HK1151593B - A locating method and communication system - Google Patents

Description

Positioning method and communication system

Technical Field

The present invention relates to communication systems, and more particularly, to a self-assisted ephemeris extension (ephemeris extension) method and system for a GNSS receiver.

Background

The GPS (Global Positioning System), GLONASS (Global orbiting Navigation Satellite System), and GALILEO (GALILEO) Satellite Navigation systems are three examples of GNSS (Global Navigation Satellite System). GNSS is based on the earth-orbiting constellation of multiple satellites, each broadcasting a signal indicating its precise position and range information. At any location on or near the earth, a GNSS receiver may normally determine its navigation information from satellite broadcast signals from multiple GNSS satellites. The time required for the first fix (i.e., position calculation) is reduced when the GNSS receiver is preceded by a model of the received satellite orbits and clocks. The model is broadcast by GNSS satellites and is commonly referred to as ephemeris or ephemeris data. The ephemeris may be broadcast to the GNSS receiver as part of a GNSS broadcast signal or navigation message. The broadcast ephemeris may include navigation information for the transmitting GNSS satellites. The navigation information includes a standard satellite orbit model, a clock model, and/or information related to the operating state of the relevant GNSS satellites (healthy or unhealthy) for determining navigation information such as position fix (fix) and speed of the GNSS receiver. The broadcast ephemeris is typically valid only for a limited period of time, such as 2-4 hours into the future (from the start of the broadcast time). Before the validity period is over, the GNSS receiver needs to acquire new broadcast ephemeris in order to continue to operate to accurately compute the position fix and/or velocity of the GNSS receiver.

Other drawbacks and disadvantages of the prior art will become apparent to one of ordinary skill in the art upon examination of the following system of the present invention as described in conjunction with the accompanying drawings.

Disclosure of Invention

A self-service ephemeris extension method and system for a GNSS receiver in accordance with aspects of the invention is substantially as shown in and/or described in connection with at least one of the figures and as set forth more completely in the claims.

According to an aspect of the present invention, a positioning method is provided, the method comprising:

performing, by one or more processors and/or circuits in a Global Navigation Satellite System (GNSS) enabled mobile device:

receiving GNSS signals from a plurality of visible (visible) GNSS satellites; and

generating, on the GNSS enabled mobile device, future ephemeris for each of the plurality of visible GNSS satellites using the received GNSS signals.

Preferably, the method further comprises determining a location of the GNSS enabled mobile device using at least one of the generated future ephemeris of the plurality of visible GNSS satellites.

Preferably, the method further comprises determining the location of the GNSS enabled mobile device before the GNSS enabled mobile device receives the latest broadcast ephemeris from the plurality of visible GNSS satellites.

Preferably, the method further comprises scheduling said generating operation in dependence on the expiry date and/or the visible time of each available future ephemeris for the corresponding GNSS satellite.

Preferably, the method further comprises incorporating (integrating) the respective available broadcast ephemeris into an orbit model for each of the plurality of visible GNSS satellites.

Preferably, the method further comprises determining respective orbit model parameters of the orbit model for each of the plurality of visible GNSS satellites using a multi-step numerical integration (muti-step numerical integration) method.

Preferably, the method further comprises transmitting the respective available broadcast ephemeris using the orbit model to generate future ephemeris for each of the plurality of visible GNSS satellites.

Preferably, the method further comprises reformatting the generated future ephemeris into a model or format supported by the GNSS enabled mobile device.

Preferably, the method further comprises curve fitting the generated future ephemeris for each of the plurality of visible GNSS satellites to determine a corresponding curve fit polynomial.

Preferably, the method further comprises storing the determined corresponding curve-fitting polynomial for each of the plurality of visible GNSS satellites in place of the generated future ephemeris.

According to still another aspect of the present invention, there is provided a communication system including:

one or more processors and/or circuitry for use in a Global Navigation Satellite System (GNSS) enabled mobile device, wherein the one or more processors and/or circuitry are to:

receiving GNSS signals from a plurality of visible GNSS satellites; and

generating, on the GNSS enabled mobile device, future ephemeris for each of the plurality of visible GNSS satellites using the received GNSS signals.

