Kiyoshi Igarashi

Bio: Kiyoshi Igarashi is an academic researcher from National Institute of Information and Communications Technology. The author has contributed to research in topics: Attenuation & Ku band. The author has an hindex of 7, co-authored 16 publications receiving 130 citations.

Rain attenuation model for south east asia countries

Abstract: A model for predicting rain attenuation on Earth-to-space is developed by using the measured data obtained from tropical and equatorial regions that was revised from the ITU model. The proposed rain attenuation model uses the complete rainfall rate cumulative distribution as input data. It is shown that significant improvements in terms of prediction error over existing attenuation models are obtained.

Analysis of Tropospheric Scintillation Intensity on Earth to Space in Malaysia

Abstract: This paper presents the results of a study on tropospheric scintillation on satellite link that has been performed at University Sains Malaysia (USM) to obtain statistics of scintillation from the 12.255 GHz Superbird C satellite with an elevation angle of 40.10. The objective of this analysis was to determine whether the long-term scintillation follows the log normal or gamma distribution. It was found that the long term probability distribution follows the log-normal distribution. The short term probability distribution also follows the log-normal model for the driest and the wettest month. It has been proven that the log-normal model is also suitable for prediction at moderate angles.

Rain Attenuation of Satellite link in Ku-band at Bangkok

Abstract: Rain attenuation is a major factor to degrade the system performance in a frequency above 10 GHz. This paper presents a statistical analysis of the rainfall rate and the rain attenuation data on satellite to ground propagation path. By measuring 12.7-GHz beacon signal attenuation from JCSAT satellite and the rainfall rate continuously. Yearly cumulative distribution functions were then compared to predicted models. The Crane Global model for the rain zone H provides overestimated predicted values to the measured ones. For the rain zone G, the Crane global model provides close values to ITU-R model; both are smaller than the measured ones

Measurement of Tropospheric Scintillation from Satellite Beacon at Ku-Band In South East Asia

Abstract: Summary This paper presents the results of beacon measurements on a moderate elevation satellite link at 12.255 GHz during the present of scintillation were analyzed. The spectra of the beacon signal were extracted from the raw beacon data using high pass filter with suitable cutoff frequency where the scintillation here are characterized by standard deviation of the amplitude fluctuations and by the distribution of amplitude deviations from their mean. The mean of the power spectra that’s been displayed by two asymptotic with the values was found to be close to the slope of the Kolmogorov spectra.

Millimeter-Wave Communications: Physical Channel Models, Design Considerations, Antenna Constructions, and Link-Budget

Abstract: The millimeter wave (mmWave) frequency band spanning from 30 to 300 GHz constitutes a substantial portion of the unused frequency spectrum, which is an important resource for future wireless communication systems in order to fulfill the escalating capacity demand. Given the improvements in integrated components and enhanced power efficiency at high frequencies, wireless systems can operate in the mmWave frequency band. In this paper, we present a survey of the mmWave propagation characteristics, channel modeling, and design guidelines, such as system and antenna design considerations for mmWave, including the link budget of the network, which are essential for mmWave communication systems. We commence by introducing the main channel propagation characteristics of mmWaves followed by channel modeling and design guidelines. Then, we report on the main measurement and modeling campaigns conducted in order to understand the mmWave band’s properties and present the associated channel models. We survey the different channel models focusing on the channel models available for the 28, 38, 60, and 73 GHz frequency bands. Finally, we present the mmWave channel model and its challenges in the context of mmWave communication systems design.

A Comprehensive Survey on Millimeter Wave Communications for Fifth-Generation Wireless Networks: Feasibility and Challenges

Abstract: Fifth-generation (5G) cellular networks will almost certainly operate in the high-bandwidth, underutilized millimeter-wave (mmWave) frequency spectrum, which offers the potentiality of high-capacity wireless transmission of multi-gigabit-per-second (Gbps) data rates. Despite the enormous available bandwidth potential, mmWave signal transmissions suffer from fundamental technical challenges like severe path loss, sensitivity to blockage, directivity, and narrow beamwidth, due to its short wavelengths. To effectively support system design and deployment, accurate channel modeling comprising several 5G technologies and scenarios is essential. This survey provides a comprehensive overview of several emerging technologies for 5G systems, such as massive multiple-input multiple-output (MIMO) technologies, multiple access technologies, hybrid analog-digital precoding and combining, non-orthogonal multiple access (NOMA), cell-free massive MIMO, and simultaneous wireless information and power transfer (SWIPT) technologies. These technologies induce distinct propagation characteristics and establish specific requirements on 5G channel modeling. To tackle these challenges, we first provide a survey of existing solutions and standards and discuss the radio-frequency (RF) spectrum and regulatory issues for mmWave communications. Second, we compared existing wireless communication techniques like sub-6-GHz WiFi and sub-6 GHz 4G LTE over mmWave communications which come with benefits comprising narrow beam, high signal quality, large capacity data transmission, and strong detection potential. Third, we describe the fundamental propagation characteristics of the mmWave band and survey the existing channel models for mmWave communications. Fourth, we track evolution and advancements in hybrid beamforming for massive MIMO systems in terms of system models of hybrid precoding architectures, hybrid analog and digital precoding/combining matrices, with the potential antenna configuration scenarios and mmWave channel estimation (CE) techniques. Fifth, we extend the scope of the discussion by including multiple access technologies for mmWave systems such as non-orthogonal multiple access (NOMA) and space-division multiple access (SDMA), with limited RF chains at the base station. Lastly, we explore the integration of SWIPT in mmWave massive MIMO systems, with limited RF chains, to realize spectrally and energy-efficient communications.

Improvements of the International Reference Ionosphere model for the topside electron density profile

Abstract: [1] Shortcomings of the representation of the topside electron density profile in the International Reference Ionosphere (IRI) model have been noted in comparison with recently analyzed topside sounder data and also with total electron content (TEC) data. Various studies have proposed corrections of the IRI formulas or have introduced a new formalism. This paper reviews the different approaches, their implications for IRI, and their current status. An important challenge for topside modeling is the truthful representation of profiles in the equatorial anomaly (EA) region over the whole range of the EA fountain. This means that the latitudinal representation has to reproduce the merging of the double-peak signature at F region heights into a single peak at the top of the fountain. In this context, special emphasis is given to the coupling between topside and plasmaspheric models.