The invention relates to methods, notably carried out by global or regional navigation satellite system (NSS) receivers, which involve receiving satellite-specific, nadir-angle dependent correction information associated with each of at least two NSS satellites among a plurality of NSS satellites. The correction information is useful to correct observed NSS signals, so as to mitigate the effects of satellite-specific, nadir-angle dependent biases in the NSS signals, and thus improve the performance of position determination systems. The invention also relates to methods for generating such correction information, to methods for designing a satellite, to NSS receivers, to apparatuses for generating correction information to be sent to the receivers, and to computer programs and storage mediums.