Preferably, the one or more processors and/or circuits are operable to determine a location of the GNSS enabled mobile device using at least one of the generated future ephemeris of the plurality of visible GNSS satellites.

Preferably, the one or more processors and/or circuitry are configured to determine the location of the GNSS enabled mobile device before the GNSS enabled mobile device receives the latest broadcast ephemeris from the plurality of visible GNSS satellites.

Preferably, the one or more processors and/or circuits are operable to schedule the generation of the plurality of GNSS satellites in accordance with the expiration dates and/or the visible times of the respective available future ephemeris for the corresponding GNSS satellites.

Preferably, the one or more processors and/or circuits are operable to incorporate the respective available broadcast ephemeris into an orbit model for each of the plurality of visible GNSS satellites.

Preferably, the one or more processors and/or circuits are operable to determine respective orbit model parameters of the orbit model for each of the plurality of visible GNS satellites using a multi-step numerical integration (muti-step numerical integration) method.

Preferably, the one or more processors and/or circuits are operable to transmit the respective available broadcast ephemeris using the orbit model to generate future ephemeris for each of the plurality of visible GNSS satellites.

Preferably, the one or more processors and/or circuits are operable to reformat the generated future ephemeris into a model or format supported by the GNSS enabled mobile device.

Preferably, the one or more processors and/or circuits are operable to curve fit the generated future ephemeris for each of the plurality of visible GNSS satellites to determine a corresponding curve fit polynomial.

Preferably, the one or more processors and/or circuits are operable to store the determined corresponding curve-fitting polynomial for each of the plurality of visible GNSS satellites in place of the generated future ephemeris.

The following detailed description of specific embodiments is provided to facilitate an understanding of various advantages, aspects, and novel features of the invention as they may be better understood when considered in connection with the accompanying drawings.

Drawings

FIG. 1 is a diagram illustrating a communication system for locating a GNSS receiver using self-assisted ephemeris extensions on the GNSS receiver in accordance with an embodiment of the invention;

FIG. 2 is a block diagram illustrating an exemplary GNSS enabled mobile device that may determine satellite orbits using self-assisted ephemeris extensions in accordance with an embodiment of the invention;

FIG. 3 is a block diagram illustrating an exemplary GNSS receiver architecture that uses available ephemeris and/or satellite measurements to create ephemeris extensions in accordance with an embodiment of the invention;

FIG. 4 is a flowchart of a method for scheduling ephemeris extensions in a GNSS receiver according to an embodiment of the invention;

FIG. 5 is a diagram illustrating an exemplary extended ephemeris generation process for use in a GNSS receiver in accordance with an embodiment of the invention;

FIG. 6 is a diagram illustrating an exemplary transmission process for generating ephemeris extensions in a GNSS receiver in accordance with an embodiment of the invention;

FIG. 7 is a diagram illustrating an exemplary reformatting procedure for reformatting ephemeris extensions in a GNSS receiver in accordance with an embodiment of the invention.

Detailed Description

The invention provides a self-service ephemeris extension method and a self-service ephemeris extension system for a GNSS receiver. In accordance with various embodiments of the present invention, a GNSS enabled mobile device may be operable to receive GNSS signals from a plurality of visible GNSS satellites. The term "visible" refers to a GNSS enabled mobile device that is capable of receiving valid signals from a particular GNSS satellite. The GNSS enabled mobile device may be operable to extract broadcast ephemeris from the received GNSS signals to generate ephemeris extensions including future ephemeris for each of the plurality of GNSS satellites in view for the next several days. The generated future ephemeris may be used to determine a position of the GNSS enabled mobile device without the GNSS enabled mobile device receiving and/or completely receiving up-to-date broadcast ephemeris from a plurality of visible GNSS satellites.

