Radio Science Bulletin 325 - June 2008 - URSI

• Compatibility refers to the ability of space-basedpositioning, navigation, and timing services to be usedseparately or together without interfering with eachindividual service or signal;• Interoperability refers to the ability of open global andregional satellite navigation and timing services to beused together to provide better capabilities at the userlevel than would be achieved by relying solely on oneservice or signal.2.2 Experts MeetingOn September 5, an Experts Meeting was held,consisting of five scientific and technical sessions:• Prediction of natural disaster and research on climatechange and Earth science• Geodetic reference frames• Atomic time standards, Coordinated Universal Time(UTC), and time transfer• Ionospheric/tropospheric models and space-weathereffects• GNSS activities in India2.3 Second Plenary MeetingThe second Plenary Meeting was held on September6 and 7. Reports from the Providers Forum and the WorkingGroups were presented, and the Committee considered therecommendations and plans for future work of the WorkingGroups. A special report was discussed on the subject ofSatellite-based Augmentation System certification.The Committee agreed that China be recognized as aprovider of GNSS, since it was developing the CompassNavigation Satellite System.Since this was only the second full meeting of theICG, several actions were proposed to streamline the workingmethods of the Working Groups and to avoid duplications.The Committee expressed its satisfaction with thecontinuing effort by the secretariat to develop the informationportal of the Committee as part of the Web site of the Officefor Outer Space Affairs.The Committee accepted the invitation of the UnitedStates to host the third meeting, to be held in 2008, andnoted the offer of the Russian Federation to host the fourthmeeting in 2009.Two informal meetings of the Ad Hoc WorkingGroup to prepare the next meeting of the Committee wereplanned for 2008.3. ConclusionsAll presentations from the Providers’ Forum and thetechnical expert sessions as well as the Working GroupReports are available at the portal of the Committee:http://www.unoosa.org/oosa/en/SAP/gnss/icg.htmlAfter a slow start, the work by the different WorkingGroups now seems to be developing. From the subjects ofthe technical sessions mentioned above, one can concludethat there are several areas where URSI is able to makecontributions. It is planned to prepare a report for the nextPlenary meeting, summarizing URSI’s interest in variousactivities. These include both research and developmentconcerning GNSS itself, and scientific applications of theuse of the positioning and navigation system. Inputs to thisreport will be solicited from the Commissions involved.4. Annex4.1 Summary of the ICG WorkPlan and Working Group ActionsThe ICG work plan is executed by five WorkingGroups, which have defined a number of specific Actions.4.1.1 Working Group A:Compatibility and InteroperabilityThe working group formed to address compatibilityand interoperability, to be co-led by the United States ofAmerica and the Russian Federation, will pursue thefollowing actions:- Action A1: Establish a providers forum to enhancecompatibility and interoperability among current andfuture global and regional space-based systems.- Action A2: Organize a workshop(s) on measures beingtaken by Members, Associate Members, and Observersto enhance interoperability and compatibility of (1)global and regional space-based systems and (2) regionalground-based DGNSS.- Action A3: Survey the level of interoperability andstandardization among GNSS constellations andaugmentations in order to identify concrete steps thatcan be taken at different levels (regulatory, systemimplementation, user algorithms) to improveinteroperability and standardization. It is expected thatthe situation is well advanced in civil aviation andmaritime areas, the effort would therefore probablyneed to concentrate on land-based applications andusers.- Action A4: Consider guidelines for the broadcast ofnatural disaster alarms via GNSS.12TheRadio Science Bulletin No 325 (June 2008)