1. A method for generating an optimum measurement subset from a set of weighted input global navigation satellite system (GNSS) measurements, wherein the number of weighted input GNSS measurements in the set of weighted input GNSS measurements is a first integer, wherein the number of weighted input GNSS measurements in the optimum measurement subset is a specified second integer, and wherein the specified second integer is less than the first integer, the method comprising: performing the steps of: receiving the set of weighted input GNSS measurements; generating a group of trial measurement subsets by removing a different individual weighted input GNSS measurement from the set of weighted input GNSS measurements; for each trial measurement subset in the group of trial measurement subsets, calculating a value of accuracy criterion for at least one target parameter; determining a minimum value of accuracy criterion based on the values of accuracy criterion calculated for each trial measurement subset in the group of trial measurement subsets; and assigning the trial measurement subset having the minimum value of accuracy criterion as a current selected trial measurement subset; and iteratively performing the steps of: determining whether the number of weighted input GNSS measurements in the current selected trial measurement subset is equal to the specified second integer; upon determining that the number of weighted input GNSS measurements in the current selected trial measurement subset is equal to the specified second integer: assigning the current selected trial measurement subset as the optimum measurement subset; and upon determining that the number of weighted input GNSS measurements in the current selected trial measurement subset is not equal to the specified second integer: generating a new group of trial measurement subsets from the current selected trial measurement subset by removing a different individual weighted GNSS measurement from the current selected trial measurement subset; for each trial measurement subset in the new group of trial measurement subsets, calculating the value of accuracy criterion for the at least one target parameter; determining a new minimum value of accuracy criterion based on the values of accuracy criterion calculated for each trial measurement subset in the new group of trial measurement subsets; and assigning the trial measurement subset with the new minimum value of accuracy criterion as the current selected trial measurement subset.