U.S. patent application number 17/105237 was filed with the patent office on 2021-03-25 for method and apparatus for wireless network hybrid positioning.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to James DeLoach, JR., Mark Moeglein, Wyatt Riley, Douglas Rowitch, Leonid Sheynblat.
Application Number | 20210088674 17/105237 |
Document ID | / |
Family ID | 1000005241713 |
Filed Date | 2021-03-25 |
View All Diagrams
United States Patent
Application |
20210088674 |
Kind Code |
A1 |
Moeglein; Mark ; et
al. |
March 25, 2021 |
METHOD AND APPARATUS FOR WIRELESS NETWORK HYBRID POSITIONING
Abstract
Methods and apparatuses for position determination and other
operations. In one embodiment of the present invention, a mobile
station uses wireless signals from a plurality of wireless networks
(e.g., with different air interfaces and/or operated by different
service providers) for position determination (e.g., for data
communication, for obtaining time and/or frequency information, for
range measurement, for sector or altitude estimation). In one
embodiment of the present invention, mobile stations are used to
harvest statistical data about wireless access points (e.g., the
locations of mobile stations that have received signals from the
wireless access points, such as from cellular base stations,
wireless local area network access points, repeaters for
positioning signals, or other wireless communication transmitters)
and to derive location information (e.g., position and coverage
area of the wireless access points) for the wireless networks from
the collected statistical data.
Inventors: |
Moeglein; Mark; (Lummi
Island, WA) ; Rowitch; Douglas; (Honolulu, HI)
; Riley; Wyatt; (Chesterbrook, PA) ; DeLoach, JR.;
James; (Sunnyvale, CA) ; Sheynblat; Leonid;
(Hillsborough, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
1000005241713 |
Appl. No.: |
17/105237 |
Filed: |
November 25, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14505053 |
Oct 2, 2014 |
10895648 |
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17105237 |
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10877205 |
Jun 25, 2004 |
8971913 |
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14505053 |
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60483094 |
Jun 27, 2003 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 5/0257 20130101;
H04W 64/00 20130101; H04W 64/003 20130101; G01S 19/11 20130101;
G01S 5/0236 20130101; G01S 19/13 20130101; G01S 5/0036 20130101;
G01S 5/10 20130101; G01S 19/48 20130101; G01S 5/0242 20130101 |
International
Class: |
G01S 19/48 20060101
G01S019/48; G01S 5/00 20060101 G01S005/00; G01S 5/02 20060101
G01S005/02; G01S 5/10 20060101 G01S005/10; H04W 64/00 20060101
H04W064/00; G01S 19/13 20060101 G01S019/13 |
Claims
1. A method for maintaining a location database at a location
server, the method comprising: receiving, from a first mobile
station, information comprising identification for a first wireless
access point, one or more locations of the first mobile station,
and positioning information determined by the first mobile station
using signals transmitted by the first wireless access point and
received by the first mobile station at the one or more locations
of the first mobile station, wherein the positioning information
includes a signal strength measurement, a timing measurement, or
both; determining first location information of the first wireless
access point based on the one or more locations of the first mobile
station and the positioning information; creating an entry in the
location database for the first wireless access point, wherein the
entry for the first wireless access point includes the
identification for the first wireless access point and the first
location information of the first wireless access point; receiving,
from a second mobile station, a request for location information
regarding the first wireless access point, wherein the request for
location information includes the identification of the first
wireless access point; and providing, to the second mobile station,
location information for the first wireless access point wherein
the location information is obtained from the location database
based on the identification of the first wireless access point.
2. The method of claim 1, wherein the positioning information
further includes a distance between a first location of the one or
more locations of the first mobile station and a location of the
first wireless access point.
3. The method of claim 1, wherein the first location information
comprises a location of the first wireless access point, a coverage
area of the first wireless access point, or both.
4. The method of claim 1, further comprising: determining second
location information of the first wireless access point based on
information received from one or more additional mobile
stations.
5. The method of claim 4, further comprising updating the entry in
the location database for the first wireless access point based on
the second location information.
6. The method of claim 1, wherein determining the first location
information of the first wireless access point comprises using the
positioning information to determine a weight for the one or more
locations of the first mobile station.
7. The method of claim 6, wherein determining the weight for the
one or more locations of the first mobile station comprises
determining, for each of the one or more locations of the first
mobile station, a distance between the respective location of the
first mobile station and a location of the first wireless access
point.
8. The method of claim 1, wherein determining the first location
information of the first wireless access point comprises using a
time at which the positioning information was received to determine
a weight for the one or more locations of the first mobile
station.
9. The method of claim 1, wherein the first mobile station is the
same as the second mobile station.
10. The method of claim 1, wherein the first mobile station is
different than the second mobile station.
11. The method of claim 1, wherein the first wireless access point
is an access point of a local area network.
12. The method of claim 11, wherein the second mobile station is
not authorized to have access to the local area network.
13. The method of claim 11, wherein the information comprising the
identification for the first wireless access point, the one or more
locations of the first mobile station, and the positioning
information is received through a second wireless access point.
14. The method of claim 13, wherein the second wireless access
point is a cellular base station.
15. A server for maintaining a location database, the server
comprising: a communication interface; a memory configured to store
instructions; and one or more processors communicatively coupled
with the memory and the communication interface and configured to:
receive, from a first mobile station, information comprising
identification for a first wireless access point, one or more
locations of the first mobile station, and positioning information
determined by the first mobile station using signals transmitted by
the first wireless access point and received by the first mobile
station at the one or more locations of the first mobile station,
wherein the positioning information includes a signal strength
measurement, a timing measurement, or both; determine first
location information of the first wireless access point based on
the one or more locations of the first mobile station and the
positioning information; create an entry in the location database
for the first wireless access point, wherein the entry for the
first wireless access point includes the identification for the
first wireless access point and the first location information of
the first wireless access point; receive, from a second mobile
station, a request for location information regarding the first
wireless access point, wherein the request for location information
includes the identification of the first wireless access point; and
provide, to the second mobile station, location information for the
first wireless access point wherein the location information is
obtained from the location database based on the identification of
the first wireless access point.
16. The server of claim 15, wherein the positioning information
includes a distance between a first location of the one or more
locations of the first mobile station and a location of the first
wireless access point.
17. The server of claim 15, wherein the first location information
includes a location of the first wireless access point, a coverage
area of the first wireless access point, or both.
18. The server of claim 15, wherein the one or more processors are
further configured to determine second location information of the
first wireless access point based on information from one or more
additional mobile stations.
19. The server of claim 18, wherein the one or more processors are
further configured to update the entry in the location database for
the first wireless access point based on the second location
information.
20. The server of claim 15, wherein, to determine the first
location information of the first wireless access point, the one or
more processors are further configured to use the positioning
information to determine a weight for the one or more locations of
the first mobile station.
21. The server of claim 20, wherein, to determine the weight for
the one or more locations of the first mobile station, the one or
more processors are further configured to determine for each of the
one or more locations of the first mobile station, a distance
between the respective location of the first mobile station and a
location of the first wireless access point.
22. The server of claim 15, wherein, to determine the first
location information of the first wireless access point, the one or
more processors are further configured to use a time at which the
positioning information was received to determine a weight for the
one or more locations of the first mobile station.
23. A device for maintaining a location database at a location
server, the device comprising: means for receiving, from a first
mobile station, information comprising identification for a first
wireless access point, one or more locations of the first mobile
station, and positioning information determined by the first mobile
station using signals transmitted by the first wireless access
point and received by the first mobile station at the one or more
locations of the first mobile station, wherein the positioning
information includes a signal strength measurement, a timing
measurement, or both; means for determining first location
information of the first wireless access point based on the one or
more locations of the first mobile station and the positioning
information; means for creating an entry in the location database
for the first wireless access point, wherein the entry for the
first wireless access point includes the identification for the
first wireless access point and the first location information of
the first wireless access point; means for receiving, from a second
mobile station, a request for location information regarding the
first wireless access point, wherein the request for location
information includes the identification of the first wireless
access point; and means for providing, to the second mobile
station, location information for the first wireless access point
wherein the location information is obtained from the location
database based on the identification of the first wireless access
point.
24. The device of claim 23, wherein the positioning information
includes a distance between a first location of the one or more
locations of the first mobile station and a location of the first
wireless access point.
25. The device of claim 23, wherein the first location information
comprises a location of the first wireless access point, a coverage
area of the first wireless access point, or both.
26. The device of claim 23, further comprising means for
determining second location information of the first wireless
access point based on information from one or more additional
mobile stations.
27. The device of claim 26, further comprising means for updating
the entry in the location database for the first wireless access
point based on the second location information.
28. The device of claim 23, wherein the means for determining the
first location information of the first wireless access point
comprise means for using the positioning information to determine a
weight for the one or more locations of the first mobile
station.
29. The device of claim 28, wherein the means for determining the
weight for the one or more locations of the first mobile station
comprises means for determining, for each of the one or more
locations of the first mobile station, a distance between the
respective location of the first mobile station and a location of
the first wireless access point.
