Abstract: Responsive to a recalibration trigger event, magnetometer data output by a magnetometer can be compared to historical magnetometer data previously output by the magnetometer. If a match is determined, a confidence of the match can be determined using theoretically constant data related to Earth's magnetic field. The constant data can be calculated from the historical magnetometer data. If the confidence of the match exceeds a confidence threshold level, historical calibration data can be used to calibrate the magnetometer. If the confidence of the match does not exceed the confidence threshold level, a calibration procedure can be performed to generate new calibration data, and the new calibration data can be used to calibrate the magnetometer.

Abstract: A mobile device can monitor a current location using a multi-tier approach. A baseband subsystem can monitor a coarse location of the mobile device using various course location parameters, such as a mobile country code (MCC), a location area code (LAC), or a cell identifier (cell ID), as the mobile device moves closer to the geographic region. Upon determining that the mobile device is in a cell that intersects the geographic region, the baseband subsystem can transfer the monitoring to the application subsystem. The task can be performed when the application subsystem determines that the mobile device is currently located in the geographic region. A beacon network can provide more accurate estimates of mobile device location and advertise location based services available to the mobile device.

Abstract: Methods, program products, and systems of location estimation using a probability density function are disclosed. In general, in one aspect, a server can estimate an effective altitude of a wireless access gateway using harvested data. The server can harvest location data from multiple mobile devices. The harvested data can include a location of each mobile device and an identifier of a wireless access gateway that is located within a communication range of the mobile device. The server can calculate an effective altitude of the wireless access gateway using a probability density function of the harvested data. The probability density function can be a sufficient statistic of the received set of location coordinates for calculating an effective altitude of the wireless access gateway. The server can send the effective altitude of the wireless access gateway to other mobile devices for estimating altitudes of the other mobile devices.

Abstract: Measurement data is collected from a magnetic sensor in a portable device, while the device is being carried by its end user and without requiring the end user to deliberately rotate or position the device while the output data is being collected. For example, the device may be held in the user's hand while walking or standing, or it may be fixed to the dashboard of an automobile or boat. Measurement data may also be collected from one or more positing, orientation or movement sensors. The collected measurement data from one or both of the magnetic sensor and the position, orientation or movement sensor is processed. In response, either a 2D compass calibration process or a 3D process is signaled to be performed. Other embodiments are also described and claimed.

Abstract: Methods, program products, and systems of location estimation using a probability density function are disclosed. In general, in one aspect, a server can estimate an effective altitude of a wireless access gateway using harvested data. The server can harvest location data from multiple mobile devices. The harvested data can include a location of each mobile device and an identifier of a wireless access gateway that is located within a communication range of the mobile device. The server can calculate an effective altitude of the wireless access gateway using a probability density function of the harvested data. The probability density function can be a sufficient statistic of the received set of location coordinates for calculating an effective altitude of the wireless access gateway. The server can send the effective altitude of the wireless access gateway to other mobile devices for estimating altitudes of the other mobile devices.

Abstract: Methods, program products, and systems of location estimation using a probability density function are disclosed. In general, in one aspect, a server can estimate an effective location of a wireless access gateway using harvested data. The server can harvest location data from multiple mobile devices. The harvested data can include a location of each mobile device and an identifier of a wireless access gateway that is located within a communication range of the mobile device. The server can calculate an effective location of the wireless access gateway using a probability density function of the harvested data. The probability density function can be a sufficient statistic of the received set of location coordinates for calculating an effective location of the wireless access gateway. The server can send the effective location of the wireless access gateway to other mobile devices for estimating locations of the other mobile devices.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for determining a motion state of a mobile device. Accelerometer data is received from accelerometer sensors onboard the mobile device, wherein the accelerometer data represents acceleration of the mobile device in three-dimensional space. An accelerometer signal vector representing at least a force due to gravity on the mobile device is determined. Two-dimensional accelerometer data orthogonal to the accelerometer signal vector is calculated. A motion state of the mobile device is determined based on the two-dimensional accelerometer data.

Abstract: Techniques for estimating the current state (e.g., position, velocity) of a mobile device based on motion context and multiple input observation types are disclosed. In some implementations, an Extended Kalman Filter (EKF) formulation is used to combine multiple input observations received from a variety of sources (e.g., WiFi, cell, GPS) to compute a minimum error state estimate. In some implementations, the EKF is updated using position estimates from an active cell and/or a candidate active cell during a cell-hopping event.

Abstract: Methods, program products, and systems for baseband location monitoring and related functions are disclosed. A mobile device can monitor its own current location using its baseband subsystem and decide whether to selectively activate its application subsystem based on whether particular conditions are satisfied by the current location. The mobile device can also correlate location and cellular signal information using its baseband subsystem and provide the correlated location and cellular signal information to a server. The server can receive the correlated location and cellular signal information from the baseband subsystems of a large number of widely distributed mobile devices and generate respective profiles of cellular network base stations that transmitted the cellular signals to the mobile devices.

Abstract: Methods, program products, and systems for monitoring a geofence using wireless access points are disclosed. In general, in one aspect, a mobile device receives data defining a geofence. The mobile device can select, from multiple wireless access points, one or more wireless access points for monitoring the geofence. The selected wireless access points can be monitored by a wireless processor of the mobile device. The wireless processor can detect a potential entry of the geofence when at least one of the selected one or more wireless access points is detected. Upon a detection of the potential entry of the geofence by the wireless processor, the mobile device can use an application processor of the mobile device to determine whether the mobile device entered the geofence.

