A Global Navigation Satellite System (GNSS) receiver comprising: a processing device configured to: group a plurality of GNSS satellites in view of the GNSS receiver into a plurality of subsets (114, 116, 118, 120), wherein each GNSS satellite of the plurality of GNSS satellites is included in at most one subset of the plurality of subsets (114, 116, 118, 120), wherein each subset ofthe plurality of subsets (114, 116, 118, 120) includes: at least one GNSS satellite of the plurality of GNSS satellites; and fewer than all GNSS satellites ofthe plurality of satellites; and wherein at least one subset ofthe plurality of subsets (114, 116, 118, 120) includes: more than one GNSS satellite; calculate a full navigation solution using all GNSS satellites of the plurality of GNSS satellites; calculate a plurality of navigation sub-solutions based on combinations of subsets, wherein each navigation sub-solution of the plurality of navigation sub-solutions is calculated with at least one different subset ofthe plurality of subsets (114, 116, 118, 120) excluded, wherein the quantity of navigation sub-solutions to be computed is reduced by excluding at a subset level rather than excluding at a satellite level, wherein the quantity of subsets in the plurality of subsets is selected to balance increased performance with regard to the protection level provided by more subsets with decreased computational load provided by fewer subsets; and calculate a protection level based on the full navigation solution and the plurality of navigation sub-solutions. a processing device configured to: group a plurality of GNSS satellites in view of the GNSS receiver into a plurality of subsets (114, 116, 118, 120), wherein each GNSS satellite of the plurality of GNSS satellites is included in at most one subset of the plurality of subsets (114, 116, 118, 120), wherein each subset ofthe plurality of subsets (114, 116, 118, 120) includes: at least one GNSS satellite of the plurality of GNSS satellites; and fewer than all GNSS satellites ofthe plurality of satellites; and wherein at least one subset ofthe plurality of subsets (114, 116, 118, 120) includes: more than one GNSS satellite; calculate a full navigation solution using all GNSS satellites of the plurality of GNSS satellites; calculate a plurality of navigation sub-solutions based on combinations of subsets, wherein each navigation sub-solution of the plurality of navigation sub-solutions is calculated with at least one different subset ofthe plurality of subsets (114, 116, 118, 120) excluded, wherein the quantity of navigation sub-solutions to be computed is reduced by excluding at a subset level rather than excluding at a satellite level, wherein the quantity of subsets in the plurality of subsets is selected to balance increased performance with regard to the protection level provided by more subsets with decreased computational load provided by fewer subsets; and calculate a protection level based on the full navigation solution and the plurality of navigation sub-solutions. group a plurality of GNSS satellites in view of the GNSS receiver into a plurality of subsets (114, 116, 118, 120), wherein each GNSS satellite of the plurality of GNSS satellites is included in at most one subset of the plurality of subsets (114, 116, 118, 120), wherein each subset ofthe plurality of subsets (114, 116, 118, 120) includes: at least one GNSS satellite of the plurality of GNSS satellites; and fewer than all GNSS satellites ofthe plurality of satellites; and at least one GNSS satellite of the plurality of GNSS satellites; and fewer than all GNSS satellites ofthe plurality of satellites; and wherein at least one subset ofthe plurality of subsets (114, 116, 118, 120) includes: more than one GNSS satellite; more than one GNSS satellite; calculate a full navigation solution using all GNSS satellites of the plurality of GNSS satellites; calculate a plurality of navigation sub-solutions based on combinations of subsets, wherein each navigation sub-solution of the plurality of navigation sub-solutions is calculated with at least one different subset ofthe plurality of subsets (114, 116, 118, 120) excluded, wherein the quantity of navigation sub-solutions to be computed is reduced by excluding at a subset level rather than excluding at a satellite level, wherein the quantity of subsets in the plurality of subsets is selected to balance increased performance with regard to the protection level provided by more subsets with decreased computational load provided by fewer subsets; and calculate a protection level based on the full navigation solution and the plurality of navigation sub-solutions.