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Minato-ku, Japan

Suematsu N.,Tohoku University | Kameda S.,Tohoku University | Oguma H.,National Institute of Technology, Toyama College | Sasanuma M.,SKY Perfect JSAT Corporation | And 2 more authors.
2014 Asia-Pacific Microwave Conference Proceedings, APMC 2014 | Year: 2015

In the event of large scale disaster such as the great east Japan earthquake, we completely lose the terrestrial communication infrastructure and have no measure to call the outside of the disaster area. Satellite communication is only an exception and can be usable in such a situation. In this project, funded by the Ministry of Internal Affairs and Communication (MIC), Japan, we have developed a portable multi-mode very small aperture terminal (VSAT) system for disaster-resilient wireless networks. In order to realize multi-mode functionality, the VSAT indoor unit (IDU) has been developed based on the software defined radio (SDR) technology. It can be used as a wireless-local area network (W-LAN) router which is connected to 3rd generation (3G) cellular/Long Term Evolution (LTE) in the normal situation. In the case of the disaster, the connection will be changed to the satellite communication route and will provide the Internet environment to the evacuees nearby this VSAT IDU. It can also provide the dual-connection using SDR technology; one is Internet connection via private VSAT network (EsBird, provided by SKY Perfect JSAT) and another is the local authorities satellite communications network system connection via Local Authorities Satellite Communications Organization (LASCOM) network By combining the automatic uplink access test (UAT) outdoor unit (ODU), a set of IDU and ODU can be easily carried and installed by the evacuees and it will operate more than a week by the electric power supplied from a hybrid vehicle (HV) with a fill-up gas tank. In this project, digital front-end technologies for VSAT's transceiver has also been developed. The demonstration of developed VSAT was carried out in the disaster stricken area. Copyright 2014 IEICE. Source

Suzuki Y.,Nippon Telegraph and Telephone | Yamashita F.,Nippon Telegraph and Telephone | Kobayashi K.,Nippon Telegraph and Telephone | Takeda Y.,SKY Perfect JSAT Corporation
28th AIAA International Communications Satellite Systems Conference, ICSSC 2010 | Year: 2010

This paper presents a novel electrical polarization tracking method for mobile satellite communication systems that use linear polarization. It consists of two main technologies; the first estimates the mobile station antenna's relative polarization angle against that of the satellite's onboard antenna, the second forms counter polarization against the estimated value. We use a Ku-band communication satellite to evaluate the polarization tracking characteristics and BER performances. These results show that the proposed antenna offers the desired performances. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source

Yamashita F.,Nippon Telegraph and Telephone | Abe J.,Nippon Telegraph and Telephone | Uchiyama H.,Nippon Telegraph and Telephone | Suzuki Y.,Nippon Telegraph and Telephone | And 3 more authors.
28th AIAA International Communications Satellite Systems Conference, ICSSC 2010 | Year: 2010

This paper introduces the results of experiments on a Variable Polarization Frequency Division Multiplexing (VPFDM) system for Ku broadband mobile communications systems. The VPFDM system eliminates the need for earth stations to provide polarization-tracking and enables dual polarization to be used efficiently. The results allow us to conclude that Ku band polarization-tracking-free systems can be realized with the additional link budget margin of just 0.8 dB. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source

Suematsu N.,Tohoku University | Oguma H.,Toyama National College | Eguchi S.,ISB Corporation | Kameda S.,Tohoku University | And 2 more authors.
European Microwave Week 2013, EuMW 2013 - Conference Proceedings; EuMC 2013: 43rd European Microwave Conference | Year: 2013

As a result of the great east Japan earthquake, terrestrial communication infrastructure was seriously damaged. Thus the importance of secure satellite communication measures based on very small aperture antenna terminal (VSAT) systems has been recognized. In order to satisfy the various demands for urgent life line recovery, we have started an R&D project of 'Satellite Communication Networks Valid for Disaster Recovery' as the next generation VSAT system. This project contains following three research topics. (1) multi-mode VSAT's based on software defined radio (SDR) technology, (2) low power consumption VSAT's and (3) emergency mode adaptive bandwidth control technique for HUB earth station. © 2013 European Microwave Association. Source

SKY Perfect JSAT Corporation and Jsat Kabushiki Kaisha Jsat Corporation | Date: 2006-01-10

Antennas; radio wave lens for use in microwave and millimeter-wave communication; and radar reflectors.

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