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Liu J.,Tohoku University | Jiang X.,Future University Hakodate | Nishiyama H.,Tohoku University | Miura R.,Wireless Network Research Institute | And 2 more authors.
IEEE Journal on Selected Areas in Communications | Year: 2012

This paper examines the optimal forwarding problem in mobile ad hoc networks (MANETs) based on a generalized two-hop relay with limited packet redundancy f (f-cast) for packet routing. We formulate such problem as a forwarding game, where each node i individually decides a probability τ-i (i.e., a strategy) to deliver out its own traffic and helps to forward other traffic with probability 1-τ-i, τ-i[0,1], while its payoff is the achievable throughput capacity of its own traffic. We derive closed-form result for the per node throughput capacity (i.e., payoff function) when all nodes play the symmetric strategy profiles, identify all the possible Nash equilibria of the forwarding game, and prove that there exists a Nash equilibrium strategy profile that is strictly Pareto optimal. Finally, for any symmetric profile, we explore the possible maximum per node throughput capacity and determine the corresponding optimal setting of f to achieve it. © 2012 IEEE. Source


Kadowaki N.,Wireless Network Research Institute
Journal of the National Institute of Information and Communications Technology | Year: 2012

The National Institute of Information and Communications Technology (NICT) has worked toward the research and development of various satellite communications and broadcasting technologies since the 1970s. NICT developed the basic laser communication experimental equipment (LCE) for the Engineering Test Satellite-VI (ETS-VI) and performed the world's first laser communication experiment using a satellite in orbit in 1994. The Optical Inter-orbit Communications Engineering Test Satellite (OICETS), called 'Kirari' in Japanese, was developed by the Japan Aerospace Exploration Agency (JAXA). Kirari project was put on hold after the protoflight test was completed. However, the Kirari was launched successfully in August 2005. After this, NICT guided and realized a joint international project of laser communication experiments between the Kirari and each of the four optical ground stations in various locations on the ground. Source


Kawasaki K.,Wireless Network Research Institute
Journal of the National Institute of Information and Communications Technology | Year: 2014

Experimental telecommunications equipment of the Ka and S band was installed in Engineering Test Satellite VIII (ETS-VIII: KIKU No.8) launched in December, 2006. To investigate the secular distortion of this experimental telecommunications equipment, five times performance evaluation experiment was done. This experiment result represents an evaluation for the secular distortion of the equipment equipped to the satellite on the orbit, and it becomes a help in designing and production of the equipment installed to the satellite in the future. Source


Minowa T.,Social Research Center | Miura A.,Wireless Network Research Institute
Journal of the National Institute of Information and Communications Technology | Year: 2015

This paper presents the satellite-terrestrial user coexisting schemes (frequency separation scheme, frequency sharing scheme) as a key technology of Satellite and Terrestrial Integrated mobile Communication System (STICS). The frequency sharing scheme, which is expected to realize high spectrum efficiency, is introduced with its principle, the interference problem, and the interference suppression/mitigation technologies. Then, theoretical analyses and computational simulations to compare the spectrum efficiencies between frequency separation and sharing schemes are carried out to show the effectiveness of the frequency sharing scheme. Source


Fujino Y.,Toyo University | Miura A.,Wireless Network Research Institute
Journal of the National Institute of Information and Communications Technology | Year: 2015

Onboard Low Noise Amplifier (LNA) and Solid State Power Amplifier (SSPA) of STICS (Satellite/Terrestrial Integrated mobile Communication System) satellite is assumed to meet large signal interference from huge numbers of terrestrial communication terminals or to amplify hundreds of channels simultaneously. So, LNA required having high linearity and low noise figure simultaneously. We developed S-band onboard LNA which can efficiently operate high level interference wave that is 40 dB higher than that of desired wave. Also, for SSPA, we developed high linearity and high efficiency SSPA using GaN device. Source

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