TECHNOLOGY, IMPLEMENTATION AND POLICY ISSUES FOR THE MODERNIZATION OFGPS AND ITS ROLE IN A GNSS

During the past several years, a number of important investigations, p olicy initiatives and national commitments relating to the future of G PS, GLONASS and their augmentations have occurred. Substantive and on- going studies of the character and configuration of a Global Navigatio n Satellite System (GNSS) have also been evaluated worldwide, especial ly by the International Civil Aviation Organization (ICAO). These effo rts have been principally directed toward the definition of near- and far-term GNSS implementations that meet the needs and concerns of the international community. This paper briefly reviews some of the invest igations and addresses, in particular, the concerns and requirements t hat may affect the future capabilities and the dual (civil/military) c haracter of GPS. The main issues relating to the modernisation of GPS and its subsequent transition to a component of a GNSS With a viable i nternational character are presented. These include a discussion of ne w signal structure options, certain changes in operating frequencies, increased signal power levels, other system alternatives and their pot ential impact on system performance. International issues are briefly addressed, including future performance capabilities, assurance of ser vice, economic participation and benefit, reasonable cost, standards a nd international participation.