Browsing by Author "De Guzman, Mar Francis"

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  • Analyses of Beamspace MIMO Channels at 142GHz
    (2024-01-01) De Guzman, Mar Francis; Tervo, Nuutti; Kyosti, Pekka; Haneda, Katsuyuki
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This letter presents the analyses of a single-user beamspace multiple-input-multiple-output (MIMO) on measured indoor and outdoor channels at 142 GHz. The rank is evaluated under different antenna sizes, number of beams, and thresholds. We assume a total power constraint at the transmitter that results in a decrease in a signal-to-noise ratio as the link distance increases. When using spatial multiplexing, the indoor and outdoor sites demonstrate an average capacity gain of 2× and 1.5× at link distances below 60 m. Also, the rank for our measured 142 GHz channels is comparable to that at 60 GHz channels but significantly lower than the rank at 5 GHz channels reported in the literature. We also found that at 142 GHz, the indoor and outdoor sites have median ranks of 3.0 and 1.7 for the small-antenna case, and 4.9 and 2.4 for the large-antenna case assuming a rank threshold of 20 dB. The indoor site has a rank higher by 1.8 than the outdoor site, regardless of the antenna size. The rank decreases by only 20% and 15% for indoor and outdoor scenarios when the beam density is halved, allowing a significant reduction in implementation complexity of the beamspace MIMO without remarkably reducing the rank.
  • Channel sounder at millimeter-wave frequencies
    (2021-05-16) Vehkalahti, Joona
     Sähkötekniikan korkeakoulu | Bachelor's thesis
  • Comparison of Indoor Propagation Channels at 28 GHz and 140 GHz Bands
    (2024) De Guzman, Mar Francis; Haneda, Katsuyuki
     A4 Artikkeli konferenssijulkaisussa
    In this paper, a comparison between the measured 28 GHz and 140 GHz channels in an entrance hall is presented. The path loss, angular spread, delay spread, and composite power angular spectrum (PAS) are evaluated and compared with reference indoor channels in an office, existing model, and shopping mall. The existing model and office path loss curves align with the path loss of line-of-sight (LOS) and non-LOS (NLOS) links, respectively. When using the full dynamic range, the angular spread does not change with frequency, while the delay spread decreases with frequency in the entrance hall. The differences in angular spread and delay spread vary between the entrance hall and other indoor environments due to differences in layout. The composite PAS at both bands are similar for both LOS and NLOS links. The channels have larger angular and delay spread at 140 GHz than 28 GHz when the same dynamic range is used.
  • Evaluating the Beamforming Impact on Channel Dispersion Characterization Using Multi-Scenario Sub-THz Channel Measurements
    (2025) Zhang, Peize; De Guzman, Mar Francis; Lyu, Yejian; Haneda, Katsuyuki; Tervo, Nuutti; Parssinen, Aarno; Kyosti, Pekka
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    To provide substantially high capacity, future 6G networks will be able to operate in higher frequency bands than current 5G networks. However, owing to the significant differences in channel characteristics between lower bands (< 100 GHz) and sub-terahertz (sub-THz) band (i.e., 100-300 GHz), novel waveform and air interface design for sub-THz systems need to account for the radio channels observed by practical beam patterns. In this paper, we investigate the beamforming impact on the characterization of angular and time dispersion based on extensive measured channel data at 142 GHz across multiple scenarios. A post-processing method for analysis of beamforming impact on channel dispersion is proposed using measured propagation channel data. Since sub-THz radio links necessitate high antenna gains, we first find the potential beam directions from beamformed channels and then form single- and multi-beam patterns towards desired directions under practical constraints. The angular spread of the beamformed channels observed by steered beams will be widened especially in line-of-sight scenarios. The beam-weighted radio channel is considered as the basis of calculating time dispersion parameters, i.e., beam gains are multiplied by the measured propagation path gains before the analysis. Preliminary results show that the reduction of delay spread and maximum excess delay depends mainly on scenario, link distance, and used beamwidth, and partly on sidelobe level.
