Forward link repeater frequency watermarking scheme

A mobile station for receiving a plurality of forward link pilot signals and identifying the presence of a fast frequency watermark waveform to determine whether any of said forward link signals are repeated, said mobile station comprising:

• a receiver for receiving forward link signals;
• a frequency tracking loop for enabling accurate demodulation of the forward link signals;
• an AFLT searcher for detecting pilots and performing pilot phase measurements including measuring the times of arrival of said plurality of forward link pilot signals;
• and
• a repeater identification system configured to detect and identify the watermark, if any, and thereby identify a repeated forward link signal, wherein said repeater identification system searches the forward link signal for the watermark to retrieve the watermark waveform that uniquely identifies the repeater, the watermark waveform having a frequency such that the frequency tracking loop substantially does not detect said watermark.

A method for determining position location information of a mobile station from the forward link of a plurality of pilot signals, the method comprising:

• performing an AFLT search in the mobile station to detect pilots and measure an earliest time-of-arrival of said plurality of pilot signals;
• selecting a first pilot signal located during said AFLT search;
• repeater-screening said first pilot signal by performing a repeater AFLT search on said first pilot signal, including searching for a fast frequency watermark waveform that identifies a repeated signal, wherein said watermark waveform has a frequency such that a frequency tracking loop in said mobile station substantially does not detect said watermark at said mobile station;
• repeating said steps of performing and repeater-screening for a plurality of other selected pilot signals until a sufficient number of repeater-screened pilot signals to determine a position location of the mobile station is obtained;
• and
• providing pilot phase measurements and repeater information for the pilot signals obtained in said AFLT search to one of a mobile station position determining system and a network position determination entity to determine the position of said mobile station.