  Global Navigation Satellite System (GNSS) is pervasive in navigation and
positioning applications, where precise position and time referencing
estimations are required. Conventional methods for GNSS positioning involve a
two-step process, where intermediate measurements such as Doppler shift and
time delay of received GNSS signals are computed and then used to solve for the
receiver's position. Alternatively, Direct Position Estimation (DPE) was
proposed to infer the position directly from the sampled signal without
intermediate variables, yielding to superior levels of sensitivity and
operation under challenging environments. However, the positioning resilience
of DPE method is still under the threat of various interferences. Robust
Interference Mitigation (RIM) processing has been studied and proved to be
efficient against various interference in conventional two-step positioning
(2SP) methods, and therefore worthy to be explored regarding its potential to
enhance DPE. This article extends DPE methodology by incorporating RIM
strategies that address the increasing need to protect GNSS receivers against
intentional or unintentional interferences, such as jamming signals, which can
deny GNSS-based positioning. RIM, which leverages robust statistics, was shown
to provide competitive results in two-step approaches and is here employed in a
high-sensitivity DPE framework with successful results. The article also
provides a quantification of the loss of efficiency of using RIM when no
interference is present and validates the proposed methodology on relevant
interference cases, while the approach can be used to mitigate other common
interference signals.