A GNSS enabled mobile device may be operable to schedule an ephemeris extension (future ephemeris) generation operation for each of a plurality of visible satellites based on a number of factors, such as a lifetime (age) of available ephemeris extensions and/or a time of view of an associated GNSS satellite. Available ephemeris, such as current or historical broadcast ephemeris, is incorporated into an orbit model, such as a solar radiation pressure (solar radiation pressure) model, to generate future ephemeris for each visible satellite. Various numerical integration methods, such as a multi-step numerical integration method, are used to determine the relevant orbit model parameters. The resulting (stopping) orbit model is used to convey the available ephemeris of the relevant GNSS satellite for the generation of corresponding satellite ephemeris. The generated future ephemeris is reformatted into a desired model or format suitable for use with a GNSS enabled mobile device. The generated future ephemeris is curve-fitted to determine a curve-fit polynomial for each visible GNSS satellite. Storing the determined curve-fitting polynomial in a database of the GNSS enabled mobile device in place of actual generated future ephemeris, thereby saving memory space.

FIG. 1 is a diagram of a communication system for locating a GNSS receiver using self-assisted ephemeris extensions on the GNSS receiver, in accordance with an embodiment of the invention. Referring to fig. 1, a communication system 100 is shown. The communication system includes a plurality of GNSS enabled mobile devices 110a-110d, of which GNSS enabled mobile devices are shown, a plurality of GNSS satellites, of which GNSS satellites 120a-120d, are shown, and a communication network 130.

The GNSS enabled mobile device such as the GNSS enabled mobile device 110a may comprise suitable logic, circuitry, interfaces and/or code that may be operable to communicate wireless signals over the communication network 130 and to receive broadcast signals from a plurality of visible GNSS satellites such as the GNSS satellites 120a-120 d. The received GNSS signals may be utilized to determine a location and/or velocity of the GNSS enabled mobile device 110a for various location-based client applications, such as emergency calls. The received GNSS signals include ephemeris or ephemeris data for the associated GNSS satellites. The ephemeris may include navigation information such as a satellite orbit model and/or a clock model of the associated GNSS satellite. An instantaneous (instantaneous-in-space) position fix (location-in-space) of the visible GNSS satellite is calculated using the navigation information in the received ephemeris. The position fix of the GNSS enabled mobile device 110a may be estimated from the computed instantaneous spatial position fixes of the visible GNSS satellites.

Ephemeris is updated every two hours at the relevant GNSS satellite, such as GNSS satellite 120a, for example, for GPS the validity time is 4 hours (from the broadcast time). Using more than 4 hours of ephemeris may result in a calculated instantaneous satellite-space fix that is less accurate, resulting in a bias in the estimated position of the GNSS enabled mobile device 110 a. In this regard, the GNSS enabled mobile device 110a may be operable to calculate or predict ephemeris extensions or future ephemeris for each GNSS satellite using available ephemeris and/or satellite measurements. The available ephemeris may comprise current and/or historical broadcast ephemeris extracted from the GNSS signals or from old computed ephemeris. Ephemeris extensions or future ephemeris may be continually refined and refined whenever new broadcast ephemeris and/or satellite measurements become available. Ephemeris extensions include future ephemeris for the next few days. The ephemeris extensions provide current (new) ephemeris to the GNSS enabled mobile device 110a for a particular period, such as the next few days, without the GNSS enabled mobile device 110a receiving and/or completely receiving updated broadcast ephemeris from the associated GNSS satellites. By using the ephemeris extensions, the GNSS enabled mobile device 110a may be operable to accurately estimate a position fix for the next few days without the need for current (up-to-date) broadcast ephemeris received from corresponding visible GNSS satellites.

A GNSS satellite, such as GNSS satellite 120a, may comprise suitable logic, circuitry, interfaces and/or code that may be operable to provide satellite navigation information to various GNSS receivers on earth. GNSS receivers, including GPS, GALILEO, and/or GLONASS receivers, may be integrated within or externally connected to GNSS enabled mobile devices, such as the GNSS enabled mobile devices 110a-110 d. The GNSS satellite 120a may broadcast its ephemeris periodically, for example, every 30 seconds. Broadcast ephemeris is transmitted at a rate of, for example, 50 bits per second (bit), with a full ephemeris transmission time of 18 seconds. Broadcast ephemeris is used to calculate navigation information, such as position, velocity, and clock information for a GNSS receiver. The GNSS satellite 120a may update ephemeris every two hours. Broadcast ephemeris is valid for a limited period of time, such as 2-4 hours into the future (from the time of broadcast).

