Prof. Lempiäinen has concentrated to propagation of wireless systems, and to system planning challenges of wireless systems.
His mission is to find new revolutionary solutions / applications for mobile communications technology field.
Head of Radio Network Planning Group (RNP).
More information at www.tuni.fi/rnp
Field of expertise
Prof. Lempiäinen’s research interest includes different aspects of evolution of mobile communications. The evolution understanding contains several system level areas as deep technical details (e.g. need of antenna development) as knowledge of techno-economical approaches as definition of indoor/outdoor service scenarios in multi-technology environment (e.g. 5G vs. WiFi).
Prof. Lempiäinen has also expanded last seven years his knowledge and expertise in the area of critical communication.
Critical communication including 5G
Ambient backscattering Communication (ABC)
Single Path Single Access
Radio Network Planning Group (RNP). More information at www.tuni.fi/rnp
Prof. E.S. Lohan received an MSc degree in Electrical Engineering from Polytechnics University of Bucharest (1997), a DEA degree in Econometrics at Ecole Polytechnique, Paris (1998), and a PhD degree in Telecommunications from Tampere University of Technology (2003). She is now a Full Professor at the Electrical Engineering unit at Tampere University (former Tampere University of Technology) and a Visiting Professor at Universitat Autonoma de Barcelona (UAB), Spain (spcomnav group). She is leading a research group on Signal processing for wireless positioning (www.cs.tut.fi/tlt/pos). She is a co-editor of the first book on Galileo satellite system (Springer "Galileo Positioning technology"), co-editor of a Springer book on "Multi-technology positioning", and author or co-author in more than 250 international peer-reviewed publications, 6 patents and inventions. She is also an associate Editor for RIN Journal of Navigation and for IET Journal on Radar, Sonar, and Navigation. She is now the coordinator of the H2020 MSCA European Joint Doctorate A-WEAR (www.a-wear.eu), 2019-2022.
Field of expertise
signal processing for wireless positioning; GNSS algorithms; wearable computing; privacy-aware indoor and outdoor localization; digital contact tracing; interference detection, mitigation, and classification; RF fingerprinting; IoT localization
Wireless positioning, UMTS/WCDMA mobile positioning, GNSS (Galileo, GPS and modernised GPS, GLONASS, Beidou), CDMA signal processing algorithms, baseband receiver processing such as acquisition and tracking, Binary Offset Carrier (BOC) modulation studies, accurate tracking in multipath channels, unambiguous acquisition of BOC/MBOC signals, sidelobe cancellation methods, wireless channel modelling, Carrier To Noise Ratio (CNR) estimators, Simulink-based models for Galileo and GPS receivers, WLAN-based positioning, cellular based positioning, user-driven Location Based Services, user surveys and statistical analysis, compressed sensing for WLAN localisation, 3D localisation and floor detection, spectrum sensing for location purposes, signals of opportunity, 5G positioning, convergence of communication and navigation signals, users mobility models, privacy and physical layer security in mobile localisation, interference detection, classification, mitigation, and localization, location-based beamforming, IoT communication and localization, communication and positioning algorthims for commercial aviation, general aviation and Unmanned Aerial Vehickes (UAVs), location-based e-health applications, industrial internet, etc.
Over 30 years experience on electronics, computer engineering, communications engineering and positioning technologies, both in academia and industry. Organizing conferences and other events and doctoral education are close to my heart.
As a professor (since 1999) the main tasks include research fund raising, research management, supervision of doctoral and MSc students, and education and research. Director of national DELTA doctoral training network, head of the European Joint Doctorate A-WEAR at Tampere University, coordinator of APROPOS MSCA ITN, and organizer of several international conferences per year as a chairman or steering group member. Research Integrity Advisor.
Field of expertise
Expertise in embedded processor systems, reconfigurable computing, approximate computing, digital circuits and systems, digital implementations of communications receivers and networks, software-defined radio, software-defined networking, positioning technology (in particular GNSS receiver architectures).
Research assistant 1987-88, Research Scientist 1988-91, acting Associate Professor 1991-1993, Senior Research Scientist 1994, Vice President (VLSI Solution Oy) 1995-98, Full Professor 1999-
32 supervised PhD dissertations, examiner or opponent for about 50 PhD dissertations worldwide, over 150 supervised/examined MSc theses, editor of 5 books, awards as conference organizer and innovator.
