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Publications
Publications (50)
Experimental investigations by have been done to understand co-channel interference characteristics between the small cells installed in indoor environments. However, there are a lot of complex situations in the arrangement of indoor small cells, so that it seems to be hard to build the general interference modeling through experimental results due...
Although it is effective in realistic path loss prediction to consider propagation path shadowing by the vehicles which run a roadway in development of the various ITS in a city area road, it is further required in development of pedestrian-to-vehicle communications that the path loss model which can take into consideration the influence of path sh...
In MIMO transmission scheme, the low correlation between antenna branches is significant to increase the channel capacity. This paper presents simulated results of capacity increase effect in 4×2MIMO channels when the antenna spacing of base station is increased in indoor radio propagation environment where people move around the terminal stationar...
This paper presents a path-shadowing model for indoor populated environments that has been developed based on computer simulations. The propagation paths between the transmitting and receiving points in an empty rectangular space are determined using the ray-tracing method, in which moving quasi-human bodies that are modeled as cylinders with a fin...
A method for evaluating the mean effective gain (MEG) of mobile antennas in line-of-sight (LOS) street microcells with low base station antennas is investigated. The received power patterns of incident radio waves along typical streets measured in actual street microcells in urban areas of Tokyo are presented to clarify the proper distribution mode...
This paper presents a path-shadowing model in indoor populated environments based on computer simulations. The propagation paths between the transmitting and receiving points in an empty rectangular space are determined by a ray tracing method, moving quasi-human bodies modeled as a cylinder with finite height are generated in this space, and inter...
This paper presents a prediction formula of propagation loss for low antenna height scenarios on a line-of-sight (LOS) straight-line road having an intersection, for modeling the propagation loss characteristic in inter-vehicle communications (IVCs). The regression analysis is applied to the propagation loss data generated by computer simulation ba...
This paper presents a path-shadowing model in indoor populated environments based on computer simulations. The propagation paths between the transmitting and receiving points in an empty rectangular space are determined by a ray tracing method, moving quasi-human bodies modelled as a cylinder with finite height are generated in this space, and inte...
A statistical scattering model for mobile radio channels that has the following three features is proposed: 1) the effective scattering area (ESA) is expressed by an ellipse, the center of which is the mobile station (MS) location; 2) the major axis of the ellipse runs parallel along the street where the MS is located; and 3) the scattering power d...
With regard to the uplink channel in the case of a W-CDMA system with an adaptive antenna array technology, a method is presented that theoretically analyzes the uplink channel capacity with consideration of the effects of RAKE reception and of soft handover between sectors. A propagation model presuming the angle of arrival profile on the base sta...
A stochastic scatter model in mobile radio channels is proposed that has three features: (1) the effective scattering area is expressed by an ellipse the center of which is the mobile station (MS) location; (2) the major axis of the ellipse runs parallel along the street where the MS is located; (3) the scattering power density function around the...
The paper presents theoretical and experimental investigation results of the delay spread reduction effect of beam antennas in urban line-of-sight (LOS) street microcells. The 95% delay spread cumulative probability in a 600 m LOS cell length is reduced to 70% when the 3 dB beamwidth of the base station (BS) antenna is in the range from 80° to 140°...
We present results from field experiments in a street-micro scenario downtown Tokyo, which have been carried out to explore the main mechanisms leading to path parameter variations. The measurements have been carried out using a wideband-vector-channel-sounder. The transmitter (mobile station) was equipped with an omni-directional antenna whereas a...
This paper proposes a new propagation model to accurately predict outdoor-to-indoor propagation loss. Account is taken of the structural openings along the paths; it is assumed that outdoor-to-indoor paths are possible only through wall openings such as doors and windows. Introducing the angle dependency of the losses with the paths that penetrate...
This paper presents the clustering mechanism of multipath components in urban environments. A cluster in an urban area originates from a scattering point located atop a building or on a wall. The degrees of visibility both between the base station and the scattering point, and between mobile station and the scattering point determine the incoming s...
In systems beyond IMT-2000, the microcell structure will be adopted to achieve adequate system capacity and link budget. Thus base stations (BS) would be mounted closer to the road than heretofore, and the shadowing effects due to buildings will be more serious in the entrance radio link between BS. This paper uses the ray-tracing calculation metho...
The delay spread characteristics in low antenna height propagation in urban areas are difficult to accurately estimate by statistical methods that are highly dependent on the location. To understand how the road system affects the propagation characteristics, the propagation mechanism was analyzed. In practice, the identification of the propagation...
For design of optimum microcells on a university campus, it is necessary to determine the propagation characteristics within a propagation environment represented by a relatively large open space scattered with large buildings and many trees. In this paper, for the radiated waves from seven PHS base sites at 1.9 GHz experimentally installed on the...
This paper proposes a multipath propagation model for
line-of-sight (LOS) street microcells with building roof base sites (BS)
in urban areas, Multipath propagation characteristics are of great
importance in evaluating the performance of digital systems and
designing wireless links. Typical delay profiles are measured to clarify
their statistical c...
In a low-antenna-height line-of-sight (LOS) microcell, the delay spread characteristic strongly depends on the road shape, the location of the transmitting and receiving points, and so on. To analyze this propagation mechanism, it is necessary to deal with location-specific properties. This paper describes analyzed results for the multipath delay m...