The communication network 130 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to provide massive data services for various mobile devices such as the GNSS enabled mobile devices 110a-110d using a particular technology such as Ethernet, 3GPP2, LTE, Bluetooth, WiFi or WiMAX. The communication network 130 may be a wired high-speed connection such as ethernet, or a wireless network such as a 3GPP, 3GPP2, LTE, bluetooth, WiFi, or WiMAX network.

In an exemplary embodiment, a GNSS enabled mobile device such as the GNSS enabled mobile device 110a may be operable to receive GNSS signals from a plurality of visible GNSS satellites such as the GNSS satellites 120a-120 d. The GNSS enabled mobile device 110a may be operable to extract ephemeris from the received GNSS signals to calculate a position fix and/or velocity of the GNSS enabled mobile device 110 a. The GNSS enabled mobile device 110a may be operable to calculate ephemeris extensions including future ephemeris for the next several days or other time periods for each visible GNSS satellite using the extracted ephemeris or received GNSS signals. The computed ephemeris extensions provide the GNSS enabled mobile device 110a with current (up-to-date) ephemeris for the next few days or other time periods. The GNSS enabled mobile device 110a may be operable to use the computed ephemeris extensions for the next few days or other time periods to accurately estimate a position fix without receiving and/or completely receiving current (up-to-date) broadcast ephemeris from a plurality of visible GNSS satellites.

FIG. 2 is a block diagram illustrating an exemplary GNSS enabled mobile device that may determine satellite orbits using self-assisted ephemeris extensions, in accordance with an embodiment of the invention. Referring to FIG. 2, a GNSS enabled mobile device 200 is shown. The GNSS enabled mobile device 200 may include a GNSS receiver 202, a communication transceiver 204, a processor 206, and a memory 208.

The GNSS receiver 202 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to receive GNSS signals from a plurality of visible GNSS satellites. The received GNSS signals may include satellite navigation information, such as ephemeris and/or clock models, for accurately determining relevant satellite orbits and computing navigation information, such as position fix and/or velocity of the GNSS receiver 202. In this regard, the GNSS receiver 202 may be operable to calculate or predict ephemeris extensions for each visible GNSS satellite extension period (such as the next few days) using available ephemeris such as current broadcast ephemeris and/or historical broadcast ephemeris. As new broadcast ephemeris and/or satellite measurements become available, the computed ephemeris extensions or future ephemeris may be continually refined and refined. The computed ephemeris extensions include future ephemeris and provide current (new) ephemeris for the next few days to the GNSS receiver 202. Using the computed ephemeris extensions, the GNSS receiver 202 may be operable to accurately compute a position fix and/or velocity of the GNSS receiver 202 over an extended period, such as the next few days, without receiving and/or completely receiving current (up-to-date) broadcast ephemeris from the associated GNSS satellites.

The communication transceiver 204 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to transmit and/or receive wireless signals over the communication network 130. In this regard, the transmitted wireless signals may include navigation information for the GNSS enabled mobile device 200 that may be obtained from ephemeris extensions computed by the GNSS receiver 202. The communication transceiver 204 is an optional device.

Although FIG. 2 illustrates the GNSS enabled mobile device 200 implementing communication functionality via the communication transceiver 204 for self-assisted ephemeris extension, the invention is not limited thereto. Accordingly, the present invention may be applied to GNSS enabled devices that do not have communication capabilities other than to receive GNSS signals from visible GNSS satellites without departing from the spirit and scope of various embodiments of the present invention.

The processor 206 may comprise suitable logic, circuitry, interfaces and/or code that may enable processing of navigation information from the GNSS receiver 202 and signals communicated between the communication network 130 via the communication transceiver 204. The processor 206 may be configured to communicate navigation information from the GNSS receiver 202 over the telecommunications network 130 for various location-based client applications, such as finding friends and/or emergency calls. The processor 206 is used for controlling the operation cycle of the GNSS receiver 202. For example, to conserve power in the GNSS enabled mobile device 200, the processor 206 may be configured to turn the GNSS receiver on or off as needed.

The memory 208 may comprise suitable logic, circuitry, interfaces and/or code that may enable storage of information such as executable instructions and data used by the processor 206. Memory 208 includes RAM, ROM, low latency nonvolatile memory such as flash memory and/or other suitable electronic data storage.

