings of IEEE ISCAS2003, Vol IV 2003, pp. 49-52.
10. J. Karvanen: Generation of Correlated Non-Gaussian Random Variables From
Independent Components. ICA2003 Forth International Symposium on Independent
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Component Analysis and Blind Signal Separation, Nara, Japan, April 1-4, 2003 pp. 769-774.
11. J. Karvanen, A. Cichocki: Measuring Sparseness of Noisy Signals. ICA2003 Fourth
International Symposium on Independent Component Analysis and Blind Signal Separation, Nara Japan, April 1-4, 2003, pp. 125-130.
12. J. Venäläinen, L. Terho, V. Koivunen: Modulation Classification in Fading Multipath
Channel. Thirty-Sixth Asilomar Conference on Signals, Systems & Computers, Pacific Grove California USA, 3-6 November 2002, pp. 1890-1894. (CD-ROM)
13. S. Visuri, V. Koivunen: Resolving Ambiguities in Subspace-Based Blind Receiver for
Mimo Channels. Thirty-Sixth Asilomar Conference on Signals, Systems & Computers, Pacific Grove California USA, November 3-6, 2002, pp. 589-593. (CD-ROM)
14. S. Visuri, A. Medles, D. Slock: On the effect of channel kowledge inperfections at the
transmitte on the capacity of MIMO systems. The seventh Internationsl Symposium on Signal Processing and its Applications, Paris, France, June 1-4, 2003. (CD-ROM).
15. S. Visuri, A. Medles, D. Slock: On MIMO capacity for various types of partial channel
knowledge at the transmitter. 2003 IEEE Omfpr,atopm Tjerpty Workshop, Paris, France, March 31 – April 4, 2003. (CD-ROM).
16. Y. Liu, P.S.R. Diniz, T.I. Laakso: Parallel-Cascade adaptive notch filter built on
orthogonal basis. The 2003 IEEE International Symposium on Circuits and Systems, ISCAS2003, Bangkok Thailand May 25-28, 2003.
17. M. Makundi, T.I. Laakso: Efficient symbol synchronization techniques using variable
FIR or IIR interpolation filters. The 2003 IEEE International Symposium on Circuits and Systems, ISCAS2003, Bangkok Thailand, May 25-28 2003, Vol 3, pp. 570-573.
18. E. Oja, V. Koivunen: Tracking Mobile Radios Using Antenna Arrays and Particle Filters
Antenna Arrays. NATO RTO Symposium on Smart and Adaptive Antennas Manchester UK, 7-9 April 2003. (CD-ROM).
19. E. Ollila, V. Koivunen: Influence functions for array covariance matrix estimators. IEEE
Workshop on Statistical Signal Processing SSP´03, St.Louis USA, Sept. 28- Oct.1.2003, pp. 445-448.
20. E. Ollila, E. Ollila, V. Koivunen: Robust Antenna Array Processing Using M-estimators
of Pseudo-Covariance. The 14th IEEE2003 International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC2003, Beijing China, September 7-10.2003,pp. 2659-2663.
21. E. Ollila, L. Quattropani, V. Koivunen: Robust Space-Time Covariance Estimation for
Smart Antennas. NATO RTO Symposium on Smart and Adaptive Antennas, Manchester UK, 7-9 April 2003. (CD-ROM)
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22. E. Ollila, V. Koivunen: Robust space-time scatter matrix estimator for broadband antenna arrays. IEEE Vehicular Technology Conference VTC´03-Fall, Orlando USA, Oct. 6-9, 2003.
23. C. Ribeiro, M. Campos de, P.S.R. Diniz: Zero-Forcing Multiuser Detection in CDMA
Systems Using Long Codes. IEEE Global Telecommunications Conference 2330 GLOBECOM´03, San Francisco CA USA, Dec. 2003. (CD-ROM)
24. T. Roman, M. Enescu, V. Koivunen: Joint Time-Doman Tracking of Channel and
Frequency Offset for OFDM systems. IV IEEE Signal Processing Workshop on Signal Processing Advances in Wireless Communications SPAWC 2003, Rome Italy, June 15-18, 2003.
25. T. Roman, M. Enescu, V. Koivunen: Recursive Estimation of Time-Varying Channel
and Frequency Offset in MIMO OFDM Systems. The 14th IEEE 2003 International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC2003, Beijing China, September 7.-10.2003, pp. 1934-1938.
