Method and apparatus for receiving a global positioning system signal using a cellular acquisition signal

Abstract

Method and apparatus for a GPS device that uses at least one cellular acquisition signal is described. More particularly, a GPS device is configured to receive at least one cellular acquisition signal for obtaining benefits associated with AGPS with only a small subset of AGPS circuitry to interact with a cell phone network. This facilitates use of GPS devices without subscription to a cell phone service provider, thus avoiding cellular subscription fees.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of co-pending U.S. patent application Ser. No. 09 / 993,335, filed Nov. 6, 2001, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 884,874, filed Jun. 19, 2001, now U.S. Pat. No. 6,560,534, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 875,809, filed Jun. 6, 2001, now U.S. Pat. No. 6,542,820. Each of the aforementioned related patent applications is herein incorporated by reference. This application contains subject matter that is related to co-pending U.S. patent application Ser. No. 09 / 715,860, filed Nov. 17, 2000, now U.S. Pat. No. 6,417,801, which is herein incorporated by reference in its entirety.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to mobile wireless devices for mobile location systems, and more particularly to Global Positioning Satellite (GPS) receivers with improved indoor penetration for pe...

AI Technical Summary

Benefits of technology

[0011] The present invention provides apparatus and method for obtaining benefits associated with AGPS without requiring complete integration of a GPS device with a cellular handset. Furthermore, the present invention facilitates a GPS handheld or mobile device configured to operate without subscription to a cell phone service provider, and thus eliminates fees for such subscription. An aspect of the present invention is a GPS handheld device that comprises a cellular acquisition signal receiver or front end. It will be appreciated that circuitry required to receive an acquisition signal comprises only a portion of a complete cellular handset. Particularly, a transmitter portion for communicating with a base station of a cellular network is not included in the GPS handheld device. Furthermore, digital signal processor and application processor(s) configured for modulating, demodulating, voice processing, call protocols, subscriber identification and the like are absent in the GPS handheld device. The cellular acquisition signal receiver allows the GPS handheld device to have an accurate time of day and / or frequency reference, thus assisting in GPS signal acquisition and GPS position computation.

[0012] An aspect of the present invention is a method for receiving a GPS signal. More particularly, a frequency correction burst is obtained from a cellular network. A frequency offset responsive to the frequency correction burst is determined, and a window of frequency search responsive to the frequency offset is determined for receiving the GPS signal. This may be done without having to transmit a cellular signal to the cellular network, and this may be done without having to have a subscription to the cellular network.

[0013] Another aspect of the present invention is a method for receiving a GPS signal to a GPS handheld device. More particularly, a time synchronization burst is obtained from a cellular network. A timing offset responsive to the time synchronization burst is determined, and a time of day responsive to the timing offset is determined for receiving the GPS signal. This may be done without having to transmit a cellular signal to the cellular network, and this may be done without having to have a subscription to the cellular network.

[0014] Another aspect of the present invention is a method for determining position of a GPS handheld device in proximity to a cellular base station of a cellular network. More particularly, at least one of location information and identification information is obtained from the cellular base station, and a position estimate of the GPS handheld device responsive to the at least one of location information and identification information is determined. This may be done without having to transmit a cellular signal to the cellular network, and this may be done without having to have fee-based access to the cellular network.

Problems solved by technology

However, these devices have significant limitations, one of which is indoor penetration.

In particular, performance of a conventional GPS mobile device in indoor environments may be limited by ability of the GPS mobile device to decode a navigation data stream broadcast by each of a plurality of satellites.

However, a signal-to-noise ratio in indoor environments is often insufficient for navigation data bit decoding of the broadcast ephemeris.

While AGPS offers improvements in indoor penetration, addition of a cellular handset and a subscription to a wireless provider adds to the cost and power consumption of a GPS receiver.

Cellular handsets contain complex and costly components.

For example, the cost of adding a cell phone alone to a GPS receiver may be prohibitive for GPS applications where a phone would otherwise be an unnecessary addition, let alone the addition of a subscription fee of a cellular provider.

Moreover, cellular transmission consumes power.

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