The paper summarises the major results coming out from the multipath analysis carried-out at three different levels for the ATV-ISS scenario: first, multipath signal characterisation at simulation level; second, multipath effects in the Global Positioning System GPS measurements (pseudorange and carrier phase) at experimental level in order to develop a generic multipath model applicable for RVD scenarios; and finally, multipath effects in the RVD navigation performances (including the use of different multipath mitigation and RAIM techniques at software level). Using the Multipath Virtual Laboratory (MVL) software tool developed and validated by GMV through on-ground experimental campaigns in different real multipath demanding scenarios, the computation of the multipath signals characteristics present in the ATV-ISS scenario was carried-out. The simulation campaign covered different ATV/ISS relative positions and different ISS surface models. The size of the multipath effects in the pseudorange (PR) and carrier phase (CP or IDC) measurements was assessed. The results coming out from this characterisation were employed for setting the parameters related to the multipath generation of the GPS Signal Simulator used in the experimental campaign at ESTEC Navigation Laboratory. This experimental campaign was based on the use of the referred GPS Signal Simulator connected to a GPS Builder 2 receiver (hardware-in-the-loop), conveniently adapted to track GPS satellites in space environment. The so-obtained multipath effects over the GPS basic observables measurements were processed in order to derive a compact multipath mathematical model. The compact format is pursued for allowing an easy and quick adaptation to other RVD scenarios by uniquely adjusting the major model parameters. The performances of several GPS relative navigation concepts (absolute state vector based, relative state vector based in single and double GPS measurements differences, and kinematic based algorithms) are evaluated with the derived multipath model. The most promising multipath mitigation techniques at software level are identified and applied to the navigation concepts. These results, together with those coming out from the implementation of a Receiver Autonomous Integrity Monitoring (RAIM) scheme with multipath mitigation purposes, are presented.
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