U.S. patent application number 14/172612 was filed with the patent office on 2014-08-21 for position estimation assistance information for mobile station.
This patent application is currently assigned to QUALCOMM Incorporated. The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Zoltan F. Biacs, Jignesh Umesh Doshi, Dominic Gerard Farmer, Marc Anthony Ische, Mark Leo Moeglein.
Application Number | 20140232601 14/172612 |
Document ID | / |
Family ID | 43242722 |
Filed Date | 2014-08-21 |
United States Patent
Application |
20140232601 |
Kind Code |
A1 |
Ische; Marc Anthony ; et
al. |
August 21, 2014 |
POSITION ESTIMATION ASSISTANCE INFORMATION FOR MOBILE STATION
Abstract
The subject matter disclosed herein relates to providing
assistance information to a mobile station for performing position
estimation operations.
Inventors: |
Ische; Marc Anthony; (San
Diego, CA) ; Farmer; Dominic Gerard; (Los Gatos,
CA) ; Moeglein; Mark Leo; (Ashland, OR) ;
Biacs; Zoltan F.; (San Mateo, CA) ; Doshi; Jignesh
Umesh; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Assignee: |
QUALCOMM Incorporated
San Diego
CA
|
Family ID: |
43242722 |
Appl. No.: |
14/172612 |
Filed: |
February 4, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12555735 |
Sep 8, 2009 |
8665156 |
|
|
14172612 |
|
|
|
|
Current U.S.
Class: |
342/464 |
Current CPC
Class: |
G01S 19/27 20130101;
G01S 5/0236 20130101; G01S 5/0009 20130101; G01S 19/252
20130101 |
Class at
Publication: |
342/464 |
International
Class: |
G01S 5/00 20060101
G01S005/00; G01S 5/02 20060101 G01S005/02 |
Claims
1. A method, comprising: receiving, at a server, fix information
records associated with position estimations of a first plurality
of mobile stations, wherein each received fix information record is
associated with a corresponding mobile station position estimation
and comprises measurements of one or more one or more wireless
transmitter signals; computing, for each of the received fix
information records, a corresponding fix score; and determining,
based, at least in part, on the corresponding fix scores, whether
to store one or more fix information records.
2. The method of claim 1, further comprising storing the one or
more fix information records in a network database according to a
priority scheme for the fix information records, when a
determination to store the one or more fix information records is
made.
3. The method of claim 2, wherein the server comprises a network
database server communicatively coupled to a wireless network.
4. The method of claim 2, further comprising determining, based, at
least in part, on the corresponding fix scores, whether to transmit
the one or more stored fix information records to a second
plurality of mobile stations.
5. The method of claim 4, further comprising transmitting the one
or more stored fix information records according to the priority
scheme for the fix information records, when a determination to
transmit the one or more fix information records is made.
6. The method of claim 5, wherein the one or more stored fix
information records is transmitted in response to requests for
assistance data received at the server.
7. The method of claim 6, wherein, in response to each request for
assistance data and prior to transmitting the one or more stored
fix information records, the server specifies an amount of
information to be included in each received fix information
record.
8. The method of claim 6, wherein the requests for assistance data
and the responses to the requests for assistance data conform to
one or more wireless positioning protocols.
9. The method of claim 8, wherein the one or more wireless
positioning protocols are based on at least one of Long Term
Evolution (LTE), Code Division Multiple Access (CDMA), CDMA 2000,
or Wireless Local Area Network (WLAN) standards.
10. The method of claim 1, wherein the fix score is computed as a
function of an independence score, a need score, and a Horizontal
Estimated Position Error (HEPE) associated with a mobile station
position estimation corresponding to each fix information record,
wherein the independence score is a measure of reliability of a
transmitter providing the corresponding received fix information
record, and the need score is measure indicating the relative
desirability of retaining a fix information record.
11. A server, comprising: a communications interface to receive fix
information records associated with position estimations of a first
plurality of mobile stations, wherein each received fix information
record is associated with a corresponding mobile station position
estimation and comprises measurements of one or more one or more
wireless transmitter signals; and a processor coupled to the
communications interface, wherein the processor is configured to:
compute, for each of the received fix information records, a
corresponding fix score; and determine, based, at least in part, on
the corresponding fix scores, whether to store one or more fix
information records.
12. The server of claim 11, further comprising: storage coupled to
the processor, the storage comprising a network database, and
wherein the processor is further configured to: store the one or
more fix information records in the network database according to a
priority scheme for the fix information records, when a
determination to store the one or more fix information records is
made.
13. The server of claim 12, wherein the server further comprises a
network database server coupled to the network database and
communicatively coupled to a wireless network.
14. The server of claim 12, wherein the processor is further
configured to: determine, based, at least in part, on the
corresponding fix scores, whether to transmit the one or more
stored fix information records to a second plurality of mobile
stations.
15. The server of claim 14, wherein the processor is further
configured to: initiate the transmission of the one or more stored
fix information records according to the priority scheme for the
fix information records, when a determination to transmit the one
or more fix information records is made.
16. The server of claim 15, wherein the processor initiates the
transmission of the one or more stored fix information records in
response to requests for assistance data received at the
server.
17. The server of claim 16, wherein, prior to initiating the
transmission of the one or more stored fix information records, the
processor is configured to: specify, in response to each request
for assistance data, an amount of information to be included in
each received fix information record.
18. The server of claim 16, wherein the requests for assistance
data and the responses to the requests for assistance data conform
to one or more wireless positioning protocols.
19. The server of claim 18, wherein the one or more wireless
positioning protocols are based on at least one of Long Term
Evolution (LTE), Code Division Multiple Access (CDMA), CDMA 2000,
or Wireless Local Area Network (WLAN) standards.
20. The server of claim 11, wherein the processor is configured to:
compute the fix score as a function of an independence score, a
need score, and a Horizontal Estimated Position Error (HEPE)
associated with a mobile station position estimation corresponding
to each fix information record, wherein the independence score is a
measure of reliability of a transmitter providing the corresponding
received fix information record, and the need score is measure
indicating the relative desirability of retaining a fix information
record.
21. A server, comprising: communications interface means, the
communications interface means to receive fix information records
associated with position estimations of a first plurality of mobile
stations, wherein each received fix information record is
associated with a corresponding mobile station position estimation
and comprises measurements of one or more one or more wireless
transmitter signals; means for computing, for each of the received
fix information records, a corresponding fix score; and means for
determining, based, at least in part, on the corresponding fix
scores, whether to store one or more fix information records.
22. The server of claim 21, further comprising: storage means
coupled to the means for determining, the storage comprising a
network database, the storage means to store the one or more fix
information records in the network database according to a priority
scheme for the fix information records, when a determination to
store the one or more fix information records is made.
23. The server of claim 22, wherein the storage means comprises
network database server means, the network database server means
coupled to the network database and communicatively coupled to a
wireless network.
24. The server of claim 22, further comprising: means for
determining, based, at least in part, on the corresponding fix
scores, whether to transmit the one or more stored fix information
records to a second plurality of mobile stations.
25. The server of claim 24, further comprising: means for
initiating the transmission of the one or more stored fix
information records according to the priority scheme for the fix
information records, when a determination to transmit the one or
more fix information records is made.
26. The server of claim 25, wherein the means for initiating the
transmission of the one or more stored fix information records
initiates the transmission in response to requests for assistance
data received at the server.
27. The server of claim 26, further comprising: means for
specifying, prior to initiating the transmission of the one or more
stored fix information records, and in response to each request for
assistance data, an amount of information to be included in each
received fix information record.
28. The server of claim 26, wherein the requests for assistance
data and the responses to the requests for assistance data conform
to one or more wireless positioning protocols.
29. The server of claim 28, wherein the one or more wireless
positioning protocols are based on at least one of Long Term
Evolution (LTE), Code Division Multiple Access (CDMA), CDMA 2000,
or Wireless Local Area Network (WLAN) standards.
30. The server of claim 21, further comprising: means for computing
the fix score as a function of an independence score, a need score,
and a Horizontal Estimated Position Error (HEPE) associated with a
mobile station position estimation corresponding to each fix
information record, wherein the independence score is a measure of
reliability of a transmitter providing the corresponding received
fix information record, and the need score is measure indicating
the relative desirability of retaining a fix information
record.
31. A computer-readable medium comprising instructions, which, when
executed by a processor, perform a method comprising: receiving, at
a server, fix information records associated with position
estimations of a first plurality of mobile stations, wherein each
received fix information record is associated with a corresponding
mobile station position estimation and comprises measurements of
one or more one or more wireless transmitter signals; computing,
for each of the received fix information records, a corresponding
fix score; and determining, based, at least in part, on the
corresponding fix scores, whether to store one or more fix
information records.
