Naoto Kadowaki

National Institute of Information and Communications Technology

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Sadao Obana

University of Electro-Communications

Naoko Yoshimura

National Institute of Information and Communications Technology

Nei Kato

Tohoku University

Hiroki Nishiyama

Kindai University

Peter Davis

Nagase ChemteX (Japan)

Satoko Itaya

National Institute of Information and Communications Technology

Morio Toyoshima

National Institute of Information and Communications Technology

Ryutaro Suzuki

Tohoku University

T. Takahashi

Tohoku University

Ryosuke Imai

Kyushu University

Cooperative Institutions

National Institute of Information and Communications Technology

Mitsubishi Electric (Japan)

Ministry of Internal Affairs and Communications

Tohoku University

The University of Tokyo

Communications Technology Laboratory

Mitsubishi Electric (Germany)

Tokyo Institute of Technology

Kyoto University

Osaka University

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Development results of partial model of a Ka-band active phased array antenna for gigabit satellite

International Journal of Satellite Communications (1999)

Shiro Kitao Hiromasa Nakaguro Hitoshi Mizutamari Akira Akaishi Ryoichi Imai

The high data rate and global satellite communication systems are expected to be an improvement agenda to the social and economic activities in the 21st century. The experimental high data rate (gigabit) communications satellite is required to face the technological challenges of the future growing multi-media applications. For this gigabit communications system, a Ka-band scanning spot beam antenna (SSBA) which realizes multiple beam forming is required. CRL and MELCO have been developing Ka-band active phased array antenna (APAA) for the SSBA as one of the most important and challenging technology. An APAA has been developed mainly for radar systems for many years. CRL and MELCO are investigating and developing the direct radiating APAA for communication satellites which can operate under wide frequency band in Ka-band. This paper describes the preliminary study results of the Ka-band APAA for gigabit satellite and the radiation performances of the partial experimental model of Ka-band APAA with two multiple beams to both transmit and receive signals. The partial model includes the active MMIC device such as HPA (high power amplifier), LNA (low noise amplifier) and PS (phase shifter), and multi-layered BFN (beam forming network) as key components. Performances such as radiation pattern, beam scanning performance and input–output performance have been measured. We also verified that the REV (rotating element electric-field vector) method was effective for pattern calibration. Copyright © 1999 John Wiley & Sons, Ltd.

Ka band

Communications satellite

Gigabit

10.1002/(sici)1099-1247(199903/06)17:2/3<187::aid-sat634>3.0.co;2-v

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Proposal of Communication Decentralization Method in Ad-hoc Network Routing

IEICE Technical Report; IEICE Tech. Rep. (2006)

Hasegawa Jun Satoko Itaya Akio Hasegawa Peter Davis Akira Yamaguchi

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On real-time data gathering in next generation satellite-routed sensor system (SRSS)

Yuichi Kawamoto Hiroki Nishiyama Nei Kato Shinichi Yamamoto Naoko Yoshimura

Recently, satellite-routed sensor systems are expected to be used as early disaster detection systems. The networks efficiently provide data collected from wide areas with small sensor terminals and satellites. In this system, each sensor terminal collects and sends data to monitoring stations on the ground via satellites. Although the future major disaster detection systems require high capacity to manage numerous sensor terminals, it is difficult to collect data from a large number of sensor terminals simultaneously since the bandwidth of each satellite is limited. Hence, an efficient system to allocate the bandwidth to each sensor terminals is required. Moreover, for early disaster detection, the real-time performance is very important. Therefore, in this paper, we discuss an appropriate bandwidth allocation model to construct a next generation satellite-routed sensor system while considering the real-time performance. In the new model, we particularly focus on the relationship between throughput of each sensor terminal and real-time performance, and introduce a method to allocate bandwidth. A numerical analysis is used to validate the new system model.

Communications satellite

10.1109/wcsp.2012.6542956

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Direction of Satcom R&D in Japan: WINDS, ETS-IX, and beyond [International Communications Satellite Systems Conference]

Naoto Kadowaki

Advance satellite communications technology has been achieved through Wideband InterNetworking engineering test Satellite (WINDS) and Engineering Test Satellite 9 (ETS-IX) projects in these two decades in Japan. WINDS achieved Gbps-class transmission capability, wide bandwidth active phased array antenna in Ka-band, and high speed onboard switching technologies. ETS-IX is currently being developed to demonstrate flexible resource management capability with wide bandwidth digital channelizer and digital beam former in Ka-band. In this chapter, very high capacity optical communications technology being developed for feeder link applications of a very high throughput satellite is reviewed. Satellite communications are thought to be beneficial for 5G coverage expansion to the ocean surface, air and space, and some trials to integrate to 5G. ETS-IX will be used as an experimental platform for such technical trials based on European Space Agency-National Institute of Information and Communications Technology (ESA-NICT) collaborations. Based on these achievements and experiences, and taking into account the recent trend of satellite communications technology for VHTS, LEO constellations, HAPS, and so on, we have studied next-generation satellite communications technology.

