Embedded chirp signal for position determination in cellular communication systems

A mobile unit receiver suitable for use in a wireless communication network, comprising:

• receiving means for receiving from a transmitting station a wireless communication signal having a communication signal with a plurality of frames and a spread spectrum chirp navigation signal embedded in the communication signal in synchronization with said frames;
• synthesizer means for generating a frequency signal;
• downconverting means for downconverting a frequency of a wireless communication signal based on with a frequency signal;
• and
• processing means for detecting the embedded navigation signal in the downconverted wireless communication signal and determining a pseudorange measurement based on the detected embedded navigation signal, wherein the processing means comprises:
• chirp generator means for generating a reference chirp signal based on timing of the frames in the communication signal;
• correlator means for correlating the reference chirp signal with the downconverted wireless communication signal and outputting a correlation signal;
• and
• means for estimating an arrival time of the communication signal based on the correlation signal by correlating the wireless communication with said reference chirp signal and outputting a pseudorange value based on the correlation signal;
• wherein said synthesizer means adjusts the frequency signal based on the pseudorange value.

A method of determining a location of a mobile unit in a communication system, the method comprising:

• extracting a chirp spread spectrum signal from a communication signal that includes a frame having a plurality of slots broadcast from a transmitter, wherein the chirp spread spectrum signal is embedded within the frame and synchronized with a frame structure of the communication signal, said extracting comprises extracting the chirp spread spectrum signal only during slots that are not used for transmission or reception of the communication signal;
• determining a pseudorange measurement between the mobile unit and the transmitter based on the extracted chirp spread spectrum signals;
• and
• determining a location of the mobile unit based on the pseudorange measurement.

A method of determining a position of a mobile unit in a communication system, comprising:

• (a) extracting from a received communication signal a spread spectrum chirp signal that includes a first chirp portion of a first sense and a second chirp portion of a second sense that is opposite to the first sense, wherein said extracting comprises extracting the chirp spread spectrum signal only during time slots that are not used for transmission or reception by the mobile unit;
• (b) determining a pseudorange measurement between the mobile unit and a transmitter that transmits the communication signal based on the spread spectrum chirp signal;
• and
• (c) determining a position of the mobile unit based on the pseudorange measurement.