November 2024
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Publications (63)
October 2024
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8 Reads
IEEE Antennas and Wireless Propagation Letters
This paper presents the frequency dependence of the path loss exponent (PLE) based on measurement results of multiple frequency bands in indoor environments and explains the propagation mechanisms that cause frequency dependence. Path loss measurements from 0.8 GHz to 66.5 GHz in two indoor open office environments were used to derive the parameters of a close-in free space reference distance model (CI model) and an alpha-beta-gamma model (ABG model). We revealed that the PLE of the single-frequency CI model tended to decrease with increasing frequency, while the frequency coefficient of the ABG model was smaller than that of the free space loss (FSPL), indicating a different frequency dependence than FSPL in these environments. Furthermore, the propagation mechanisms of the waveguide effect and the first Fresnel zone shielding cause this frequency dependence. Ray-tracing simulations revealed that the PLE becomes large and small in the low- and high-frequency bands, respectively, when the ceiling height is low, consistent with the measurements. The PLE becomes small regardless of the frequency band when the ceiling height is high, indicating frequency dependence along the propagation mechanism in both the ray-tracing simulation and measurement results.
September 2024
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2 Reads
July 2024
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5 Reads
June 2024
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3 Reads
June 2024
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1 Read
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1 Citation
March 2024
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10 Reads
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2 Citations
March 2024
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6 Reads
March 2024
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3 Reads
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1 Citation
October 2023
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2 Reads
Citations (32)
... This setup fails to capture the omnidirectional multipath characteristics, where significant multipath rays can arrive from 360° in the azimuth plane, as demonstrated in this study. An exception is the work in [24], which conducted measurements in a real office desk environment within the 110 [31]. However, these studies typically focused on longer-range communications, such as cellular or WLAN-type communications, where the propagation characteristics differ significantly from those in personal office desk environments. ...
- Citing Conference Paper
June 2024
... The authors of [17] developed a sub-THz massive multipleinput multiple-output (MIMO) channel sounder using 896 antenna elements, offering a high time-spatial channel resolution. The developed channel sounder could determine how many pathways arrived with a lower received power in real time. ...
- Citing Conference Paper
March 2024
... The authors of [7] utilized visual data obtained from multi-view sensing cameras to predict path loss. The authors of [8] utilized side-view images between the transmitter and receiver, along with frequency information, to predict path loss. The work in [9] employed 2D satellite images of the target area as input to a deep neural network to predict path loss distributions at various UAV altitudes. ...
- Citing Article
October 2023
IEICE Communications Express
... For DOA measurement, methods using array antennas with super-resolution algorithms [4,5] and methods using physically rotating large aperture antennas [6,7] are employed. For frequencies beyond 100 GHz, the first method is not easy to prepare array antennas. ...
- Citing Conference Paper
March 2023
... In next-generation mobile communications, the proactive use of millimeter-wave (mm-wave) and terahertz-wave (THz-wave) frequencies, which can secure a wide frequency bandwidth, is anticipated to achieve further high-speed and large-capacity communications. Various studies have reported on the characteristics of path-loss, delay, and direction-of-arrival (DOA) for these frequencies in different scenarios [1][2][3]. ...
- Citing Conference Paper
March 2023
... In [74] the imaging method, a variant of ray tracing, is approached with a quantum annealer. Given a number of VOLUME 11, 2023 interactions N and a set of M interaction objects, the problem to be solved is to find the dominant propagation path, i.e., the path that experiences exactly N reflections or diffractions and has minimal propagation loss (PL). ...
- Citing Conference Paper
December 2022
... Several applications of DNN for the next generation of wireless communication systems (e.g., 6G) have recently emerged [3]. Models utilizing this technique have been proposed for path loss estimation, which is essential for the cell and system design of wireless communications [4,5,6,7]. These models use the convolutional neural network (CNN) as the DNN [5,7], which enables feature quantities (e.g., building profile) to be automatically and internally extracted from input images and utilized for estimation. ...
- Citing Conference Paper
March 2022
... Despite promising features, major challenges in the effective usage of higher frequency bands include high free space path loss (FSPL), atmospheric attenuation in gasses and rainfall, and non-line of sight (NLOS) propagation issues, that lead to the degradation of signal-to-noise ratio (SNR) and data rates [11][12][13][14][15]. To solve these issues, high-gain and highly-directive antennas have been commonly used; however, as a result, the beam coverage has become quite narrow, limiting the practicality of such systems. ...
- Citing Article
- Full-text available
April 2022
International Journal of Microwave and Wireless Technologies
... 10 to 100 times of the current 5G peak rate [4]. The other characteristics encompass remarkable penetrability [5], the capacity to traverse non-metallic materials without inflicting any damage, and the low energy levels that minimize harm to living organisms, thereby facilitating non-destructive testing. ...
- Citing Conference Paper
March 2021
... Against the previous methods, Sotiroudis et al. [19] developed a long short-term memory neural network for the prediction of PL with the frequency of 2-26 GHz. Other relevant works adopted DL or ML to predict PL over a channel [20]- [22]. Some of the methods are support vector machine (SVM) [23], random forest [24], and K-nearest neighbors (KNN) [25]. ...
- Citing Conference Paper
March 2021