In one embodiment of the present invention, the GNSS receiver 202 may be operable to receive GNSS signals from each of the visible GNSS satellites. The GNSS receiver 202 may be operable to extract broadcast ephemeris from the received GNSS signals. The GNSS receiver 202 may be operable to calculate ephemeris extensions for an extended period, such as the next few days, for each visible GNSS satellite using available ephemeris, such as current and/or historical extracted broadcast ephemeris. The computed ephemeris extensions provide the next few days of current (new) ephemeris to the GNSS receiver 202. The GNSS receiver 202 may be operable to accurately calculate a position fix and/or velocity of the GNSS receiver 202 over an extended period, such as the next few days, without receiving and/or completely receiving current (new) broadcast ephemeris from corresponding visible GNSS satellites. The calculated positioning information is forwarded to the processor 206 and processed for communication with the network 130 through the communication transceiver 204 for various location-based client applications, such as roadside assistance (roadside assistance).

FIG. 3 is a block diagram illustrating an exemplary GNSS receiver architecture that uses available ephemeris and/or satellite measurements to create ephemeris extensions in accordance with an embodiment of the invention. Referring to FIG. 3, a GNSS receiver 300 is shown. The GNSS receiver 300 may comprise a GNSS antenna 301, a GNSS front-end 302, a GNSS processor 304, a Long Term Orbit (LTO) database 306, and a memory 308. The memory 308 includes long-term orbit software 310a and orbit conversion software 310 b.

The GNSS antenna 301 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to receive GNSS signals from a plurality of visible GNSS satellites such as the GNSS satellites 120a through 120 d. The GNSS antenna 301 may be operable to communicate the received GNSS signals to the GNSS front-end 302 for further processing.

The GNSS front-end 302 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to convert the received GNSS signals to GNSS baseband signals that may be suitable for further processing in the GNSS processor 304 to compute navigation information for the GNSS receiver 300.

The GNSS processor 304 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to process GNSS baseband signals from the GNSS front-end 302. The GNSS processor 304 may be operable to extract ephemeris including satellite navigation information from the GNSS baseband signals. The GNSS processor 304 may use the available ephemeris, such as the extracted current and/or historical broadcast ephemeris, to calculate or predict an ephemeris extension or future ephemeris for the next few days for the corresponding visible GNSS satellite. The GNSS processor 304 may be operable to refine the computed ephemeris extensions using the new broadcast ephemeris and/or new satellite measurements. The calculated ephemeris extensions include predicted or future ephemeris for an extended period, such as the next few days.

The GNSS processor 304 may be operable to compute or predict ephemeris of the associated GNSS satellites, in part by communicating the available ephemeris using various multi-step numerical integration methods such as Gauss-Jackson. The available ephemeris includes current broadcast ephemeris, historical broadcast ephemeris, and old estimated ephemeris. With the assistance of the computed ephemeris extensions, the GNSS processor 304 may be operable to accurately compute a position fix of the GNSS receiver 300 within the next few days without receiving and/or completely receiving the latest broadcast ephemeris from the relevant GNSS satellites. For each visible GNSS satellite, the GNSS processor 304 may be operable to generate a synthesis and/or update the corresponding ephemeris extensions in accordance with a particular schedule (schedule). Factors such as the effective period and/or time of visibility of the available ephemeris extensions for a corresponding GNSS satellite may be considered when scheduling the generation of ephemeris extensions for a particular visible GNSS satellite.

Assuming that the generated ephemeris extensions do not match the orbit model and/or format expected or supported by the associated mobile device, such as the GNSS enabled mobile device 200, the GNSS processor 304 may reformat the generated ephemeris extensions into the expected orbit model and/or format prior to computing, for example, a position fix of the GNSS receiver 300. The GNSS processor 304 may be operable to store the generated ephemeris extensions in the LTO database 306 for accurately computing a position fix for the GNSS receiver even without the need to receive and/or fully receive current (up-to-date) broadcast ephemeris from corresponding visible GNSS satellites. In this regard, the generated ephemeris is extended to a polynomial fit, for example, in 180 second steps. The resulting polynomial fitting program (fit routine) may be stored in the LTO database 306 instead of the actual predicted ephemeris, thereby saving memory space of the GNSS receiver 300.

