Kiyotaka Fujisaki

Ku-band long distance site-diversity (SD) Characteristics using new measuring system

This paper deals with the short (10 km) and long distance (300-1400 km) site-diversity (SD) characteristics by using a newly developed measuring system. In the proposed measuring system, six earth stations transmit 14-GHz band QPSK signals, and one measuring earth station receives 12-GHz band signals and processes them to determine SD characteristics. As a result, easy operation and maintenance, low-cost measuring system construction and highly accurate data have been obtained. By comparing those measured results with the SD joint probability approximation equation in ITU-R Rec.P.618-7, a good agreement can be obtained. Furthermore, the effect of typhoons on SD characteristics were measured.

Measurement of Ku-band rain attenuation using several VSATs in Kyushu Island, Japan

Rain attenuation at three different locations about 100 km from each other within Kyushu Island, Japan, are simultaneously measured in the Ku-band by utilizing JCSAT-1B communication satellite and several very small aperture terminals (VSATs). Two points are highlighted. The first one is the relation between rain attenuation and rain intensity. The relation is shown at uplink, downlink, and total link paths and is compared with the estimated International Telecommunication Union Radio Communication Sector (ITU-R). The second one is the rain attenuation distribution for a small percentage of time for a year for the total link path. These experimental results suggest the necessitity of detailed study on rain attenuation at local points and of presentation of a method for predicting bit errors, when using effectively Ka-band satellite systems with multispot beams.

THEORETICAL ANALYSIS OF BIT ERROR RATE OF SATELLITE COMMUNICATION IN KA-BAND UNDER SPOT DANCING AND DECREASE IN SPATIAL COHERENCE CAUSED BY ATMOSPHERIC TURBULENCE

We study the influence of atmospheric turbulence on satellite communication by the theoretical analysis of propagation characteristics of electromagnetic waves through inhomogeneous random media. The analysis is done by using the moment of wave fields given on the basis of a multiple scattering method. We numerically analyze the degree of the spatial coherence (DOC) of electromagnetic waves on a receiving antenna and the bit error rate (BER) of the Geostationary Earth Orbit (GEO) satellite communication in Ka-band at low elevation angles on the assumption that the spatial coherence of received waves decreases and spot dancing only occurs. In this analysis, we consider the Gaussian and the Kolmogorov models for the correlation function of inhomogeneous random media. From the numerical analysis, we find that the increase in BER for the uplink communication is caused by the decrease in the average intensity due to spot dancing of received beam waves and that the increase in BER for the downlink communication is caused by the decrease in DOC of received beam waves. Furthermore, we find that the decrease in DOC of received waves and the increase in BER becomes much more in the Kolmogorov model than in the Gaussian model. 226 Hanada, Fujisaki, and Tateiba

Fade Dynamics on Earth-Space Paths at Ku-Band in Fukuoka, Japan Fade-Slope Evaluation, Comparison, and Model

Using an efficient approach for data analysis, we discuss the evaluation of the fade slope as a function of sampling rate. From our analysis, we found that the standard deviation of the fade slope, as a function of attenuation, has a maximum and does not match the model recommended in ITU-R P.1623. Based on this observation, an improved fade-slope model is proposed.

Long distance site-diversity (SD) characteristics by using new measuring system

This paper deals with the short and long distance (10-1400 km) site-diversity (SD) characteristics by using a newly developed measuring system. In the proposed measuring method six Earth-stations transmit QPSK signals and one measuring Earth-station receives signals and processes them for site-diversity characteristics. As a result, easy operation and maintenance, low cost measuring system construction and high accuracy data can be obtained. By comparing these measured results with the site-diversity joint probability approximation equation in CCIR Rep. 564-4, relatively good agreement can be found.

Theoretical Analysis of Bit Error Rate for Satellite Communications in Ka-Band Under Atmospheric Turbulence Given by Kolmogorov Model

We study the influence of atmospheric turbulence on satellite communications by the theoretical analysis of propagation characteristics of electromagnetic waves through inhomogeneous random media. The analysis is done by using the moment of wave fields given on the basis of a multiple scattering method. We analyze the bit error rate (BER) using the average received intensity or power for the Geostationary Earth Orbit (GEO) satellite communications in Ka-band at low elevation angles under atmospheric turbulence whose statistical characteristics are given by the Kolmogorov model. From the analysis, the degradation in BER for the uplink is found to be caused by the decrease in the average received intensity due to spot dancing and wave form distortion of wave beams; on the other hand, for the downlink, the degradation in BER is caused by the decrease in the spatial coherence of received waves.