32. The computer-readable medium of claim 31, further comprising
storing the one or more fix information records in a network
database according to a priority scheme for the fix information
records, when a determination to store the one or more fix
information records is made.
33. The computer-readable medium of claim 32, wherein the server
comprises a network database server communicatively coupled to a
wireless network.
34. The computer-readable medium of claim 32, further comprising
determining, based, at least in part, on the corresponding fix
scores, whether to transmit the one or more stored fix information
records to a second plurality of mobile stations.
35. The computer-readable medium of claim 34, further comprising
transmitting the one or more stored fix information records
according to the priority scheme for the fix information records,
when a determination to transmit the one or more fix information
records is made.
36. The computer-readable medium of claim 35, wherein the one or
more stored fix information records is transmitted in response to
requests for assistance data received at the server.
37. The computer-readable medium of claim 36, wherein, in response
to each request for assistance data and prior to transmitting the
one or more stored fix information records, the server specifies an
amount of information to be included in each received fix
information record.
38. The computer-readable medium of claim 36, wherein the requests
for assistance data and the responses to the requests for
assistance data conform to one or more wireless positioning
protocols.
39. The computer-readable medium of claim 38, wherein the one or
more wireless positioning protocols are based on at least one of
Long Term Evolution (LTE), Code Division Multiple Access (CDMA),
CDMA 2000, or Wireless Local Area Network (WLAN) standards.
40. The computer-readable medium of claim 31, wherein the fix score
is computed as a function of an independence score, a need score,
and a Horizontal Estimated Position Error (HEPE) associated with a
mobile station position estimation corresponding to each fix
information record, wherein the independence score is a measure of
reliability of a transmitter providing the corresponding received
fix information record, and the need score is measure indicating
the relative desirability of retaining a fix information
record.
41. A method, comprising: generating, at a mobile station (MS), one
or more fix information records, wherein each fix information
record is associated with a corresponding position estimation of
the MS and comprises measurements of one or more wireless
transmitter signals; compute a distinct score associated with each
fix information record in a subset of the generated fix information
records; and determining, based, at least in part, on the
corresponding fix scores, whether to transmit at least one fix
information record in the subset.
42. The method of claim 41, further comprising: transmitting at
least one fix information record in the subset into a network when
a determination to transmit the one or more fix information records
is made.
43. The method of claim 41, wherein the determination to transmit
the at least one fix information record in the subset is made,
based, in part, on a comparison of the distinct score of the at
least one fix information record with scores of stored fix
information records in the MS.
44. The method of claim 41, wherein the at least one fix
information record is transmitted as part of one or more wireless
positioning protocols.
45. The method of claim 44, wherein the one or more wireless
positioning protocols are based on at least one of Long Term
Evolution (LTE), Code Division Multiple Access (CDMA), CDMA 2000,
or Wireless Local Area Network (WLAN) standards.
46. The method of claim 41, wherein, an amount of information in
each transmitted fix information record is specified by a network
entity.
47. The method of claim 41, further comprising: determining, based,
at least in part, on the corresponding fix scores, whether to store
one or more fix information records in the subset on the MS.
48. The method of claim 47, further comprising: storing the one or
more fix information records in the subset on the MS according to a
priority scheme for the one or more fix information records, when a
determination to store the one or more fix information records in
the subset is made.
49. The method of claim 41, wherein the fix score is computed as a
function of an independence score, a need score, and a Horizontal
Estimated Position Error (HEPE) associated with a MS position
estimation corresponding to each fix information record, wherein
the independence score is a measure of reliability of a transmitter
providing the corresponding received fix information record, and
the need score is measure indicating the relative desirability of
retaining a fix information record.
50. The method of claim 40, wherein the wireless transmitter
signals comprise one or more of femtocell, Wi-Fi, Wi-Max,
Bluetooth, Satellite Positioning System (SPS), and cellular
transmitter signals.
51. A mobile station (MS), comprising: a receiver to receive one or
more wireless signals from one or more wireless transmitters; a
processor coupled to the receiver, wherein the processor is
configured to: generate one or more fix information records,
wherein each fix information record is associated with a
corresponding position estimation of the MS and comprises
measurements of one or more wireless transmitter signals; compute a
distinct score associated with each fix information record in a
subset of the generated fix information records; and determine,
based, at least in part, on the corresponding fix scores, whether
to transmit at least one fix information record in the subset.
52. The MS of claim 51, further comprising: a transmitter, a
transmitter coupled to the processor, the transmitter to transmit
at least one fix information record in the subset into a network
when a determination to transmit the one or more fix information
records is made.
53. The MS of claim 51, wherein the determination to transmit the
at least one fix information record in the subset is made, based,
in part, on a comparison of the distinct score of the at least one
fix information record with scores of stored fix information
records in the MS.
54. The MS of claim 51, wherein the transmitter transmits the at
least one fix information record as in conformance with one or more
wireless positioning protocols.
55. The MS of claim 54, wherein the one or more wireless
positioning protocols are based on at least one of Long Term
Evolution (LTE), Code Division Multiple Access (CDMA), CDMA 2000,
or Wireless Local Area Network (WLAN) standards.
56. The MS of claim 51, wherein, an amount of information in each
transmitted fix information record is specified by a network
entity.
57. The MS of claim 51, wherein the processor is further configured
to: determine, based, at least in part, on the corresponding fix
scores, whether to store one or more fix information records in the
subset.
58. The MS of claim 57, further comprising: a memory coupled to the
processor, wherein the processor is configured to store the one or
more fix information records in the subset in the memory according
to a priority scheme for the one or more fix information records,
when a determination to store the one or more fix information
records in the subset is made.
59. The MS of claim 51, wherein the processor is configured to
compute the fix score as a function of an independence score, a
need score, and a Horizontal Estimated Position Error (HEPE)
associated with a MS position estimation corresponding to each fix
information record, wherein the independence score is a measure of
reliability of a transmitter providing the corresponding received
fix information record, and the need score is measure indicating
the relative desirability of retaining a fix information
record.
60. The MS of claim 51, wherein the receiver is capable of
receiving wireless transmitter signals comprising one or more of
femtocell, Wi-Fi, Wi-Max, Bluetooth, Satellite Positioning System
(SPS), and cellular transmitter signals.
61. A mobile station (MS), comprising: receiving means for
receiving one or more wireless signals from one or more wireless
transmitters; means for generating one or more fix information
records coupled to the receiving means, wherein each generated fix
information record is associated with a corresponding position
estimation of the MS and comprises measurements of one or more
wireless transmitter signals; means for computing a distinct score
associated with each fix information record in a subset of the
generated fix information records; and means for determining,
based, at least in part, on the corresponding fix scores, whether
to transmit at least one fix information record in the subset.
62. The MS of claim 61, further comprising: transmitting means
coupled to the means for determining, the transmitting means to
transmit at least one fix information record in the subset into a
network when a determination to transmit the one or more fix
information records is made.
63. The MS of claim 61, wherein the determination to transmit the
at least one fix information record in the subset is made, based,
in part, on a comparison of the distinct score of the at least one
fix information record with scores of stored fix information
records in the MS.
64. The MS of claim 61, wherein the transmitting means transmits
the at least one fix information record as in conformance with one
or more wireless positioning protocols.
65. The MS of claim 64, wherein the one or more wireless
positioning protocols are based on at least one of Long Term
Evolution (LTE), Code Division Multiple Access (CDMA), CDMA 2000,
or Wireless Local Area Network (WLAN) standards.
66. The MS of claim 61, wherein, an amount of information in each
transmitted fix information record is specified by a network
entity.
67. The MS of claim 61, further comprising: means for determining,
based, at least in part, on the corresponding fix scores, whether
to store one or more fix information records in the subset.
68. The MS of claim 67, further comprising: storage means coupled
to the means for determining whether to store one or more fix
information records in the subset, the storage means to store the
one or more fix information records in the subset in the storage
means according to a priority scheme for the one or more fix
information records, when a determination to store the one or more
fix information records in the subset is made.
69. The MS of claim 61, wherein the processor is configured to
compute the fix score as a function of an independence score, a
need score, and a Horizontal Estimated Position Error (HEPE)
associated with a MS position estimation corresponding to each fix
information record, wherein the independence score is a measure of
reliability of a transmitter providing the corresponding received
fix information record, and the need score is measure indicating
the relative desirability of retaining a fix information
record.
70. The MS of claim 61, wherein the receiving means is capable of
receiving wireless transmitter signals comprising one or more of
femtocell, Wi-Fi, Wi-Max, Bluetooth, Satellite Positioning System
(SPS), and cellular transmitter signals.