30. The device of claim 23, wherein the means for determining the
first location information of the first wireless access point
comprises means for using a time at which the positioning
information was received to determine a weight for the one or more
locations of the first mobile station.
31. A non-transitory computer-readable medium storing instructions
for maintaining a location database at a location server, the
instructions comprising code for: receiving, from a first mobile
station, information comprising identification for a first wireless
access point, one or more locations of the first mobile station,
and positioning information determined by the first mobile station
using signals transmitted by the first wireless access point and
received by the first mobile station at the one or more locations
of the first mobile station, wherein the positioning information
includes a signal strength measurement, a timing measurement, or
both; determining first location information of the first wireless
access point based on the one or more locations of the first mobile
station and the positioning information; creating an entry in the
location database for the first wireless access point, wherein the
entry for the first wireless access point includes the
identification for the first wireless access point and the first
location information of the first wireless access point; receiving,
from a second mobile station, a request for location information
regarding the first wireless access point, wherein the request for
location information includes the identification of the first
wireless access point; and providing, to the second mobile station,
location information for the first wireless access point wherein
the location information is obtained from the location database
based on the identification of the first wireless access point.
32. The non-transitory computer-readable medium of claim 31,
wherein the positioning information includes a distance between a
first location of the one or more locations of the first mobile
station and a location of the first wireless access point.
33. The non-transitory computer-readable medium of claim 31,
wherein the first location information comprises a location of the
first wireless access point, a coverage area of the first wireless
access point, or both.
34. The non-transitory computer-readable medium of claim 31,
wherein the instructions comprise code for determining second
location information of the first wireless access point based on
information from one or more additional mobile stations.
35. The non-transitory computer-readable medium of claim 34,
wherein the instructions comprise code for updating the entry in
the location database for the first wireless access point based on
the second location information.
36. The non-transitory computer-readable medium of claim 31,
wherein, to determine the first location information of the first
wireless access point, the instructions comprise code for using the
positioning information to determine a weight for the one or more
locations of the first mobile station.
37. The non-transitory computer-readable medium of claim 36,
wherein, to determine the weight for the one or more locations of
the first mobile station, the instructions comprise code for
determining for each of the one or more locations of the first
mobile station, a distance between the respective location of the
first mobile station and a location of the first wireless access
point.
38. The non-transitory computer-readable medium of claim 31,
wherein, to determine the first location information of the first
wireless access point, the instructions comprise code for, using a
time at which the positioning information was received to determine
a weight for the one or more locations of the first mobile station.
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/505,053, filed Oct. 2, 2014, which is a
divisional of U.S. patent application Ser. No. 10/877,205, filed
Jun. 25, 2004, now U.S. Pat. No. 8,971,913, issued Mar. 3, 2015,
which claims the benefit of U.S. Provisional Patent Application
Ser. No. 60/483,094, filed Jun. 27, 2003, each of which is
expressly incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to position determination systems, and
more particularly to hybrid positioning using wireless
communication signals.
BACKGROUND
[0003] To perform position location in wireless cellular networks
(e.g., a cellular telephone network), several approaches perform
trilateration based upon the use of timing information sent between
each of several base stations and a mobile device, such as a
cellular telephone. One approach, called Advanced Forward Link
Trilateration (AFLT) in CDMA or Enhanced Observed Time Difference
(EOTD) in GSM or Observed Time Difference of Arrival (OTDOA) in
WCDMA, measures at the mobile device the relative times of arrival
of signals transmitted from each of several base stations. These
times are transmitted to a Location Server (e.g., a Position
Determination Entity (PDE) in CDMA), which computes the position of
the mobile device using these times of reception. The transmit
times at these base stations are coordinated such that at a
particular instance of time, the times-of-day associated with
multiple base stations are within a specified error bound. The
accurate positions of the base stations and the times of reception
are used to determine the position of the mobile device.
[0004] FIG. 1 shows an example of an AFLT system where the times of
reception (TR1, TR2, and TR3) of signals from cellular base
stations 101, 103, and 105 are measured at the mobile cellular
telephone 111. This timing data may then be used to compute the
position of the mobile device. Such computation may be done at the
mobile device itself, or at a location server if the timing
information so obtained by the mobile device is transmitted to the
location server via a communication link. Typically, the times of
receptions are communicated to a location server 115 through one of
the cellular base stations (e.g., base station 101, or 103, or
105). The location server 115 is coupled to receive data from the
base stations through the mobile switching center 113. The location
server may include a base station almanac (BSA) server, which
provides the location of the base stations and/or the coverage area
of base stations. Alternatively, the location server and the BSA
server may be separate from each other; and, the location server
communicates with the base station to obtain the base station
almanac for position determination. The mobile switching center 113
provides signals (e.g., voice communications) to and from the
land-line Public Switched Telephone Network (PSTN) so that signals
may be conveyed to and from the mobile telephone to other
telephones (e.g., land-line phones on the PSTN or other mobile
telephones). In some cases the location server may also communicate
with the mobile switching center via a cellular link. The location
server may also monitor emissions from several of the base stations
in an effort to determine the relative timing of these
emissions.
[0005] In another approach, called Uplink Time of Arrival (UTOA),
the times of reception of a signal from a mobile device is measured
at several base stations (e.g., measurements taken at base stations
101, 103 and 105). FIG. 1 applies to this case if the arrows of
TR1, TR2, and TR3 are reversed. This timing data may then be
communicated to the location server to compute the position of the
mobile device.
[0006] Yet a third method of doing position location involves the
use in the mobile device of circuitry for the United States Global
Positioning Satellite (GPS) system or other Satellite Positioning
Systems (SPS), such as the Russian GLONASS system and the proposed
European Galileo System, or a combination of satellites and
pseudolites. Pseudolites are ground-based transmitters, which
broadcast a PN code (similar to a GPS signal) modulated on an
L-band carrier signal, generally synchronized with SPS time. Each
transmitter may be assigned a unique PN code so as to permit
identification by a mobile device. Pseudolites are useful in
situations where SPS signals from an orbiting satellite might be
unavailable, such as tunnels, mines, buildings or other enclosed
areas. The term "satellite", as used herein, is intended to include
pseudolite or equivalents of pseudolites, and the term GPS signals,
as used herein, is intended to include GPS-like signals from
pseudolites or equivalents of pseudolites. Methods which use an SPS
receiver to determine a position of a mobile station may be
completely autonomous (in which the SPS receiver, without any
assistance, determines the position of the mobile station) or may
utilize the wireless network to provide assistance data or to share
in the position calculation. Examples of such methods are described
in U.S. Pat. Nos. 6,208,290; 5,841,396; 5,874,914; 5,945,944; and
5,812,087. For instance, U.S. Pat. No. 5,945,944 describes, among
other things, a method to obtain from cellular phone transmission
signals accurate time information, which is used in combination
with SPS signals to determine the position of the receiver; U.S.
Pat. No. 5,874,914 describes, among other things, a method to
transmit the Doppler frequency shifts of in view satellites to the
receiver on the mobile device through a communication link to
determine the position of the mobile device; U.S. Pat. No.
5,874,914 describes, among other things, a method to transmit
satellite almanac data (or ephemeris data) to a receiver through a
communication link to help the receiver to determine its position;
U.S. Pat. No. 5,874,914 also describes, among other things, a
method to lock to a precision carrier frequency signal of a
cellular telephone system to provide a reference signal at the
receiver for SPS signal acquisition; U.S. Pat. No. 6,208,290
describes, among other things, a method to use an approximate
location of a receiver to determine an approximate Doppler for
reducing SPS signal processing time; and, U.S. Pat. No. 5,812,087
describes, among other things, a method to compare different
records of a satellite data message received to determine a time at
which one of the records is received at a receiver in order to
determine the position of the receiver. In practical low-cost
implementations, both the mobile cellular communications receiver
and the SPS receiver are integrated into the same enclosure and,
may in fact share common electronic circuitry.
[0007] In yet another variation of the above methods, the round
trip delay (RTD) is found for signals that are sent from the base
station to the mobile device and then are returned. In a similar,
but alternative, method the round trip delay is found for signals
that are sent from the mobile device to the base station and then
returned. Each of these round-trip delays is divided by two to
determine an estimate of the one-way propagation delay. Knowledge
of the location of the base station, plus a one-way delay
constrains the location of the mobile device to a circle on the
earth. Two such measurements from distinct base stations then
result in the intersection of two circles, which in turn constrains
the location to two points on the earth. A third measurement (even
an angle of arrival or cell sector identification) resolves the
ambiguity.
[0008] A combination of either the AFLT or U-TDOA with an SPS
system may be referred to as a "hybrid" system. For example, U.S.
Pat. No. 5,999,124 describes, among other things, a hybrid system,
in which the position of a cell based transceiver is determined
from a combination of at least: i) a time measurement that
represents a time of travel of a message in the cell based
communication signals between the cell based transceiver and a
communication system; and, ii) a time measurement that represents a
time of travel of an SPS signal.