Head of A-WEAR joint doctoral program at Tampere University, vice chair of the steering group of the international BSc program, steering group member of four international conferences (chairman in two: IEEE Nordic Circuits and Systems Conference, International Conference on Localization and GNSS), member of the VLSI Systems and Applications technical committee at IEEE Circuits and Systems Society, editorial board member in three international scientific journals. Tampere Congress Ambassador. Research Integrity Advisor.
Aditi Site, Jari Nurmi, and Elena Simona Lohan, “Machine-learning-based diabetes prediction using multi-sensor data,” in IEEE Sensors, 2023, doi: 10.1109/JSEN.2023.3319360.
Joaquin Torres Sospedra, Pavel Pascacio de Los Santos, Sven Casteleyn, Elena Simona Lohan, and Jari Nurmi, “L/F-CIPS: Collaborative indoor positioning for smartphones with lateration and fingerprinting,” in IEEE Sensors, 2023, doi: 10.1109/JSEN.2023.3308147.
Dewant Katare, Diego Perino, Jari Nurmi, Martijn Warnier, Marijn Janssen, and Aaron Yi Ding, “A Survey on Approximate Edge AI for Energy Efficient Autonomous Driving Services,” in IEEE Communications Surveys & Tutorials, 2023, doi: 10.1109/COMST.2023.3302474.
Darwin Quezada-Gaibor, Lucie Klus, Roman Klus, Elena Simona Lohan, Jari Nurmi, Mikko Valkama, Joaquín Huerta, and Joaquín Torres-Sospedra, “Auto-Encoder Extreme Learning Machine for Fingerprint-Based Positioning: A Good Weight Initialization is Decisive,” in IEEE Journal of Indoor and Seamless Positioning and Navigation, vol. 1, 2023, pp. 53-68 doi: 10.1109/JISPIN.2023.3299433.
Hans Jakob Damsgaard, Aleksandr Ometov, Md Munjure Mowla, Adam Flizikowski, and Jari Nurmi, “Approximate Computing in B5G and 6G Wireless Systems: A Survey and Future Outlook,” in Computer Networks, Elsevier, 2023.
Antoine Grenier, Elena Simona Lohan, Aleksandr Ometov, and Jari Nurmi, “A Survey on Low-Power GNSS,” in IEEE Communications Surveys and Tutorials, 2023. doi: 10.1109/COMST.2023.3265841.
Lucie Klus, Roman Klus, Joaquin Torres Sospedra, Elena Simona Lohan, Carlos Granelli, Jari Nurmi, “EWOk: Towards Efficient Multidimensional Compression of Indoor Positioning Datasets,” in IEEE Transactions on Mobile Computing, 2023.
Iñigo Cortés, Johannes Rossouw Van der Merwe, Elena Simona Lohan, Jari Nurmi, and Wolfgang Felber, “Low-Complexity Adaptive Full Direct-State Kalman Filter for Robust GNSS Tracking,” in Sensors, 2023, 23, 3658. https://doi.org/10.3390/s23073658.
Tiago Troccoli, Juho Pirskanen, Jari Nurmi, Aleksandr Ometov, Jorge Morte, Elena Simona Lohan, and Ville Kaseva, “Direction-of-Arrival Method for L-Shaped Array with RF Switch: An Embedded Implementation Perspective,” in Sensors, MDPI, 2023, 23(6), 3356, doi: 10.3390/s23063356.
Aleksandr Ometov, Anzhelika Mezina and Jari Nurmi, "On Applicability of Imagery-Based CNN to Computational Offloading Location Selection," in IEEE Access, vol. 11, pp. 2433-2444, 2023, doi: 10.1109/ACCESS.2022.3232469.
Joaquín Torres-Sospedra, Darwin Quezada Gaibor, Jari Nurmi, Yevgeni Koucheryavy, Elena Simona Lohan, and Joaquin Huerta, “Scalable and Efficient Clustering for Fingerprint-Based Positioning,” in IEEE Internet of Things Journal, vol. 10, no. 4, pp. 3484-3499, Feb.15, 2023, doi: 10.1109/JIOT.2022.3230913.
Hans Jakob Damsgaard, Aleksandr Ometov, and Jari Nurmi, “Approximation Opportunities in Edge Computing Hardware: A Systematic Literature Review,” in ACM Computing Surveys, 2022 (online), doi: 10.1145/3572772.