71. A non-transitory computer-readable medium comprising
instructions, which when executed by a processor perform steps in a
method, the steps comprising: generating, at a mobile station (MS),
one or more fix information records, wherein each fix information
record is associated with a corresponding position estimation of
the MS and comprises measurements of one or more wireless
transmitter signals; compute a distinct score associated with each
fix information record in a subset of the generated fix information
records; and determining, based, at least in part, on the
corresponding fix scores, whether to transmit at least one fix
information record in the subset.
72. The computer-readable medium of claim 71, further comprising:
transmitting at least one fix information record in the subset into
a network when a determination to transmit the one or more fix
information records is made.
73. The computer-readable medium of claim 71, wherein the
determination to transmit the at least one fix information record
in the subset is made, based, in part, on a comparison of the
distinct score of the at least one fix information record with
scores of stored fix information records in the MS.
74. The computer-readable medium of claim 71, wherein the at least
one fix information record is transmitted as part of one or more
wireless positioning protocols.
75. The computer-readable medium of claim 74, wherein the one or
more wireless positioning protocols are based on at least one of
Long Term Evolution (LTE), Code Division Multiple Access (CDMA),
CDMA 2000, or Wireless Local Area Network (WLAN) standards.
76. The computer-readable medium of claim 71, wherein, an amount of
information in each transmitted fix information record is specified
by a network entity.
77. The computer-readable medium of claim 71, further comprising:
determining, based, at least in part, on the corresponding fix
scores, whether to store one or more fix information records in the
subset on the MS.
78. The computer-readable medium of claim 77, further comprising:
storing the one or more fix information records in the subset on
the MS according to a priority scheme for the one or more fix
information records, when a determination to store the one or more
fix information records in the subset is made.
79. The computer-readable medium of claim 71, wherein the fix score
is computed as a function of an independence score, a need score,
and a Horizontal Estimated Position Error (HEPE) associated with a
MS position estimation corresponding to each fix information
record, wherein the independence score is a measure of reliability
of a transmitter providing the corresponding received fix
information record, and the need score is measure indicating the
relative desirability of retaining a fix information record.
80. The computer-readable medium of claim 71, wherein the wireless
transmitter signals comprise one or more of femtocell, Wi-Fi,
Wi-Max, Bluetooth, Satellite Positioning System (SPS), and cellular
transmitter signals.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of and claims the benefit
of and priority under 35 U.S.C. .sctn.120 to co-pending U.S. patent
application Ser. No. 12/555,735 filed Sep. 8, 2009, entitled
"Position Estimation Assistance Information for Mobile Station,"
which is assigned to the assignee hereof and expressly incorporated
by reference herein in its entirety.
BACKGROUND
[0002] 1. Field
[0003] The subject matter disclosed herein relates to providing a
mobile station with assistance information related to estimating a
position for the mobile station.
[0004] 2. Information
[0005] The position of a mobile station, such as a cellular
telephone, may be estimated based on information gathered from
various systems. One such system may comprise a Global Navigation
Satellite System (GNSS), which is one example of a satellite
positioning system (SPS). SPS systems such as GNSS may comprise a
number of space vehicles (SV) orbiting the earth. Another example
of a system that may provide a basis for estimating the position of
a mobile station is a cellular communication system comprising a
number of terrestrial base stations to support communications for a
number of mobile stations. A further example of a system that may
provide a basis for estimating the position of a mobile station is
a wireless network compatible with the Institute of Electrical and
Electronics Engineers (IEEE) 802.11 wireless local access network
(WLAN) standard, which may also be referred to as a Wi-Fi network.
Such a network may include access points and sensors, for
example.
[0006] A position estimate, which may also be referred to as a
position "fix", for a mobile station may be obtained based at least
in part on distances or ranges measured from the mobile station to
one or more transmitters, and also based at least in part on
knowledge of the locations of the one or more transmitters. Such
transmitters may comprise SVs in the case of an SPS and/or
terrestrial base stations in the case of a cellular communications
system and/or Wi-Fi/802.11x transmitters or similar beacon
transmitters, for example.
[0007] An almanac may be maintained for systems used for position
estimation. The almanac may contain various types of information,
including, for example, information that may be used in position
estimation operations. Such information may include the identities
and locations of the various transmitters of the system, for
example.
SUMMARY
[0008] In an aspect, a mobile station may determine additional fix
information associated with an estimation of a position of the
mobile station, and the additional fix information may include one
or more measurements obtained from processing the one or more
received wireless signals. Signals representative of at least a
subset of the additional fix information may be transmitted into a
network. Further, one or more signals representative of updated
almanac information may be received from the network. The updated
almanac information may be based, at least in part, on the subset
of additional fix information.
BRIEF DESCRIPTION OF THE FIGURES
[0009] Non-limiting and non-exhaustive examples will be described
with reference to the following figures, wherein like reference
numerals refer to like parts throughout the various figures.
[0010] FIG. 1 is a schematic block diagram of an example global
navigation satellite system (GNSS) and an example cellular
network.
[0011] FIG. 2 is a schematic block diagram illustrating an example
mobile station.
[0012] FIG. 3 is an illustration depicting an example base station
almanac server in communication with a number of mobile stations
via one or more wireless communication networks.
[0013] FIG. 4 is a flow diagram of an example process for
estimating a position of a mobile station based at least in part on
information from a base station almanac.
[0014] FIG. 5 is a flow diagram of an example process for
estimating a plurality of positions of a mobile station and storing
information related to the position estimations in a memory in the
mobile station.
[0015] FIG. 6 is a flow diagram of an example process for
estimating a plurality of positions of a mobile station and storing
information related to the position estimations in a memory in the
mobile station and transmitting at least a subset of the
information to an assistance server.
[0016] FIG. 7 is an illustration of a building having a location in
an SPS coordinate system.
[0017] FIG. 8 is a diagram illustrating an example inertial
measurement unit with a plurality of degrees of freedom.
[0018] FIG. 9 is a flow diagram depicting an example process for
determining a position of an access point utilizing sensor
measurement information.
[0019] FIG. 10 is a flow diagram depicting an additional example
process for determining a position of an access point utilizing
sensor measurement information.
[0020] FIG. 11 is a schematic block diagram depicting an example
mobile station.
[0021] FIG. 12 is a schematic block diagram of an example computing
platform.
DETAILED DESCRIPTION
[0022] As discussed above, information organized in an almanac may
be used in performing position estimation operations for a mobile
station. A position estimate for a mobile station may be obtained
at least in part from distances or ranges from the mobile station
to one or more transmitters such as space vehicles (SV) and/or
terrestrial base stations at known locations. As mentioned
previously, an almanac may contain various types of information,
including, for example, identities and locations of the various
transmitters.
[0023] In another aspect, a mobile station may be provided with
information related to one or more SVs that may enhance a time to
first fix (TTFF) for the mobile station. For example, a mobile
station may be provided with predicted orbital information for a
number of SVs. In one particular implementation, such information
may help the mobile station to narrow search windows for acquiring
signals from one or more of the SVs, allowing quicker acquisition
of such signals, for example. Additionally, a mobile station may be
provided with timing information from an SPS to further enhance
position estimation performance.
[0024] In one aspect, a mobile station may receive orbital and
timing information from a network entity such as an assistance
server. A number of mobile stations may provide information related
to acquired signals from a variety of SVs and/or other beacon
transmitters identified with unique identifiers or other
characteristics to the assistance server, and the assistance server
or some other network entity may utilize the gathered information
to predict orbital patterns. These predictions may be broadcast to
one or more mobile stations for the mobile stations to use in
performing position estimation operations, often referred to as
position fixes. As used herein, the terms "position estimation
operation" and "position fix" are synonymous, and are used
interchangeably.
[0025] In another aspect, a plurality of mobile stations may gather
information related to wireless transmitters, which may be referred
to herein as "base stations", as the mobile stations perform
position fixes. Such information may be referred to as "fix
information" and may comprise measurement information related to
one or more signals received from one or more base stations and/or
utilized in obtaining a position fix. Fix information may also
comprise transmitter location information that may be broadcasted
by at least some base stations. Fix information may further
comprise information generated by one or more sensors of a mobile
station. A mobile station may store information related to a number
of position fixes, and such information may enhance the performance
of future position fix operations for that particular mobile
station. In an aspect, information gathered in the course of a
position fix may be referred to a position fix information, or more
simply as "fix information". Such fix information may be stored in
a memory of a mobile station in what may be referred to as a "fix
database" in which the fix information is organized and/or indexed
according to particular instances of position fixes. Fix
information may also be stored in a "cell database" in which fix
information may be organized and/or indexed according to particular
base stations observed and/or identified during position fix
operations. In one example implementation, a mobile station may
comprise one of a cell database and a fix database. In another
example implementation, a mobile station may comprise both a cell
database and a fix database. However, the scope of claimed subject
matter is not limited to any particular count or type of databases
capable of storing position fix information. Similarly, the scope
of claimed subject matter is not limited to any particular
organization and/or indexing of fix information.