[0009] Altitude aiding has been used in various methods for
determining the position of a mobile device. Altitude aiding is
typically based on a pseudo-measurement of the altitude. The
knowledge of the altitude of a location of a mobile device
constrains the possible positions of the mobile device to a surface
of a sphere (or an ellipsoid) with its center located at the center
of the earth. This knowledge may be used to reduce the number of
independent measurements required to determine the position of the
mobile device. For example, U.S. Pat. No. 6,061,018 describes,
among other things, a method where an estimated altitude is
determined from the information of a cell object, which may be a
cell site that has a cell site transmitter in communication with
the mobile device.
SUMMARY OF THE DESCRIPTION
[0010] In one aspect of the present invention, a method to
determine information about a wireless access point includes:
communicating between a server and one or more mobile stations
through one or more first wireless access points of a first
wireless network for location determination of the one or more
mobile stations; collecting data specifying a plurality of
locations from which wireless signals transmitted from a second
wireless access point of a second wireless network are received by
the one or more mobile stations wherein the second wireless network
is different than the first wireless network; and determining
location information about the second wireless access point from
the data. The location information may include an estimated
position of the second wireless access point. This estimated
position of the second wireless access point may be determined from
a weighted average of the plurality of locations; a weight for the
weighted average may be based on positioning information which
indicates a distance between a corresponding one of the plurality
of locations to the second wireless access point of the second
wireless network. The positioning information may be an indicator
of received signal level for signals transmitted from the second
wireless access point and received at a mobile station at the
corresponding one of the plurality of locations. In one exemplary
implementation, the location information includes a coverage area
of the second wireless access point and an estimated position of
the second wireless access point which is determined from the
coverage area of the second wireless access point. In certain
exemplary implementations, positioning information such as ranges
that specify distances between each of the plurality of locations
and the second wireless access point of the second wireless network
may be further collected; and, the location information includes an
estimated position of the second wireless access point, which is
determined from the range information and the data collected.
[0011] In another aspect of the present invention, a method to
determine information about a wireless network includes: collecting
data specifying a plurality of locations of mobile stations at
which wireless signals transmitted from a first wireless access
point of a first wireless network are received during determination
of the plurality of locations, the mobile stations receiving
signals from the first wireless access point and also communicating
signals between the mobile stations and at least a second wireless
point of a second wireless network which is different than the
first wireless network; and determining a location of the first
wireless access point from a coverage area defined by the plurality
of locations. In one example of this method, statistics of any
mobile station being in an area in which wireless signals
transmitted from the first wireless access point can be received
during position determination is determined. The location of the
wireless access point may be determined from a weighted average of
the plurality of locations; and a weight for the weighted average
is based on an indicator of received signal level for signals
transmitted from the wireless access point and received by a mobile
station at a corresponding one of the plurality of locations. The
first wireless access point may operate in accordance with a
standard for a wireless local area network (e.g., IEEE 802.11).
[0012] In another aspect of the present invention, a method for a
mobile station of a position determination system includes:
determining, at the mobile station, first identification
information of a first wireless access point of a first wireless
network; determining first position information that relates to a
first position of the mobile station in a signal coverage area of
the first wireless access point; and communicating first data
indicating a correlation between the first identification
information and the first position information from the mobile
station to a server which is remote to the first wireless access
point. The communicating is through a second wireless access point
of a second wireless network which is different than the first
wireless network. In one example of this method, first position
information indicates a distance between the first position of the
mobile station and a position of the first wireless access point,
and this first position information is determined and transmitted
as a part of the first data. The first position information may be
an indication of a signal level for signals that are transmitted
from the first wireless access point and received at the first
position by the mobile station. Alternatively, the first position
information may be an actual position (for example, one determined
through a GPS "fix"). The first position information may include
one of: a) a measurement of a distance between the first position
of the mobile station and the position of the first wireless access
point; b) a measurement of a time delay in signal transmission from
the first wireless access point to the mobile station at the first
position; and c) a measurement of a round trip time delay for
signal transmission between the first wireless access point and the
mobile station at the first position. In one example, the first
wireless access point is an access point of a local area network
(e.g., an IEEE 802.11 wireless LAN); and, the first identification
information includes a Media Access Control (MAC) address. In one
example, the first wireless access point supports two-way
communication. In one example, Satellite Positioning System (SPS)
signals from at least one SPS satellite is received to determine
the first position information (which may include a measurement of
pseudorange to an SPS satellite).
[0013] In one example, the first data is communicated to the server
through the first access point. In another example, the first data
is communicated to the server through a second wireless access
point, where the first wireless access point is an access point of
a local area network and where the second wireless access point is
a cellular base station. In one example, the mobile station further
determines: i) second identification information of a second
wireless access point, and ii) second position information that
indicates a second position of the mobile station in a signal
coverage area of the second wireless access point; and then, second
data indicating a correlation between the second identification
information and the second position is communicated from the mobile
station to the server. In one example, the first and second data
are communicated from the mobile station to the server through a
cellular base station. In one example, the mobile station
determines second identification information of another wireless
access point and communicates the second identification information
from the mobile station to the server to determine a second
position of the mobile station in a signal coverage area of the
second wireless access point; where the first and second wireless
access points may be a same access point (e.g., both the first data
and the second identification are communicated from the mobile
station to the server through a cellular base station).
[0014] The present invention includes methods and apparatuses which
perform these methods, including data processing systems which
perform these methods, and computer readable media which when
executed on data processing systems cause the systems to perform
these methods. Further, the inventions described herein may be
implemented on different nodes within a system, such nodes
including a mobile station, a base station (such as a wireless
access point) or a location server or other nodes in a network or
wireless network.
[0015] Other features of the present invention will be apparent
from the accompanying drawings and from the detailed description
which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present invention is illustrated by way of example and
not limitation in the figures of the accompanying drawings in which
like references indicate similar elements.
[0017] FIG. 1 shows an example of a prior art cellular network
which determines the position of a mobile cellular device.
[0018] FIG. 2 shows an example of a server which may be used with
the present invention.
[0019] FIG. 3 shows a block diagram representation of a mobile
station according to one embodiment of the present invention.
[0020] FIG. 4 shows one example of a hybrid positioning system
according to one embodiment of the present invention.
[0021] FIG. 5 shows another example of a hybrid positioning system
according to one embodiment of the present invention.
[0022] FIG. 6 illustrates one method to determine the position of a
wireless access point according to one embodiment of the present
invention.
[0023] FIG. 7 illustrates another method to determine the position
information of a wireless access point according to one embodiment
of the present invention.
[0024] FIG. 8 shows a method of hybrid position determination using
a plurality of wireless networks according to one embodiment of the
present invention.
[0025] FIG. 9 shows a method of hybrid position determination using
two wireless networks for communication with a server according to
one embodiment of the present invention.
[0026] FIG. 10 shows a method to generate location information
about a wireless access point according to one embodiment of the
present invention.
[0027] FIG. 11 shows a hybrid position determination method using
one wireless network for communication and another wireless network
for the measurement of positioning parameters according to one
embodiment of the present invention.
[0028] FIG. 12 is a flowchart showing another exemplary embodiment
of the invention.
[0029] FIG. 13 is a flowchart showing another exemplary embodiment
of the invention.
[0030] FIG. 14 is a flowchart showing another exemplary embodiment
of the invention.
DETAILED DESCRIPTION
[0031] The following description and drawings are illustrative of
the invention and are not to be construed as limiting the
invention. Numerous specific details are described to provide a
thorough understanding of the present invention. However, in
certain instances, well known or conventional details are not
described in order to avoid obscuring the description of the
present invention. References to one or an embodiment in the
present disclosure are not necessary to the same embodiment; and,
such references mean at least one.
[0032] Recent development of wireless communication technologies
leads to the deployment of various different wireless networks with
substantial overlapping coverage in some areas. In the present
application, a wireless network refers to a set of wireless access
points (e.g., base stations) with a same air interface, operated by
one service provider (e.g. Verizon Wireless or Sprint), such that a
mobile unit can access the network through one of the set of the
wireless access points when in the coverage area of the network;
and, the union of the coverage areas of the wireless access points
of the wireless network is the coverage area of the network.
Further, data communication refers to the transmission of data in a
two-way communication system although, in certain embodiments, data
communication may be a one-way communication or may include
extracting information embedded in a signal which is broadcasted
regardless whether the receiver needs it or not. A wireless access
point may be considered to be a cell tower or a base station or
other wireless transmitter or receiver which is coupled to a
network of other nodes (for example, the wireless access point is
coupled by wireless or wire line to the other nodes).
[0033] In certain areas, especially urban metropolitan areas,
different wireless networks have substantially overlapping
coverage. For example, different service providers may offer the
same type of wireless service (e.g., cellular phone communication)
in the same area. Further, different types of wireless services,
such as wireless phone services (e.g., cellular phone services for
data, voice or both) and wireless digital communication services
(e.g., wireless local area networks such as Wi-Fi networks,
bluetooth, ultra-wideband), may have overlapping in coverage area.
