December 2017
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4 Reads
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1 Citation
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December 2017
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4 Reads
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1 Citation
October 2017
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10 Reads
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3 Citations
September 2017
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25 Reads
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1 Citation
NTT Technical Review
Before frequencies are allocated to new wireless communication systems, it is important to investigate frequency sharing to avoid interference with existing systems. The International Telecommunication Union Radiocommunication Sector Study Group 3 (ITU-R SG 3) supports activities of other SGs by developing and maintaining recommendations for radiowave propagation characteristics and prediction models necessary for frequency sharing studies. This article introduces the activities of ITU-R SG 3 focused on the use of high frequency bands in new wireless communication systems such as the fifthgeneration mobile communication system (5G).
August 2017
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24 Reads
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1 Citation
IEICE Transactions on Communications
This paper describes analytical results obtained for floor penetration loss characteristics and their frequency dependency by measurements in multiple frequency bands, including those above 6 GHz, in an indoor office environment. Measurement and analysis results confirm that the floor penetration loss depends on two dominant components: the transmission path through floors, and the path traveling through the outside building. We also clarify that these dominant paths have different path loss characteristics and frequency dependency. The transmission path through floors rapidly attenuates with large inter-floor offsets and in high frequency bands. On the other hand, the path traveling through outside of the building attenuates monotonically as the frequency increases. Therefore, the transmission path is dominant at short inter-floor offsets and low frequencies, and the path traveling through the outside is dominant at high number of floors or high frequency. Finally, we clarify that the floor penetration loss depends on the frequency dependency of the dominant path on the basis of the path loss characteristics of each dominant path.
July 2017
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5 Reads
NTT Technical Review
NTT Access Network Service Systems Laboratories and NTT DOCOMO have been carrying out joint research and development (R&D) toward construction of the fifth-generation mobile communications system (5G). This article presents a path loss model developed as one of our R&D activities.
April 2017
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7 Reads
NTT Technical Review
Tsukuba Forum 2016 was held on October 25 and 26. The theme of the forum was "Future Social Infrastructure: Co-creating a Better Life with Valued Partners - Innovative Access Network to Actualize the NetroSphere Concept." This article gives a brief overview of the speeches and exhibits presented at the forum.
March 2017
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2 Reads
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1 Citation
Measurement results of path loss characteristics up to 37 GHz band in street microcell environments are described. Ray tracing is used to analyze the effects of building shapes on path loss characteristics at an intersection. A comparison between measured and calculated results clarified the dominant paths in which specular reflection from a chamfered shaped building contributes the power. The results show that the median prediction error value ranged from about 4.1 to 7.0 dB for bands between 2.2 and 37.1 GHz. This confirms that the building shapes significantly affect the path loss characteristics in NLOS street microcell environments.
February 2017
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14 Reads
IEICE Transactions on Communications
This paper proposed that a path loss model for outdoor-to-indoor corridor is presented to construct next generation mobile communication systems. The proposed model covers the frequency range of millimeter wave bands up to 40 GHz and provides three dimensional incident angle characteristics. Analysis of path loss characteristics is conducted by ray tracing. We clarify that the paths reflected multiple times between the external walls of buildings and then diffracted into one of the buildings are dominant. Moreover, we also clarify how the paths affect the path loss dependence on frequency and three dimensional incident angle. Therefore, by taking these dependencies into consideration, the proposed model decreases the root mean square errors of prediction results to within about 2 to 6 dB in bands up to 40 GHz. © 2017 The Institute of Electronics, Information and Communication Engineers.
December 2016
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17 Reads
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2 Citations
NTT Technical Review
To design coverage areas for wireless communication systems and evaluate the performance of the systems, it is necessary to develop a path loss model that can be used for the systems' frequency bands. The fifth-generation mobile communication system (5G) is expected to use high frequency bands above 6 GHz. Therefore, developing a path loss model for wireless access communication systems using high frequency bands has become a pressing issue. NTT Access Network Service Systems Laboratories has developed path loss models for the 20-40 GHz bands that are suitable for use scenarios of mobile phones and wireless local area networks. This article introduces the developed models.
April 2016
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12 Reads
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11 Citations
... 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. ...
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. ...
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. ...
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. ...
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]. ...
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). ...
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. ...
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. ...
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. ...
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]. ...
March 2021