A Global Navigation Satellite System receiver (102) comprising at least one processor (104) is provided. The processor is configured to: determine a weighted false alarm probability allocation for at least one sub-solution in a solution separation based integrity monitoring module (130), wherein the weighted false alarm probability allocation is based on pre-determined values for missed detection probability and fault probability for the sub-solution, wherein the at least one sub-solution is created by excluding a set of potentially faulty satellites from a full solution, wherein a fault mode occurs when there is a faulty satellite in the excluded set of potentially faulty satellite, wherein the at least one sub-solution's missed detection probability is probability that detection of associated fault mode occurrence in a sub-solution was missed, and wherein the at least one sub-solution's fault probability is probability that the fault mode occurs; compute a weighted protection level based on the weighted false alarm probability.