Implementation of a RFID-based System for Library Management

Using electromagnetic coupling, an RFID tag can get power supplier by a reader and communicate with it for data exchange. Because the RFID system enables non-contact communication, various services and applications including the management of a library catalogue are possible. However, the system is affected easily by neighboring environment and the resonant frequency, thus the communication performance is degraded. In this paper, is used 13.56MHz RFID system for the management of the library. We evaluate the influence that papers or other RFID tags give to the resonant frequency of an RFID tag.

Theoretical Analysis of Effects of Atmospheric Turbulence on Bit Error Rate for Satellite Communications in Ka-Band

In electromagnetic wave propagation through the earth’s atmosphere like satellite communications, it is known that random fluctuations of the dielectric constant of atmosphere affect propagation characteristics of electromagnetic waves (Fante, 1975; 1980; Ishimaru, 1997; Rytov et al., 1989; Strohbehn, 1977; Tatarskii, 1961; 1971; Tatarskii et al., 1993; Uscinski, 1977; Wheelon, 2003). The random fluctuations, called atmospheric turbulence, cause spot dancing, wave form distortion, scintillations of the received intensity, the decrease in the spatial coherence of wave beams etc. These effects make the received power decrease, and result in the degradation in the performance on satellite communication links. Fig. 1 shows the image of spot dancing and wave form distortion of wave beams. Fig. 2 presents the image of the decrease in the spatial coherence of transmitted waves due to a wave front distortion. The effects of atmospheric turbulence are not negligible in satellite communications in high carrier frequencies at low elevation angles. For example, tropospheric scintillation, caused by turbulence in the lowest layer of atmosphere, has been observed in satellite communications in Ku-band at low elevation angles (Karasawa, Yamada & Allnutt, 1988; Karasawa, Yasukawa & Yamada, 1988). Therefore, it becomes important to consider the effects of atmospheric turbulence appropriately in the design of such satellite communication systems. Somemodels to predict tropospheric scintillation have been developed for applications up to around 14 GHz in the carrier frequency on the basis of both theoretical and empirical studies (Ippolito, 2008). However, because a carrier frequency becomes higher according to the increase in the required channel capacity of satellite communication links in the next generation, the analysis of the effects of atmospheric turbulence should be done for applications at the higher carrier frequencies such as Ka-band, a millimeter wave and an optical wave. Some studies are conducted for satellite communications in such frequencies (Marzano et al., 1999; Matricciani et al., 1997; Matricciani & Riva, 2008; Mayer et al., 1997; Otung, 1996; Otung & Savvaris, 2003; Peeters et al., 1997). We study the effects of atmospheric turbulence on satellite communications in such high frequencies by the theoretical analysis of the moments of wave fields given on the basis of a multiple scattering method (Tateiba, 1974; 1975; 1982). We investigate the method to estimate 2

Average bit error rate for satellite downlink communications in Ka-band under atmospheric turbulence given by Gaussian model

We study the influence of atmospheric turbulence on satellite communications by the theoretical analysis of propagation characteristics of electromagnetic waves through inhomogeneous random media. We analyze the average bit error rate (BER) for the Geostationary Earth Orbit satellite downlink communications in Ka-band under atmospheric turbulence whose statistical characteristics are given by the Gaussian model. The average BER is deduced by the probability density function of the received intensity, which function is obtained by the moments of the received intensity. From the analysis, we find that the variance of received intensity caused by wave form distortion results in the degradation in BER performance at low elevation angles.

Average bit error rate for satellite uplink communications in Ka-band under atmospheric turbulence given by Gaussian model

We study the influence of atmospheric turbulence on satellite communications by the theoretical analysis of propagation characteristics of electromagnetic waves through inho-mogeneous random media. The analysis is done by using the moment of wave fields given on the basis of a multiple scattering method. We analyze the average bit error rate (BER) which is derived from the probability density function of a received intensity for the Geostationary Earth Orbit (GEO) satellite uplink communications in Ka-band under atmospheric turbulence whose statistical characteristics are given by the Gaussian model. From the analysis, we find that the degradation in BER for the uplink communications is caused by spot dancing of received wave beams due to atmospheric turbulence at low elevation angles when wave beams are transmitted from a large aperture antenna.