For example, wireless LAN (Local Area Network) access points (e.g.,
for an IEEE 802.11 based wireless network) may be located within
the coverage areas of wireless telecommunication networks (e.g.,
based on Telecommunications Industry Association (TIA)/Electronic
Industries Alliance (EIA) Standards, such as IS-95, IS-856 or
IS-2000), such as those based on TDMA (Time Division Multiple
Access), GSM (Global System for Mobile communications), CDMA (Code
Division Multiple Access), WCDMA (Wideband Code Division Multiple
Access), UMTS (United Mobile Telecommunication System), TD-SCDMA
(Time Division Synchronous Code Division Multiple Access), iDEN
(Integrated Digital Enhanced Network), HDR (High Data Rate), or
other similar cellular networks.
[0034] At least one embodiment of the present invention seeks a
comprehensive system which supports positioning using these
disparate sources of wireless signals to determine measurements and
to obtain aiding information (e.g., the position and the coverage
area of an access point, Doppler frequency shifts for in view SPS
satellites, SPS ephemeris data) to form a flexible and ubiquitous
navigation solution. In this comprehensive system, when information
about an access point (e.g., base station almanac, such as the
location and coverage area of the base station) is available, it is
used and may be enhanced. Where it is not, the system may
automatically gather and enhance such information for the benefit
of future positioning attempts.
[0035] At least one embodiment of the present invention uses
wireless signals transmitted from access points of more than one
wireless network to combine information, such as SPS observations,
wireless network observations, terrain elevation information and
others, to obtain a position solution for a mobile station. In one
embodiment of the present invention, a mobile station of a hybrid
position system transfers information over access points of more
than one wireless network (in two-way communication) to aid in the
acquisition of SPS signals, time stamping for measurements and
other operations at the mobile station. In one embodiment of the
present invention, a mobile station of a hybrid position system
performs measurements using signals from access points of different
wireless networks, while communicating with a remote server using
one or more of the wireless networks.
[0036] Typically, information describing the identification,
location, and coverage area of the sectors of a wireless network is
stored in a base station almanac, which has been used in a hybrid
positioning system using a single wireless network. However, when
different wireless networks (e.g., different service providers or
different types of networks) have overlapping coverage, a typical
mobile station does not have access to such information for the
access points of the different wireless networks, even though the
wireless signals transmitted from the access points of the
different wireless networks are in the air and available to the
mobile station. This is usually because the mobile station is
allowed or is authorized to have access to one wireless network but
not another wireless network. One simple example of this is a cell
phone which has been authorized access to a first wireless network
(e.g. a cell phone network operated by a service provider such as
Verizon Wireless) but has not been authorized access to a second
wireless network (e.g. Sprint's cell phone network) or to a third
wireless network (e.g. a Wi-Fi "hotspot").
[0037] In one embodiment of the present invention, when available,
information from small and localized transmitters, such as an IEEE
802.11 wireless LAN access point, is incorporated into the wireless
navigation solution. In many cases, the location information for
these transmitters is not well known. In some cases, the "almanac"
information describing the physical characteristics of a wireless
network (e.g. ID, location, and coverage area of access points) is
not available to users who might like to use it. Some network
providers may choose not to share such information, while still
others may not have it available. In one embodiment of the present
invention, information for deriving the physical characteristics of
a network is gathered from mobile stations that use another
wireless network for communication. In one embodiment of the
present invention, using the wireless signals available in the air
from different wireless networks and the abilities of the mobile
station for position determination (e.g. a cell phone with a GPS
receiver or with a portion of a GPS receiver), mobile stations
harvest information about the access points of the different
wireless networks, which in general may not be under control of an
operator of a wireless network through which the mobile stations
typically perform data communication. The harvested information is
used to derive location information (e.g., the location, coverage
area) about the access points, which can be used for aiding hybrid
position determination for future position determinations.
[0038] In one embodiment of the present invention, the signals used
to provide time information and/or frequency information to a
mobile station are not the same as the one over which data
communication transactions are carried out.
[0039] A mobile station that supports multiple wireless
communication interfaces (e.g., IEEE 802.11 [and other IEEE 802
standards such as 802.15, 802.16, and 802.20], bluetooth, UWB
[Ultra-Wideband], TDMA, GSM, CDMA, W-CDMA, UMTS, TDSCDMA, IDEN,
HDR, or other similar networks) is used in one embodiment of the
present invention to use multiple wireless networks. Such a mobile
station may have, for example, several different portions in a
communication section which support the transmission and/or
reception of data for these different communication interfaces.
Thus, one portion may handle the transmission and/or reception of
Wi-Fi signals (e.g. IEEE 802.11 or 802.16) and another portion of
the communication section may support a cellular telephone
interface such as a CDMA interface. This also gives the user
alternative communication paths from which to choose when deciding
to communicate. For example, the availability, coverage, expense,
data speed, and ease of use may be considered when choosing which
communication path to use.
[0040] In one embodiment of the present invention, a first wireless
network is used for communications and positioning, while a second
wireless network is used for positioning and optionally
communications. For example, each of these wireless networks might
use a completely different air interface (e.g., different TIA/EIA
standards), such as an air interface that is for a typical wireless
cell phone (e.g. TDMA, GSM, CDMA, W-CDMA, UMTS, TD-SCDMA, IDEN,
HDR, or other similar cellular networks) or some other wireless air
interface, such as that in accordance with IEEE 802.11, bluetooth
or UWB. A plurality of these wireless networks is used for
positioning purposes, even when only one wireless network may be
used for communications. The advantages of a hybrid approach
according to at least some of the embodiments of the present
invention include: improved redundancy for a more fail-safe
solution, higher positioning availability, better accuracy, and
faster time to fix.
[0041] FIG. 4 shows one example of a hybrid positioning system
according to one embodiment of the present invention. In FIG. 4,
mobile station 407 utilizes signals in the air that are transmitted
from both wireless access point 403 of wireless network A and
wireless access point 405 of wireless network B for position
determination. In one embodiment of the present invention, the
mobile station includes a receiver for receiving SPS signals from
SPS satellites (e.g., GPS satellites, not shown in FIG. 4). Timing
measurements (e.g., pseudorange, round trip time, times of arrival
of signals, time differences of arrival of signals) based on the
wireless signals from one or both of wireless networks A and B (and
SPS signals) may be used to determine the position of the mobile
station. It is understood that, in general, each of wireless
networks A and B includes a number of access points (e.g., cellular
base stations such as wireless access points 403 and 405). Wireless
networks A and B may use the same type of air interface, operated
by different service providers or they may operate with the same
communication protocols but at different frequencies. However,
wireless networks A and B may also use different types of air
interfaces (e.g., TDMA, GSM, CDMA, W-CDMA, UMTS, TD-SCDMA, IDEN,
HDR, bluetooth, UWB, IEEE 802.11, or other similar networks),
operated by the same service provider or by different service
providers.
[0042] In one embodiment of the present invention, the position
determination is performed at location server 411 shown in the
example depicted in FIG. 4. Mobile station 407 communicates the
information extracted from the observed SPS signals (e.g., SPS
pseudorange measurements, a record of an SPS message for comparison
to determine a time of signal reception) and the information
extracted from the observed wireless signals (e.g., the
identification of an access point, round trip or one-way time
measurements between mobile station 407 and at least one of the
wireless access points, received signal levels) to the location
server through one of the wireless networks, such as wireless
network A (e.g., when the mobile station is a subscriber of
wireless network A but not a subscriber of wireless network B).
Servers 413 and 415 maintain the almanac data for wireless networks
A and B respectively. This almanac data may simply be, in one
exemplary implementation, a database listing a latitude and
longitude for each wireless access point which is specified by an
identification information (e.g. MAC address or cell tower
identifier, etc.). Location server 411 uses the information
communicated from the mobile station and the data in the almanac
servers 413 and 415 to determine the position of the mobile
station. The location server 411 may determine the location of the
mobile station in a number of different ways. It may, for example,
retrieve from servers 413 and 415 the locations of wireless access
points 403 and 405 and use those locations and the range
measurements, which indicate a distance between the mobile station
407 and the points 403 and 405, and the SPS pseudorange
measurements and SPS ephemeris information to calculate a position
of the mobile station 407. U.S. Pat. No. 5,999,124 provides a
discussion of how range measurements from a single wireless network
and SPS pseudorange measurements may be combined to calculate a
position of a mobile station. Alternatively, the location server
411 may use only terrestrial range measurements (or other types of
measurements such as signal strength measurements) to multiple
wireless access points of multiple wireless networks to calculate
the position if many (e.g. more than 3) such range measurements can
be made; in this case, there is no need to obtain SPS pseudoranges
or SPS ephemeris information. If SPS pseudoranges to SPS satellites
are available, these pseudoranges can be combined with SPS
ephemeris information, obtained either by the mobile station or by
a collection of GPS reference receivers as described in U.S. Pat.
No. 6,185,427, to provide additional information in the position
calculations.
[0043] Network 401 may include local area networks, one or more
intranets and the Internet for the information exchange between the
various entities. It is understood that servers 411, 413 and 415
may be implemented as a single server program, or different server
programs in a single data processing system or in separate data
processing systems (e.g., maintained and operated by different
service providers).