In a low-antenna-height line-of-sight (LOS) microcell, the delay spread characteristic strongly depends on the road shape, the location of the transmitting and receiving points, and so on. To analyze this propagation mechanism, it is necessary to deal with location-specific properties. This paper describes analyzed results for the multipath delay m...
A channel model is presented for line-of-sight (LOS) street
microcells with low-antenna-height base sites. This channel model
assumes some virtual reflection points (VRPs) located at the
intersection points along the LOS street and at building walls under the
LOS condition. The VRP locations can be specified for the street
structure, so this channe...
This paper reports coverage prediction results for 5-GHz-band TDMA
mobile communication systems that transmit high-speed digital signals at
bit rates of 2 Mb/s to 30 Mb/s in urban microcell environments. The
predictions are mainly based on radio propagation characteristics
obtained by ray-tracing calculations on an urban line-of-sight street.
Based...
This paper presents an inexpensive antenna that has a
bidirectional radiation pattern in the H-plane. It covers its
construction, electrical characteristics, and evaluation results of the
propagation characteristics in the street-microcellular environment. In
this antenna, two printed dipole antennas are placed adjacent to each
other, they are fed...
A multipath propagation model and a prediction equation for r.m.s. delay spread are discussed for LOS street microcells with building roof base sites in urban areas. The proposed model is established to explain a mechanism of multipath propagation. The delay profiles calculated using the model agreed well with the measured profiles. The factors inf...
The paper proposes a channel model for LOS street microcells with
low antenna height base sites. This channel model assumes some virtual
source point (VSP) and locates then at the intersection points along the
LOS street and building walls under the LOS condition, and so is
developed as a location-specific model. The predicted delay spread has
exce...
In Personal Handy-phone Systems (PHS), the service area is covered by a large number of micro-cells. Therefore, cell design based on propagation characteristics is of great importance. This paper first addresses the micro-cell propagation environment and propagation loss characteristics in urban areas. Then it presents delay spread characteristics,...
The configuration of two parallel half-wave dipoles is the basic space-diversity branch for space-diversity reception in mobile radio communications.
This paper presents theoretical and experimental study on the antenna diversity branch connected to a 50-ohm receiver. Post-detection selection diversity is applied to determine the relation of the me...
By means of the spatial network method, the characteristics of a planar inverted-F antenna on an infinite ground plane are analyzed. The electric field between the planar element and ground plane and the surface current distribution on the antenna for different values of the width of the short-circuit plate are found. In addition, by Fourier transf...
Antenna diversity reception can significantly alleviate fading with a relatively simple configuration. Hence, this technique will be indispensable in future portable radio systems. In the antenna diversity system installed in a portable transceiver, degradation of the diversity effect due to artificial variation of the radiation pattern (polarizati...
Methods for evaluating the crosspolarization power ratio (XPR) in mobile communication include the one using a crossed dipole, the one using a dipole antenna and a turnstile antenna, and that using a dipole antenna and a loop antenna. However, measurement errors in these methods have not been investigated.
In this paper, the measurement error chara...
It is shown that the input impedance of the PIFA (planar inverted
F antenna) can be calculated using the SNM (spatial network method). The
transition characteristics of the resonant frequency and the bandwidth
of the PIFA are described for various values of the shape ratio and the
shorted width of the planar element. The calculated results are in c...
A method is described for analyzing the mean effective gain (MEG)
of antennas moving in a mobile communication environment. The MEG
characteristics of a mobile antenna are determined by the mutual
relation between the antenna patterns and the statistical distribution
of incident waves in an environment. To analyze this relation
theoretically, a gen...
A method for estimating the average effective gain of mobile
antennas in a multipath propagation environment is discussed. The
effective gain is defined as the ratio of the average received power of
mobile antennas to the sum of the incident power of the vertically
polarized (VP) waves and the horizontally polarized (HP) waves. This is
called the a...
The pattern averaging gain (PAG) method to estimate the average gain of mobile antennas in a multipath propagation environment is proposed. By using this method and a wire-grid model, the radiation characteristics of the planar inverted F antenna (PIFA) mounted on a portable radio case is analyzed. In particular, the variation of the antenna gain w...
Detachable mobile radio units have been developed to meet customer demands for mobile radio units that can be used outside the vehicles in which they have been installed. This paper describes configurations for and performance characteristics of antennas used with detachable mobile radio units. A built-in planar inverted F antenna (PIFA) mounted on...
First Page of the Article
To meet customer demand for mobile radio units to be used outside in cars, detachable mobile radio units (DMUs), which can be used not only in cars but also as portable radio units outside in cars, have been proposed. The features of a portable DMU will greatly influence service quality in portable usage. This paper describes the philosophy and met...
Detachable mobile radio units have been developed to meet customer demand for mobile radio units that can be used outside the cars in which they have been installed. This paper describes configurations for and the performance characteristics of antennas used with detachable mobile radio units. When both portability and detachability are taken into...
Detachable mobile radio units, which can be used not only in a car but also as a portable radio unit outside the car, have been developed by the Electrical Communication Laboratories, NTT, for use in the existing 800 MHz mobile radio telephone system in Japan. This paper describes the circuit configuration and principal techniques to reduce volume,...
First Page of the Article
This paper reviews a method of evaluating the performance of mobile antennas that uses the theoretical expressions, proposed by the author, of the "Mean Effective Gain (MEG)" and the correlation coefficient between antenna diversity branches. Furthermore, the "Cross polarization Power Ratio (XPR)" measurement method, the directional statistical mod...