26. T. Roman, M. Enescu, V. Koivunen: Time-domain method for tracking dispersive
channels in MIMO OFDM systems. IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Hong Kong, April 6-10, 2003, vol.4, pp. 393-396. (CD-ROM)
27. T. Roman, M. Enescu, V. Koivunen: Time-Domain Method for Tracking Dispersive
Channels in OFDM Systems. IEEE Vehicular Technology Conference, VTC 03 Spring, Jeju, Korea, 2003, Vol.2, pp. 1318-1321.
28. T. Roman, M. Enescu, V. Koivunen: Time-Doman method for tracking dispersive in
MIMO OFDM systems. Multimedia and Expo 2003, ICME´03, Baltimore USA 6-9 July 2003, Volume 2, pp. 609-612.
29. M. Sirbu, V. Koivunen: Low complexity synchronization method for uplink long-cpde
DS/CDMA. 2003 International Symposium on Intellegent Signal Processing and Communication Systems ISPACS2003, Awaji Island Japan, Dec. 7-10, 2003. (CD-ROM)
30. M. Sirbu, V. Koivunen: One-Step Refinement Method for Joint Channel Estimation and
Timing Acquisition in OFDM Transmission. 1st International Workshop in Signal Processing for Wireless Communications 2003, London UK, May 19-20, 2003. (CD-ROM)
31. M.L.R., de Campos, S. Werner, Jr. Apolinario, A. Jose: On an Efficient Implementation
of the Multistage Wiener Filter Through Householder Reflections for DS-CDMA Interference Suppression. IEEE Global Telecommunications Conference 2003 GLOBECOM´03 San Francisco CA USA, December, 2003. (CD-ROM).
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32. K. Järvinen, M. Tommiska, J. Skyttä: A Fully Pipelined Memoryless 17.8 Gbps AES-128 Encryptor. ACM/SIGDA 11th ACM International Symposium on Field Programmble Gate Arrays, Monterey California USA Feb. 23-25.2003. pp.207-215.
33. M. Elmusrati, M. Rintamäki, I. Hartimo, H. Koivo: Fully Distributed Power Control
Algorithm with One Bit Signaling and Nonlinear Error Estimation. 2003 IEEE 58th Vehicular Technology Conference - VTC2003-Fall, Orlando, Florida, USA, 6-9 October 2003. USA 2003, IEEE, 5 pp. (CD-ROM)
34. J. Hämäläinen, R. Wichman: Performance of Transmit Time Selection Diversity in
Multipath Fading Channels. The 6th International Symposium on Wireless Personal Multimedia Communications,WPMC´03, Yokosuka, Kanagawa, Japan October 19-22,2003. Japan 2003, pp. V3-207-211. (CD-ROM)
35. J. Hämäläinen, R. Wichman: On the Site Selection Diversity Transmission.
The 14th IEEE 2003 International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC2003, Beijing China, September 7-10, 2003. pp. 1031-1035.
36. J. Kairus, J. Forsten, M. Tommiska, J. Skyttä,: Bridging the gap between future software
and hardware engineering; a case study using the nios softcore processor. Frontiers in Education Conference-FIE2003, Colorado USA, November 5-8, 2003.
37. J. Hämäläinen, R. Wichman, J. Hulkkonen, T. Kähkönen, T. Korpi, M. Säily: On the
Performance of GSM/EDGE Transmit Diversity Schemes when Employing Dual-Polarized Antennas. IEEE Vehicular Technology Conference, Cheju Korea, April 2003. (CD-ROM)
38. J. Hämäläinen, R. Wichman: Bit error probabilitiesina two-rate communication system.
IEEE International Conference on Communications, Anchorage Alaska, May 10-18.2003. (CD-Rom)
39. J. Hämäläinen, R. Wichman: On Correlations between Dual-Polarized Base Station
Antennas. IEEE Global Telecommunications Conference 2003 GLOBECOM´03 San Francisco CA USA, December 2003.
11.4 Other Published Presentations at Scientific Meetings 1. H. Xu, T.I. Laakso: Joint Transmit and Receive Filter Design with Pre- and
Postequalization for Wireline Channels. The 2003 Finnish Signal Processing Symposium, Finsig´03, Tampere, Finland May 19, 2003, pp. 78-81.
