Position determination for a wireless terminal in a hybrid position determination system

A method for determining a position estimate for a wireless terminal, comprising:

• determining a pseudo-range residual associated with each of one or more base stations included in a synchronous cellular communication system, wherein determining the pseudo-range residual associated with each of one or more base stations comprises:
• determining an accurate position estimate for the terminal based on measured pseudo-ranges to a plurality of satellites in a Global Positioning System (GPS);
• computing an expected pseudo-range to each of the one or more base stations, the expected pseudo-range based on the accurate position estimate for the terminal and a location for each of the one or more base stations;
• obtaining a measured pseudo-range to each of the one or more base stations;
• and
• determining the pseudo-range residual associated with each of the one or more base stations based on the expected pseudo-range and the measured pseudo-range for the associated base station;
• and
• determining the position estimate for the wireless terminal, wherein determining the position estimate for the wireless terminal comprises:
• obtaining a measured pseudo-range for each of a plurality of transmitters, wherein the plurality of transmitters includes at least one base station of the one or more base stations;
• accessing the pseudo-range residual associated with each of the at least one base station included in the plurality of transmitters and correcting the measured pseudo-range using the associated pseudo-range residual;
• and
• determining the position estimate for the wireless terminal based on a plurality of pseudo-ranges for the plurality of transmitters, wherein the plurality of pseudo-ranges include at least one corrected pseudo-range for the at least one base station included in the plurality of transmitters.

A method for determining a position estimate for a wireless terminal based on first and second position determination sub-systems, the method comprising:

• determining the position estimate for the terminal based on the first position determination sub-system if the first position determination sub-system is available, the first position determination sub-system having synchronized transmitters;
• accessing a residual associated with at least one transmitter included in the second position determination system, the second position determination system having synchronized transmitters;
• determining the position estimate for the terminal based on the first and second position determination sub-systems if the first position determination sub-system is partially available, wherein a measurement for each transmitter included in the second position determination sub-system used to determine the position estimate is corrected based on a residual associated with the transmitter;
• and
• determining the position estimate for the terminal based solely on the second position determination sub-system if the first position determination sub-system is unavailable, wherein the measurement for each transmitter included in the second position determination sub-system used to determine the position estimate is corrected based on the residual associated with the transmitter;
• wherein the residual associated with each transmitter included in the second position determination sub-system is determined based on a difference between a previous position estimate obtained at a first time using the first position determination sub-system and previous position estimate obtained at the first time using the second position determination sub-system.

A memory communicatively coupled to a digital signal processing device (DSPD) capable of interpreting digital information to:

• obtain an accurate position estimate for a wireless terminal based on a first position determination sub-system having synchronized transmitters;
• determine a residual associated with each of one or more synchronous transmitters included in a second position determination sub-system based on a difference between the accurate position estimate and a position estimate obtained based on the second position determination sub-system;
• obtain a measurement for each of a plurality of transmitters, wherein the plurality of transmitters include at least one transmitter in the second position determination sub-system;
• correct the measurement for each of the at least one transmitter in the second position determination sub-system based on the residual associated with the transmitter;
• and
• determine an updated position estimate for the terminal based on a plurality of measurements associated with the plurality of transmitters, wherein the plurality of measurements includes at least one corrected measurement for the at least one transmitter in the second position determination sub-system.

A computer program product comprising coded instructions stored in memory and configured to be executed by a processor to determine a position estimate for a wireless terminal, the instructions comprising:

• code to obtain an accurate position estimate for the terminal based on a first position determination sub-system having synchronized transmitters;
• code to determine a residual for associated with each of one or more transmitters included in a second position determination sub-system based on a difference between the accurate position estimate and a position estimate obtained based on the second position determination sub-system;
• code to obtain a measurement for each of a plurality of transmitters, wherein the plurality of transmitters includes at least one transmitter in the second position determination sub-system;
• code to correct the measurement for each of the at least one transmitter in the second position determination sub-system based on the residual associated with the transmitter;
• and
• code to determine an updated position estimate for the terminal based on a plurality of measurements for the plurality of transmitters, wherein the plurality of measurements include at least one corrected measurement for the at least one transmitter in the second position determination sub-system.