[0026] In the course of operation of a mobile station, the mobile
station may interact with a number of cells, whether the cells are
actual serving cells or are non-serving cells. Signals received
from such serving and non-serving cells may be used, in some cases,
to perform position estimation operations, and measurement
information gleaned from these operations may be stored in a fix
database and/or a cell database for future reference in order to
enhance the performance of future position fixes. In another
aspect, some transmitters may broadcast their location, perhaps as
part of a beacon signal in some cases. Information related to the
positions of such transmitters may also be stored in fix databases
and/or cell databases in the same manner as information gleaned
from position estimation operations, even if the broadcasted
transmitter location information is not used as part of position
estimation operations. Also, as discussed previously, information
from fix and/or cell databases may, in another aspect, be shared
with other mobile stations so that such other mobile stations may
take advantage of the obtained information.
[0027] In another aspect, a user of a mobile station may elect to
allow the mobile station to transmit position fix information
and/or broadcasted transmitter location information from a cell
database and/or from a fix database to a central resource such as
an assistance server in order to share the position fix information
with other mobile stations. In return, in another aspect, the
mobile station may receive position fix information gathered by
other mobile stations. In an additional aspect, at least a portion
of the gathered position fix information may be delivered to the
mobile station in the format of a base station almanac, although
the scope of claimed subject matter is not limited in this respect.
In gathering position fix information, a number of mobile stations
may provide information related to signals acquired from a variety
of SVs and/or other stationary and mobile terrestrial beacon
transmitters that may be identified via unique identifiers and/or
characteristics. Further, as will be discussed below, fix
information from transmitters located within buildings may be
gathered by a number of mobile stations equipped with one or more
sensors in order to update and/or maintain a transmitter
information database such as a base station almanac, for
example.
[0028] As previously mentioned, information related to various
land-based transmitters of a wireless communication system may be
stored in what may be referred to as a base station almanac (BSA).
The term "base station almanac" as used herein is meant to include
any organized set of information related to a plurality of
transmitters of a wireless communication network. A base station
almanac may be stored in a memory of a computing platform, such as
an assistance server, for example, or in a memory of mobile
station, for another example. In another aspect, base station
almanac may be transmitted from an assistance server to one or more
mobile stations. In a further aspect, a subset of a BSA stored at
an assistance server may be transmitted to one or more mobile
stations, and may further be referred to as base station almanac
information. Such base station almanac information may comprise a
"sparse" base station almanac in one aspect, or may comprise a
regional base station almanac in another aspect. Of course, these
are merely examples of base station almanac information that may be
delivered from an assistance server to a mobile station, and the
scope of claimed subject matter is not limited in this respect.
Further, the scope of claimed subject matter is not limited to base
stations. Rather, example implementations may include any
transmitter of beacon signals that may be identified via unique
identifiers or other characteristics. In another aspect, a base
station almanac may be formed by gathering transmitter location
information that may be broadcasted by individual base stations.
Such an almanac may be updated as additional transmitter location
information is received at one or more mobile stations and the
mobile stations transmit such information to an assistance server
maintaining the BSA, in an example implementation. The assistance
server may aggregate transmitter location information received from
the various mobile stations, and may transmit an updated BSA to one
or more mobile stations, in an aspect.
[0029] In one aspect, a mobile station may use the received BSA
information to perform position estimation operations, for example
by trilateration using information and measurements from a number
of transmitters. The mobile station may also use the received BSA
information, in another aspect, to narrow a code phase search
window for acquiring signals transmitted by an SPS in order to
perform position estimation operations using, at least in part,
measurements from signals received from one or more space vehicles
(SV). For example, to narrow a search window, a mobile station may
use base station almanac information to associate an identification
of a sector currently serving the mobile station with a base
station almanac entry. The entry may provide a location of the
transmitter for the serving sector, from which an approximate
location (within a couple of kilometers, for example) of the mobile
station may be obtained.
[0030] Also, as previously mentioned, base station almanac
information may further include fix information gathered by a
number of mobile stations in performing position fix operations. An
assistance server, a data manager, or other network entity may
receive the position fix information gathered by the mobile
stations and may determine which of the fix information to include
in the base station almanac information to be delivered to a mobile
station.
[0031] FIG. 1 is a schematic block diagram of an SPS 110 and a
cellular network 120 in communication with a mobile station 200.
Cellular network 120, for this example, may provide voice
communication for a number of mobile stations including mobile
station 200, for example, and may further support position
estimation for the mobile stations in addition to providing voice
communication. Cellular network 120 may comprise any of a number of
cellular network types, several examples of which are described
below. Cellular network 120 for this example comprises base
stations 132, 134, and 136 that provide communication for a number
of wireless terminals such as, for example, mobile station 200. For
simplicity, only a few base stations 132, 134, and 136 are depicted
and one mobile station 200 is depicted in FIG. 1. Of course, other
examples may include additional numbers of base stations, and the
configuration of base stations depicted in FIG. 1 is merely an
example configuration. Also, cellular network 120 is merely an
example wireless communications system, and the scope of claimed
subject matter is not limited in this respect. Further, more than
one type of wireless network may be utilized in one or more example
wireless systems.
[0032] As used herein, the term "base station" is meant to include
any wireless communication station and/or device installed at a
fixed terrestrial location and/or movable and used to facilitate
communication in a wireless communications system, such as, for
example, a cellular network, although the scope of claimed subject
matter is not limited in this respect. In another aspect, base
stations may be included in any of a range of electronic device
types. In an aspect, a base station may comprise a wireless local
area network (WLAN) access point, for example. Such a WLAN may
comprise an IEEE 802.11x network in an aspect, although the scope
of claimed subject matter is not limited in this respect. WLAN
access points may be relatively small in size, and may be easily
moved by a user configuring a network. This is merely one example
of a base station that may change position from time to time, or
that may be mobile. It should be noted that the scope of claimed
subject matter is further not limited to stationary base stations,
but rather the scope of claimed subject matter may include any type
of wireless signal transmitter, whether stationary or mobile.
Further, in another aspect, position fix information may be
determined from any type of beacon signal, including signals from
visual technologies including cameras, information from sensors,
and Bluetooth wireless signals, to name but a few examples.
[0033] As used herein, the term "mobile station" (MS) refers to a
device that may from time to time have a position location that
changes. The changes in position location may comprise changes to
direction, distance, orientation, etc., as a few examples. In
particular examples, a mobile station may comprise a cellular
telephone, wireless communication device, user equipment, laptop
computer, other personal communication system (PCS) device,
personal digital assistant (PDA), personal audio device (PAD),
portable navigational device, and/or other portable communication
devices. A mobile station may also comprise a processor and/or
computing platform adapted to perform functions controlled by
machine-readable instructions.
[0034] In an aspect, SPS 110 may comprise a number of SVs, for
example SVs 112, 114, and 116. For an example, SPS 110 may comprise
one or more satellite positioning systems, such as GPS, GLONASS and
Galileo, or any other present or future GNSS, although the scope of
claimed subject matter is not limited in this respect. In one or
more aspects, mobile station 200 may receive signals from SVs 112,
114, and 116, and may communicate with one or more of base stations
132, 134, and 136. For example, mobile station 200 may obtain one
or more measurements from one or more signals received from one or
more of the SVs and/or base stations. However, in some
circumstances timing signals from an SPS may not be available. In
such a circumstance, mobile station 200 may gather propagation
delay information through communication with one or more of base
stations 132, 134, and/or 136. Mobile station 200 may calculate a
position fix for the mobile station based, at least in part, on
timing calibration parameters received through communication with
one or more of base stations 132, 134, and/or 136, and further
based, at least in part, on known position locations of the base
stations. The mobile station may also make use of an estimated
propagation delay for signals received from a base station source,
a satellite source, or both.
[0035] In another aspect, position location determination
calculations may be performed by a network entity such as, for
example, location server 170 depicted in FIG. 1, rather than at
mobile station 200. Such a calculation may be based, at least in
part, on information gathered by mobile station 200 from one or
more of base stations 132, 134, and/or 136. In a further aspect,
location server 170 may transmit the calculated position location
to mobile station 200.
[0036] A mobile switching center (MSC) 140 for this example may be
coupled to base stations 132, 134, and 136, and may further couple
to other systems and networks, such as a public switched telephone
network (PSTN), a packet data serving node (PDSN) 160, and so on.
