METHOD TO OPTIMIZE PROVIDING ASSISTANCE INFORMATION TO GPS

• US 20140062773A1
• Filed: 08/30/2013
• Published: 03/06/2014
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Grosman, Yefim, Huang, Ronald Keryuan, Mayor, Robert W., MacGougan, Glenn D.
• Granted Patent: US 9,535,163 B2
• Time in Patent Office: Days
• US Class Current: 342/357.28
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
• CPC Class Codes: G01S 5/0236 Assistance data, e.g. base station almanac

Abstract

Methods and apparatus to provide assistance data for satellite navigation in a wireless communication device are disclosed. Processing circuitry in the wireless communication device determines whether to obtain assistance data for navigation based on a set of criteria. The set of criteria include one or more of a property of a geographic region in which the wireless communication device operates, a satellite signal quality estimate measured by the wireless communication device, and a user setting of the wireless communication device. When the set of criteria indicates that assistance data for navigation is beneficial for satellite navigation in the wireless communication device, the processing circuitry obtains one or more sets of assistance data. The processing circuitry configures operation of the wireless communication device for navigation based at least in part on the one or more sets of assistance data obtained.

Claims

1. A wireless communication device, comprising:

a global positioning system (GPS) module configured to receive global navigation satellite system (GNSS) signals and to determine a GPS position of the wireless communication device based at least in part on received GNSS signals; and

processing circuitry coupled to the GPS module, the processing circuitry configured to control the wireless communication device to at least;

obtain an altitude difference model for a region in which the wireless communication device operates;

obtain a wireless local area network (WLAN) access point density model for the region;

determine a geographic type for the region based at least in part on the altitude difference model and the WLAN access point density model; and

obtain GPS assistance data when the region in which the wireless communication device operates is a dense urban region.

2. The wireless communication device of claim 1, wherein the processing circuitry is further configured to control the wireless communication device to:

alter a duty cycle of operation of the GPS module when the wireless communication device operates in a dense urban region.

3. The wireless communication device of claim 1, wherein the processing circuitry is further configured to control the wireless communication device to:

obtain a bare-earth altitude model for the region in which the wireless communication device operates;

obtain a first-return altitude model for the region in which the wireless communication device operates; and

calculate the altitude difference model for the region in which the wireless communication device operates based at least in part on the bare-earth altitude model and the first-return altitude model.

4. The wireless communication device of claim 1, wherein the processing circuitry of the wireless communication device obtains the WLAN access point density model by measuring a number of available WLAN access points in the region in which the wireless communication device operates during a time period.

5. The wireless communication device of claim 1, wherein the processing circuitry of the wireless communication device obtains the WLAN access point density model by retrieving information from local storage in the wireless communication device or from a remote server through a cellular wireless network.

6. The wireless communication device of claim 1, wherein the processing circuitry is further configured to control the wireless communication device to:

obtain sensor information from one or more sensors in the wireless communication device;

determine additional GPS assistance data based at least in part on the sensor information; and

provide the additional GPS assistance data to the GPS module.

7. The wireless communication device of claim 1, wherein the processing circuitry is configured to control the wireless communication device to obtain GPS assistance data when the wireless communication device operates in the dense urban region by downloading GPS assistance information for the region in which the wireless communication device operates from an external wireless network.

8. The wireless communication device of claim 1, wherein the processing circuitry is configured to determine the geographic type for the region in which the wireless communication device operates by classifying the region as one of:

dense urban, open suburban, dense rural, and open rural.

9. The wireless communication device of claim 8, wherein the geographic type of the region in which the wireless communication device operates is classified as dense urban when the altitude difference model indicates an altitude difference in the region exceeding an altitude threshold and the WLAN access point density model in the region exceeds a density threshold.

10. The wireless communication device of claim 8, wherein the geographic type of the region, in which the wireless communication device operates, is classified as open rural when the altitude difference model indicates an altitude difference in the region falls below an altitude threshold and the WLAN access point density model in the region falls below a density threshold.

11. A method to provide assistance data to a satellite navigation system in a wireless communication device, the method comprising:

determining whether to obtain assistance data for navigation in the wireless communication device based on a set of criteria including one or more of;

a property of a geographic location of the wireless communication device, a satellite signal quality estimate measured by the wireless communication device, and a user setting of the wireless communication device;

when the set of criteria indicates a requirement for assistance data for navigation, obtaining one or more sets of assistance data; and

configuring operation of the wireless communication device for navigation by the satellite navigation system based at least in part on the one or more sets of assistance data.

12. The method of claim 11, further comprising:

obtaining an initial set of geographic data for a particular region in which the wireless communication device is located, the initial set of geographic data indicating whether detailed geographic data for the particular region is available; and

wherein

determining whether to obtain assistance data for navigation comprises determining when detailed geographic data for the particular region is available.

13. The method of claim 11, further comprising:

obtaining a bare-earth altitude model for a particular region in which the wireless communication device is located;

obtaining a first-return altitude model for the particular region in which the wireless communication device is located; and

calculating an altitude difference model for the particular region in which the wireless communication device is located based at least in part on the bare-earth altitude model and the first-return altitude model;

wherein determining whether to obtain assistance data for navigation comprises determining whether the property of the geographic location comprises a dense urban region based at least in part on the altitude difference model.

14. The method of claim 13, wherein determining whether the property of the geographic location comprises the dense urban region is further based on a measured density of wireless local area network (WLAN) access points in the particular region.

15. The method of claim 14, wherein the property of the geographic location comprises the dense urban region when the measured density of WLAN access points in the particular region exceeds a WLAN density threshold for a time period exceeding a time threshold.

16. The method of claim 11, wherein the set of criteria indicates the requirement for assistance data for navigation by identifying when reception of satellite signals from a minimum number of satellites by the wireless communication device exceeds a time threshold.

17. The method of claim 13, wherein the property of the geographic location comprises the dense urban region when the altitude difference model indicates an altitude difference in the particular region exceeding an altitude threshold.

18. The method of claim 12, wherein the detailed geographic data for the particular region includes a characterization of geographic properties of the particular region as one or more of:

open rural, dense rural, dense urban, and open suburban.

19. The method of claim 18, wherein the particular region is characterized as a dense urban region, and wherein configuring operation of the wireless communication device for navigation comprises one or more of:

downloading GPS assistance information for the particular region;

providing GPS assistance information to a GPS module;

enabling one or more sensors to assist in navigation;

setting a duty cycle of the GPS module to operate more frequently, and

setting a map alignment threshold to a wider geographic area.

20. A computer program product for providing assistance data for a satellite navigation system in a wireless communication device, the computer program product comprising at least one non-transitory computer readable storage medium having computer program code stored thereon, the computer program code comprising:

computer program code for obtaining an initial set of geographic data for a region in which the wireless communication device operates;

computer program code for determining from the initial set of geographic data for the region whether additional detailed geographic data for the region is available;

computer program code for obtaining the detailed geographic data for the region when available and when the wireless communication device operates in a dense urban region; and

computer program code for providing at least a portion of the detailed geographic data for the region to a GPS module in the wireless communication device to assist with navigation by the wireless communication device.