[0044] In one embodiment of the present invention, different
service providers operate wireless networks A and B, which are used
by the mobile station for position determination. A typical mobile
station is a subscriber only to one of them, and thus the mobile
station is authorized to use (and to have access to) only one
wireless network. However, it is often still possible to at least
receive signals from the wireless network which is not subscribed
to and thus it is still possible to make range measurements or
signal strength measurements relative to wireless access points in
the wireless network which is not subscribed to. One specific
example of this situation would involve a user of a tri-mode CDMA
cellular phone which can receive PCS frequency band signals (such
as, for example, from the wireless network operated by Sprint,
which is a first service provider) and can also receive other CDMA
signals at other frequencies (such as, for example, from the
wireless network operated by Verizon Wireless, which is a second
service provider). If the user has subscribed only to Sprint's
wireless network, then the user's phone (a form of a mobile
station) is authorized to operate with Sprint's wireless network
but not Verizon's wireless network. The user may use the phone in
an environment in which only one Sprint wireless access point (e.g.
a Sprint cellular base station) is capable of radio communication
with the user's phone, but in this environment there are numerous
Verizon wireless access points which are within radio communication
range of the user's phone. In this context, it is still possible
for the phone to obtain SPS assistance data (if desired) from a
location server through Sprint's wireless network and to transmit
SPS pseudoranges, obtained at the phone, to the location server.
However, it will not be possible to obtain more than one range
measurement to a wireless access point unless range measurements to
Verizon's wireless access points are obtained. With an embodiment
of the invention, the phone obtains range measurements to the
available Verizon wireless access points, thereby providing at
least a few range measurements (e.g. distances between the phone
and two Verizon cellular base stations) which can be used in the
position calculations that are performed to determine the position
of the phone.
[0045] The service providers maintain the almanac information on
servers 413 and 415 separately. Although mobile station 407 has
communication access to only one of the wireless networks, location
server 411 may have access to both servers 413 and 415 for base
station almanac data. After determining the identities of base
stations (e.g. the wireless access points 403 and 405) of both
wireless networks A and B, the mobile station 407 transmits the
base station identifications to location server 411, which uses
servers 413 and 415 to retrieve the corresponding positions of the
base stations, which can be used in determining the position of the
mobile station.
[0046] Alternatively, the cooperation between the service providers
to share almanac data is not necessary. For example, the operator
of location server 411 maintains both almanac servers 413 and 415
(e.g., through a survey process to obtain the almanac data, or
through a data harvesting process using mobile stations, which will
be described in detail with FIGS. 6 and 7 and 10).
[0047] In one embodiment of the present invention, mobile station
407 uses both wireless networks A and B for communicating with the
location server (instead of using only one of the wireless networks
for communication purpose). As known in the art, various types of
information can be exchanged between the mobile station and the
location server for position determination. For example, location
server 411 can provide the mobile station 407 with Doppler
frequency shift information for in view satellites of the mobile
station (e.g., through wireless network A); and, the mobile station
can provide pseudorange measurements for SPS signals, the
identification information of the base stations and associated
range measurements (e.g., round trip time measurements) to the
location server for the calculation of the position of the mobile
station (e.g., through wireless network B). In one embodiment of
the present invention, a mobile station is capable of communicating
through more than one wireless network to the location server when
in the coverage area of these wireless networks. However, the
trade-off between cost and performance may dictate communication
with the server using one of the wireless networks, while using the
others only for timing measurements (or other measurements, such as
received signal levels) or for aiding in measurement, such as
obtaining time information from wireless transmission from an
access point for time stamping measurements (e.g., for resolving
ambiguity), or locking to the accurate carrier frequency of a
wireless cellular base station for calibrating the local oscillator
of the mobile station.
[0048] In one embodiment of the present invention, the location of
the mobile station is determined at the location server using the
information communicated from the mobile station and then
transmitted back to the mobile station. Alternatively, the position
calculation can be performed at the mobile station using assistance
information from the location server (e.g., Doppler frequency
shifts for in view satellites, positions and coverage areas of
access points, differential GPS data, altitude aiding
information).
[0049] FIG. 5 shows another example of a hybrid positioning system
according to one embodiment of the present invention. An access
point of one wireless network (e.g., cellular base station 503) is
used for the communication between mobile station 507 and location
server 511. A method for determining the position of mobile station
507 may use SPS signals (e.g., from satellite 521), wireless
signals from the access points (e.g. cellular phone base station
503) of the wireless network used for data communication, as well
as the wireless signals from access points of other wireless
networks, such as those from access point B (505), which can be a
base station of a different wireless cellular phone network (e.g.,
operated by a different service provider, or using a different air
interface), and from access point A (509), which can be a wireless
LAN access point (e.g., a bluetooth access point or a Wi-Fi
wireless access point).
[0050] Typically, a wireless LAN access point (or other similar low
power transmitters) has a small coverage area. When available, the
small coverage area of such an access point provides a very good
estimate of the location of the mobile station. Further, wireless
LAN access points are typically located near or inside buildings,
where the availability of other types of signals (e.g., SPS signals
or wireless telephone signals) may be low. Thus, when such wireless
transmissions are used with other types of signals, the performance
of the positioning system can be greatly improved.
[0051] In one embodiment of the present invention, the wireless
signals from different wireless networks are used for position
determination. For example, the wireless signals from the different
wireless networks can be used to determine the identities of the
corresponding access points, which are then used to determine the
locations and coverage areas of the corresponding access points.
When precision range information (e.g., round trip time or signal
traveling time between an access point and the mobile station) is
available, the range information and the location of the access
point can be used in obtaining a hybrid positioning solution. When
approximate range information (e.g., received signal level, which
can be approximately correlated with an estimated range) is
available, the location of the access point can be used to estimate
the position of the mobile station (or determine the estimated
altitude of the mobile station). Further, the mobile station can
use precision carrier frequency from one of the wireless networks
(e.g., from access point 505 or 509), which may not be the one used
for the data communication purpose, to calibrate the local
oscillator of the mobile station. More details about locking to a
precision carrier frequency of a wireless signal to provide a
reference signal at an SPS receiver for signal acquisition can be
found in U.S. Pat. No. 5,874,914. Further, the mobile station can
use the accurate time information in the wireless signals from one
of the wireless networks (e.g., from access point 505 or 509),
which may not be the one used for the data communication purpose.
More details about using the accurate time information (e.g.,
timing markers, or system time) for time stamping can be found in
U.S. Pat. No. 5,945,944.
[0052] Since some of the access points of the different wireless
networks do not have well-known almanac data (e.g., position of the
wireless access point, coverage area of the wireless access point),
one embodiment of the present invention derives the almanac data
from the information collected from mobile stations. FIG. 6
illustrates one method to determine the position of a wireless
access point according to one embodiment of the present invention.
In FIG. 6, a location server does not know the position of access
point antenna 601. To calculate the position of the access point,
the location server correlates the positions of one or more mobile
stations and their corresponding ranges to the access point, which
are obtained from the mobile stations while performing position
determination for the mobile stations. For example, a mobile
station at position L.sub.1 (611) determines range R.sub.1 (613) to
access point antenna 601. The mobile station obtains measurements
based on SPS signals (e.g. measurements of SPS pseudoranges and
extraction of SPS ephemeris information from SPS signals) and
wireless transmissions (e.g. range measurements). The mobile
station may calculate its position using the measurements and
transmit to the location server the calculated position with: i)
the range to the access point antenna; and, ii) the identity of the
access point antenna. Alternatively, the mobile station may
transmit: i) the measurements; ii) the range to the access point
antenna; and, iii) the identity of the access point antenna to the
location server, which calculates the position of the mobile
station using the measurements and which stores the range
measurements (e.g. R.sub.1, R.sub.2 and R.sub.3 and the
corresponding positions (e.g. L.sub.1, L.sub.2, and L.sub.3). When
a number of data points are available, each of which data points
correlates the position of a mobile station and the range from the
mobile station to the access point antenna, the location server
determines the position of the access point antenna. It can be seen
from FIG. 6 that as few as three range measurements (R.sub.1,
R.sub.2, and R.sub.3) and their corresponding positions (L.sub.1,
L.sub.2, and L.sub.3) are sufficient to specify a particular
location of the identified access point (which is shown at the
intersection of three circles specified by the three ranges).
Various methods that have been used in the art for: calculating the
position of a mobile station based on range information can be used
to calculate the position of the access point. Note that the data
points may be from a single mobile station or from a number of
mobile stations.
[0053] Further, the accumulated data points of the locations of
mobile stations show the coverage area of the access point (e.g.,
in a scatter plot of the mobile locations). When the position of
the access point is not known, the collected data points can be
used to estimate the position and the coverage of the access point.
When an initial estimation of the position of the access point is
available, the collected data points can be used to improve the
estimation. The collection and enhancement process can be a
continuous process during the service of the location server. Note
that the collection and enhancement operations can also be
performed on a different server other than the location server. For
example, in one embodiment of the present invention, the collection
and enhancement operations are performed in almanac server 513,
which communicates with location server 511 in performing hybrid
position determination for mobile stations.
