A GNSS receiver configured to receive a GNSS signal from a satellite, said GNSS receiver comprising a channel decoder configured to decode information carried by the GNSS signal, the GNSS receiver being further configured to: - determine parameters relative to inputs of a statistical propagation channel model (301, 302, 303), the statistical propagation channel model being a Prieto channel model or a Perez-Fontan channel model, - compute a statistical channel attenuation from said statistical propagation channel model using the determined parameters, - compute LLRs from a detection function adapted to the statistical propagation channel model, using the computed statistical channel attenuation, and - use the said LLRs to feed the channel decoder, the GNSS receiver further comprising means configured to determine a type of propagation environment from a plurality of possible propagation environments and configured to provide at least some of the parameters relative to inputs of a statistical propagation channel model, the means for determining a type of propagation environment comprising a vision sensor configured to take an image of the sky, the GNSS receiver further comprising a processing unit associated with the vision sensor and configured to: - determine a ratio of clear sky in the image of the sky, and - choose a type of propagation environment from a set of propagation environments by comparing the ratio of clear sky with one or more thresholds. - determine parameters relative to inputs of a statistical propagation channel model (301, 302, 303), the statistical propagation channel model being a Prieto channel model or a Perez-Fontan channel model, - compute a statistical channel attenuation from said statistical propagation channel model using the determined parameters, - compute LLRs from a detection function adapted to the statistical propagation channel model, using the computed statistical channel attenuation, and - use the said LLRs to feed the channel decoder, the GNSS receiver further comprising means configured to determine a type of propagation environment from a plurality of possible propagation environments and configured to provide at least some of the parameters relative to inputs of a statistical propagation channel model, the means for determining a type of propagation environment comprising a vision sensor configured to take an image of the sky, the GNSS receiver further comprising a processing unit associated with the vision sensor and configured to: - determine a ratio of clear sky in the image of the sky, and - choose a type of propagation environment from a set of propagation environments by comparing the ratio of clear sky with one or more thresholds. the GNSS receiver further comprising means configured to determine a type of propagation environment from a plurality of possible propagation environments and configured to provide at least some of the parameters relative to inputs of a statistical propagation channel model, the means for determining a type of propagation environment comprising a vision sensor configured to take an image of the sky, the GNSS receiver further comprising a processing unit associated with the vision sensor and configured to: - determine a ratio of clear sky in the image of the sky, and - choose a type of propagation environment from a set of propagation environments by comparing the ratio of clear sky with one or more thresholds. - determine a ratio of clear sky in the image of the sky, and - choose a type of propagation environment from a set of propagation environments by comparing the ratio of clear sky with one or more thresholds.