A digital signal processor comprising:

• means for obtaining an accurate position estimate for the terminal based on a first position determination sub-system having synchronized transmitters;
• means for determining a residual associated with each of one or more transmitters included in a second position determination sub-system based on a difference between the accurate position estimate and a position estimate obtained based on the second position determination sub-system;
• means for determining a measurement for each of a plurality of transmitters, wherein the plurality of transmitters include at least one transmitter in the second position determination sub-system;
• means for correcting the measurement for each of the at least one transmitter in the second position determination sub-system based on the residual associated with the transmitter;
• and
• means for determining an updated position estimate for the terminal based on a plurality of measurements for the plurality of transmitters, wherein the plurality of measurements include at least one corrected measurement for the at least one transmitter in the second position determination sub-system.

A receiver unit in a wireless communication system, comprising:

• a first receiver operative to receive and process a received signal to provide data for a first position determination sub-system having synchronized transmitters;
• a second receiver operative to receive and process the received signal to provide data for a second position determination sub-system;
• and
• a processing unit coupled to the first and second receivers and operative to:
• obtain an accurate position estimate for a terminal based on the data for the first position determination sub-system,
• determine a residual associated with each of one or more transmitters included in a second position determination sub-system based on a difference between the accurate position estimate and a position estimate obtained based on the second position determination sub-system,
• obtain an actual measurement for each of a plurality of transmitters based on the data for the sub-system to which each transmitter belongs, wherein the plurality of transmitters include at least one transmitter in the second position determination sub-system,
• correct the actual measurement for each of the at least one transmitter in the second position determination sub-system based on the residual associated with the transmitter, and
• determine an updated position estimate for the terminal based on a plurality of measurements for the plurality of transmitters, wherein the plurality of measurements include at least one corrected measurement for the at least one transmitter in the second position determination sub-system.

A wireless terminal in a wireless communication system, comprising:

• a first receiver operative to receive and process a received signal to provide data for a first position determination sub-system having synchronized transmitters;
• a second receiver operative to receive and process the received signal to provide data for a second position determination sub-system;
• and
• a processing unit coupled to the first and second receivers and operative to:
• obtain an accurate position estimate for the terminal based on the data for the first position determination sub-system,
• determine a residual associated with each of one or more transmitters included in a second position determination sub-system based on a difference between the accurate position estimate and a position estimate obtained based on the second position determination sub-system,
• obtain an actual measurement for each of a plurality of transmitters based on the data for the sub-system to which each transmitter belongs, wherein the plurality of transmitters include at least one transmitter in the second position determination sub-system,
• correct the actual measurement for each of the at least one transmitter in the second position determination sub-system based on the residual associated with the transmitter, and
• determine an updated position estimate for the terminal based on a plurality of measurements for the plurality of transmitters, wherein the plurality of measurements include at least one corrected measurement for the at least one transmitter in the second position determination sub-system.

A wireless terminal in a wireless communication system, comprising:

• a first receiver operative to receive and process a received signal to provide data for a first position determination sub-system having synchronized transmitters;
• a second receiver operative to receive and process the received signal to provide data for a second position determination sub-system;
• and
• a processing unit coupled to the first and second receivers and operative to:
• determine a position estimate for the terminal based on the first position determination sub-system if the first position determination sub-system is available,
• determine the position estimate for the terminal based on the first and second position determination sub-systems if the first position determination sub-system is partially available, wherein an actual measurement for each transmitter included in the second sub-system used to determine the position estimate is corrected based on a residual associated with the transmitter, and
• determine the position estimate for the terminal based solely on the second position determination sub-system if the first position determination sub-system is unavailable, wherein the actual measurement for each of at least one transmitter included in the second sub-system used to determine the position estimate is corrected based on the residual associated with the transmitter,
• wherein the residual is determined based on a difference between a previous position estimate obtained at a first time using the first position determination sub-system and previous position estimate obtained at the first time using the second position determination sub-system.