2. M. Elmusrati, M. Rintamäki, I. Hartimo, H. Koivo: Estimated Step Power Control
Algorithm for Wireless Communication Systems. The 2003 Finnish Signal Processing Symposium - Finsig'03, Tampere, Finland, May 19, 2003. Tampere, Finland 2003, Institute of Signal Processing, Tampere University of Technology, pp. 32-34. (CD-ROM)
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3. F. Belloni, V. Koivunen : High-resolution Direction Finding Using Uniform Circular Array. Signal Processing Advances and Smart Antenna Systems, Helsinki, 7-8 October 2003.
4. M. With, S. Werner, T. Aittomäki, V. Koivunen: Anti-Jamming Receivers for Satellite
Navigation Systems. Signal Processing Advances and Smart Antenna Systems, Helsinki 7-8, November 2003. (CD-ROM)
11.5 Nonrefereed Articles and Reports 1. K. Kettunen: Soft Detection and decoding in wideband CDMA systems. Espoo, Report
38, 2003, pp.80. 2. A. Jääskeläinen (editor): Annual Report 2002, Espoo, Report 39, 2003, pp.30. 3. M. Rintamäki: Adaptive Power Control in CDMA Cellular Communication Systems.
Espoo. Report 40, 2003, pp.73. 4. T. Roman, M. Enescu, V. Koivunen: Joint Time-Doman Tracking of Channel and
Frequency Offset for MIMO OFDM Systems. Espoo, Report 41, 2003, pp. 23. 5. M. Sirbu, V. Koivunen: Delay estimation in long-code asynchronous DS/CDMA systems
using multiple antennas. Espoo, Report 42, 2003, pp. 25. 6. M. Pukkila: Iterative Receivers and Multichannel Equalisation for Time Division
Multiple Access Systems. Espoo, Report 43, 2003, pp. 70. 7. M. Sirbu: Channel and Delay Estimation Algorithms for Wireless Communication
Systems. Espoo, Report 45, 2003, pp. 95. 8. J. Anttila, J. Hämäläinen, J. Saranen: Spline Collocation For Pseudodifferential
Equations On The Torus. Oulu, 2003, pp. 18 (Report). 11.6 Patents 1. European Patent Office; EP 1 074 098 B1. Transmission Antenna Diversity. Nokia
Corporation, Espoo. (A. Hottinen, R. Wichman). Hak. 99916946.9, 23.04.1999. Julk. 2003. pp. 31
2. United States Patent; US 6,584,302 B1. Method and Arrangement for Forming a Beam.
Nokia Corporation, Espoo. (A. Hottinen, R. Wichman). Hak. 09/419,854, Oct.19,1999. Julk. 2003. pp. 20
3. United States Patent; US 6,594,248 B1. Data Transmission Method and a Radio
System. Nokia Corporation, Espoo. (J. Kärna, A. Toskala, P. Soininen, K. Kalliojärvi, A. Hottinen, R. Wichman). Hak. 09/407,568, Sep.28, 1999. Julk. 2003. pp. 14.
4. China; 99805390.2. Transmission Antenna Diversity. NOKIA, Oulu. (A. Hottinen, R.
Wichman). Hak. HO4B 7/06, 1999. Julk. 2003.
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12. PUBLICATIONS 2004
12.1 Books and Chapters in Books 1. V. Koivunen, M. Enescu, M. Sirbu: Blind and Semiblind Channel Estimation. In:
Nonlinear Signal and Image Processing Theory, Methods, and Applications. CRC PRESS 2004, Boca Raton Florida, pp. 257-294.
2. E. Ollila, V. Koivunen: Robust ML-estimation of the Transmitter Location. In: Theory
and Applications of Recent Robust Methods. Basel Switzerland 2004, Birkhäuser, pp. 247-258.
3. I. Pietarinen, P. Ahonen, N. Godenhjelm, I. Hartimo, P. Kilpeläinen, J. Korpela, T.
Kotovirta, S. Mattila, P. Saastamoinen, M. Taskinen: ATK-sanakirja. (13. painos). Helsinki 2004, Talentum Media Oy. 720 pages. http://www.kielikone.fi
4. M.L.R. de Campos, S. Werner, J.A. Apolinário Jr: Constrained Adaptive Filters. In:
Satish Chandran (editor), Adaptive Antenna Arrays. Springler Verlag, NY, June 2004. 5. J. Hämäläinen, R. Wichman, T. Korhonen: Multi-channel Adaptive Beam-forming. In:
Satish Chandran (editor), Adaptive Antenna Arrays, Springler Verlag, NY, June 2004. 12.2 Refereed Journal Articles 1. E. Ollila, C. Croux, H. Oja: Influence function and asymptotic efficiency at the affine
equivariant rank covariance matrix. Statistica Sinica, 2004. Vol. 14, nro 1, pp. 297-316. 1. J. Eriksson, V. Koivunen: Identifiability, Separability, and Uniqueness of Linear ICA
Models. IEEE Signal Processing Letters, 2004. Vol. 11, nro 7, pp.601-604. 3. M. Melvasalo, V. Koivunen: Blind Channel Estimation in Multicode CDMA Using
Multiantenna Receiver. Wireless Personal Communications, 2004. Nro 28, pp.163-178. 4. J. Karvanen, V. Koivunen: Independent component analysis via optimum combining
of kurtosis and skewness-based criteria. Journal of The Frankling Institute, 2004. Vol.341,pp.401-418.