[0054] However, precision information of range to some access
points may not be available to mobile stations of a location
server. FIG. 7 illustrates another method to determine the position
information of a wireless access point according to one embodiment
of the present invention. A larger number of data points (e.g.,
711, 713, 715, 721, 723, 725) of the locations of mobile stations
that can receive signals from the access point (e.g., 703) define a
coverage area (e.g., 705) of the access point (e.g., through a
scatter plot of the locations, the smallest circle enclosing the
data points). From the coverage area, the location server can
calculate an estimated position of the access point (e.g., the
geometric center of the coverage area). Further, range information
(e.g., an indicator of the received signal level, a round trip
time) may be used to define a weight for determining the weighted
average of the coverage area (e.g., the closer to the access point,
the larger the weight), from which the estimated position of the
access point is determined. Further, in one embodiment, the
location server determines the probability of a mobile station
being at a particular location from the statistics of the mobile
stations, given certain range information is specified. Other
information, such as the signal level of wireless transmission from
other transmitters, can then be further used to narrow the possible
locations of the mobile station.
[0055] For example, a wireless LAN access point is located inside
building 701. While SPS signals (e.g., signals from SPS satellites
741-745) and wireless cellular phone signals (e.g., signals from
cellular base station 751) may be weak inside building 701, the
position of a mobile station can be easily determined (e.g.,
without using the signals from access point 703) at certain
locations around the building (e.g., locations 711-725, which may
be just outside the building or at certain locations inside the
building, such as spots close to windows). In one embodiment of the
present invention, the identification of the access point is
determined and sent to the server with the location of the mobile
station (or information specifying the location of the mobile, such
as pseudoranges to in view satellites) for the determination of the
coverage area (and/or the position) of the access point 703. The
location information of the access point (e.g., coverage area,
position) can be maintained at the server (or a different server).
When a mobile station is inside a building (or at a position near
the building), where the blockage of some of the SPS signals and
cellular phone signals occurs, the location information about the
access point can be used to aid in determining the position of the
mobile station.
[0056] It is understood that some access points may be moved from
one location to another. In one embodiment of the present
invention, the server tracks the collected position information
about one or more mobile stations that receive the transmission
from one access point in order to determine if the access point is
moved. For example, the server may compare the old coverage area
with the recent coverage area (e.g., through comparing the center
and the radius of the coverage area) to determine if the access
point is moved. Alternatively, the server may periodically discard
old information in view of newly collected information. Further,
the server may weight the collected information so that the freshly
collected data carries more weight in determining the coverage area
and/or the location of the access point and the influence from the
data collected previously may eventually diminish over time.
Further, the server may determine if an access point moves
frequently; and, if the access point moves frequently, the access
point may be disqualified as a reference point for the position
determination. Further, in one embodiment, when an access point has
not been observed for a certain period of time, the access point is
removed from the database; similarly, when a new access point is
observed, it is added to the database. Thus, the server may update
the information about the access point in an ongoing basis.
[0057] In at least one embodiment of the present invention, a
mobile station can determine its position without a communication
link. The mobile station has memory for storing at least some of
the information about the locations of the mobile station and the
corresponding received signal levels or range measurements of a
number of wireless access points (e.g., for cellular phone access,
or for wireless LAN access). The mobile station transmits the data
to a server when a communication link (e.g., a wire connection
through a communication port of the mobile station or a wireless
connection through a transceiver of the mobile station) is
available. Alternatively, the mobile station may directly use the
stored information to derive the position information about the
access point in determining its own position when needed.
[0058] FIG. 8 shows a general method of hybrid position
determination using a plurality of wireless networks according to
one embodiment of the present invention. In operation 801, a mobile
station receives wireless signals transmitted from a plurality of
wireless access points of different wireless networks (e.g.,
wireless networks of different air interfaces, wireless networks of
different service providers, wireless networks operating at
different frequencies, wireless networks using different
communication protocols, etc.). In operation 803, the mobile
station utilizes the wireless signals from each of the access
points of the different wireless networks in determining the
position of the mobile station (e.g., to determine the identity of
the access point, to lock a local oscillator of the mobile station
to a precision carrier frequency of a wireless signal, to obtain a
timing indicator from a wireless signal, to determine signal
transmission delay between the mobile station and one of the access
points, to communicate with a server). In general, the mobile
station may use the wireless signals from access points of
different wireless networks to perform different operations,
although the mobile station may use the wireless signals from
access points of some different wireless networks to perform a
number of similar operations. In operation 805, the mobile station
communicates with a server to determine the position of the mobile
station using at least one of the different wireless networks.
Typically, the mobile station communicates with the server using
only one of the different wireless networks; however, the mobile
station may communicate with the server using more than one
wireless network (e.g., to transmit the time of reception at an
access point for a signal transmitted from the mobile station, to
transmit a round trip time, or to transmit other information to or
from a location server).
[0059] FIG. 9 shows a method of hybrid position determination using
two wireless networks for communication with a server according to
one embodiment of the present invention. Operation 821 receives, at
a mobile station, SPS signals transmitted from one or more SPS
satellites and wireless signals transmitted from a plurality of
wireless access points of more than one wireless network. The
mobile station may use the received wireless signals from one or
more wireless networks to aid in SPS signal acquisitions (e.g., to
extract Doppler frequency shifts for in view satellites of the
mobile station, to calibrate the local oscillator of the mobile
station, to obtain a timing indicator to time stamp a measurement).
The mobile station uses the SPS signals to determine pseudoranges
to in view satellites, and the mobile station uses wireless signals
from the wireless access points to identify the access points and
to perform range measurements to the wireless access points for
position determination. These received signals are typically
broadcast from the transmitters of the satellites and wireless
access points and available to any mobile station that chooses to
use them. Operation 823 communicates first information (e.g., a
record of an SPS message) between the mobile station and a server
using an access point of a first wireless network (e.g., a wireless
local area network). Operation 825 communicates second information
(e.g., Doppler frequency shifts, ephemeris data for in view SPS
satellites) between the mobile station and a server using an access
point of a second wireless network (e.g., a wireless cellular phone
network). Operation 827 determines the position of the mobile
station from the communication of the first information and the
second information. Typically, the availability, coverage, expense,
data speed, and ease of use are considered when choosing which
communications path to use. Further, the mobile station may use
different communication paths at different locations. For example,
when the mobile station is within the coverage area of a wireless
LAN (e.g., a home network), the mobile station may use the wireless
LAN (e.g., through internet) to communicate with the server for
information that does not need to pass through the base station of
a wireless cellular phone system (e.g., Doppler frequency shifts);
and, use the base station of the wireless cellular phone system to
transmit the information that is related to the base station (e.g.,
round trip time measurement to the base stations of the wireless
cellular phone system). In a further example, the mobile station
may choose to use either the wireless cellular phone system or the
wireless LAN for communication according to the communication cost
and availability. In one embodiment of the present invention, the
mobile station automatically determines the communication path
according to a set of rules (e.g., availability, cost, priority,
and others) which may be specified by a user of the mobile station
or may be set as a default setting by one of the wireless
networks.
[0060] FIG. 10 shows a method to generate location information
about a wireless access point according to one embodiment of the
present invention. Operation 841 detects, at a mobile station,
wireless signals transmitted from a wireless access point (e.g., a
wireless access point that is in compliance with the IEEE 802.11
standard for wireless local area network, or other types of
ground-based wireless transmitters that transmit signals with their
identification information). Note that, in the present application,
wireless access points do not include satellite-based transmitters.
Operation 843 determines identification information, which may be a
unique identifier, of the wireless access point (e.g., the MAC
address of the wireless access point or an identifier of a cellular
base station) from the wireless signals. Operation 845 determines
the position of the mobile station (e.g., at the mobile station or
at a location server). For example, the mobile station may
calculate the position based on the pseudorange measurements and
other range information; or, the mobile station may transmit the
pseudorange measurements and the range information to a location
server, which calculates the position of the mobile station (and,
the location server may send back the calculated position to the
mobile station). Operation 847 correlates the position of the
mobile station with the identification information of the wireless
access point. This correlation may be transmitted to a location
server so that future positioning operations of mobile stations may
use the position and identification information to determine a
position of the identified wireless access point. Operation 849
generates location information about the wireless access point
(e.g., access point almanac, statistics of coverage area of the
wireless access point). Typically, the correlation data is sent to
a server (e.g., a location server, or an access point almanac
server) which generates location information about the access point
based on a number of positions of one or more mobile stations that
report the reception of signals transmitted from the access point.
The location information about the wireless access point can be
derived from a weighted average method as described above (or other
methods, such as, using the range information as shown in FIG. 6).
However, a mobile station may also track the correlation and derive
the location information about the wireless access point (e.g.,
from data points collected at different time instances). The
location information about the wireless access point can then be
used for position determination.