  • How many beams does sub-THz channel support
    (2022-01) Kyosti, Pekka; De Guzman, Mar Francis; Haneda, Katsuyuki; Tervo, Nuutti; Parssinen, Aarno
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Antenna, radio frequency (RF) circuit, algorithm, and system researchers on sub-THz RF are interested in knowing characteristics of corresponding radio channels. Among other things, a relevant question is the number of beams supported by the channel. From wideband directional propagation measurements one can estimate how many significant paths are present in a measurement location, but interpreting that to separable beams is not trivial. In this letter, we introduce three methods to approximate the number of beams that a measured power angular delay profile can support. We show also example evaluations and distribution functions of beam numbers, estimated from indoor D-band measurement data.
  • Integration of Communication and Sensing in 6G: A Joint Industrial and Academic Perspective
    (2021-09-13) Wymeersch, Henk; Shrestha, Deep; De Lima, Carlos Morais; Yajnanarayana, Vijaya; Richerzhagen, Bjorn; Keskin, Musa Furkan; Schindhelm, Kim; Ramirez, Alejandro; Wolfgang, Andreas; De Guzman, Mar Francis; Haneda, Katsuyuki; Svensson, Tommy; Baldemair, Robert; Parkvall, Stefan
     A4 Artikkeli konferenssijulkaisussa
    6G will likely be the first generation of mobile communication that will feature tight integration of localization and sensing with communication functionalities. Among several worldwide initiatives, the Hexa-X flagship project stands out as it brings together 25 key players from adjacent industries and academia, and has among its explicit goals to research fundamentally new radio access technologies and high-resolution localization and sensing. Such features will not only enable novel use cases requiring extreme localization performance, but also provide a means to support and improve communication functionalities. This paper provides an overview of the Hexa-X vision alongside the envisioned use cases. To close the required performance gap of these use cases with respect to 5G, several technical enablers will be discussed, together with the associated research challenges for the coming years.
  • Path loss, angular spread and channel sparsity modeling for indoor and outdoor environments at the sub-THz band
    (2024-10) Selimis, Dimitrios G.; De Guzman, Mar Francis; Manganaris, Kyriakos N.; Lazarakis, Fotis I.; Haneda, Katsuyuki; Peppas, Kostas P.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In this paper, we present new measurement results to model large-scale path loss, angular spread and channel sparsity at the sub-THz (141–145 GHz) band, for both indoor and outdoor scenarios. Extensive measurement campaigns have been carried out, taking into account both line-of-sight (LoS) and non line-of-sight (NLoS) propagation. For all considered propagation scenarios, omni-directional and directional path loss models have been developed, based on the so-called close-in (CI) free-space reference distance model. A power angular spread analysis is further presented. The sparsity of the wireless channel has also been studied by employing suitable metrics, namely the so-called Gini index (GI), the Ricean K-factor and the root mean square (RMS) delay spread.
  • Ray-optics simulations of sub-THz wave propagation, targeting 6G wireless Communications
    (2024-08-19) Arshad, Nida
     Sähkötekniikan korkeakoulu | Master's thesis
    The thesis investigates the challenges associated with wireless communication in urban environment, paying particular attention to the effects of multipath, shadowing and reflection loss on signal coverage and quality. The study finds the optimal concrete permittivity value and generates detailed coverage map that takes reflection loss and link blockage into account using ray optics modeling technique. The study enhances the precision of coverage predict and provides insights for wireless network design and optimization. With implications for upcoming developments in 6G technologies, these findings deepen the understanding of the interaction between urban obstacles and sub-terahertz (sub-THz) wave propagation.