MSC 140 for this example provides coordination and control for the
base stations coupled to it and further controls the routing of
data to/from the mobile stations served by these base stations. For
the example depicted in FIG. 1, PDSN 160 may couple MSC 140 to
location server 170 and to a BSA database server 180. Location
server 170 may collect and format location data, may provide
assistance to mobile stations for position estimation, and/or may
perform computations to obtain position estimates for the mobile
stations. BSA database server 180 manages a BSA database 185, which
for this example stores a base station almanac for cellular network
110.
[0037] In one aspect, base station server 180 may provide BSA
information to mobile station 200. Information to be included in
the BSA provided to mobile station 200 may be a subset of BSA
database 185 selected based at least in part upon any of a number
of parameters. Of course, the amount of information provided to a
mobile station may be limited due to storage capacity issues of the
mobile station. In an aspect, base station almanac information
delivered to mobile station 200 may comprise a sparse base station
almanac, although the scope of claimed subject matter is not
limited in this respect.
[0038] By nature, a base station almanac such as BSA 185 may
contain information that does not often change. However, in one
aspect, cellular network 120 for this example may alert mobile
station 200 that revised BSA information is available in the event
cellular network 120 is modified in a way that warrants alerting
the mobile station. Mobile station 200 may request revised BSA
information at least in part in response to receiving such an alert
from BSA database server 180. In one aspect, additional and/or new
fix database information may be made available by way of the base
station almanac, and the availability of such information may
trigger, in one example, an alert to the mobile stations that
revised BSA information is available.
[0039] FIG. 2 is a schematic block diagram of an example
implementation of mobile station 200. In an aspect, mobile station
200 comprises an SPS receiver 210 and a cellular communication
receiver 220. Thus, mobile station 200 may communicate both with
one or more SPS such as SPS 110 and one or more terrestrial
wireless networks, such as cellular network 120. In another aspect,
mobile station 200 may further comprise a memory device that is
partitioned, in one example, to store position fix information in a
fix database memory 230 and to store base station almanac
information in a base station almanac storage area 240. In
addition, for this example, the memory of mobile station 200 may be
partitioned to store a cell database 250. In a further aspect,
mobile station 200 may comprise one or more sensors that for this
example are incorporated into Inertial Measurement Unit (IMU) 270.
Mobile station 200 further comprises processor 260, for this
example. Of course, this is merely one example of a configuration
of a mobile station, and the scope of claimed subject matter is not
limited in this respect.
[0040] In one example, a mobile station such as mobile station 200
may estimate its position based, at least in part, on timing
information received from an SPS, and also based, at least in part,
on signals received from SVs, such as satellites. In particular,
such a device and/or system may obtain "pseudorange" measurements
comprising approximations of distances between associated
satellites and a navigation satellite receiver. To estimate its
position, a mobile station such as mobile station 200 may obtain
pseudorange measurements to three or more satellites based upon
transmissions from the satellites, as well as based on positions of
the satellites at time of transmitting. A satellite's position at a
point in time may be calculated based, at least in part, on the
satellite's known or estimated orbital parameters. Mobile station
200 in another aspect may perform dead reckoning navigation
operations based on sensor data to track the position of mobile
station 200 in circumstances where mobile station 200 is not able
to receive transmissions from SVs to perform position fixes.
[0041] Just as knowing an SV's orbital parameters and the SPS'
timing information may allow a mobile station to estimate its
position location, having accurate information, such as, for
example, accurate position information, regarding base stations may
also allow the mobile station to more quickly and accurately
estimate its position. In an aspect, a mobile station may estimate
its location based, at least in part, on signal propagation delay
information gathered through communications with one or more base
stations in a wireless network and further based, at least in part,
on known position locations of the one or more base stations. As
used herein, the term "propagation delay information" is meant to
include any information related to propagation times for signals,
such as between a mobile station and a base station. Such
information may comprise round trip delay estimates, for example.
Such information may further comprise, for another example,
information related to an observed time difference of arrival for
signals between different base stations and the mobile station, for
example. For another example, such propagation delay information
may comprise information related to downlink timing adjustments.
However, these are merely examples of propagation delay information
types, and the scope of claimed subject matter is not limited in
these respects.
[0042] Further, as used herein, the term "known position location"
as it relates to base stations in a wireless network is meant to
include any information that may identify physical locations of the
base stations. In one implementation, such known position location
information for one or more base stations may be stored in a
position determination entity in a wireless network, and/or may be
stored in any of a wide range of other resources in the wireless
network, as more fully described below. For an additional example,
known position location information for one or more base stations
may be stored in a mobile station. Further, for an example, known
position location may comprise longitude and latitude, and may for
another example comprise altitude information. However, these are
merely examples of known position location, and the scope of
claimed subject matter is not limited in this respect. In another
aspect, some base stations may broadcast their locations, and such
location information may be stored in one or more databases in the
mobile station. Such base station location information may be
shared with other network entities, such as an assistance server,
for example. Further, in another aspect, the accuracy of the
broadcasted location information for any particular base station
may not be known. Techniques for estimating a location for the
transmitting base station may be utilized to check the
trustworthiness of the broadcasted information. For example, if a
number of estimated locations for the base station are determined
by a number of mobile stations, and the estimated locations largely
correlate with the broadcasted location, the broadcasted location
may be considered to be accurate.
[0043] FIG. 3 is an illustration depicting an example assistance
server 350 in communication with a number of mobile stations 320,
labeled as mobile stations 322 and 324, via one or more wireless
communication networks 332 and 334 and via Internet 340. For this
example, mobile station 322 represents a multi-mode device capable
of supporting communication with both a packet-switched wireless
local area network (WLAN) 332 and a cellular network 334. Of
course, these are merely examples of the types of wireless
communications networks with which a multimode device may
communicate, and the scope of claimed subject matter is not limited
in this respect. Also for this example, mobile station 324
represents a single-mode device capable of supporting communication
with cellular network 334. Again, the cellular network is merely
one example of a wireless communication network with which a mobile
station may establish communication.
[0044] FIG. 3 further depicts a number of transmitter types 310
that mobile stations 322 and 324 may monitor. Mobile stations 322
and 324 may or may not be subscribed to any given network
associated with the various respective transmitter types 310 to be
able to monitor signals transmitted from the various transmitter
types 310. Therefore, BSA information provided to the mobile
stations may or may not include information associated with
networks to which the mobile stations are not subscribed. As
mentioned previously, a mobile station may receive SPS orbital
and/or timing information, and may further receive position fix
information gathered from a number of other mobile stations. As
previously mentioned, such position fix information gathered from a
number of mobile stations may be combined and included in a base
station almanac 355 by a network entity such as, for example, an
assistance server 350 and/or a data manager 360.
[0045] The information in base station almanac 355 may comprise
measurements and/or other information obtained from signals
received from various base stations at one or more mobile stations
such as mobile stations 322 and 324 during position fix operations.
As previously mentioned, such position fix information may be
stored in either a cell database or a fix database in a memory of a
mobile station. In one or more example implementations, a mobile
station may comprise both a cell database and a fix database,
although the scope of claimed subject matter is not limited in this
respect.
[0046] A fix database, for example, may comprise a number of
entries, wherein the individual entries correspond to individual
position fix operations performed by a mobile station at a point in
time at a location. As is explained in more detail below, fix
database entries may be assigned a fix score that may be used in
determining which information to transmit to a mobile station or
for a mobile station to determine whether to discard an entry of
the fix database. In another aspect, a fix database may incorporate
a first-in, first out priority scheme for storing fix database
entries. For the first-in, first-out priority scheme, information
from more recent position fixes are assigned priorities higher than
for information from less recent position fixes. Of course, the
first-in, first-out priority scheme is merely an example priority
scheme, and the scope of claimed subject matter is not limited in
this respect.
[0047] A cell database, for one example, may comprise a number of
entries, wherein the individual entries correspond to individual
base station transmitters and/or cells from which one or more
signals are received by a mobile station in the course of
performing position fix operations. Any of a number of techniques
may be utilized in determining which information to store in the
cell database and in determining which information to discard in
the event that a maximum size for the cell database is reached. In
one example, more recent entries may be given higher priority than
less recent entries, although the scope of claimed subject matter
is not limited in this respect.