[0061] FIG. 11 shows a hybrid position determination method using
one wireless network for communication and another wireless network
for the measurement of positioning parameters according to one
embodiment of the present invention. Operation 861 detects, at a
mobile station, wireless signals transmitted from a wireless access
point (e.g., a wireless access point that is in compliance with the
IEEE 802.11 standard for wireless local area network, or a cellular
communication base station) of a first wireless network (e.g., a
wireless local area network, or a cellular phone communication
system). Operation 863 determines the identification information of
the wireless access point (e.g., the MAC address, or the base
station ID) from the wireless signals. Operation 865 retrieves
location information about the wireless access point (e.g., access
point almanac) using the identification information. For example,
the mobile station may transmit identification information of the
wireless access point to location server, which retrieves the
location information about the wireless access point using the
identification information (e.g., from a database, or from another
server, such as an access point almanac server). In another
example, the mobile station maintains the location information
about the wireless access point in memory; thus, the location
information is simply retrieved from the memory of the mobile
station. Operation 867 determines the position of the mobile
station using the location information and using a communication
link between the mobile station and a wireless access point of a
second wireless network (e.g., a cellular phone network). For
example, satellite assistance data (e.g., Doppler frequency shifts)
for the acquisition of SPS signals or timing measurements (e.g.,
pseudoranges or time of arrivals of SPS signals) are communicated
through the second wireless network for the determination of the
position of the mobile station.
[0062] FIG. 12 shows another exemplary method of the inventions. In
this method, a mobile station receives, in operation 901, first
signals transmitted from a first wireless access point of a first
wireless network. The first wireless network may support two-way
communication between the various nodes within the first wireless
network as well as nodes outside of this network. In operation 903,
at least one range measurement is determined using the first
signals. If additional signals from other wireless access points of
the first wireless network are also available, then additional
range measurements to these other wireless access points (and their
identification information) are obtained. In an alternative
implementation of operation 903, another measurement (e.g. a signal
strength measurement of the first signals) may be taken by the
mobile station without attempting to make a range measurement using
the first signals. In one exemplary implementation, a time of
travel of the first signals from the first wireless access point to
the mobile station is measured and an identification of this first
wireless access point is received from the first wireless access
point. In operation 905, second signals are communicated between
the mobile station and a second wireless access point of a second
wireless network, which is different than the first wireless
network. The mobile station may, in this operation, receive the
second signals (which may include SPS assistance data, etc.) from
the second wireless access point. In operation 907, the mobile
station and the server communicate to determine the position of the
mobile station, and this communication may be through the second
wireless access point. For example, the mobile station may, in
operation 907, transmit the range measurements and identification
information, performed in operation 903, and SPS pseudoranges,
obtained by the mobile station, to the server through the second
wireless access point. The identification information is used to
obtain the location of the wireless access points to which range
measurements (or other measurements) were obtained, and the server
may then determine the position of the mobile station using at
least some of the available measurements (e.g. the SPS pseudoranges
to SPS satellites and the range measurements, or other
measurements, to various terrestrial wireless access points).
Alternatively, the mobile station may determine its position
(rather than the server doing so) using the range measurements and
SPS pseudo ranges and using information provided by the server
(such as the location of the identified wireless access points in
one or both of the wireless networks).
[0063] The first wireless network in FIG. 12 may be a wireless
local area network and, in this case, the first wireless access
point may be a wireless router operating according to a Wi-Fi
standard. Alternatively, the first wireless network may be a
wireless cellular telephone network operated by a first service
provider, and the second wireless network may be another
(different) wireless cellular telephone network operated by a
second service provider, and the mobile station, which may be a
cellular telephone with an integrated GPS receiver, is authorized
to operate with only the second wireless network and not the first
wireless network. Various other alternatives, discussed herein, may
also apply to this example of FIG. 12.
[0064] FIG. 13 is another example of a method of the inventions. In
this example, the mobile station, in operation 931, obtains an
identification information of a first wireless access point of a
first wireless network that is accessible (e.g. within radio
communication) to the mobile station. This identification may be a
MAC address (e.g. for an Ethernet local area network) or a cellular
telephone base station (e.g. "cell tower") identifier. In operation
933, the mobile station transmits, through a second wireless access
point of a second wireless network, the identification information
to a server (e.g. a location server) during a position
determination operation. In this example, the second wireless
network is different than the first wireless network (e.g.
different air interfaces, different service providers, etc.). Then,
in operation 935, the server uses the identification information of
the first wireless access point to determine the location of the
first wireless access point (which may have been
harvested/collected through methods described herein, such as in
FIG. 14). The server may also, in operation 935, use other data
(e.g. SPS pseudoranges determined at a GPS receiver which is
integrated into the mobile station and then transmitted to the
server) to determine the position of the mobile station. The server
may, for example, combine the SPS pseudoranges with the
measurements on signals from the wireless access points to
determine the position of the mobile station. Alternatively, the
SPS pseudoranges may be combined with the known locations of the
wireless access points (particularly in the case of wireless LANs
which have shorter signal ranges). In another alternative to
operation 935, the server may provide assistance data (e.g. the
location of the first wireless access point and possibly other data
such as Doppler data for SPS satellites in view of the mobile
station, etc.) to the mobile station but the server does not
compute the position of the mobile station; rather, the mobile
station performs the position solution using at least some of the
available measurements (e.g. SPS pseudoranges, range measurements
or other measurements relative to the wireless access points of one
or all available wireless networks) and the available assistance
data from the server.
[0065] FIG. 14 shows another exemplary method of the inventions.
This method ultimately determines positions of wireless access
points so that future position determination operations for mobile
stations can be performed using multiple wireless networks as
described herein. In operation 971, data is collected. This data
specifies a plurality of locations of mobile stations at which
wireless signals, transmitted from at least a first wireless access
point of a first wireless network, are received during
determinations of the plurality of locations. The mobile stations
may, in operation 973, receive signals from the first wireless
access points and also communicate signals between the mobile
stations and at least one second wireless access point of a second
wireless network (which is different than the first wireless
network). This communication with the second wireless network may
be for the purpose of providing information used in collecting the
data which is used to determine the locations of wireless access
points of the first wireless network. In operation 975, the
location of at least the first wireless access point is determined
(e.g. in the manner shown in FIG. 6) from the coverage area defined
by the plurality of locations.
[0066] FIG. 2 shows an example of a data processing system which
may be used as a server in various embodiments of the present
invention. For example, as described in U.S. Pat. No. 5,841,396,
the server (201) may provide assistance data such as Doppler or
other satellite assistance data to the GPS receiver in a mobile
station. In addition, or alternatively, the same server or a
different server may perform the final position calculation rather
than the mobile station (after receiving pseudoranges or other data
from which pseudoranges can be determined from the mobile station)
and then may forward this position determination result to the base
station or to some other system. The data processing system as a
server (e.g., a location server, an almanac server) typically
includes communication devices 212, such as moderns or network
interface. The location server may be coupled to a number of
different networks through communication devices 212 (e.g., modems
or other network interfaces). Such networks include one or more
intranets, the network, the cellular switching center or multiple
cellular switching centers 225, the land based phone system
switches 223, cellular base stations (not shown in FIG. 2), GPS
receivers 227, or other processors or location servers 221.
[0067] Multiple cellular base stations are typically arranged to
cover a geographical area with radio coverage, and these different
base stations are coupled to at least one mobile switching center,
as is well known in the prior art (e.g., see FIG. 1). Thus,
multiple base stations would be geographically distributed but
coupled together by a mobile switching center. The network 220 may
be connected to a network of reference GPS receivers which provide
differential GPS information and may also provide GPS ephemeris
data for use in calculating the position of mobile systems. The
network is coupled through the modem or other communication
interface to the processor 203. The network 220 may be connected to
other computers or network components. Also network 220 may be
connected to computer systems operated by emergency operators, such
as the Public Safety Answering Points which respond to 911
telephone calls. Various examples of methods for using a location
server have been described in numerous U.S. patents, including:
U.S. Pat. Nos. 5,841,396, 5,874,914, 5,812,087 and 6,215,442.
[0068] The server 201, which is a form of a data processing system,
includes a bus 202 which is coupled to a microprocessor 203 and a
ROM 207 and volatile RAM 205 and a non-volatile memory 206. The
processor 203 is coupled to cache memory 204 as shown in the
example of FIG. 2. The bus 202 interconnects these various
components together. While FIG. 2 shows that the non-volatile
memory is a local device coupled directly to the rest of the
components in the data processing system, it will be appreciated
that the present invention may utilize a non-volatile memory which
is remote from the system, such as a network storage device which
is coupled to the data processing system through a network
interface such as a modem or Ethernet interface. The bus 202 may
include one or more buses connected to each other through various
bridges, controllers and/or adapters as is well known in the art.
In many situations the location server may perform its operations
automatically without human assistance. In some designs where human
interaction is required, the I/O controller 209 may communicate
with displays, keyboards, and other I/O devices.
[0069] Note that while FIG. 2 illustrates various components of a
data processing system, it is not intended to represent any
particular architecture or manner of interconnecting the components
as such details are not germane to the present invention. It will
also be appreciated that network computers and other data
processing systems which have fewer components or perhaps more
components may also be used with the present invention and may act
as a location server or a PDE (position determination entity).
[0070] In some embodiments, the methods of the present invention
may be performed on computer systems which are simultaneously used
for other functions, such as cellular switching, messaging
services, etc. In these cases, some or all of the hardware of FIG.
2 would be shared for several functions.