Communications satellite

10.1049/cp.2019.1237

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Improving Performance of On-demand Routing under Multipath Fading

Suhua Tang Masahiro Watanabe Naoto Kadowaki Sadao Obana

Despite many routing protocols proposed for mobile ad hoc networks few have considered link quality and route stability. Weak links contained in the routes often lead to route breaks. Multipath fading and mobility make link quality timevariant. When the link metric is associated with link quality the routes may change frequently. In times of transmission failure due to collision or fading, the routing packets are susceptible to loss owing to the lack of retransmission mechanism for the broadcast packets. For these reasons, the routes become unstable. In this paper, we investigate the long-term link quality and route stability in the on-demand routing protocols. We compare the link metric policies, optimize the route discovery and use the soft detection scheme to avoid false link breaks. The simulation results show that both Packet Error Ratio (PER) and throughput in the enhanced on-demand routing protocol can be greatly improved under the Rayleigh fading environment.

Multipath routing

Retransmission

10.1109/vetecs.2006.1682958

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Research and development issues of satellite communication systems for large scale disaster mitigation

IEICE Technical Report; IEICE Tech. Rep. (2011)

Naoto Kadowaki T. Takahashi Akioka Maki Yoshiyuki Fujino Morio Toyoshima

Communications satellite

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Analysis of Characteristics of Flooding for Inter-Vehicle Communications

Jōhō Shori Gakkai kenkyū hōkoku (2005)

Peter Davis Satoko Itaya Jun Hasegawa Akio Hasegawa Naoto Kadowaki

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Disaster satellite communication experiments using WINDS and wireless mesh network

Takashi Takahashi Byeong-pyo Jeong Mitsugu Okawa Akira Akaishi Toshio Asai

An unprecedented Great East Japan Earthquake occurred on March 11, 2011, and serious damage occurred. The terrestrial network were damaged and to take contact with the affected area was very difficult. Satellite communication has the feature of disaster resistant, and satellite mobile phone became the precious communication means just as after the earthquake disaster. The National Institute of Information and Communications Technology (NICT) built a broadband satellite line between the disaster preventions agencies and their dispatched team which worked on disaster response activities in the affected area using Wideband InterNetworking engineering test and Demonstration Satellite (WINDS). NICT researches and develops the resilient network against a disaster using wireless network and satellite network. Three types of earth stations for satellite communication were developed, fully-automatic transportable earth station, large-scale in-vehicle earth station and small mobile vehicle earth station. NICT carried out the disaster satellite communication experiments using those earth stations. One experiment was connected two wireless mesh network using satellite link and another was transmitted HDTV image from moving earth station.

Communications satellite

Mesh networking

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Trigger update based local optimization for on-demand routing protocols

Suhua Tang Masahiro Watanabe Naoto Kadowaki Sadao Obana

In mobile ad hoc networks on-demand routing protocols are very attractive due to low overhead. In these protocols, however, (1) the routes tend to contain weak links that have a low rate and high packet error ratio; (2) the routes are susceptible to breaks in the presence of mobility. Our major concern in this paper is to locally optimize the routes in the on-demand routing protocols in terms of link quality and mobility. The local optimization is realized by two main techniques: relating link metric with received signal strength and preferring the route with a shorter metric through trigger update (TU). In this manner the initial routes converge to the local optimum in the static case, and adapt to topology variations and link quality changes caused by mobility. Also, the routing overhead is controlled. Simulation results show that AODV with the application of local optimization (AODV-TU) achieves a much higher performance than the original AODV

10.1109/lcn.2005.133

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156 Mbps ATM transmission experiment using N-STAR

17th AIAA International Communications Satellite Systems Conference and Exhibit (1998)

Naoko Yoshimura Takashi Takahashi Ahmed Saifuddin Naoto Kadowaki

In recent years there has been much interest in constructing a Global Information Infrastructure (Gil). Because of advantages including coverage of a wide area, flexibility of the network configuration, and multicast connection capability, a satellite communications system will play an important part in developing this Gil. On the other hand, satellite communication systems have lower link capacities and longer delay than do fiber optic networks. To build a hybrid network, we must consider a communications protocol. The Communications Research Laboratory (CRL) has been researching the Asynchronous Transfer Mode (ATM) protocol, which has come into wide use in multimedia communication applications in fiber optic networks. We have conducted an ATM transmission experiment in which a transmission rate of 156 Mbps was achieved using the Ka-band. This paper describes the experimental results of this experiment and future applications experiments.

Star (game theory)

10.2514/6.1998-1264

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Citations (1)