In addition, the GNSS receiver 304 may be operable to communicate with a computer server to obtain one or more orbit model parameters that are computed and/or updated on the computer server using relevant resources such as computing functionality, memory and more historical ephemeris data. The GNSS processor 304 is configured to perform orbit propagation using one or more orbit model parameters downloaded from a computer server). Thus, the accuracy of the resulting ephemeris extensions can be improved at low cost.

The LTO database 306 may comprise suitable logic, circuitry, interfaces and/or code that may enable management and storage of data, including an ephemeris polynomial fitting routine (ephemerirespectively multinuclear) for each visible GNSS satellite. The ephemeris polynomial fitting routine in the LTO database 306 may be updated as needed or periodically.

The memory 308 may comprise suitable logic, circuitry, interfaces and/or code that may enable storage of information such as executable instructions and data for use by the GNSS processor 304. The executable instructions include algorithms for computing a position fix for the GNSS receiver 300 using the new ephemeris provided by the LTO database 306. The memory 308 includes long-term orbit software 310a for communicating available ephemeris for visible GNSS satellites. The memory 308 may include orbit conversion software 310b for converting the predicted ephemeris in the LTO database 306 to an orbit model and/or format expected and/or supported by an associated device, such as the GNSS enabled mobile device 110 a. The memory 308 includes data such as local GNSS measurements and navigation data. Memory 308 includes RAM, ROM, low latency nonvolatile memory such as flash memory and/or other suitable electronic data storage.

In an exemplary operation, the GNSS antenna 301 may receive GNSS signals from a plurality of visible GNSS satellites. The received GNSS signals may be communicated to the GNSS front-end 302. The GNSS front-end 302 may be operable to convert the received GNSS broadcast signals to GNSS baseband signals for further processing in the GNSS processor 304. The GNSS processor 304 may be operable to generate ephemeris extensions or future ephemeris for an extended period, such as the next few days, for corresponding visible GNSS satellites using available ephemeris, such as broadcast ephemeris extracted from the received GNSS baseband signals. The GNSS processor 304 may generate ephemeris extensions by transmitting the available ephemeris using various multi-step numerical integration methods, such as the Gauss-Jackson method. The generation schedule for ephemeris extensions for a particular GNSS satellite may be scheduled based on, for example, the validity period and/or the visibility time of available ephemeris extensions for the corresponding visible GNSS satellite in the LTO database 306. The GNSS processor 304 may reformat the generated ephemeris extensions into an orbit model and/or format expected by the relevant mobile device, such as the GNSS enabled mobile device 200. The GNSS processor 304 may perform curve fitting on the generated ephemeris extensions and store the resulting ephemeris polynomial fitting routine in the LTO database 306 to save memory space.

FIG. 4 is a flowchart of a method for scheduling ephemeris extension generation in a GNSS receiver according to an embodiment of the invention. Referring to FIG. 4, exemplary steps begin at step 402. In step 402, the GNSS receiver 300 may be required to schedule a plurality of GNSS visible satellites to generate ephemeris extensions including future ephemeris for an extension period, such as the next few days. Depending on the configuration, the GNSS receiver 300 may be operable to schedule the present or future schedules of visible GNSS satellites, such as after 4 days. In step 404, for each visible GNSS satellite, the GNSS receiver 300 may be operable to evaluate the validity period and/or the visible time of the available ephemeris extensions in the LTO database 306. In step 406, the GNSS receiver 300 may schedule generation of corresponding ephemeris extensions for the visible GNSS satellites based on the validity period of the available ephemeris extensions in the LTO database 306 and/or the visible time of the corresponding GNSS satellites. In step 408, the GNSS receiver 300 may be operable to generate ephemeris extensions for each of the visible GNSS satellites according to a scheduled schedule. The exemplary steps end at step 410.

