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Papers - Mitsugi, Jin

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Experimental study on UHF passive RFID readability degradation

Mitsugi Jin, Hada Hisakazu

52 - 55 2006

Readability of passive RFID fundamentally depends on the tag empowering. The minimum required power, usually referred to as sensitivity, depends on the chip and antenna manufacturing. The sensitivity affects the readability but it is not the sole determinant of readability. The readability of RFID comprises a number of factors, particularly in the UHF band. This paper proposes a classification of tag readability degradation factors and measurement methods to quantify the factors. It is shown that tag performance change at the attachment may affect the readability. A tag probe, a power measurement antenna at the position of tag attachment, can monitor essential data to comprehend the situation and establish a countermeasure to improve the tag readability. The operating environment, involving reader antenna positions and standing waves result from the multipath fading, is another important factor for the readability. The characteristics of the environment could be also grasped by using the tag probe. © 2005 IEEE.

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Spatial beam analysis with large displacement for deployable truss structures

Ozawa Satoru, Harada Satoshi, Mitsugi Jin

Nihon Kikai Gakkai Ronbunshu, C Hen/Transactions of the Japan Society of Mechanical Engineers, Part C 70 ( 11 ) 3108 - 3115 2004.11

ISSN 0387-5024

A formula of multibody finite element analysis based on the corotational formulated finite element method and the direct coordinate partitioning for deployable truss structures is proposed. A beam element used in linear finite element analyses is a basic element in the formula. A corotational frame is defined by node coordinate systems attached to a beam element. A tangent stiffness matrix contains a virtual rotation displacement of the corotational frame. By the appropriate transformation of this virtual displacement, a simple geometric stiffness for the formula is obtained. The formula makes it possible to analyze the deploying motions of large deformed deployable truss structures, to be applicable to general finite elements, and to increase convergence speed of the Newton method in a solution algorithm. This improvement is achieved by neglecting virtual work done by rigid body motion in the process of employing the geometric stiffness to the conventional formula. A validity of this formula is confirmed through results of a numerical deployment analysis of a deployable beam structure.

Enhanced multi-correlator AFC for fast and wide range frequency acquisition

Yamashita Fumihiro, Kobayashi Kiyoshi, Nakasuga Yoshinori, Mitsugi Jin, Ueba Masazumi

IEICE Transactions on Communications E87-B ( 8 ) 2072 - 2081 2004.08

ISSN 0916-8516

This paper presents a new automatic-frequency control (AFC) configuration capable of removing wide range frequency offsets (up to about ±0.625 fs, where is is signal symbol rate). The new configuration consists of an AFC that removes frequency offsets between ±0.125 fs and another AFC that detects the frequency offset range coarsely between ±0.625 fs. This paper describes the principle of the new AFC configuration. The proposed AFC configuration employs four correlators to enhance the acquisition range. It also adopts the reverse modulation scheme to decrease the acquisition time. The performance of the new AFC configuration is confirmed via computer simulations. It is shown that the proposed configuration can accommodate wide range frequency offsets as well as reduce the. acquisition time.

Shadowing countermeasure technology with layer 3 diversity reception for Ku band mobile satellite communication systems

Nagase Fumiaki, Mitsugi Jin, Nakayama Masayoshi, Ueba Masazumi

349 - 354 2004

A layer 3 diversity reception scheme that enhances the transmission characteristics of Ku band mobile satellite communication systems is presented. The initial thrust for developing this scheme is to realize high-speed communication for trains that experience shadowing caused by terrestrial obstacles such as tunnels, buildings, bridges and structures that support trolley wires. Layer 3 diversity was chosen for long distance diversity to prevent signal shadowing caused by terrestrial obstacles and to yield packets in the same order as in the original packet stream while minimizing the alterations of existing receivers. The technology enables high-speed communication under simulated shadowing conditions in a running train environment while assuring correct packet order. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Broadband and scalable mobile satellite communication system for future access networks

Ueba Masazumi, Ohata Kohei, Mitsugi Jin, Umehira Masahiro

395 - 404 2004

The future prospects of satellite communications by the year 2010 in Japan, is discussed. The prospects of providing services of broadband Internet services to passengers in airplane, long-haul trains, or sea-going vessel is under process. After estimating the demand, a next-generation of broadband and scalable mobile satellite communication systems is proposed that could offer these services at affordable price. It is stated that to realize such a system key technologies must be developed to meet the technical challenges posed by the communication system and the problem related to the payload of the satellite.