Aditi Site, Saigopal Vasudevan, Samuel Afolaranmi, Jose L. Martinez Lastra, Jari Nurmi, and Elena Simona Lohan, “A Machine-Learning-Based Analysis of the Relationships between Loneliness Metrics and Mobility Patterns for Elderly,” in Sensors, MDPI, 2022, 22(13), 4946. doi: 10.3390/s22134946.
Iñigo Cortés, Johannes Rossouw van der Merwe, Elena Simona Lohan, Jari Nurmi, and Wolfgang Felber, “Performance Evaluation of Adaptive Tracking Techniques with Direct-State Kalman Filter,” in Sensors, MDPI, 2022, 22(2), 420. doi: 10.3390/s22020420.
Darwin Quezada Gaibor, Joaquín Torres-Sospedra, Jari Nurmi, Yevgeni Koucheryavy, and Joaquín Huerta, “Cloud Platforms for Context-Adaptive Positioning and Localisation in GNSS-denied Scenarios - A Systematic Review,” in Sensors, MDPI, 2022, 22, 110. doi: 10.3390/s22010110
Aleksandr Ometov, Oliver Liombe Molua, Mikhail Komarov, and Jari Nurmi, “A Survey of Security in Cloud, Edge, and Fog Computing,” in Sensors, MDPI, 2022, 22, 927. doi: 10.3390/s22030927.
Aditi Site, Jari Nurmi, and Elena Simona Lohan, “Systematic Review on Machine-Learning Algorithms used in Wearable-based eHealth Data Analysis,” in IEEE Access, 2021, doi: 10.1109/ACCESS.2021.3103268.
Pavel Pascacio, Sven Casteleyn, Joaquin Torres Sospedra, Elena Simona Lohan, and Jari Nurmi, “Collaborative Indoor Positioning Systems: A Systematic Review,” in Sensors, MDPI, 2021, 21, 1002. https://doi.org/10.3390/s21031002.
Lucie Klus, Roman Klus, Elena Simona Lohan, Carlos Granell, Jukka Talvitie, Mikko Valkama, and Jari Nurmi, “Direct Lightweight Temporal Compression for Wearable Sensor Data,” in IEEE Sensors Letters, Jan. 2021, doi: 10.1109/LSENS.2021.3051809.
Iñigo Cortés, Johannes Rossouw van der Merwe, Jari Nurmi, Alexander Rügamer, and Wolfgang Felber, “Evaluation of Adaptive Loop-Bandwidth Tracking Techniques in GNSS Receivers,” in Sensors, MDPI, 2021, 21, 502. https://doi.org/10.3390/s21020502.
Most cited publications (Google Scholar):
Xin Wang, Tapani Ahonen, and Jari Nurmi, “Applying CDMA Technique to Network-on-Chip,” in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, Vol. 15, No. 10, pp. 1091-1100, October 2007.
Jari Nurmi, Hannu Tenhunen, Jouni Isoaho, and Axel Jantsch (Eds.), Interconnect-Centric Design for Advanced SoC and NoC, Kluwer Academic Publishers, 2004, ISBN 1-4020-7835-8.
Tapani Ahonen, David Sigüenza Tortosa, and Jari Nurmi, “Topology Optimization for Application-Specific Networks-on-Chip,” in Proc. 6th International Workshop on System Level Interconnect Prediction, Paris, France, February 14-15, 2004.
Jari Nurmi (Ed.), Processor Design: System-on-Chip Computing for ASICs and FPGAs, Springer, 2007, ISBN 978-1-4020-5529-4.
Pavel Pascacio, Sven Casteleyn, Joaquin Torres Sospedra, Elena Simona Lohan, and Jari Nurmi, “Collaborative Indoor Positioning Systems: A Systematic Review,” in Sensors, MDPI, 2021, 21, 1002. doi: 10.3390/s21031002.
David Sigüenza Tortosa and Jari Nurmi, “Proteo: A New Approach to Network-on-Chip,” in Proc. International Conference on Communication Systems and Networks (CSN’02), Malaga, Spain, September 9-12, 2002, pp. 355-357.
Ilkka Saastamoinen, David Sigüenza Tortosa and Jari Nurmi, ”Interconnect IP Node for Future System-on-Chip Designs,” in Proc. 1st International Workshop on Electronic Design, Test & Applications Delta2002, Christchurch, New Zealand, January 29-31, 2002, pp. 116-120.