[0048] For the example of FIG. 3, mobile stations 322 and 324 may
request BSA information comprising at least a subset of a BSA
database from assistance server 350. Mobile stations 322 and 324
may also receive fix information as part of the BSA information
from assistance server 350. Assistance server 350 may further
receive position fix information from cell and/or fix databases in
mobile stations 322 and 324, wherein the information from the cell
and/or fix databases are generated by mobile stations 322 and 324
in performing position fix operations. In another aspect, data
manager 360 may periodically, or at some other regular or
non-regular time period, consolidate information from various
current network almanacs with mobile station-generated cell and/or
fix databases. Also, data manager 360 may transmit consolidated fix
information to assistance server 350. Data manager 360 may further
provide updates to assistance server 350 with respect to fix
information so that assistance server 350 can update base station
almanacs intended for various mobile stations, and may make a
determination as to whether the changes received from data manager
360 warrant a transmission of a new version of the databases.
However, this is merely an example of how a data manager may
interact with an assistance server, and the scope of claimed
subject matter is not limited in this respect.
[0049] In another aspect, assistance server 350 may receive local
cell and/or fix databases from mobile stations such as mobile
stations 322 and 324. Assistance server 350 may pass the
information received from the mobile stations to data manager 360.
As previously mentioned, in an aspect, data manager 360 may
consolidate information received from a variety of sources. For
example, a number of mobile stations may store position fix
information in their respective cell and/or fix databases, and may
gather such information over a period of time. Data manager 360 may
receive and combine this information from a number of sources to
make adjustments according to confidence factors supplied with the
fix information, in one example aspect. Types of position fix
information that may be provided to assistance server 350 from
mobile stations may include, but are not limited to, phase and/or
timing relationships, measures of signal strength, residual errors
from the mobile station's position, and/or clock bias estimates, to
list but a few examples. Such information may come from data
already available from the wireless modem for communications
purposes, such as the information found in an IS-2000 Pilot
Strength Measurement Message or messages with similar purposes for
Universal Mobile Telecommunications System (UMTS) or Global System
for Mobile communications (GSM) networks, for example. In another
aspect, data manager 360 may implement algorithms to derive more
accurate position fixes and to reduce uncertainty for cell
information in a base station almanac.
[0050] Although FIG. 3 depicts a single assistance server 350,
other example implementations are possible where separate upload
and download servers are utilized. Also, in an aspect, data files
for base station almanac information to be delivered to mobile
stations may be separate in one example implementation from the
files of SPS orbital information provided to mobile stations. In an
alternate example implementation, base station almanac information
and SPS orbital information may be provided to mobile stations as a
combined data file, although the scope of claimed subject matter is
not limited in this respect. Also, in an example, base station
almanac information may be encrypted for transmission to the mobile
stations to prevent unauthorized access to the information.
Further, in another aspect, the uploading of fix information from
mobile stations to assistance server 350 may be accomplished
anonymously, so that a user can not be associated with the data
included in the fix database. In an additional aspect, mobile
stations that incorporate communication functions for WLAN networks
such as Wi-Fi/802.11x may provide fix information to an assistance
server and/or may receive information from the assistance server
via the mobile station's data connectivity over the WLAN.
[0051] Although the example of FIG. 3 depicts two mobile stations,
in practice a wide variety of mobile station types exhibiting a
wide range of different functionalities and/or storage capabilities
may be utilized to communicate with a large variety of potential
network types. Further, the mobile stations may exhibit a wide
range of different usage patterns. Therefore, it may be
advantageous for BSA database server 350 to provide individualized
subsets of BSA information that the individual mobile stations may
require and/or request, and it may be further advantageous to
provide such information formatted in a flexible manner according
to a specified file size, coverage area, and/or transmitter type,
to name but a few examples of parameters that may be specified. In
one aspect, these parameters may be specified by the mobile
stations.
[0052] In another aspect, once a mobile station has uploaded its
fix and/or cell database to assistance server 350 and/or to data
manager 360, the fix and/or cell database storage may be cleared,
allowing the mobile station to begin collecting fix information
anew, although the scope of claimed subject matter is not limited
in this respect. Also, any of a wide range of air interfaces may be
supported by the techniques described herein. For example,
supported air interfaces may include, but are not limited to,
Universal Mobile Telecommunications System (UMTS), Global System
for Mobile communications (GSM), WiFi, lx, Evolution Data-Optimized
(EVDO), and Long Term Evolution (LTE). Mobile television air
interfaces may also be supported, including but not limited to
MFLO, Digital Video Broadcasting-Handheld (DVB-H), Terrestrial
Digital Multimedia Broadcast (TDMB), Satellite Digital Multimedia
Broadcasting (SDMB), etc. Similarly, the techniques described
herein may utilized with Bluetooth systems, Terrestrial TV, FM and
local transaction and/or payment sources. However, these are merely
example communications systems that may be utilized with the
example techniques described herein, and the scope of claimed
subject matter is not limited in these respects.
[0053] For yet another example, the determination of whether to
include information for a given group of transmitters in the base
station almanac information to be provided to a mobile station may
be made conditionally, based at least in part on an availability of
storage space in the receiving mobile station. In one example,
position fix information provided to mobile stations may comprise a
file of about 50 kB, although the scope of claimed subject matter
is not limited in this respect.
[0054] In some examples described herein, a mobile station such as
mobile station 322 is described as requesting BSA information from
an assistance server such as server 350. In response to receiving
the request from mobile station 322, assistance server 350 may
configure the appropriate information and deliver it to the mobile
station. However, there may be a number of variations to these
examples, in that there may be various techniques to communicate
base station almanac information to mobile station 322. In some
cases, the technique used may depend at least in part on the type
of air interface. In some air interfaces, the transmitting entity
may also be able to store and forward its own BSA information or
that of its neighbors. For example, referring to FIG. 1, base
station 132 may store BSA information, and may forward at least a
portion of that BSA information to mobile station 200 upon
receiving a request from mobile station 200. Base station 132 may
compress and/or encrypt the information in an aspect. In another
aspect, base station 132 may authenticate mobile station 200 before
granting the mobile station's request for BSA information.
[0055] In an additional aspect, a mobile station may be expected to
report a specified amount of information to an assistance server,
for example, in exchange for more complete base station almanac
information. Position fix information gathered and reported by the
mobile station may comprise a series of locations along with
respective location uncertainties, and may further comprise
attributes of base stations observed and/or determined by the
mobile station from those locations. Such observed and/or
determined attributes might include base station identification
information, for example, as well as position information, signal
frequency, relative and/or absolute signal strength, color coding,
slot timing, and/or any other pertinent information that may help
the assistance server or other network entity to map the coverage
area of the individual transmitters. The attributes may further
include code phase for individual transmitters, and/or timing
relationships between some standard timing source (such as SPS
time) and the framing structure of one or more received signals.
This information may be stored in a database internal to the mobile
device. The database may be organized to store a list of positions
and their associated measurements or it may be organized as an
almanac of statistics for known transmitters and their respective
identifiers, positions, and/or service areas.
[0056] FIG. 4 is a flow diagram illustrating an example process for
estimating a position of a mobile station based, at least in part,
on enhanced base station almanac information. At block 410, a base
station almanac may be received at a mobile station from a base
station almanac server via a wireless communication network. At
block 420, the received base station almanac may be stored in a
memory of the mobile station. At block 430, the base station
almanac stored in the mobile station may be enhanced with
information gleaned from signals received at the mobile station
from one or more base stations. As described above according to
particular implementations, the stored base station almanac may be
enhanced by adding information related to one or more position fix
operations. In an aspect, information from one or more signals
received at the mobile station from one or more base stations may
be stored in a cell database and/or in a fix database. In one
example, information stored in the cell database and/or fix
database may be combined with or added to the base station almanac
information at the mobile station to generate enhanced base station
almanac information. At block 440, a location of the mobile station
may be estimated based, at least in part, on information from the
base station almanac, including the enhanced information. Other
examples in accordance with claimed subject matter may include all,
less than, or more than blocks 410-440. Further, the order of
blocks 410-440 is merely an example order, and the scope of claimed
subject matter is not limited in this respect.
[0057] FIG. 5 is a flow diagram depicting an example process for
sharing enhanced base station almanac information. At block 510,
position fix information may be received from a plurality of mobile
stations. As discussed above, such position fix information may be
stored in fix databases or in cell databases in the memories of the
mobile stations. In some cases, a mobile station may include both a
fix database and a cell database. At block 520, the position fix
information received from the plurality of mobile stations may be
combined. The combined information may be utilized in generating a
base station almanac. The inclusion of the position fix information
received from the plurality of mobile stations may allow a network
entity such as an assistance server to generate an enhanced base
station almanac, in that the base station almanac may be more
complete and/or more accurate. At block 530, at least a subset of
the base station almanac may be transmitted to one or more mobile
stations. In one example implementation, in order for a mobile
station to receive the enhanced base station almanac information,
the mobile station may be requested to provide position fix
information. In this manner, position fix information gathered from
a number of mobile stations may be shared with a number of other
mobile stations. As mentioned, in one example implementation, the
gathered information may be shared as part of a base station
almanac. Of course, examples in accordance with claimed subject
matter may include all, less than, or more than blocks 510-530.
