Ichirou Ida - Profile on Academia.edu (original) (raw)

Papers by Ichirou Ida

A simple path loss model for body area network in the bed side monitoring applications

In this paper, a path loss model around the human body for a bed side monitoring application is p... more In this paper, a path loss model around the human body for a bed side monitoring application is proposed. The proposed path loss model includes on-body propagation channel, free-space propagation channel, and human body shadowing effect, which all are unavoidable in bed side monitoring applications. A low-profile circular patch antenna that operates in monopole mode is designed at 2.4 GHz to use in the measurements. The measurements are all conducted in static scenarios only.

Reduction and characterization of a drift error in measurement of small antennas using a network analyzer

International Symposium on Antennas, Propagation and EM Theory, 2000

The radiation resistances of a monopole antenna and a dielectric loaded monopole antenna have pre... more The radiation resistances of a monopole antenna and a dielectric loaded monopole antenna have precisely been measured on the basis of the Wheeler cap (1947) method. The precision of the measurement has been proved to improve with the use of the stub tuner. To give a theoretical background for the improvement in the measured radiation resistance, the drift error of

Accurate measurement and FDTD simulation of the efficiency-bandwidth product for dielectric loaded antennas

Antennas and Propagation Society International Symposium, 2000

There are several criteria for antenna evaluation. The authors have studied on the efficiency-ban... more There are several criteria for antenna evaluation. The authors have studied on the efficiency-bandwidth product (EB) for small dielectric loaded antennas (DLAs). The EBs of DLAs were accurately measured and compared with calculated ones. The calculation simulated the procedure of the Wheeler (1947) cap method. Enhancement of the EB was observed even with the loading of lower permittivity. There seemed

A simple circularly polarized beam-switching patch array antenna for satellite communication

Antennas and Propagation Society International Symposium, 2001

The performance of a simple beam-switching four-patch array antenna, radiating circular polarizat... more The performance of a simple beam-switching four-patch array antenna, radiating circular polarization at 2.6 GHz, is presented. This antenna generates a directive beam allowing the tracking of the signal emitted by a satellite. Two methods of feeding the antenna, to realize the beam-tracking, are analyzed. First, when the feeding source is switched off. Second, when one element is fed with

Dependence of the efficiency-bandwidth product on electrical volume of small dielectric loaded antennas

IEEE Transactions on Antennas and Propagation, 2002

The efficiency fractional efficiency bandwidth product (EB) that is expressed as a ratio of the r... more The efficiency fractional efficiency bandwidth product (EB) that is expressed as a ratio of the radiation resistance to the absolute value of an input reactance of an antenna is used as a performance measure for small dielectric-loaded monopole antennas (DLMAs). The dependence of the efficiency bandwidth (EB) on the permittivity of the dielectric loading (i.e., the electrical volume) is experimentally

Realizing safe and reliable vital sings monitoring with wireless body area networks

2013 IEEE Region 10 Humanitarian Technology Conference, 2013

ABSTRACT In this paper, we report development and performance verification of a wireless body are... more ABSTRACT In this paper, we report development and performance verification of a wireless body area network prototype compliant with the MAC protocol of the IEEE802.15.6 BAN. The relaying functionality which utilizes a relay between a hub and a node is confirmed when a direct path between them is not available due to shadowing effects. The delay due to switching to the relay topology is less than one second. Also, ID-based frequency channel hopping mechanism is introduced and verified to be able to quickly avoid frequency channel interference among BANs. In addition to that, transmission power control with body movement detection is employed to reduce sporadic disconnection through giving an extra amount of transmission power when the node detects a large fluctuation in received power. With functionalities mentioned above, the prototype is expected to be used for medical monitoring applications where requirements for data delay and disconnection are rather severe.

Clustering results of estimated MIMO double-directional channel data of a small macrocell

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Adaptive Control of Antenna Impedance Matching for Mobile Communication Systems

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Evaluation for dielectric loaded small dipole antennas usingefficiency-bandwidth product

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Identification of relatively strong clusters in an NLOS scenario at a small urban macrocell mobile station

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Propagation Characteristics at Mobile Station in an Urban Macrocellular Environment at 4.5 GHz

Diversity antenna loaded with reactance control circuits configured with variable capacitors for effective combining

Diversity antenna loaded with the reactance control circuits configured with variable capacitors ... more Diversity antenna loaded with the reactance control circuits configured with variable capacitors was proposed. Advantages of this proposed configuration are that signals are detected only by one receiver and that the hardware architecture is simple. However, eective combining has not been achieved due to a mismatch between the combiner and the receiver. In order to improve this problem, we con- sidered the resistance of the output load. Finally, we show that the performance of the proposed system is close to selection combining.