5. M. Sirbu, V. Koivunen: Delay Estimation in Long-Code Asynchronous DS-CDMA Systems Using Multiple Antennas. EURASIP Journal on Wireless Communications and Networking, 2004. Nro 1, pp.84-97.
6. M. Rintamäki, H. Koivo, I. Hartimo: Adaptive Closed-Loop Power Control Algorithms
for CDMA Cellular Communications Systems. IEEE Transactions on Vehicular Technology, 2004. Vol. 53, nro 6, pp.1756-1768.
7. S. Werner, M.L.R. de Campos, P.S.R. Diniz: Partial-update NLMS algorithms with
data-selective updating. IEEE Transactions on Signal Processing, 2004. Vol. 52, nro April, 2004, pp.938-949.
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8. T. Roman, M. Enescu, V. Koivunen: Joint Time-Roman Tracking of Channel and
Frequency Offsets for MIMO OFDM Systems. Wireless Personal Communications, 2004. Vol.31, pp.181-200.
9. J. Anttila, J. Hämäläinen, J. Saranen: On the Linear Spline Collocation for
Pseudodifferential Equations on the Torus. Physics Mathematics, 2004. Vol. 53, nro 3, pp. 139-147.
10. J. Anttila, J. Hämäläinen, J. Saranen: On the Spline Collocation for Some
Pseudodifferential Equations on the Torus With Non-Uniform Meshes. International Journal of Pure and Applied Mathematics, 2004. Vol. 17, nro 1, pp. 103-117.
11. J. Hämäläinen, K. Pajukoski, E. Tiirola, R. Wichman, J. Ylitalo: On the Performance of
Multiuser MIMO in UTRA FDD Uplink, EURASIP Journal on Wireless Communications and Networking, December 2004, pp. 297-308.
12.3 Published Proceedings of International Conferences 1. M. Enescu, V. Koivunen: On the estimation of correlated noise statistics in a class of
state-space models. Thirty-seventh Asilomar Conference on Signals, Systems and Computers, CA USA, November 9-12 2003.
2. T. Abrudan, M. Sirbu, V. Koivunen: A Block-Toeplitz VCMA Equalizer for MIMO-
OFDM Systems. Thirty Seventh Asilomar Conference on Signals, Systems and Computers 2003, San Francisco CA USA, 9-12. Nov.2003. pp.1037-1041. (CD-ROM)
2. T. Roman, V. Koivunen: Blind CFO Estimation in OFDM Systems Using Diagonality
Criterion. IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2004, Montreal Canada, May 17.-21 2004. IV369-IV372.
4. T. Aittomäki, V. Koivunen: Recursive Householder-based Space-time Processor for
Jammer Mitigation in Navigation Receivers. 38th Annual CISS2004 Conference on Information Sciences and Systems, USA, March 17-19 2004. (CD-ROM)
5. J. Järvinen, V. Koivunen: Delta-signed Correlation Method for Noisy Channel
Identification. Thirty-Seventh Asilomar Conference on Signals, Systems & Computers, November 9-12.2003 CA, USA. pp.1138-1141. (CD-ROM)
6. M. Rintamäki, H. Koivo, I. Hartimo: Application on the generalized predictive control
method in closed-loop power control of CDMA cellular communication systems. 6th IEEE Nordic Signal Processing Symposium, NORSIG 2004, Finland, June 9-11, 2004. (CD-ROM)
7. P. Jantunen, G. Gámez, T.I. Laakso: Measurements and Modelling of Nonlinear
Power Amplifiers. 6th IEEE Nordic Signal Processing Symposium, NORSIG 2004, June 9-11, 2004 Espoo Finland. (CD-ROM)
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8. M. Cheong, S. Werner, T.I. Laakso: Design of Predistorters for Power Amplifiers in Future Mobile Communications Systems. 6th IEEE Nordic Signal Processing Symposium, NORSIG 2004, June 9-11, 2004. Espoo Finland. (CD-ROM)
9. F.H. Gregorio, J.E. Cousseau, J.L. Figueroa: Reducing impulsive noise in DSL
systems - robustness and delay. 6th IEEE Nordic Signal Processing Symposium, NORSIG 2004, June 9-11, 2004. Espoo Finland. (CD-ROM)
10. E. Ramirez, N. Nefedov: Soft Output Detection using Path Detector for Multiple Antennas. 6th Nordic Signal Processig Symposium, NORSIG 2004, June 9-11,2004 Espoo Finland. (CD-ROM)
11. T. Abrudan, A. Hjørungnes, V. Koivunen: A Blind equalizer for MIMO OFDM
Systems. International Zurich Seminar on Communications, Zurich Switzerland, 2004. pp. 212-215.