Further, the order of blocks 510-530 is merely an example order,
and the scope of claimed subject matter is not limited in this
respect.
[0058] FIG. 6 is an additional flow diagram. For this example, the
flow diagram illustrates an example process for estimating a
position of a mobile station and sharing fix information. At block
610, one or more wireless signals may be received at a mobile
station from one or more base stations. For the present example,
the mobile station may comprise a mobile station such as mobile
station 200 depicted in FIG. 2, although the scope of claimed
subject matter is not limited in this respect. At block 620, one or
more measurements may be obtained from the one or more wireless
signals received from the one or more base stations at block 610.
At block 630, a position of the mobile station may be estimated at
least in part on the one or more measurements obtained from the one
or more received wireless signals. Such a position estimate may be
further based, at least in part, on base station almanac
information received from an assistance server. The base station
almanac information may be stored in a memory of the mobile
station. At block 640, additional fix information associated with
the position estimate of the mobile station may be determined. In
an aspect, the determined additional fix information may comprise
the one or more measurements obtained from the respective one or
more received wireless signals. In another aspect, the additional
fix information may comprise one or more attributes related to the
one or more base stations observed during the position fix
described above. For example, the additional fix information may
comprise phase and/or timing relationships, measures of signal
strength, residual errors from the mobile's position and/or clock
bias estimates, to list a few example types of information. At
block 650, the additional fix information may be stored in the
memory of the mobile station. In an aspect, the additional fix
information may be stored in a cell database in the memory of the
mobile station. In another aspect, the additional fix information
may be stored in a fix database in the memory of the mobile
station. In some cases, a mobile station may store both a cell
database and a fix database in its memory, although the scope of
claimed subject matter is not limited in this respect. As noted
above, a cell database may comprise fix information organized
and/or indexed according to particular base stations observed
and/or identified during position fix operations. A fix database
may comprise fix information that may be organized and/or indexed
according to particular instances of position fixes. However, these
are merely examples of how position fix information may be
organized and/or indexed in a memory of a mobile station, and the
scope of claimed subject matter is not limited in this respect.
[0059] In another aspect, a priority scheme may be used to
determine whether to store the additional fix information, for
example in situations where a maximum database size has been
reached and where one or more database entries would need to be
removed from the database in order to accommodate the additional
information. For one example priority scheme, fix information
related to more recent position fixes may be given a higher
priority than fix information related to less recent position
fixes. In such a case, the additional fix information determined at
block 640 would be stored in the fix and/or cell database, and if a
maximum database size would be exceeded with the inclusion of the
additional fix information, fix information related to the least
recent position fix represented in the database may be removed to
make room for the additional fix information. Of course, this is
merely an example priority scheme, and the scope of claimed subject
matter is not limited in this respect. At block 660, signals
representative of at least a subset of the additional fix
information may be transmitted to an assistance server. In an
aspect, an entire cell and/or fix database may be transmitted from
the mobile device to the assistance server. In other examples,
subsets of the information stored in the fix and/or cell database
may be transmitted. Examples in accordance with claimed subject
matter may include all, less than, or more than blocks 610-660.
Further, the order of blocks 610-660 is merely an example order,
and the scope of claimed subject matter is not limited in this
respect.
[0060] As previously mentioned, as a mobile station obtains
measurement information from wireless signals encountered from
various transmitters, and/or as broadcasted transmitter locations
are received from various transmitters, decisions may be made to
decide which information to add to a fix database and/or a cell
database that may have a specified maximum size due to limited
storage capacity. For example, it may be advantageous to keep the
size of a fix database at 50 kB or less, in one example
implementation. Of course, this is merely an example storage
capacity, and the scope of claimed subject matter is not limited in
this respect. Of course, the size of the fix database and/or cell
database may vary from implementation to implementation, as various
mobile stations may vary in their capabilities and/or requirements.
In one example implementation, a fix database may be at least large
enough to hold information related to at least 256 fixes. In
another aspect, a maximum number of fixes may also be specified.
For example, a fix database may have a maximum of 1000 fixes, in
one example implementation. Alternatively, as previously alluded
to, the maximum may be expressed as a maximum file size, such as
the previous example of 50 kB.
[0061] In another aspect, if a mobile station periodically receives
predicted orbital information for an SPS system, base station
almanac information may also be delivered at approximately the same
time. In another aspect, the SPS information and the base station
almanac information may comprise the same data file, although the
scope of claimed subject matter is not limited in this respect.
Possible advantages of integrating the SPS and base station almanac
information downloads into a single download may be seen in terms
of reducing the number of connection setups that may be required as
well as centralizing the symbiotic relationship between uploads and
downloads.
[0062] As previously mentioned, a priority scheme may be utilized
to determine which fix information to store in a fix database in
the event of limited storage capacity for the fix database. The
limited storage capacity may be based, in one example, on a
specified maximum file size. In another example, limited storage
capacity may be due to a finite size of a memory device in a mobile
station. In an aspect, fix information related to horizontal
estimated position error (HEPE) may be relatively valuable
information, as a fix with a lower error estimate may be given more
weight than one with a higher error estimate, and therefore may be
assigned a higher priority. Another type of possibly valuable fix
information may comprise the number of transmitters of interest
observed during a position fix operation. It may be more efficient
to provide fix information for large numbers of transmitters
referenced to a single position. Furthermore, in an
interference-limited system, those fixes with a greater number of
terrestrial measurements are likely to be closer to the edge of a
transmitter's coverage area, thus helping to more effectively
define the limits of a transmitter's service area.
[0063] In a further aspect, a higher weight in the priority scheme
may be given to new transmitters, meaning transmitters for which
little or no information is currently available. For example, if a
mobile station has stored in its memory base station almanac
information that does not include information related to a base
station observed by the mobile station in the course of performing
a position fix for the mobile station, the mobile station may
assign a high priority to storing information related to this base
station so that an assistance server or other network entity may
incorporate information gleaned from the base station in a future
version of a base station almanac. Similarly, relatively high
weight may also be given to transmitters whose almanac information
is not considered to be reliable, or where a confidence factor is
below a threshold level. On the other hand, transmitters whose
almanac information is considered to be reliable and/or accurately
reported may be given a low priority in the priority scheme, since
it may be less important to gather information related to
transmitters whose almanac information is already accurately
recorded. However, it is possible for almanac information to
change, or for transmitter characteristics to change. Therefore, it
may still be of value to gather information for such transmitters,
although at a lower priority, for the present example.
[0064] For one example of a priority scheme for determining which
fix information to store in a fix database, measurements related to
particular position fixes may be assigned an "independence score".
For measurements related to transmitters with highly accurate or
reliable base station almanac information available such as, for
example, an antenna location for a transmitter that is believed to
be accurate within a specified margin of error, the independence
score may be assigned a value of 0 for this example. If accurate or
reliable almanac information is not available for the transmitter
from which the measurements originate, the independence score for
an associated measurement may be given according to the
following:
Independence Score=(.DELTA..sub.P/MAR)*(.DELTA..sub.T/10 min)
(1)
wherein .DELTA..sub.P comprises a smaller of a distance to a prior
position fix and a distance to a following position fix, and
wherein .DELTA..sub.T comprises a shortest time between the fix
associated with the additional fix information and the neighboring
fixes. Of course, equation (1) is merely an example of how an
independence score may be calculated, and the scope of claimed
subject matter is not limited in this respect. In an aspect, a goal
of the scoring techniques described herein may be to select a
subset of fixes that may provide an independent view, both in time
and in space, of the network. Therefore, the scoring technique may
be useful in selecting the least independent fixes for removal from
the list or database to make room for a new, more independent fix.
In another example, the independence score may be calculated to
maximize either temporal or spatial diversity. In one aspect, the
emphasis may be shifted to give one of the two elements of temporal
and spatial diversity more weight than the other. It may also be
desirable, in a further aspect, to utilize different independence
scoring techniques for different radio access types, or as an
adaptation for different networks.
[0065] In a further aspect, and continuing the present example
priority scheme, a "need score" is also determined for the fix
measurements. This example scoring mechanism may be utilized to
quantify the relative need for keeping one fix over another, based
at least in part upon a current state of a base station almanac
entry for a given measurement. The need score for this example may
be based on the origins of the base station almanac, and/or a
confidence in the almanac information. For the present example, if
the base station almanac is provided by a trusted source, the need
score for the particular fix measurement is assigned the integer
value of 0. If a base station almanac entry associated with the
transmitter that is the subject of the fix measurement under
consideration is understood with relatively great statistical
significance, the need score is assigned an integer value of 1, for
this example. In the event the base station almanac information
indicates a known coverage area, but more information is desired,
the need score is assigned the integer value of 2. On the other
hand, if the base station almanac information is labeled as
unreliable or is absent altogether, the need score is assigned a
value of 10.