FIG. 5 is a diagram illustrating an exemplary extended ephemeris generation process for use in a GNSS receiver, in accordance with an embodiment of the invention. Referring to FIG. 5, exemplary steps begin at step 502. In step 502, the GNSS receiver 300 may be required to generate ephemeris extensions for visible GNSS satellites, such as the GNSS satellite 120 a. In step 504, the GNSS receiver 300 may be operable to collect satellite data of the GNSS satellite 120a via the GNSS front-end 302. In step 506, the GNSS processor 304 may be operable to extract satellite navigation information, such as ephemeris, from the collected satellite data. In step 508, the GNSS processor 304 may be operable to transmit the available ephemeris, such as current and/or historical extracted broadcast ephemeris, to generate ephemeris extensions for the GNSS satellite 120 a. In step 510, the GNSS processor 304 may be operable to curve fit the generated ephemeris extensions. In step 512, the GNSS processor 304 may be operable to store the resulting curve-fitting polynomial in the LTO database 306. The exemplary step ends at step 514.

FIG. 6 is a diagram illustrating an exemplary transmission process for generating ephemeris extensions in a GNSS receiver, in accordance with an embodiment of the invention. Referring to FIG. 6, exemplary steps begin at step 602. In step 602, for visible GNSS satellites, the GNSS receiver 300 performs ephemeris integration using the selected orbit model solar radiation pressure model. The parameter Δ includes a transmission step size. In step 604, the GNSS receiver 300 may be operable to acquire ephemeris available for the visible GNSS satellites. The available ephemeris may include current broadcast ephemeris, historical broadcast ephemeris and/or old estimated ephemeris available to the GNSS receiver 300. In step 606, the GNSS receiver 300 may be operable to determine orbit model parameters, and incorporate the acquired available ephemeris into the orbit model using various multi-step numerical integration methods such as Gauss-Jackson method. In step 608, the GNSS receiver 300 may be operable to transmit the acquired available ephemeris in steps of Δ using the orbit model with the determined model parameters to generate ephemeris extensions for the next few days of visible GNSS satellites. The exemplary steps end at step 610.

FIG. 7 is a diagram illustrating an exemplary reformatting procedure for reformatting ephemeris extensions in a GNSS receiver in accordance with an embodiment of the invention. Referring to FIG. 7, exemplary steps begin at step 702. In step 702, a GNSS enabled mobile device, such as the GNSS enabled mobile device 110a, may need to use ephemeris extensions in an orbit model and/or format expected or supported by the associated mobile device, such as the GNSS enabled mobile device 110 a. In step 704, the GNSS processor 304 may be operable to retrieve ephemeris extensions provided by the LTO database 308 in the form of corresponding curve-fitting polynomials. In step 706, it may be determined whether the retrieved ephemeris extensions match an orbit model and/or format expected by the GNSS enabled mobile device 110 a. Assuming the retrieved ephemeris extensions do not match the orbit model and/or format expected by the GNSS enabled mobile device 110a, then the GNSS processor may proceed to step 708 where the GNSS processor may convert the retrieved ephemeris extensions into the orbit model and/or format expected by the GNSS enabled mobile device 110a using the orbit conversion software 310 b. The exemplary steps end at step 710.

In step 706, the exemplary steps conclude with step 710, assuming the retrieved ephemeris extensions match the orbit model and/or format expected by the GNSS enabled mobile device 110 a.

Various embodiments of the present invention provide a self-service ephemeris extension method and system for a GNSS receiver. In accordance with various embodiments of the invention, a GNSS enabled mobile device, such as the GNSS enabled mobile device 110a, may be operable to receive GNSS signals from a plurality of visible GNSS satellites, such as the GNSS satellites 120a through 120d, via the GNSS receiver 202. The GNSS receiver 202 in the GNSS enabled mobile device 110a may be operable to extract broadcast ephemeris from the received GNSS signals and may be operable to generate ephemeris extensions or future ephemeris for an extended period, such as the next few days, for each of a plurality of visible GNSS satellites, such as the GNSS satellites 120a through 120d, using the extracted information. The generated future ephemeris may be used to determine a position of the GNSS enabled mobile device 110 a. The generated future ephemeris may accurately determine a position fix for an extended period of the GNSS enabled mobile device 110a, such as the next few days, even without requiring the GNSS enabled mobile device 110a to receive and/or completely receive the latest broadcast ephemeris from the plurality of GNSS satellites 120a-120 d.