Aleksandr Ometov, Oliver Liombe Molua, Mikhail Komarov, and Jari Nurmi, “A Survey of Security in Cloud, Edge, and Fog Computing,” in Sensors, MDPI, 2022, 22(3), 927. doi: 10.3390/s22030927.
Ilkka Saastamoinen, Mikko Alho and Jari Nurmi, “Buffer Implementation for Proteo Networks-on-Chip,” in Proc. International Symposium on Circuits and Systems ISCAS 2003, Bangkok, Thailand, May 25-28, 2003.
Jari Nurmi, Elena-Simona Lohan, Stephan Sand, and Heikki Hurskainen (Eds.), GALILEO Positioning Technology, Springer, 2014, ISBN 978-94-007-1829-6, Doi 10.1007/978-94-007-1830-2.
David Sigüenza Tortosa, Tapani Ahonen and Jari Nurmi, “Issues in the Development of a Practical NoC: The Proteo Concept,” in Integration, The VLSI Journal, Elsevier, Vol. 38, pp. 95-105, October 2004.
Waleed Bin Qaim, Aleksandr Ometov, Antonella Molinaro, Ilaria Lener, Claudia Campolo, Elena Simona Lohan, and Jari Nurmi, “Towards Energy Efficiency in the Internet of Wearable Things: A Systematic Review,” in IEEE Access, 2020, doi: 10.1109/ACCESS.2020.3025270.
Jari Nurmi, “Network-on-Chip: A New Paradigm for System-on-Chip Design,” invited paper in Proc. International Symposium on System-on-Chip SoC 2005, Tampere, Finland, November 15-17, 2005, pp. 2-6.
David Sigüenza Tortosa and Jari Nurmi, “VHDL-based Simulation Environment for Proteo NoC,” in Proc. Seventh Annual IEEE International Workshop on High Level Design Validation and Test (HLDVT’02), Cannes, France, October 27-29, 2002, pp. 1-6.
Omer Anjum, Tapani Ahonen, Fabio Garzia, Jari Nurmi, Claudio Brunelli, and Heikki Berg, “State of the Art Baseband DSP Platforms for Software Defined Radio: a Survey,” in EURASIP Journal on Wireless Communication and Networking, Hindawi, June 2011. doi:10.1186/1687-1499-2011-5.
Heikki Hurskainen, Elena Simona Lohan, Xuan Hu, Jussi Raasakka, and Jari Nurmi, “Multiple Gate Delay Tracking Structures for GNSS Signals and Their Evaluation with Simulink, SystemC and VHDL,” in International Journal of Navigation and Observation, Hindawi, vol. 2008, Article ID 785695, 17 pages, 2008. Doi:10.1155/2008/785695.
Francescantonio Della Rosa, Mauro Pelosi, and Jari Nurmi, "Human-Induced Effects on RSS Ranging Measurements for Cooperative Positioning," in International Journal of Navigation and Observation, vol. 2012, Article ID 959140, 13 pages, 2012. doi:10.1155/2012/959140.
Faculty of Information Technology and Communication Sciences
Microelectronics, analog/RF/mixed-signal circuits, digital integrated circuits, data conversion, nanometer-scale CMOS, signal processing
My research is broadly on developing architectures, circuit techniques and signal processing concepts towards energy-efficient high-performance analog/digital/RF/mixed-signal integrated circuits and systems in nanometer-scale CMOS nodes. A dominant theme is to explore the possibility of building analog/mixed-signal circuits with digital/switch components by utilizing time-based parameters of pulse waveform for representation of analog information, thus improving the scaling-friendliness and cross-technology portability of analog interfaces. Starting from behavioral modeling of systems and communication links along with underlying nonidealities, we develop new system architectures and circuit techniques to push the performance boundary, and validate them in Silicon by designing and characterizing prototype chips in nanometer-scale CMOS technologies. Application areas of interest include 5G-Advanced/6G wireless transceivers, high-speed serial links and wireline transceivers, biomedical electronics etc. The group works in close collaboration with the SoC Hub, an ecosystem created Tampere University and a consortium of local businesses to boost research and education in the area of system-on-chip design, thus achieving synergy with industrial interests.
