1) Ground Based Augmentation System (GBAS)
  • • Precision navigation will compress the density of terminal operation without impacting safety, thus increasing capacity. Efficiency benefits include reduced time and distance in the terminal area leading to fuel savings, i.e., cost savings and green air operations. Though the cost and security justification for GPS automatic landing are compelling and though the basic technology for these operations was demonstrated in the early 1990s, neither the FAA nor the Armed Forces has yet approved a GPS automatic landing system. Strikingly, the major obstacle in approving such a system is the difficulty of demonstrating that hazardous misleading navigation errors are sufficiently improbable to meet aviation safety standards.
             
  •  • The Local Area Augmentation System (LAAS) is the United States FAA version of the Ground Based Augmentation System, or GBAS, that has been defined by the International Civil Aviation Organization (ICAO). GNSSLab@KAIST , in close association with both the United States Federal Aviation Administration (FAA) and the Stanford Global Positioning System (GPS) lab works to develop methods for Category II/ III LAAS which will eventually support automatic landings at high-traffic hub airports. We will perform research on the system architectures, technologies, and algorithms needed for the system. This will enable another advance in LAAS robustness and availability by the inclusion of the second GPS frequency and other GNSS (e.g. Galileo, Compass, and GLONASS). The multiplicity of systems will provide geometric diversity or measurement redundancy, and the pair of aviation frequencies will enable us to completely obviate the effect of ionospheric storms or radio frequency interference.

2) Evolutionary GNSS
    

  • • In the year 2020 time frame, when Chinese Compass and European Galileo are deployed on schedule, we will have approximately 120 satellites from four GNSS constellations including current GLONASS and GPS. This multiple civil GNSS frequencies will offer a great advantage to the civilian user in terms of better availability, integrity and accuracy. The addition of signals from the new satellite systems will provide measurement redundancy for the airborne user. This redundancy enables us to adapt Receiver Autonomous Integrity Monitoring (RAIM) techniques and place integrity responsibility on the avionics. If that is the case, we will achieve worldwide approach capability without ground monitors or with light monitoring.

 

  • • GNSSLab@KAIST tackles fundamental challenges in GNSS and construct realizable paths for the future GNSS architecture to proceed. Our goals are to enhance integrity theory, methodology, and architecture, throughout the modernization of satellite based navigation systems, and eventually to enable a reasonable path to an automatic landing capability with sufficient integrity worldwide.
3) Integrity Theory
    

  • • Integrity validation is an emerging field that develops hard bounds on the probability of worst case performance faults. In particular, aircraft guidance seeks to guarantee a very low probability of hazardously large navigation errors. GNSSLab@KAIST extends the theory of integrity assurance and validation designed for aeronautical systems to those of various mechanical, electrical and aerospace systems. New theoretical approaches will be required to assess and evaluate integrity for realistic error distributions found in each application, including heavy-tailed and multi-mode error distributions. Safety validation will also require the fusion of integrity concepts with the analysis of dynamic systems.
4) Integrity Generalization
    

  • • GNSSLab@KAIST aims to realize integrity innovation through technology integration. Depending on a targeted system, technologies from diverse fields will strengthen integrity theory, methodology, and architecture when skillfully integrated. As examples, many safety critical systems require real-time integrity information. Communications and networks technologies which provide lower bit error rates and latency will greatly reduce a burden on integrity design. Advances in sensing and control theory will improve system and integrity performance. Also many of those are complex and long-lifecycle systems, and thus they are expected to evolve over time. If we design an integrity architecture based on strategic planning, it will easily adapt to any necessary changes with low cost. Sometimes those strategies should also address system certification issues and international and political issues.

 

  • • Our research is an important step toward the generalization of integrity assurance for a wide range of safety critical systems such as intelligent transportation systems, wireless safety communication and emergency warning systems, and intelligent urban facility management systems. That is ultimately what will make the world safer.


Global Navigation Satellite Systems Laboratory, Department of Aerospace Engineering
KAIST 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea
Tel) +82-42-350-3725 Fax) +82-42-350-5765