12. M. With, S. Werner, V. Koivunen: Householder-based Anti-jamming Navigation
Receiver Structures. SAM2004 Third IEEE Sensor Array Multichannel Signal Processing Workshop, Sitges, Spain, July 18-21, 2004.
13. C. Ribeiro, E. Ollila, V. Koivunen: Stochastic maximum likelihood method for
propagation parameter estimation. 2004 IEEE 15th International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC2004, Barcelona Spain, 5-8 September 2004.
14. A. Hämäläinen, M. Tommiska, J. Skyttä: FPGA-Based Implementation of a 59-Neuron
Feedforward Neutral Network with a 17.1 Gbps Interlayer Throughput. International Conference on Artificial Intelligence, IC-AI´04, Las Vegas, Nevada, USA June 21-24, 2004. (CD-ROM)
15. S. Visuri, H. Bölcskei: On Multiple Accessing For Frequency-Selective Mimo
Channels. XII. European Signal Processing Conference EUSIPCO-2004. pp. 523-527.
16. M. Enescu, T. Roman, M. Herdin: Kalman-Based Estimation of Measured Channels in Mobile MIMO OFDM System. XII. European Signal Processing Conference EUSIPCO-2004, September 6-10,2004 Vienna Austria. pp. 1865-1868. http://www.ieee.org
17. S. Werner, M. With, V. Koivunen: Householder based Low-Rank Space-time
Processor For Anti-jamming Navigation Receivers. XII.European Signal Processing Conference EUSIPCO-2004, September 6-10, 2004 Vienna, Austria. pp. 825-828. (CD-Rom)
18. T. Roman, S. Visuri, V. Koivunen: Performance bound for blind CFO estimation in
OFDM with real-valued constellations. 2004 IEEE 60th Vehicular Technology Conference, 26-29 September 2004, LA, California, USA. (CD-ROM)
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19. J. Eriksson, V. Koivunen: Complex-Valued ICA Using Second Order Statistics. Workshop on Machine Learning for Signal Processing XIV, Sao Luis, Brazil September 29 – October 1, 2004. pp. 183-191.
20. E. Ollila, V. Koivunen: Generalized Complex Elliptical Distributions. SAM2004
Third IEEE Sensor Array Multichannel Signal Processing Workshop July, 18-21, 2004 Sitges, Spain.
21. E. Ollila: Unitary Invariant Random Hermitian Matrices and Complex Elliptical
Distributions. The Thirteent International Workshop on Matrices and Statistics, IWMS´04, Bedlewo Poland, 18-21 August 2004.
22. P. Eskelinen, P. Vuorimaa, P. Vainikainen, I. Niemelä, R. Smeds, M. Tommiska, M.
Sipilä, K. Hytönen, K. Tenhonen, A.Paloheimo: Mobile security - in search for comprehensive integrity. IEEE 3G 2004 Conference, London, UK, 18-20 October. 5 p.