Applications are invited from highly motivated and talented individuals towards doctoral studies and postdoctoral research (salaried positions), throughout the year. Paid master thesis work and summer jobs are also available in the area of IC design and signal processing. Please contact for more information.
Active research areas/projects include the following, but are not limited to those.
K. Spoof, M. Tenhunen, V. Unnikrishnan, K. Stadius, M. Kosunen and J. Ryynänen, "True-Time-Delay Receiver IC With Reconfigurable Analog and Digital Beamforming," in IEEE Access, vol. 10, pp. 116375-116383, 2022, doi: 10.1109/ACCESS.2022.3219938.
O. Järvinen et al., "Energy-Efficient Cyclic-Coupled Ring Oscillator With Delay-Based Injection Locking," in IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 69, no. 9, pp. 3709-3713, Sept. 2022, doi: 10.1109/TCSII.2022.3176805.
O. Järvinen, I. Kempi, V. Unnikrishnan, K. Stadius, M. Kosunen and J. Ryynänen, "Fully Digital On-Chip Wideband Background Calibration for Channel Mismatches in Time-Interleaved Time-Based ADCs," in IEEE Solid-State Circuits Letters, vol. 5, pp. 9-12, 2022, doi: 10.1109/LSSC.2022.3145918.
O. Järvinen, V. Unnikrishnan, W. Siddiqui, T. Korhonen, K. Koli, K. Stadius, M. Kosunen, J. Ryynänen, "A 100–750 MS/s 11-Bit Time-to-Digital Converter With Cyclic-Coupled Ring Oscillator," in IEEE Access, vol. 9, pp. 48147-48156, 2021, doi: 10.1109/ACCESS.2021.3068838.
V. Unnikrishnan, O. Järvinen, W. Siddiqui, K. Stadius, M. Kosunen and J. Ryynänen, "Data Conversion With Subgate-Delay Time Resolution Using Cyclic-Coupled Ring Oscillators," in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 29, no. 1, pp. 203-214, Jan. 2021, doi: 10.1109/TVLSI.2020.3031028.
K. Spoof, M. Zahra, V. Unnikrishnan, K. Stadius, M. Kosunen and J. Ryynänen, "A 0.6–4.0 GHz RF-Resampling Beamforming Receiver With Frequency-Scaling True-Time-Delays up to Three Carrier Cycles," in IEEE Solid-State Circuits Letters, vol. 3, pp. 234-237, 2020, doi: 10.1109/LSSC.2020.3012654.
K. Spoof, V. Unnikrishnan, M. Zahra, K. Stadius, M. Kosunen and J. Ryynänen, "True-Time-Delay Beamforming Receiver With RF Re-Sampling," in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 67, no. 12, pp. 4457-4469, Dec. 2020, doi: 10.1109/TCSI.2020.3005475.
O. Olabode, M. Kosunen, V. Unnikrishnan, T. Palomäki, T. Laurila; K. Halonen, J. Ryynänen, "Time-Based Sensor Interface for Dopamine Detection," in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 67, no. 10, pp. 3284-3296, Oct. 2020, doi: 10.1109/TCSI.2020.3008363.
V. Unnikrishnan and M. Vesterbacka, "Mitigation of Sampling Errors in VCO-Based ADCs," in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 64, no. 7, pp. 1730-1739, July 2017, doi: 10.1109/TCSI.2017.2670058.
V. Unnikrishnan and M. Vesterbacka, "Time-Mode Analog-to-Digital Conversion Using Standard Cells," in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 61, no. 12, pp. 3348-3357, Dec. 2014, doi: 10.1109/TCSI.2014.2340551.
I am working as a staff scientist at the faculty of Information Technology and Communication Sciences, at Tampere University, in close collaboration with the Electrical Engineering Unit in the field of Communications Engineering and Radio Systems. Also, I am one of the responsible persons related to drone operations at Tampere University.
Wireless communications infrastructure: RF lab (TC407b), 4G/5G mobile networks, LoRAWAN IoT network, and wireless mesh network around Hervanta campus.
I am responsible for the wireless communications research infrastructure located at the Hervanta campus. I also study the corresponding research field.
In addition, my responsibilities include, but are not limited to: teaching, MSc supervision, responsible person of EE webpages, networking and research services for industry and research organizations. Supporting research application preparations related to the use of wireless infrastructures.
5G, B5G, 6G networks, UAV and UAS, IoT technologies.