A-RAIM vs. R-RAIM: A comparative study

Yiping Jiang, Jinling Wang

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review


GNSS Receiver Autonomous Integrity Monitoring (RAIM) has been widely
used in civil aviation with the purpose of keeping the users notified of the
integrity risk of the navigation solutions. It is based on the scheme of
consistency check among redundant observations and therefore independent
of any augmentation systems. With the modernized GPS and GLONASS, as
well as the new GNSS systems (Compass, GALILEO) well underway, the
increase in the number of satellites and the multiple frequency signals are
available. It is therefore reasonable to pursue the possibility of using RAIM
in civil aviation for more stringent procedures, such as LPV-200 for vertical
guidance on a global scale. This possibility is explored by US Federal
Aviation Administration (FAA) under the panel of GNSS Evolutionary
Architecture Study (GEAS), which has attracted attention of researchers
thereafter. Two major architectures have been identified as feasible choices
to meet the LPV-200 requirement: a) Advanced RAIM (A-RAIM), b)
Relative RAIM (R-RAIM). With different advantages and disadvantages for
the two architectures, it is realistic to have a comprehensive comparison.
And then, reasonable choices can be made based on the requirements for
specific applications.

The comparison is conducted mainly at the algorithm level. In this paper, the
Multiple Hypotheses Solution Separation (MHSS) method based on
local tests with multiple alternative hypotheses is adopted. Based on the
common threat model, A-RAIM and R-RAIM are compared with results of
VPL. The comparison of VPL within a world-wide map and a time series is
provided to illustrate the difference. This paper is concluded with analysis
and suggestions based on the comparison.
Original languageEnglish
Title of host publicationIGNSS Symp., Sydney
Publication statusPublished - 2011
Externally publishedYes


  • RAIM
  • R-RAIM
  • A-RAIM
  • GNSS
  • Civil Aviation


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