Abstract: Methods, program products, and systems for monitoring geofence exits using wireless access points are disclosed. In general, in one aspect, the mobile device can select, from multiple wireless access points, one or more wireless access points for monitoring a geofence. Selecting the one or more wireless access points can include determining multiple geographic regions corresponding to the geofence. The mobile device can select the one or more wireless access points based on a maximum total number of wireless access points to be selected and an access point allowance for each of the geographic regions. The access point allowance can indicate a maximum number of wireless access points to be selected for the geographic region. The mobile device can detect a potential entry or exit of the geofence by monitoring the selected one or more wireless access points using a wireless processor.

Abstract: Methods, program products, and systems for monitoring geofence exits using wireless access points are disclosed. In general, in one aspect, a mobile device can detect one or more entry gateways that are wireless access points selected for monitoring a geofence. The mobile device can determine that the mobile device is located in the geofence based on the detection. The mobile device can monitor the entry gateways and one or more exit gateways, which can be wireless access points observable by the mobile device when the mobile device is in the geofence. When the mobile device determines, after a number of scans using a wireless processor, that the entry gateways and exit gateways are unobservable, the mobile device can use an application processor to determine whether the mobile device has exited from the geofence.

Abstract: Methods, program products, and systems of location estimation using multiple wireless access gateways are disclosed. In general, in one aspect, a mobile device can scan and detect multiple wireless access gateways. The mobile device can determine an initial estimate of distance between the mobile device and each wireless access gateway. The mobile device can receive, from a server, location data of the detected wireless access gateways. The location data can include an estimated location of each wireless access gateway, an uncertainty of the estimated location, and a reach of each wireless access gateway. The mobile device can assign a weight to each estimated location using the uncertainty, the reach, and the initial estimate. The mobile device can estimate the location of the mobile device using the weighted locations.

Abstract: In some implementations, a location of a mobile device can be determined by calculating an average of the locations of wireless signal transmitters that have transmitted signals received by the mobile device. In some implementations, locations are weighted with coefficients and the average is a weighted average. In some implementations, the locations of the wireless signal transmitters are determined based on identification information encoded in the wireless signals received by the mobile device. The identification information can include an identifier for a wireless signal transmitter. The identification information can include characteristics of the received wireless signal that can be used to identify wireless signal transmitters. In some implementations, identification information from one signal can be combined with identification information from another signal to determine a location of a wireless transmitter.

Abstract: The magnitude of a sensed, raw magnetic field in a portable device is monitored over a given time interval. The monitored magnitude is compared with predetermined criteria. Based on the comparison, recalibration of a compass function is signed. Other embodiments are also described and claimed.

Abstract: The magnitude of a sensed, raw magnetic field in a portable device is monitored over a given time interval. The monitored magnitude is compared with predetermined criteria. Based on the comparison, recalibration of a compass function is signed. Other embodiments are also described and claimed.

Abstract: A parameter related to the Earth's magnetic field can be used to determine accuracy of a magnetometer of a mobile device. In one aspect, a first instance of a parameter related to Earth's magnetic field is determined using data generated by the magnetometer. The magnetometer data can be based in part on a position of the mobile device with respect to the Earth. A second instance of the parameter can be determined using data generated by a model of Earth's magnetic field. The model data can also be based in part on the position of the mobile device with respect to the Earth. The first instance of the parameter can be compared with the second instance of the parameter. An accuracy metric for the magnetometer can be determined based on a result of the comparison. An indication of the accuracy metric can be presented by the mobile device.

Abstract: A mobile device can monitor a current location using a multi-tier approach. A baseband subsystem can monitor a coarse location of the mobile device using various course location parameters, such as a mobile country code (MCC), a location area code (LAC), or a cell identifier (cell ID), as the mobile device moves closer to the geographic region. Upon determining that the mobile device is in a cell that intersects the geographic region, the baseband subsystem can transfer the monitoring to the application subsystem. The task can be performed when the application subsystem determines that the mobile device is currently located in the geographic region. A beacon network can provide more accurate estimates of mobile device location and advertise location based services available to the mobile device.

Abstract: A parameter related to the Earth's magnetic field can be used to determine accuracy of a magnetometer of a mobile device. In one aspect, a first instance of a parameter related to Earth's magnetic field is determined using data generated by the magnetometer. The magnetometer data can be based in part on a position of the mobile device with respect to the Earth. A second instance of the parameter can be determined using data generated by a model of Earth's magnetic field. The model data can also be based in part on the position of the mobile device with respect to the Earth. The first instance of the parameter can be compared with the second instance of the parameter. An accuracy metric for the magnetometer can be determined based on a result of the comparison. An indication of the accuracy metric can be presented by the mobile device.

Abstract: Methods, program products, and systems for multi-tier geofence detection are disclosed. In general, in one aspect, a mobile device can be configured to perform a task when the mobile device enters a geographic region. The mobile device can monitor a current location using a multi-tier approach. A baseband subsystem can monitor a coarse location of the mobile device using various course location parameters, such as a mobile country code (MCC), a location area code (LAC), or a cell identifier (cell ID), as the mobile device moves closer to the geographic region. Upon determining that the mobile device is in a cell that intersects the geographic region, the baseband subsystem can transfer the monitoring to the application subsystem. The task can be performed when the application subsystem determines that the mobile device is currently located in the geographic region.