PhD position at CentraleSupélec

11 Mai 2022

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Catégorie : Doctorant

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Terahertz (THz)-band (0.1-10 THz) communication is envisioned as a key wireless technology of the next decade. The THz band will help overcome the spectrum scarcity problems and capacity limitations of current wireless networks, by providing an unprecedentedly large bandwidth which can enable applications including Terabit-per second backhaul systems, ultra-high-definition content streaming among mobile devices and wireless high-bandwidth secure communications [1].

More recently, THz communications has been identified by IEEE COMSOC as one of the nine communication technology trends to follow. As 5G technology becomes commercial, Terahertz communication is where fundamental scientific and engineering breakthroughs will occur. Nonetheless, the THz band, which lies in between mm-waves and the far infrared, remains still one of the least explored regions in the EM spectrum. For many decades, the lack of compact high-power signal sources and high-sensitivity detectors able to work at room temperature has hampered the use of the THz band for any application beyond sensing. However, many recent advancements with different technologies are finally closing the so-called THz gap. THz-band communication brings many new opportunities to the wireless communication community [1].

However, still open challenges are remaining, it is well known that the adverse channel conditions at sub-THz frequencies make the communication a hard challenge, however it can be compensated by means of using a large number of antennas, which results in large array gains [3]. However, digital beamforming techniques for such antenna arrays cannot be implemented easily due to their high cost and power consumption. Therefore, analog and hybrid beamforming (HB) techniques have been proposed [2-3].

Besides HB, the application of spatial modulation (SM) techniques [4] in sub-THz communications has also recently attracted substantial research interest. In this family of modulation schemes, we have two principal members: the generalized SM (GSM) and the generalized precoding SM (GPSM). For both, two data streams are transmitted in parallel: one in the in-phase/quadrature (IQ) domains by using conventional signal constellations, and the other in the spatial domain where the information is transmitted via the activated transmitting (receiving) antenna indices in the GSM (GPSM) case [5] [6].

The general target of this PhD is to propose efficient Hybrid precoded beam (HB) structures in downlink spatial modulation, using available Sub-THz channel state information (CSI) knowledge. The techniques to be proposed should enable Sub-THz communication in a multi-User MIMO context and should target at minimizing the energy consumption at the base station.

 

Detailed/main targets of this Thesis are:

1. Literature review (6 months)
2. Ob1: Propose innovative adaptive multi-user multiple antennas (MU-MIMO) schemes combining spatial modulation (SM) and Hybrid Beamforming (HB) schemes, taking into account the characteristics of the Sub-THz communication band. The starting MIMO model will be the GSM (generalized SM).
3. Ob2: Explore the downlink SM in Sub-THz with MU-MIMO systems, where the spatial information is conveyed by the indices of the receiving IQ streams. Consider innovative indexation schemes to enhance the spectral efficiency and reduce the required transmit energy at the base station coupled with proposed HB structures.

References:

 

[1] Zhi Chen;Xinying Ma;Bo Zhang;Yaxin Zhang;Zhongqian Niu;Ningyuan Kuang;Wenjie Chen;Lingxiang Li;Shaoqian Li, “A survey on terahertz communications “ China Communications Volume: 16, Issue: 2. Year 2019.

[2] Chong Han; Longfei Yan; Jinhong Yuan, “Hybrid Beamforming for Terahertz Wireless Communications: Challenges, Architectures, and Open Problems”, IEEE Wireless Communications, Volume: 28, Issue: 4. Year: 2021

[3] J. T. Wang, S. Y. Jia, J. Song, “Generalized spatial modulation system with multiple active transmit antennas and low complexity detection scheme,” IEEE Trans. Wireless Commun., vol.11, no. 4, pp. 1605-1615, Apr. 2012.

[4] M Di Renzo, H Haas, PM Grant, “Spatial modulation for multiple-antenna wireless systems: A survey. IEEE Communications Magazine 49 (12), 182-191, 2011.

[5] L. He, J. Wang, and J. Song, “Spectral-efficient analog precoding for generalized spatial modulation aided mmwave MIMO,” IEEE Transactions on Vehicular Technology, vol. 66, no. 10, pp. 9598–9602, 2017.

 

This PhD. project will start approximately in October 2022 and will be supervised by Dr. A. NAFKHA (HDR), Dr. Georgios ROPOKIS from CentraleSupélec, Rennes and Dr. Yahia MEDJAHDI from IMT Nord Europe, Lille. Only shortlisted candidates will be contacted.

 

Covered Areas:

MIMO schemes, Digital communications, Beyond 5G, Signal processing

 

Contacts:

●Amor NAFKHA, Associate Professor (HDR), CentraleSupélec, Rennes

amor.nafkha@centralesupelec.fr

●Georgios ROPOKIS, Associate Professor, CentraleSupélec, Rennes

georgios.ropokis@centralesupelec.fr

●Yahia MEDJAHDI, MCF, IMT Nord Europe, Lille

yahia.medjahdi@imt-nord-europe.fr

 

Keywords: Sub-THZ band, Hybrid Beamforming, Spatial Modulation, MU-MIMO