Double-directional channel modeling approach for MIMO mobile communication systems

Proceedings of 2011 Asia-Pacific Microwave Conference, 2011

In this paper, the polarisation behaviour of the mobile MIMO radio channel is analysed from polar... more In this paper, the polarisation behaviour of the mobile MIMO radio channel is analysed from polarimetric double directional channel measurements, which were performed in a macro-cell rural environment in Tokyo. The recorded data comprise non line of sight, obstructed line of sight and line of sight conditions. The gradient based Maximum-Likelihood estimation framework RIMAX was used to estimate both specular

EURASIP Journal on Wireless Communications and Networking, 2009

Multipath clusters in a wireless channel could act as additional channels for spatial multiplexin... more Multipath clusters in a wireless channel could act as additional channels for spatial multiplexing MIMO systems. However, identifying them in order to come up with better cluster channel models has been a hurdle due to how they are defined. This paper considers the identification of these clusters at the mobile station through a middle ground approach-combining a globally optimized automatic clustering approach and manual clustering of the physical scatterers. By including the scattering verification in the cluster identification, better insight into their behavior in wireless channels would be known, especially the physical realism and eventually a more satisfactorily accurate cluster channel model could be proposed. The results show that overlapping clusters make up the majority of the observed channel, which stems from automatic clustering, whereas only a few clusters have clear delineation of their dispersion. In addition, it is difficult to judge the physical realism of overlapping clusters. This further points to a need for the physical interpretation and verification of clustering results, which is an initial step taken in this paper. From the identification results, scattering mechanisms of the clusters are presented and also their selected first and second order statistics.

Polarimetric beamforming comparison of the multipath clusterization of ML estimates and the measurement data of a MIMO macrocell channel

2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, 2009

ABSTRACT Clusters produced by multipath clusterization were comparatively evaluated using the dir... more ABSTRACT Clusters produced by multipath clusterization were comparatively evaluated using the directional power spectrum of the measured channel, which was obtained by polarimetric beamforming due to the dual-polarized nature of the channel sounding data. The clusters were from the results of the clusterization of maximum-likelihood-based path parameter estimates of a macrocell channel. The approach provides a way to render the physical meaning of clustering results in line with the measured channel. The result shows some slight offset from the measured channel, nevertheless, the cluster locations were comparable.

Cluster polarization behavior of a MIMO system: Measurement, modeling and statistical validation of the correlation of its channel parameters

2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, 2009

ABSTRACT This paper presents clusterwise polarization characteristics based on an estimated MIMO ... more ABSTRACT This paper presents clusterwise polarization characteristics based on an estimated MIMO channel of a small urban macrocell at 4.5 GHz. Polarization path gain, cross-polarization ratio, and co-polarization ratio characteristics as influenced by channel parameters such as delay, azimuth and elevation angle of arrival were investigated. Hypothesis testing was used as a verification of the results. This statistical verification clarifies the independence of polarization characteristics from an azimuth angle of arrival, whereas some correlation was found between the cross-polarization ratio and the elevation angle of arrival. The results also confirmed a log-normal cross-polarization ratio.

Experimental Evaluation of MIMO Antena Selection System using RF-MEMS Switches on a Mobile Terminal

2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

ABSTRACT This paper describes experimental results of an antenna selection system that is applied... more ABSTRACT This paper describes experimental results of an antenna selection system that is applied to a receiver side of multiple- input multiple-output (MIMO) systems. We proposed an antenna selection system that each MIMO receive branch has different polarization and directional pattern antennas and selects one antenna combination by using radio frequency micro electro mechanical system (RF-MEMS) switches. A 2 x 2 MIMO -OFDM transmission system is constructed to evaluate the performance of the proposed antenna selection system, which can not only measure real-time bit error rate (BER) but also control the antenna switch based on an antenna selection algorithm. BER measurement experiments were conducted in an indoor office environment, and it was found that more than 3 dB receive power improvement was achieved with the proposed antenna selection system comparing to the vertical polarization fixed receive antennas from the result of the averaged BER performances.

Street dependent propagation at mobile station based on an urban residential macrocellular measurement

2006 First European Conference on Antennas and Propagation, 2006