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Mobile radio network planning is challenging since the service demand in a practical network is not geographically uniform and network deployments are becoming increasingly irregular. Our main goal has been to develop a methodology that provides a new general theoretical framework for the analysis of the dependencies between different network factors (service demand, load, channels, etc).

Recent examples of publications:

D. G. Gonzalez, H. Hakula, A. Rasila, J. Hämäläinen: "Spatial Mappings for Planning and Optimization of Cellular Networks", IEEE/ACM Transactions on Networking, Vol. 26, No. 1, February 2018.

D. G. Gonzalez, J. Hämäläinen: "Looking at Cellular Networks Through Canonical Domains and Conformal Mapping", IEEE Transactions on Wireless Communications, Vol.15, No.5, 2016.

IoT is a promising research direction with notable practical importance. Our focus has been in the massive mobile network connectivity for delay tolerant IoT devices. Work includes protocol design and use of multi-antenna systems for IoT.

Recent examples of publications:

Y. Zou, K. T. Kim, X. Lin, M. Chiang, Z. Ding, R. Wichman, J. Hämäläinen: "Low-Overhead Joint Beam-Selection and Random-Access Schemes for Massive Internet-of-Things with Non-Uniform Channel and Load", IEEE International Conference on Computer Communications (INFOCOM), 2020.

A. Dowhuszko, G. Corral-Briones, J. Hämäläinen, R. Wichman: "Performance of Quantized Random Beamforming in Delay-Tolerant Machine-Type Communication", IEEE Transactions on Wireless Communications, Vol.15, No.8, August 2016.

This is a new but promising research direction. The VLC research community is still quite small, but we expect that VLC will gain momentum in the near future.

Recent examples of publications:

A. Dowhuszko, M. C. Ilter, J. Hämäläinen: "Visible Light Communication System in Presence of Indirect Lighting and Illumination Constraints", IEEE International Conference on Communications (ICC), 2020.

A. Dowhuszko, M. C. Ilter, P. Pinho, J. Hämäläinen: "The effect of power allocation on visible light communication using commercial phosphor-converted led lamp for direct illumination", IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), 2020.

In this field work has covered information theoretic questions where the extreme value theory and free probability theory can be applied, and irregular signal constellations that can be used to improve physical layer efficiency.

Recent examples of publications:

R. Duan, Z. Zheng, R. Jäntti, J. Hämäläinen, Z. J. Haas: "Asymptotic Analysis for Spectrumsharing Systems with TAS/MRC Using Extreme Value Theory: An Overlooked Aspect", IEEE Access, vol.7, No.1, December 2019.

M. C. Ilter, H. U. Sokun, H. Yanikomeroglu, R. Wichman, J. Hämäläinen: "The Joint Impact of Fading Severity, Irregular Constellation, and Non-Gaussian Noise on Signal Space Diversity-Based Two-Way Relaying Networks", IEEE Access, Vol.7, 2019.

Z. Zheng, L. Wei, R. Speicher, R. Muller, J. Hämäläinen, J. Corander: "Asymptotic Analysis of Rayleigh Product Channels: A Free Probability Approach", IEEE Transactions on Information Theory, Vol. 63, No. 3, March 2017.

The V2X communication has recently attracted a lot of research interest in both academic and industry communities. The automotive industry is investing heavily on the development of road safety and autonomous driving applications that in many cases assume fast and reliable communication between vehicle and network or between vehicle and other road users. We started the work from physical layer models including V2X channel modelling but recently research has covered system level studies.

Recent examples of publications:

M. U. Sheikh, J. Hämäläinen, D. Gonzalez G, R. Jäntti and O. Gonsa: "Usability Benefits and Challenges in mmWave V2V Communications: A Case Study", International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), 2019.

U. Saeed, J. Hämäläinen, M. Garcia-Lozano, D. Gonzalez G.: "On the Feasibility of Remote Driving application over Dense 5G Roadside Networks", International Symposium on Wireless Communication Systems (ISWCS), 2019.

S. Yoo, D. Gonzalez G., J. Hämäläinen, and K. Kim: "Doppler Spectrum Analysis of a Roadside Scatterer Model for Vehicle-to-Vehicle Channels: An Indirect Method", IEEE Transactions on Wireless Communications, Vol. 17, No. 12, December 2018.

Herein large part of our research is related to the development and performance analysis of mobile communication systems from early G’s until 5G and beyond. Main research topics have been: Multi-antenna methods, network energy efficiency, self-organizing networks, radio layer scheduling, relaying and flexible spectrum use.

Some examples of publications:

[24] Q. Chen, G. Yu, H. M. Elmaghraby, J. Hämäläinen, Z. Ding: "Embedding LTE-U within Wi-Fi Bands for Improved Spectrum Efficiency", IEEE Network Magazine, Vol.31, No.2, March/April 2017.

[25] D. G. Gonzalez, J. Hämäläinen, H. Yanikomeroglu, M. Garcia-Lozano, G. Senarath: "A Novel Multiobjective Cell Switch-O_ Framework for Cellular Networks", IEEE Access, Vol.4, 2016, pp. 7883 - 7898.

[26] B. B. Haile, A. Dowhuszko, J. Hämäläinen, R. Wichman, Z. Ding: "On the Performance of Some CoMP Techniques under Channel Power Imbalance and Limited Feedback", IEEE Transactions on Wireless Communications, Vol.14, No.10, August 2015.