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Navigation Systems that Take Advantage of a Next-Generation GNSS Environment

The Global Navigation Satellite System (GNSS) has recently been replacing existing ground-based radio facilities used for air navigation. The performance of onboard GNSS receivers will be improved by taking advantage of a next-generation GNSS environment in which other GNSSs, such as the Russian GLONASS or the European Galileo systems, will be available. This will differ from the present case, where processing is done based on the American GPS only. In order to utilize GNSS, it is necessary to apply an augmentation system, either SBAS or GBAS; these augmentation systems must be upgraded for the multiple GNSS environment.
 GNSSs are known to be affected significantly by the ionosphere, which is a plasma layer 300 to 400 km above the ground. To mitigate its impact and maximize GNSS performance, we are examining utilization of space weather information as a countermeasure against the active ionosphere. The ionospheric activity forecast derived from space weather information may contribute to preventing degradation of GNSS performance. Additionally, ionospheric effects can be further reduced by using dual-frequency transmission and multiple GNSSs.
 It has been pointed out that GNSS has some vulnerability to jamming and spoofing attacks because it uses radio signals. For safe navigation, security measures that can be applied to GNSS must be developed.
 In this research, we will develop dual-frequency multiconstellation (DFMC) navigation systems to take advantage of the next-generation GNSS environment, and seek performance improvements by investigating local ionosphere conditions over Japan and GNSS security measures.

Research Group