The GNSS enabled mobile device 110a may schedule generation of future ephemeris for each of the GNSS satellites 120a-120d based on factors such as an extended validity period (age) of available ephemeris in the LTO database 306 and/or a time of view for the associated GNSS satellite. Available ephemeris, such as current or historical broadcast ephemeris, is incorporated into a selected orbit model, such as a solar radiation pressure (solar radiation pressure) model, to generate future ephemeris for each of the GNSS satellites 120a-120 d. Various multi-step numerical integration methods such as the Gauss-Jackson method are used to determine the relevant orbit model parameters. The resulting (stopping) orbit model is used to convey the available ephemeris of the relevant GNSS satellites for the generation of corresponding future ephemeris. The generated future ephemeris may be reformatted into a model or format expected by the GNSS enabled mobile device 110 a. The generated future ephemeris is curve-fitted to determine a curve-fit polynomial for each visible GNSS satellite. The determined curve-fitting polynomial is stored in the LTO database 306 in place of the actual generated future ephemeris, thereby saving memory in the GNSS enabled mobile device 110 a.

Another embodiment of the present invention provides a machine and/or computer readable storage and/or medium, having stored thereon, a machine code and/or a computer program having at least one code section executable by a machine and/or a computer, thereby enabling the machine and/or computer to perform the steps described herein for self-assisted ephemeris extensions for GNSS receivers.

In general, the invention can be implemented in hardware, software, firmware, or a combination thereof. The present invention can be realized in an integrated manner in at least one computer system or in a separate manner by placing different components in a plurality of interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware, software, and firmware may be a specialized computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein.

The present invention can also be implemented by a computer program product, which comprises all the features enabling the implementation of the methods of the invention and which, when loaded in a computer system, is able to carry out these methods. The computer program in the present document refers to: any expression, in any programming language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following a) conversion to another language, code or notation; b) reproduced in different formats to implement specific functions.

While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (8)

1. A method of positioning, the method comprising:

performing, by one or more processors and/or circuits in a GNSS enabled mobile device:

receiving GNSS signals from a plurality of visible GNSS satellites; and

generating future ephemeris on the GNSS enabled mobile device for each of the plurality of visible GNSS satellites using the received GNSS signals,

wherein the generating operation is scheduled in dependence of the expiry date and/or the visible time of each available future ephemeris for the corresponding GNSS satellite,

wherein the generated future ephemeris for each of the plurality of visible GNSS satellites is curve-fit to determine a corresponding curve-fit polynomial.

2. The method of claim 1, further comprising determining a location of the GNSS enabled mobile device using the generated future ephemeris of at least one of the plurality of visible GNSS satellites.

3. The method of claim 1, further comprising determining the location of the GNSS enabled mobile device before the GNSS enabled mobile device receives the latest broadcast ephemeris from the plurality of visible GNSS satellites.

4. The position location method of claim 1, further comprising incorporating respective available broadcast ephemeris into an orbit model for each of the plurality of visible GNSS satellites.

5. A communication system, the system comprising:

one or more processors and/or circuitry for use in a GNSS enabled mobile device, wherein the one or more processors and/or circuitry are to:

receiving GNSS signals from a plurality of visible GNSS satellites; and

generating, on the GNSS enabled mobile device, future ephemeris for each of the plurality of visible GNSS satellites using the received GNSS signals, the generating including performing numerical integration,

the one or more processors and/or circuits may be further configured to schedule the generation of the plurality of visible GNSS satellites based on the age and/or the visible time of each available future ephemeris for the corresponding GNSS satellite,

the one or more processors and/or circuits are further configured to curve fit the generated future ephemeris for each of the plurality of visible GNSS satellites to determine a corresponding curve fit polynomial.

6. The communication system according to claim 5, wherein said one or more processors and/or circuits are operable to determine a location of said GNSS enabled mobile device using at least one of said generated future ephemeris of said plurality of visible GNSS satellites.

7. The communication system according to claim 5, wherein said one or more processors and/or circuits are operable to determine the location of said GNSS enabled mobile device before said GNSS enabled mobile device receives the latest broadcast ephemeris from said plurality of visible GNSS satellites.

8. The communication system according to claim 5, wherein said one or more processors and/or circuits are operable to incorporate respective available broadcast ephemeris into an orbit model for each of said plurality of visible GNSS satellites.