Aim of the activity is to study the impact of multipath characterization on GNSS sensor station, vehicular, pedestrian, aeronautical and maritime receivers performance, considering channel complexity and limitation in the description, receiver characteristics and Signal-In-Space (SIS) properties. Analysis, synthesis and integration of models and design and development of an emulation hardware tool able to support high fidelity channel models for RFCS is part of the activity. Early mitigation techniques based on the results of the analysis shall be investigated.

The effects of propagation impairments, in particular multipath on GNSS receivers is well known, affecting availability, accuracy and continuity of service. Initial investigations on the possibility to reduce complexity of channel models for characterizing GNSS Rx in terms of tracking and/or PVT performance has been performed for example in the "GALILEO SIS TESTING" activity.Although promising results have been seen for the characterization of the statistics of the Rx, still limitations exist in this model reduction for characterising punctual fails (e.g. false lock due to high delay). Moreover, it is clear that multipath modelling for GNSS receivers performance can be highly dependent on receivers' characteristics and Signal-In-Space (SIS) properties and this is not addressed in the "GALILEO SIS TESTING" activity. At the same time, techniques for further studying model reduction and adaptation to hardware emulators can be foreseen based for example on second order moment of the channel and SIS/receiver properties. Therefore, the effects of channel modelling limits (like channel length, number of taps, channel memory, etc) shall be further investigated together with SIS and Rx characteristics (like effects of the bandwidth of the SIS and of the Rx) on Rx performance characterization (code and phase and data demodulation errors). In fact, the dependency between channel model reduction/adaptation and Rx performance characterization revealed even tighter when targeting strong reduction of the complexity of the model. The capabilities and limitations of channel simulation in existing Radio Frequency Constellation Simulators shall be analysed and adapted models shall be proposed accordingly. Furthermore, a channel emulation platform compatible with RFCS signal shall be designed and developed.Content of the activity will be:- Analysis of the impact of multipath characterization on GNSS receivers (sensor station, vehicular, pedestrian, aeronautical and maritime).- Analysis of limitations of current RFCS regarding the simulation of high fidelity channel models for GNSS receivers for ensor stations, vehicular, pedestrian, aeronautical and maritime.- Development of hardware channel emulator to be interfaced with existing RFCS able to reproduce high fidelity channels.- Characterization of the SIS in terms of Rx tracking and/or PVT performance with the new models. - Testing of existing multipath mitigation techniques and development of new potential techniques