Communication capacity enhancement with adaptive resource assignment for multi-beam mobile satellite communication systems

Nakasuga Yoshinori, Mitsugi Jin, Ohata Kohei, Ueba Masazumi

336 - 348 2004

Mobile satellite communication systems are attracting much attention as an effective way to provide broadband communications in planes, ships, and long-haul trains in which economical services are not effectively provided by terrestrial systems. Such a system usually requires a wide frequency bandwidth and a satellite with high electrical output power, but these resources are severely restricted. A multi-beam system with frequency reuse is able to spread the usable bandwidth virtually. Applying an adaptive modulation method to the system achieves efficient use of resources. In this system, optimally assigning resources to beams is indispensable in enhancing the system capacity. However, this optimization method becomes complex since it is necessary to consider the influence of inter-beam interference which may depend on the variation in the communication traffic distribution. We propose a new adaptive resource assignment method in order to overcome this complexity and to enhance the system capacity. In the proposed method, a bandwidth vector and an approximate curve of the spectrum efficiency are introduced. Based on case studies assuming 19 beams, we show that the proposed method achieves 4.2 times higher system capacity than that of a system in which resources of each beam are fixed. Copyright © 2004 by NTT Corporation.

Phased array fed reflector antennas with interpolation network for next generation mobile satellite communication systems

Suzuki Yoshinori, Imaizumi Yutaka, Mitsugi Jin, Ueba Masazumi

3043 - 3046 2004

The phased array fed reflector antennas with interpolation network for next generation mobile satellite communication systems are discussed. A small satellite, such as 2kW-payload power, was used to reduce system cost. The improvement in onboard antenna performance is achieved by increasing reflector diameter. A modification of the directional constrained minimum power (DCMP) method is proposed to handle interpolation networks. The validity of the method is confirmed by calculating antenna patterns of a designed phased-array-fed reflector antenna.

AFC configuration applicable to a wide range of frequency offset

Yamashita Fumihiro, Kobayashi Kiyoshi, Nakasuga Yoshinori, Mitsugi Jin, Ueba Masazumi

2003

This paper presents a new automatic-frequency control (AFC) configuration capable of removing a large amount of frequency offset (up to about +/- 0.625 fs, where fs means symbol rate of signals). The new AFC consists of the AFC that removes frequency offsets between +/- 0.125 fs and another AFC that detects the frequency offset range coarsely between +/- 0.625 fs. First, the principle of the new AFC configuration is described. Then, the performance of the new AFC is confirmed via computer simulation. It is shown that the proposed AFC configuration can accommodate wide range frequency offsets as well as reduce the acquisition time. © 2003 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Ku band mobile multimedia satellite communications system for trains

Nagase Fumiaki, Mitsugi Jin, Nakayama Masayoshi, Ueba Masazumi

2003

This paper presents the results of train experiments and their analysis of Ku band mobile multimedia satellite communication system. First, the requirements for the satellite-tracking antenna are described. And then, the satellite signal availability as well as the network performance, which were measured on trains, are described. Based on these data, it is confirmed that the satellite visibility from a train, which varies in accordance with the train's route, can be related to network throughput and the network throughput can be conceived as a high-speed Internet access. It is verified that major cause of network throughput degradation was identified by our laboratory tests. © 2003 by the American Institute of Aeronautics and Astronautics.

A novel technique for suppressing heat in onboard High-Power amplifiers

Kaho Takana, Nakasuga Yoshinori, Mitsugi Jin, Ueba Masazumi

2003

Satellite communication systems have entered the mobile multimedia communication era. To support small earth terminals, the satellites must have high levels of effective isotropic radiated power. Onboard high-power amplifier not only need to generate high RF output power, but also to generate as little heat as possible. To address this issue, we present a new technique that reduces the amount of heat generated in high power amplifiers on a satellite. The technique makes use of heat suppression signals so as to maintain the amplifier's power efficiency. The potential impact on satellite systems is presented. To minimize the interference of the heat suppression signals on the carrier, some techniques are proposed using a multi-port amplifier and an antenna array and a reflector. © 2003 by the American Institute of Aeronautics and Astronautics, Inc.

