Research On SBAS Interoperability And Its Key Technology

GNSS plays an incredible important role in terms of positioning, navigation and timing, etc. With its application fields expanded, some high-precision users, especially aviation users have some higher requirements in integrity. Consequently, the Satellite Based Augmentation System(SBAS) comes into public vision. As SBAS service region is territorial, how to accomplish the SBAS interoperability and achieve the seamless global SBAS service has attracted more and more attention.Based on the regional restriction of SBAS service, with the achievement of SBAS interoperability as its research priorities, and accomplishment of the seamless link of global SBASs as the ultimate goal, this paper analyzes the overall architecture and technical feature of the current SBAS system. Upon all its needs, this paper analyzes the connotation and implementation of SBAS interoperability and its key technologies on the research subjects on the frequency selection, message design, ranging code optimization and DFMC SBAS integrity, etc.Specific research work is shown as follows:(1) Based on the background of SBAS, the system architecture and features of the SBAS are analyzed. Upon this basis, the traditional definition of SBAS is extended to enhance whole GNSS instead of GPS only. And the definition,system components and corresponding technical characteristics of state-of-art SBAS is analyzed.(2) Based on the regional restriction of SBAS service, with its frequency selection for L1 and L5, the paper studies the connotation and definition of SBAS interoperability. Aim at the accomplishment of SBAS interoperability,DFMC SBAS is expounded systematically. And SBAS signal, one of the important elements of SBAS interoperability, is analyzed briefly.(3) According to the RTCA standards, the format, content and error correction code of SBAS interoperability message is analyzed. Based on the recommendation of IWG for the SBAS L5 message, a new and morecomprehensive SBAS interoperability message is designed. This provides a reference for the future design of the SBAS systems.(4) Based on the generation of Weil codes, an optimum selection method for ranging codes is proposed and its feasibility is verified. Then the correlation characteristics between the optimized Weil codes and ranging codes existing in L5 band is analyzed in order to demonstrate the performance of the optimized codes. This provides a reference for the signal design in SBAS interoperability.(5) For the system feature of DFMC SBAS, the DFMC SBAS integrity connotation is analyzed from two aspects, i.e. information integrity and airborne equipment integrity monitoring. Based on the HDOP, HPL calculation model is analyzed under different numbers of augmentation constellation. In summary, according to the research on SBAS interoperability and its key technology, the paper analyzes the connotation of SBAS interoperability, and designs the SBAS interoperability message according to the RTCA standards. The paper provides an alternative method and reference for the selection of ranging codes in the SBAS design. At the same time, the DFMC SBAS integrity is studied preliminarily. The research on SBAS interoperability and its key technology is of great significance for the accomplishment of SBAS interoperability, especially for the BD-SBAS.