Matti Hämäläinen

Dr. Matti Hämäläinen

Centre for Wireless Communications, University of Oulu, Oulu, Finland
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Research Focus & Metrics

Academic Career Length

29Years (1998-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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2 May 2021 in Sensors
Verified
Journal Article
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MHMatti Hämäläinen
Matti Hämäläinen
Lorenzo MucchiLorenzo Mucchi
Lorenzo Mucchi
Stefano CaputoStefano Caputo
Stefano Caputo
Lorenzo BiottiLorenzo Biotti
Lorenzo Biotti
LCLorenzo Ciani
Lorenzo Ciani
Gabriele PatriziGabriele Patrizi
Gabriele Patrizi
In this paper, we propose an unobtrusive method and architecture for monitoring a person’s presence and collecting his/her health-related parameters simultaneously in a home environment. The system is based on using a single ultra-wideband (UWB) impulse-radar as a sensing device. Using UWB radars, we aim to recognize a person and some preselected movements without camera-type monitoring. Via the experimental work, we have also demonstrated that, by using a UWB signal, it is possible to detect small chest movements remotely to recognize coughing, for example. In addition, based on statistical data analysis, a person’s posture in a room can be recognized in a steady situation. In addition, we implemented a machine learning technique (k-nearest neighbour) to automatically classify a static posture using UWB radar data. Skewness, kurtosis and received power are used in posture classification during the postprocessing. The classification accuracy achieved is more than 99%. In this paper, we also present reliability and fault tolerance analyses for three kinds of UWB radar network architectures to point out the weakest item in the installation. This information is highly important in the system’s implementation.

20 March 2020 in IEEE Access
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Open access
Mariella SärestöniemiMariella Särestöniemi
Mariella Särestöniemi
CPCarlos Pomalaza-Raez
Carlos Pomalaza-Raez
CKChaïmaâ Kissi
Chaïmaâ Kissi
MBMarkus Berg
Markus Berg
MHMatti Hämäläinen
Matti Hämäläinen
JIJari Iinatti
Jari Iinatti
This paper presents a study on the ultra wideband (UWB) radio channel characteristics between a capsule endoscope and a directive on-body antenna in different parts of the small intestine. The study is conducted using a finite integration technique (FIT) based electromagnetic simulation software CST Studio Suite and four of its anatomical voxel models. The capsule endoscope model is set inside different areas of the small intestine of the voxel models. A recently published directive on-body antenna designed for in-body communications is used in the evaluations. The obtained frequency and time domain channel characteristics are compared with previously published results with another directive on-body antenna designed for capsule endoscopy communications. Power flow presentations are used to understand differences obtained with two on-body antennas. Different rotation angles of the capsule are also considered in this study. It is found that channel characteristics vary remarkably depending on the antenna location in the small intestine and location of the on-body antenna. Thus, the on-body antennas should be located carefully to ensure coverage over the whole intestine area. Path loss does not only depend on the distance between a capsule and the on-body antenna but also on the tissues between the capsule and on-body antennas. Obviously, the antenna patterns have clear impact on the received signal’s strength. Furthermore, orientation of the capsule affects also strongly impact when linearly polarized antennas are used.

14 August 2020 in IEEE Access
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Journal Article
Open access
MHMatti Hämäläinen
Matti Hämäläinen
Lorenzo MucchiLorenzo Mucchi
Lorenzo Mucchi
MGMarc Girod-Genet
Marc Girod-Genet
TPTuomas Paso
Tuomas Paso
JFJohn Farserotu
John Farserotu
PDPhilippe Dallemagne
Philippe Dallemagne
This paper presents a condensed review of the European smart body area network (BAN) standardization work and its already published standards. The work is carried out under the ETSI Technical Committee (TC) SmartBAN. The goal of ETSI TC SmartBAN is to define and develop new European BAN standards; fostering the successful market adoption of wireless BAN technology by providing a standardized way to bring new interoperable products into the health, medical, sport, leisure and IoT markets, targeting to global exploitation. TC SmartBAN covers wireless communications, especially the physical and medium access control layers, associated security, semantic interoperability and open data representation, which are necessary features in the data transmissions, as well as building blocks of the future smart coordinator. The use of smart coordinator centralizes the network intelligence to the hub, which enables implementation of simple nodes. The SmartBAN approach will be computationally light, and it supports reliable operations across heterogeneous networks. Due to the semantic approach in all functional levels, SmartBAN also supports high interoperability. For emergency traffic, SmartBAN provides different priority classes and fast channel access associated with a low latency. Novel concept adopted in the SmartBAN for high-priority traffic is a multi-use channel access, which can also improve the spectral efficiency. Not only on-body nodes and applications, TC SmartBAN is considering in-body communications for capsule endoscopy. In addition, SmartBAN collaborates with other standardization groups, such as oneM2M and AIOTI, to widen the impact of its work.

1 March 2013
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Conference Paper
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TTTommi Tuovinen
Tommi Tuovinen
TKTimo Kumpuniemi
Timo Kumpuniemi
KYKamya Yekeh Yazdandoost
Kamya Yekeh Yazdandoost
MHMatti Hämäläinen
Matti Hämäläinen
JIJari Iinatti
Jari Iinatti
In this paper, the interaction between the ultra wideband (UWB) antenna and human body is considered and demonstrated in the range of 0-30 mm above the body surface, which could be practical operation distance for the on-body antenna. Two different planar UWB antennas (loop and dipole) are used for the examinations. First, the antenna performance in free space (FS) is shown. Then, the effect of the antenna-body distance on the antenna operation is analysed in the terms of the matching, i.e., reflection coefficient S 11 . Measurements are carried out in the proximity of a real human body while the simulations are run by using the whole body model having a frequency-dependent behaviour. Observations are concluded to commensurate with the antenna field regions and the size of antenna's reactive near-field was satisfied to be an important factor in the evaluation of an acceptable on-body operation. No significant differences between different antennas were observed through investigations. Both antennas perform satisfactory when the distance is high enough. The results of this study are helpful to engineers and designers evaluating antennas for the use in UWB wireless body area network (WBAN) applications.

1 November 2009
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Conference Paper
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HVHarri Viittala
Harri Viittala
MHMatti Hämäläinen
Matti Hämäläinen
JIJari Iinatti
Jari Iinatti
ATA. Taparugssanagorn
A. Taparugssanagorn
In this paper, a summary of the IEEE802.15.6 wireless body area network (WBAN) radio channel models is given and the models are compared to the corresponding results obtained from the measurements carried out at the Oulu University hospital, Oulu, Finland. CWC has done a set of experimental UWB on-body channel modeling independently of the measurements that are behind the IEEE model. Being statistically more reliable, CWC's results correspond with the models presented by the IEEE806.15.6 task group. Different scenarios for the WBAN link setups have been considered in both campaigns.

25 June 2003
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Conference Paper
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VHV. Hovinen
V. Hovinen
MHMatti Hämäläinen
Matti Hämäläinen
TPT. Patsi
T. Patsi