An excitation weight determination method for onboard phased array antennas with weight interpolation network

Suzuki Yoshinori, Imaizumi Yutaka, Mitsugi Jin, Ueba Masazumi

517 - 522 2003

In order to realize lightweight onboard satellite antennas, we proposed a technique that uses linear interpolation to reduce the number of control circuits. Compared to the conventional approach, the reduction is about 70%. To apply the technique to practical multi-beam systems with frequency reuse, it is necessary to meet the requirement in term of beam isolation. This paper presents a method for determining the excitation weights so as to meet the requirement of multi-beam systems with frequency reuse. We confirm the validity of the method by calculating the antenna patterns generated by the excitation weights output.

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Single-hop connection between user terminals for geo-satellite mobile communication systems

Ebina Kazuhito, Nakasuga Yoshinori, Yamashita Fumihiro, Kataoka Nobuyuki, Mitsugi Jin, Ueba Masazumi

NTT R and D 51 ( 4 ) 325 - 332 2002

ISSN 0915-2326

Single-hop connection methods, which establish direct mobile to mobile communication links in the existing domestic mobile satellite communications system, are investigated. The difficulty for the single-hop connection stems from the PDC frame format, in which traffic and control channels reside in one frame. Two single-hop connection methods, based on a non-regenerative transponder satellite and a regenerative transponder satellite, are derived and evaluated in accordance with the required functionality on mobile terminal, base station and satellite. In each of the two methods, the satellite transponder has to involve such circuit as narrow-band filter bank, channel switch and beam switch. A regenerative transponder satellite has to have MODEM and frame decompose/compose circuits, additionally. Those circuits can be build by applying digital signal processing technology with relatively small circuit under a given satellite life time and space environment.

IP network performance of a Ku band mobile multimedia satellte system

Nagase Fumiaki, Tanaka Hiroshi, Mitsugi Jin, Ueba Masazumi

2002

We have proposed a mobile multimedia satellite communication system designed to realize high-speed multimedia communications. This system uses a mobile network for the return link and a newly developed tracking antenna that receives high-speed satellite signals for the forward link. This paper describes the system configuration, the tracking antenna performance and the IP network's performance in mobile environments. The tracking antenna was accurate to within 0.80 degree rms and 0.25 degree rms in azimuth and elevation, respectively. These accuracies meet the pointing loss requirement, 1 dB, in the link analysis. The network performance of the system was evaluated both in stationary and mobile environments by measuring the round trip time and the throughput. These characteristics were measured for several return link implementations, e.g., PDC (Japanese Cellular Standard), PDC-Packet (Packet communication service of PDC) and Satellite phone. Even in mobile environments, 1 Mbit/s of throughput, which is limited by the system round trip time, can be achieved for file downloading with TCP as transport protocol. This throughput can be increased to almost the network limit when XTP is applied as the transport protocol. © 2002 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Mobile multimedia satellite communication system

Nagase Fumiaki, Tanaka Hiroshi, Nakayama Masayoshi, Mitsugi Jin, Ueba Masazumi, Mizuno Hideki

NTT R and D 51 ( 4 ) 317 - 324 2002

ISSN 0915-2326

We have proposed the mobile multimedia satellite communication system designed to realize high-speed multimedia communications. This system uses a mobile network for the return link and the newly developed satellite-tracking antenna that receives high-speed satellite signals for the forward link. This paper describes the system configuration featuring the satellite-tracking antenna performance and network performances measured by network throughput. The satellite-tracking antenna achieves 0.42 degree rms and 0.13 degree rms accuracy in the azimuth and the elevation, respectively. These accuracies meet the pointing loss requirements, 1 dB, in the link analysis. Even in mobile environments, 1 Mbit/s of throughput, which is limited by the system round trip time, can be achieved for file downloading when TCP is used as the transport protocol. This throughput can be improved when XTP is applied as the transport protocol.