[0071] It will be apparent from this description that aspects of
the present invention may be embodied, at least in part, in
software. That is, the techniques may be carried out in a computer
system or other data processing system in response to its processor
executing sequences of instructions contained in memory, such as
ROM 207, volatile RAM 205, non-volatile memory 206, cache 204 or a
remote storage device. In various embodiments, hardwired circuitry
may be used in combination with software instructions to implement
the present invention. Thus, the techniques are not limited to any
specific combination of hardware circuitry and software nor to any
particular source for the instructions executed by the data
processing system. In addition, throughout this description,
various functions and operations are described as being performed
by or caused by software code to simplify description. However,
those skilled in the art will recognize what is meant by such
expressions is that the functions result from execution of the code
by a processor, such as the processor 203.
[0072] A machine readable medium can be used to store software and
data which when executed by a data processing system causes the
system to perform various methods of the present invention. This
executable software and data may be stored in various places
including for example ROM 207, volatile RAM 205, non-volatile
memory 206 and/or cache 204 as shown in FIG. 2. Portions of this
software and/or data may be stored in any one of these storage
devices.
[0073] Thus, a machine readable medium includes any mechanism that
provides (i.e., stores and/or transmits) information in a form
accessible by a machine (e.g., a computer, network device, personal
digital assistant, manufacturing tool, any device with a set of one
or more processors, etc.). For example, a machine readable medium
includes recordable/non-recordable media (e.g., read only memory
(ROM); random access memory (RAM); magnetic disk storage media;
optical storage media; flash memory devices; etc.), as well as
electrical, optical, acoustical or other forms of propagated
signals (e.g., carrier waves, infrared signals, digital signals,
etc.); etc.
[0074] FIG. 3 shows a block diagram representation of a mobile
station according to one embodiment of the present invention. The
mobile station includes a portable receiver, which combines a
communication transceiver with GPS receiver for use in one
embodiment of the present invention. The combined mobile unit 310
includes circuitry for performing the functions required for
processing GPS signals as well as the functions required for
processing communication signals received through a communication
link. The communication link, such as communication link 350 or
360, is typically a radio frequency communication link to another
component, such as base station 352 having communication antenna
351 or wireless LAN access point 362 with antenna 361. Although
FIG. 3 illustrates an embodiment that communication antenna 311 is
used for receiving signals from different types of wireless access
points (e.g., from access point 362 for wireless LAN and from based
station 352 for cellular phone service), the combined receiver may
use separate and distinct antennas for receiving signals of
different air interfaces. Further, the combined receiver may use
separate and distinct components for at least a partial processing
of the received wireless signals and may or may not share some
components in the processing of the wireless signals of different
air interfaces. For example, the combined receiver may have
separate circuits for the RF signal processing and share same data
processor resources. From this description, various combinations
and variations of the combined receiver will be apparent to one
skilled in the art.
[0075] Portable receiver 310 is an example of a combined GPS
receiver and a communication receiver and transmitter. The
communication receiver and transmitter may be implemented as
multiple receivers and transmitters for the different wireless
networks. For example, the communication transceiver 305 may
include a transceiver portion for receiving and/or transmitting
cellular telephone signals and another transceiver portion for
receiving and/or transmitting Wi-Fi signals. Receiver 310 contains
a GPS receiver stage including acquisition and tracking circuit 321
and communication transceiver section 305. Acquisition and tracking
circuit 321 is coupled to GPS antenna 301, and communication
transceiver 305 is coupled to communication antenna 311. GPS
signals (e.g., signal 370 transmitted from satellite 303) are
received through GPS antenna 301 and input to acquisition and
tracking circuit 321 which acquires the PN (Pseudorandom Noise)
codes for the various received satellites. The data produced by
circuit 321 (e.g., correlation indicators) are processed by
processor 333 for transmittal {e.g. of SPS pseudoranges) by
transceiver 305. Communication transceiver 305 contains a
transmit/receive switch 331 which routes communication signals
(typically RF) to and from communication antenna 311 and
transceiver 305. In some systems, a band splitting filter, or
"duplexer," is used instead of the T/R switch. Received
communication signals are input to communication receiver 332 and
passed to processor 333 for processing. Communication signals to be
transmitted from processor 333 are propagated to modulator 334 and
frequency converter 335. Power amplifier 336 increases the gain of
the signal to an appropriate level for transmission to base station
352 (or to wireless LAN access point 362).
[0076] In one embodiment of the present invention, communication
transceiver section 305 is capable of being used with a number of
different air interfaces (e.g., IEEE 802.11, bluetooth, UWB,
TD-SCDMA, IDEN, HDR, TDMA, GSM, CDMA, W-CDMA, UMTS, or other
similar networks) for communication (e.g., through communication
links 350 and 360). In one embodiment of the present invention,
communication transceiver section 305 is capable of being used with
one air interface for communication and capable of being used to
receive signals with other air interfaces. In one embodiment of the
present invention, communication transceiver section 305 is capable
of being used with one air interface for communication while also
being capable of being used with signals in another air interface
to extract timing indicators (e.g., timing frames or system time)
or to calibrate the local oscillator (not shown in FIG. 3) of the
mobile station. More details about the mobile station for
extracting timing indicators or calibrating the local oscillator
can be found in U.S. Pat. Nos. 5,874,914 and 5,945,944.
[0077] In one embodiment of the combined GPS/communication system
of receiver 310, data generated by acquisition and tracking circuit
321 is transmitted to a server over communication link 350 to base
station 352 or over communication link 360 to wireless LAN access
point 362. The server then determines the location of receiver 310
based on the data from the remote receiver, the time at which the
data were measured, and ephemeris data received from its own GPS
receiver or other sources of such data. The location data can then
be transmitted back to receiver 310 or to other remote locations.
More details about portable receivers utilizing a communication
link can be found in U.S. Pat. No. 5,874,914.
[0078] In one embodiment of the present invention, the combined GPS
receiver includes (or is coupled to) a data processing system
(e.g., a personal data assistant, or a portable computer). The data
processing system includes a bus which is coupled to a
microprocessor and a memory (e.g., ROM, volatile RAM, non-volatile
memory). The bus interconnects various components together and also
interconnects these components to a display controller and display
device and to peripheral devices such as input/output (I/O)
devices, which are well known in the art. The bus may include one
or more buses connected to each other through various bridges,
controllers and/or adapters as are well known in the art. In one
embodiment, the data processing system includes communication ports
(e.g., a USB (Universal Serial Bus) port, a port for IEEE-1394 bus
connection). In one embodiment of the present invention, the mobile
station stores the locations and identifications (e.g., MAC
address) of wireless access points (e.g., according to the types of
the wireless access points) for extracting and enhancing the
location information about the wireless access points using the
memory and software program instructions stored in the memory. In
one embodiment, the mobile station only stores the locations of the
mobile station and identifications of the wireless access points
for transmission to a server (e.g., through a communication port,
or a wireless communication link) when a communication connection
is established.
[0079] Although the methods and apparatus of the present invention
have been described with reference to GPS satellites, it will be
appreciated that the descriptions are equally applicable to
positioning systems which utilize pseudolites or a combination of
satellites and pseudolites. Pseudolites are ground-based
transmitters which broadcast a PN code (similar to a GPS signal),
typically modulated on an L-band carrier signal, generally
synchronized with GPS time. Each transmitter may be assigned a
unique PN code so as to permit identification by a remote receiver.
Pseudolites are useful in situations where GPS signals from an
orbiting satellite might be unavailable, such as tunnels, mines,
buildings or other enclosed areas. The term "satellite", as used
herein, is intended to include pseudolites or equivalents of
pseudolites, and the term GPS signals, as used herein, is intended
to include GPS-like signals from pseudolites or equivalents of
pseudolites.
[0080] In the preceding discussion the invention has been described
with reference to application upon the United States Global
Positioning Satellite (GPS) system. It should be evident, however,
that these methods are equally applicable to similar satellite
positioning systems, and in particular, the Russian GLONASS system
and the proposed European Galileo System. The GLONASS system
primarily differs from GPS system in that the emissions from
different satellites are differentiated from one another by
utilizing slightly different carrier frequencies, rather than
utilizing different pseudorandom codes. In this situation
substantially all the circuitry and algorithms described previously
are applicable. The term "GPS" used herein includes such
alternative satellite positioning systems, including the Russian
GLONASS system, and the European Galileo System.
[0081] Although the operations in the above examples are
illustrated in specific sequences, from this description, it will
be appreciated that various different operation sequences and
variations can be used without having to be limited to the above
illustrated examples.
[0082] The above examples are illustrated without presenting some
of the details known in the art; as pointed out in the above
discussion, these details can be found in publications, such as
U.S. Pat. Nos. 5,812,087, 5,841,396, 5,874,914, 5,945,944,
5,999,124, 6,061,018, 6,208,290, and 6,215,442, all of which are
hereby incorporated here by reference.
[0083] In the foregoing specification, the invention has been
described with reference to specific exemplary embodiments thereof.
It will be evident that various modifications may be made thereto
without departing from the broader spirit and scope of the
invention as set forth in the following claims. The specification
and drawings are, accordingly, to be regarded in an illustrative
sense rather than a restrictive sense.
* * * * *