23. M. Sirbu, E. Delfino, V. Koivunen: MMSE Delay Acquisition of Pulse-Shaped Signals
in Satellite Navigation Systems. IEEE Vehicular Technology Conference 2004-Fall "Wireless Technologies for Global Security", Los Angeles, California, Sept 26-29, 2004. (CD-ROM)
24. M. Makundi, T.I. Laakso, A. Hjørungnes: Iterative Symbol Synchronization Using
Variable IIR and FIR Fractional-Delay Filters with Arbitrary Oversampling Ratios. 1st International Symposium on Wireless Communication Systems, Mauritius, 20-22 September, 2004. (CD-ROM)
25. M. Makundi, T.I. Laakso, A. Hjørungnes: Generalized Symbol Synchronization Using
Variable IIR and FIR Fractional-Delay Filters with Arbitrary Oversampling Ratios. ICASSP 2004 IEEE Conference on Acoustics, Speech & Signal Processing, Montreal, Canada, May 2004. (CD-ROM)
26. M. Sirbu, E. Delfino, V. Koivunen: A Novel Method for Time-Delay Acquisition in
Satellite Navigation Systems. 2004 International Symposium on Spread-Spectrum Technologies and Applications, Sydney, Australia Aug.30- Sept.2, 2004. (CD-ROM)
27. K. Järvinen, M. Tommiska, J. Skyttä: A Scalable Architecture for Elliptic Curve Point
Multiplication. The 2004 IEEE International Conference on Field-Programmable Technology, FPT 2004, Brisbane, Queensland, Australia, December, 6-8, 2004. pp.303-306.
28. K. Järvinen, M. Tommiska, J. Skyttä: A VHDL Generator for Elliptic Curve
Cryptography. The 14th International Conference on Field Programmable Logic and Applications, FPL 2004, Antwerp, Belgium, August 29 - September 1, 2004. pp.1098-1100.
29. M. Enescu, M. Herdin, T. Roman, V. Koivunen: Parameter estimation of measured
channels in mobile MIMO OFDM system. The 4th IEEE International Symposium on
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Signal Processing and Information Technology IEEE ISSPIT2004, Rome, Italy, December 18-21, 2004. pp.123-126. http://www.ieee.org
30. T. Nyblom, T. Roman, M. Enescu, V. Koivunen: Time-Varying Carrier Offset
Tracking in OFDM Systems Using Particle Filtering . The 4th IEEE International Symposium on Signal Processing and Information Technology IEEE ISSPIT2004, Rome, Italy December 18-21, 2004. pp. 217-220. http://www.ieee.org
31. J. Hämäläinen, R. Wichman: Performance of Multiuser Diversity in the Presence of
Feedback Errors. 2004 IEEE 15th International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC2004, Barcelona, Spain, 5-8 September, 2004.
32. J. Hämäläinen, R. Wichman: Quantization of Channel Quality Indicator in Maximum
SNR Scheduling. Nordic Radio Symposium 2004, Oulu, Finland 16-18 August, 2004. 33. F.H. Gregorio, T.I. Laakso, R. Wichman: Comparison of Clustered and Antenna
Interleaving OFDM in Multiple-Antenna Systems with Amplifier Nonlinearities. 2004 International Conference on Signal Processing and Communications SPCOM2004, Bangalore, India.
34. J. Cousseau, P. Doñate, Y. Liu: Factorized all-pass IIR adaptive notch filters. IEEE
International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Montreal, Canada, May 17-21, 2004.
35. J. Hämäläinen, K. Pajukoski, E. Tiirola, R. Wichman, J. Ylitalo: MIMO Performance
in UTRA FDD Uplink. IEEE International Symposium of Spread Spectrum Techniques and Applications, September 2004, Sydney, Australia.
12.4 Nonrefereed Articles and Reports 1. J. Eriksson, V. Koivunen: Identifiability, Separability and Uniqueness of Complex ICA
Models. Espoo: Teknillinen korkeakoulu, 2004. pp.33 (Signal Processing Laboratory, Report 44).
2. J. Eriksson: Contributions to Theory and Algorithms of Independent Component
Analysis and Signal Separation. Espoo: 2004. pp. 59 (Signal Processing Laboratory, Report 47).
3. F. Belloni, V. Koivunen: Beamspace Transform for UCA: Error Analysis and Bias
Reduction. Espoo: 2004. (Signal Processing Laboratory, Report 48). 4. T. Abrudan, V. Koivunen: Convergence Analysis of a Blind Receiver for MIMO-
OFDM Systems. Espoo: 2004. pp. 29 (Signal Processing Laboratory, Report 49).
12.5 Patents 1. Suomi - Finland, FI 113818 B. Menetelmä Informaation välittämiseksi tiedonsiirto-
järjestelmässä, tiedonsiirtojärjestelmä, verkkoelementti sekä langaton viestin. Nokia Corporation, Helsinki. ( Wichman Risto ja Ranta Pekka). Hak. 20002568, 23.11.2000. Julk. 2004. 28 s.