Deployment analysis of large space antenna using flexible multibody dynamics simulation

Mitsugi Jin, Ando Kazuhide, Senbokuya Yumi, Meguro Akira

Acta Astronautica 47 ( 1 ) 19 - 26 2000.07

ISSN 0094-5765

Flexible multibody dynamics is applied to the deployment analysis of a large space antenna composed of a reflective mesh, a cable network and a deployable truss structure. It is clarified that the tension of some of the cables increase when the reflector is stowed. The largest deployment force is observed slightly before the completion of the deployment. A proper allocation of both translational and rotational springs can provide an efficient deployment force. A deployment experiment on a 4.8 m aperture reflector model verifies the computational results. It is concluded that a flexible multibody dynamics simulation is an indispensable design tool for reducing the weight and ensuring the secure deployment of low-cost mesh reflectors.

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Analyses of cable-membrane structure combined with deployable truss

Ando Kazuhide, Mitsugi Jin, Senbokuya Yumi

Computers and Structures 74 ( 1 ) 21 - 39 2000.01

ISSN 0045-7949

The authors have been developing a large deployable mesh reflector for advanced satellite communication. This large reflector consists of a mesh membrane surface and a deployable truss structure. In this paper, analysis methods for a large deployable mesh reflector structure are introduced, and the theoretical basis for the analysis is explained. By using those analysis methods, we manufactured prototype reflector modules and carried out an experiment on them. The validity of the analysis methods were verified from the results of the analyses and experiments. The design procedure of mesh reflector surface and the effect of the mesh surface tension on the truss deployment are discussed.

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Comparative analysis of deployable truss structures for mesh antenna reflectors

Mitsugi Jin

AIAA Journal 36 ( 8 ) 1546 - 1548 1998.08

ISSN 0001-1452

Direct strain measure for large displacement analyses on hinge connected beam structures

Mitsugi J.

Computers and Structures 64 ( 1-4 ) 509 - 517 1997.07

ISSN 0045-7949

A multibody dynamics formulation based on a nonlinear finite element method is presented, particularly targeting beams connected with hinges. A nonlinear kinematics, called direct strain measure, is employed to extract the strains of beams subjected to large displacement, including finite rotations but small strain. Hinges are mathematically expressed in terms of the relation between connecting nodes, rather than Lagrange multipliers. The resultant dynamic equation is a differential equation of minimum set of degree of freedom, while the sparsity of mass and stiffness matrices are preserved. Computational examples prove the validity of the proposed method. © 1997 Civil-Comp Ltd and Elsevier Science Ltd.

Thermal distortion of over 10 Meter diameter reflectors formed by truss structure

Miyasaka Akihiro, Mitsugi Jin

1997

This paper describes how an on-board satellite large reflector structure was designed based on the thermal distortion predicted by structural analysis in coordination with thermal estimation. As the reflector consists of many small similar modules, it is possible to simplify the analytical model and the fabrication process. Module size and number are decided by estimating the surface accuracy for a 13 m aperture reflector. The maximum thermal distortion is found to be occurred during eclipses. As the module number increases, the thermal distortion increases. When the antenna system is used in 2.5. G Hz (S frequency bands), total surface accuracy needs to be 2.4 mm RMS (specified value). This requirement is satisfied by a reflector composed of 14 modules; maximum error is 1.6 mm RMS by slight repositioning the reflector.

Module composition and deployment method on deployable modular-mesh antenna structures

Watanabe Mitsunobu, Meguro Akira, Mitsugi Jin, Tsunoda Hiroaki

Acta Astronautica 39 ( 7 ) 497 - 505 1996.10

ISSN 0094-5765

A deployable modular-mesh antenna is the concept behind a large space antenna. To ensure reliable deployment, a synchronously deployable truss structure forming a curved reflector surface has been developed. The proposed antenna's main reflector formed by two types of modules using mesh and cable network maintains a sufficient level of rigidity at deployment and deploys with high reliability. Importance has also been placed on the numerical analyses of cables, the mesh, and the truss structures. The truss structure analysis is based on a non-linear finite element method, rather than on multi-body dynamics, so that elastic motions of all truss members during the deployment can easily be handled. © 1997 Elsevier Science Ltd.

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