Systems and methods for providing timely location estimates when a user equipment initiates a call to an emergency number are disclosed. The system enables a user equipment and network nodes (e.g., eSMLC/LMF) to send multiple location responses instead of just one so that the PSAP can benefit from accurate location techniques in a timely manner. For example, when a user equipment is located in an outdoor environment, it can immediately send its A-GNSS location after meeting quality-of-service (QoS) criteria, and the eSMLC/LMF can forward the location estimate to the PSAP immediately without first waiting for all of the other location estimates. When location estimates become available from other technologies (e.g., E-CID, or DBH, or both), the eSMLC/LMF can send to the PSAP another location response for that technology. As a result, the PSAP can always have the most accurate and up-to-date location information available to timely and accurately respond to emergency calls.

A method of mapping and localization is disclosed that includes, reconstructing a point cloud and a camera pose based on VSLAM, synchronizing the camera pose and a GPS timestamp at a first set of GPS coordinate points and transforming the first set of GPS coordinate points corresponding to the GPS timestamp into a first set of ECEF coordinate points. The method also includes determining a translation and a rotation between the camera pose and the first set of ECEF coordinate points, transforming the point cloud and the camera pose into a second set of ECEF coordinates based on the translation and the rotation and transforming the point cloud and the camera pose into a second set of GPS coordinate points. The method further includes constructing and storing a key-frame image, a key-frame timestamp and a key-frame GPS based on the second set of GPS coordinate points.

A method of mapping and localization is disclosed that includes, reconstructing a point cloud and a camera pose based on VSLAM, synchronizing the camera pose and a GPS timestamp at a first set of GPS coordinate points and transforming the first set of GPS coordinate points corresponding to the GPS timestamp into a first set of ECEF coordinate points. The method also includes determining a translation and a rotation between the camera pose and the first set of ECEF coordinate points, transforming the point cloud and the camera pose into a second set of ECEF coordinates based on the translation and the rotation and transforming the point cloud and the camera pose into a second set of GPS coordinate points. The method further includes constructing and storing a key-frame image, a key-frame timestamp and a key-frame GPS based on the second set of GPS coordinate points.

A method of inferring the GPS location of a device with a GPS receiver is disclosed. The method includes using signals from two GPS satellites to determine two candidate GPS locations. Geographic information can be used to estimate the probability that the device is at each location. If one of the two candidate GPS locations has a substantially higher probability of being the correct location, that location may be selected as the inferred GPS location. The method may also include making use of additional sensed data that could be provided using sensors onboard the device.

A method of inferring the GPS location of a device with a GPS receiver is disclosed. The method includes using signals from two GPS satellites to determine two candidate GPS locations. Geographic information can be used to estimate the probability that the device is at each location. If one of the two candidate GPS locations has a substantially higher probability of being the correct location, that location may be selected as the inferred GPS location. The method may also include making use of additional sensed data that could be provided using sensors onboard the device.

A system for determining a position of a receiver from as few as two or three transmitters. The receiver may be stationary or moving with a known velocity. The system includes a receiver clock having a clock bias and a clock drift relative to a reference clock and may also include a motion sensor. A decoder receives transmitted signals from a number of transmitters and determine pseudo-ranges and transmitter frequencies therefrom and a processing unit receives the pseudo-ranges, the transmitter frequencies and the receiver velocity and determines the position of the receiver therefrom. When only two transmitters are available, the position of the receiver is determined dependent upon a known receiver clock drift. The system may also determine clock bias and, when three or more transmitters are available, receiver clock drift. The processing unit uses ranging and Doppler equations in combination, and may also use a measured velocity.

A system for determining a position of a receiver from as few as two or three transmitters. The receiver may be stationary or moving with a known velocity. The system includes a receiver clock having a clock bias and a clock drift relative to a reference clock and may also include a motion sensor. A decoder receives transmitted signals from a number of transmitters and determine pseudo-ranges and transmitter frequencies therefrom and a processing unit receives the pseudo-ranges, the transmitter frequencies and the receiver velocity and determines the position of the receiver therefrom. When only two transmitters are available, the position of the receiver is determined dependent upon a known receiver clock drift. The system may also determine clock bias and, when three or more transmitters are available, receiver clock drift. The processing unit uses ranging and Doppler equations in combination, and may also use a measured velocity.

A method of determining an integer ambiguity search space includes: obtaining, at an apparatus, a code phase measurement of a satellite vehicle signal comprising a pseudorandom noise code and a carrier signal; obtaining, at the apparatus, spatial information corresponding to a wireless terrestrial signal transferred between the apparatus and a terrestrial base station; determining, at the apparatus, a satellite positioning system carrier phase integer ambiguity search space based on the code phase measurement; and constraining a size of the satellite positioning system carrier phase integer ambiguity search space based on the spatial information.

A position measurement system including: an absolute positioning measuring unit configured to measure an absolute position of a mobile object, attach a first time stamp to an absolute position measurement result, and output the absolute position measurement result with the first time stamp; a relative positioning measuring unit configured to measure a relative displacement of the mobile object, attach a second time stamp to a relative displacement measurement result, and output the relative displacement measurement result with the second time stamp; and a positioning computation unit configured to execute positioning computation for calculating the absolute position of the mobile object based on the absolute position measurement result with the first time stamp and the relative displacement measurement result with the second time stamp, attach a third time stamp to a positioning computation result, and output the positioning computation result with the third time stamp.

A position measurement system including: an absolute positioning measuring unit configured to measure an absolute position of a mobile object, attach a first time stamp to an absolute position measurement result, and output the absolute position measurement result with the first time stamp; a relative positioning measuring unit configured to measure a relative displacement of the mobile object, attach a second time stamp to a relative displacement measurement result, and output the relative displacement measurement result with the second time stamp; and a positioning computation unit configured to execute positioning computation for calculating the absolute position of the mobile object based on the absolute position measurement result with the first time stamp and the relative displacement measurement result with the second time stamp, attach a third time stamp to a positioning computation result, and output the positioning computation result with the third time stamp.