  • Real-Time Over-the-Air Emulation of Rician Fading Channels for Mobile Antenna Testing
    (2024) Kourani, Ali; De Guzman, Mar Francis; Tian, Ruiyuan; Haneda, Katsuyuki
     A4 Artikkeli konferenssijulkaisussa
    As the ubiquity of 5G technology permeates various domains, coupled with the introduction of new carrier frequencies under the New Radio (NR) framework, devices employing this advanced technology require stringent and repeatable operational conformance tests. Those tests are essential to ascertain the AUT performance under realistic deployment scenarios, thereby ensuring reliability. Hence emulating realistic channel characteristics is fundamental to reach a reliable evaluation of radio components. Considering small-scale fading phenomena is imperative in evaluating the operational integrity of radio devices, as it pervades everything from vehicular communications to the mobility of user equipment. This work demonstrates implementing and validating the operation of a Rician fading channel emulator which can be integrated in an over-the-air antenna testbed. It provides a real-time cost-effective solution using off-the-shelf software defined radios (SDR). The paper provides an overview on the hardware setup and the software implementation of the Rician fading emulator. The setup is tested in an anechoic chamber and comparative analysis showed a robust correlation between the empirical data and theoretical plots of the Rician fading magnitude statistics.
  • Stochastic Characterization of outdoor Terahertz Channels Through Mixture Gaussian Processes
    (2022) Papasotiriou, Evangelos N.; Boulogeorgos, Alexandros Apostolos A.; De Guzman, Mar Francis; Haneda, Katsuyuki; Alexiou, Angeliki
     A4 Artikkeli konferenssijulkaisussa
    This contribution aims at experimentally validating the suitability of Gaussian mixture (GM) distributions to capture the stochastic characteristics of outdoor terahertz (THz) wireless channels. In this direction, we employ a machine learning enabled approach, based on the expectation maximization algorithm, in order to identify the suitable number of Gaussian distributions as well as their corresponding parameters that result to an acceptable fit. The fitting accuracy of the GMs to the empirical distributions is evaluated by means of the Kolmogorov-Smirnov (KS), Kullback-Leibler (KL), root-mean-square-error (RMSE) and R2 fitting accuracy tests. These tests verify the suitability of GMs to model the small-scale fading channel amplitude of outdoor THz wireless links. In addition, the fitting accuracy results indicate that as the number of mixtures increases the resulting GMs achieve a better fit to the empirical data.
  • Towards versatile access networks
    (2023-06-06) Ghoraishi, Mir; Alexiou, Angeliki; Cogalan, Tezcan; Conrat, Jean Marc; De Guzman, Mar Francis; Devoti, Francesco; Eappen, Geoffrey; Fang, Chao; Frenger, Pål; Girycki, Adam; Guo, Hao; Halbauer, Hardy; Haliloglu, Omer; Haneda, Katsuyuki; Koffman, Israel; Kyösti, Pekka; Leinonen, Marko; Li, Yinggang; Madapatha, Charitha; Makki, Behrooz; Navarro-Ortiz, Jorge; Nguyen, Le Hang; Nimr, Ahmad; Pärssinen, Aarno; Pollin, Sofie; Pryor, Simon; Puerta, Rafael; Rahman, Md Arifur; Ramos-Munoz, Juan J.; Ranjbar, Vida; Roth, Kilian; Sarajlic, Muris; Sciancalepore, Vincenzo; Svensson, Tommy; Tervo, Nuutti; Wolfgang, Andreas
     A3 Kirjan tai muun kokoomateoksen osa
    Compared to its previous generations, the 5th generation (5G) cellular network features an additional type of densification, i.e., a large number of active antennas per access point (AP) can be deployed. This technique is known as massive multipleinput multiple-output (mMIMO) [1]. Meanwhile, multiple-input multiple-output (MIMO) evolution, e.g., in channel state information (CSI) enhancement, and also on the study of a larger number of orthogonal demodulation reference signal (DMRS) ports for MU-MIMO, was one of the Release 18 of 3rd generation partnership project (3GPP Rel-18) work item. This release (3GPP Rel-18) package approval, in the fourth quarter of 2021, marked the start of the 5G Advanced evolution in 3GPP. The other items in 3GPP Rel-18 are to study and add functionality in the areas of network energy savings, coverage, mobility support, multicast broadcast services, and positioning.