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 bins and code bins; for a predetermined frequency bin, determining partial average value of accumulated powers over specific set of code bins so that the major part of signal energy is intentionally not included in the partial average; and subtracting the partial average value from all accumulated powers for the predetermined frequency bin; repeating the partial average calculation and subtraction for each frequency bin of a pattern to generate a two-dimensional delay-Doppler accumulated power pattern with suppressed interference effect.