A method for processing weak indoor signals in presence of cross-correlation or continuous wave interference and associated GPS receiver are provided. The method comprises providing a two-dimensional delay-Doppler accumulated power pattern having a plurality of accumulated powers corresponding to frequency and time; for a predetermined frequency, determining an average value of accumulated powers of the two-dimensional delay-Doppler accumulated power pattern over a plurality of times; and subtracting the average value from the accumulated powers used in determining the average at the frequency over the plurality of times to generate a delay-Doppler accumulated power pattern with suppressed interference effect.