[0066] For the present example, independence scores and need scores
may be utilized to generate a fix score for particular entries of
the fix database, and for any potential new addition to the fix
database. In one aspect, the fix score may be calculated as
follows:
Fix Score=sum(Independence Scores for all measurements associated
with a particular fix)*sum(Need scores for all measurements
associated with a particular fix)/HEPE (2)
where HEPE is the horizontal estimated position error associated
with the particular fix.
[0067] In another aspect, a fix score for a potential addition to
the fix database may be compared with fix scores for entries
already included in the fix database. In one example, if any of the
fix scores in the fix database are lower than a fix score for
candidate fix information entry, the candidate fix information
entry may be added to the fix database and the database entry with
the lowest fix score may be discarded. In another aspect, if a fix
information entry is removed from a fix database to make room for a
new fix information entry, the neighboring fix information entries
of the removed fix information entry are linked and their fix
scores may be recalculated. For one or more embodiments, fixes that
are neighbors in time, or perhaps space, would have their fix
scores updated. Further, as used herein, the term "linked" as it
applies to fix information entries herein may imply an association
between fixes, perhaps as in a linked list or a neighbor list which
might be kept for each sector, for one example embodiment. However,
it should be noted that the priority scheme described above is
merely an example, and the scope of claimed subject matter is not
limited in this respect. Other example implementations may use
other schemes for determining which fix information to include in a
fix database.
[0068] As previously mentioned, base station almanac information
may be incomplete, in that the base station almanac may not have
information related to the identity and/or location of at least
some transmitters. Also, even if information for all transmitters
is gathered at a point in time, many of such transmitters may not
remain stationary, and much of the base station almanac information
may become inaccurate and/or stale. One example situation of where
a base station almanac may be more likely to lack accurate
information is where a relatively large number of access points are
located in the interior of one or more buildings. Such access
points may be associated with WLAN networks, for example, although
the scope of claimed subject matter is not limited in this respect.
The large number of such access points may make it more difficult
to gather identity and location information for those access
points. Also, inside of a building, mobile stations may not receive
SPS signals. Therefore, position location operations that utilize
SPS signals may not be possible, making it more difficult to
determine a position of an access point once such an access point
is identified by a mobile station.
[0069] Because many access points may be located inside buildings
where SPS service may not be available, alternative techniques for
performing position fixes and for determining locations of access
points encountered by a mobile station may be advantageous. For one
or more example techniques, an altitude for an access point may be
determined along with latitude and longitude. Determining an
altitude for an access point may allow the access point to be
associated with a particular floor of the building in which the
access point resides. Such information may prove useful, for
example, in emergency situations where first responders may utilize
the information to locate fires and/or other emergency conditions
on particular floors. Of course, floor information may be useful in
a number of other ways, including aiding information technology
personnel to locate particular access points when maintaining a
network. Further, such altitude information may further help make
future position fixes for mobile stations more accurate.
[0070] FIG. 7 is an illustration of a building 710 having a
location 714 in an SPS coordinate system. For this example,
building 710 has an estimated location of (42.88, -71.55, 321),
presented as latitude and longitude GPS coordinates and an
elevation with respect to sea level, which may be referred to as
altitude. Although the elevation element of the location is
mentioned as referenced to sea level, other elevation references
are possible, and the scope of claimed subject matter is not
limited in this respect. In this example, the elevation is
represented as meters above sea level, but again, the scope of
claimed subject matter is not so limited. Also depicted in FIG. 7
is mobile station 200. If mobile station 200 is located outside of
building 710, for example, it may be able to receive SPS signals
from an SPS system, such as system 110, depicted in FIG. 1, and
mobile station 200 may calculate its estimated position based at
least in part on the SPS signals in combination with information
provided by location server 170, for example. However, if a user
carries mobile station 200 into building 710, SPS signals may not
be available. In such a situation, mobile station 200 may perform
dead reckoning navigation operations in an effort to track
movements of the mobile station and to continually, or at least
periodically update the mobile station's estimated location based
on the measured movements. In an aspect, the estimated position of
mobile station 200 may include an elevation component, and the dead
reckoning navigation operations may attempt to track changes in
elevation. Dead reckoning navigation operations may comprise
tracking displacements in latitude, longitude, and altitude from a
reference position, in an aspect. As is discussed more fully below,
latitude, longitude, and altitude displacement tracking operations
may be used to help estimate a location for an access point located
in a building where no SPS signals are available.
[0071] In an aspect, assume that a user carries mobile station 200
into building 710, and that the user rides an elevator from the
ground floor to the second floor. Mobile station 200 may perform
dead reckoning calculations to estimate a change in elevation
experienced as mobile station 200 moved from the ground floor to
the second floor. Such measurements may incur cumulative errors.
However, if the distance between two floors of building 710 is
known, one may adjust the estimated change in elevation calculated
by mobile station 200 to compensate for the accumulated errors. For
the present example, the vertical distance between floors of
building 710 is labeled in FIG. 7 by Floor Separation 712. Of
course, in other examples the distance between two floors of a
building may not be known, and the dead reckoning navigation
operations may be performed without the benefit of knowing the
distance between two floors.
[0072] In one or more aspects, mobile station 200 may determine an
estimated initial position. Such a position may be the last
position determined with the aid of SPS signals before mobile
station 200 enters building 710. Upon losing reception of the SPS
signals, mobile station 200 may commence dead reckoning
calculations and may make relatively frequent adjustments to the
estimated location based at least in part on the dead reckoning
operations, in one example implementation. Also, as previously
mentioned and as explained in more detail below, displacement
tracking for latitude, longitude, and altitude may be initiated at
a reference position, which for some example implementations may
not be the last known position determined with the help of SPS
signals. For example, in one or more examples that will be
described below, displacement tracking operations may utilize a
location within building 710 from which mobile station 200 observes
an access point as a reference. In such a situation, latitude,
longitude, and altitude displacement information may be reset to
zero, and mobile station 200 may commence displacement tracking
operations from that spot. Mobile station may utilize the tracked
displacement information to calculate an estimated position for the
access point at least in part in response to mobile station 200
gaining access to SPS signals so that a relatively accurate
position fix may be performed for mobile station 200.
[0073] In order to perform displacement tracking operations or dead
reckoning navigation operations, mobile station 200 may comprise
one or more sensors. In one or more example implementations, the
one or more sensors may be incorporated into an inertial
measurement unit such as IMU 270, although the scope of claimed
subject matter is not limited in this respect.
[0074] The one or more sensor incorporated into mobile station 200,
whether packaged in an IMU or whether implemented as separate
components, may comprise any of a range of sensor types. A variety
of sensors may be available to support a number of applications.
These sensors may convert physical phenomena into analog and/or
electrical signals. Such sensors may include, for example, an
accelerometer. An accelerometer may sense the direction of gravity
and any other force experienced by the sensor. The accelerometer
may be used to sense linear and/or angular movement, and may also
be used, for example, to measure tilt and/or roll. Yet another
sensor type may include a gyroscope which measures the Coriolis
effect and may be used in applications measuring heading changes or
in measuring rate of rotation.
[0075] Another sensor type may include a barometric pressure
sensor. A barometric pressure sensor may be used to measure
atmospheric pressure. Applications for the barometric pressure
sensor may include determining altitude. Other applications may
include observing atmospheric pressure as it relates to weather
conditions.
[0076] Another type of sensor may include a magnetic field sensor
that may measure the strength of a magnetic field and,
correspondingly, the direction of a magnetic field. A compass is an
example of a magnetic field sensor. The compass may find use in
determining absolute heading in car and pedestrian navigation
applications.
[0077] FIG. 8 is a diagram illustrating example IMU 270 with a
plurality of degrees of freedom. As noted above, in navigation
applications, accelerometers, gyroscopes, geomagnetic sensors, and
pressure sensors may be utilized to provide various degrees of
observability. In an aspect, IMU 270 may comprise at least one
accelerometer and at least one gyroscope, although the scope of
claimed subject matter is not limited in this respect. For one
example, and as depicted in FIG. 8, the accelerometer and gyroscope
may provide six axes of observability (i, j, k, .theta., .phi.,
.psi.). As mentioned above, the accelerometer may sense linear
motion (translation in any plane, such as a local horizontal
plane). This translation may be measured with reference to at least
one axis. The accelerometer may also provide a measure of an
object's tilt (roll or pitch). Thus, with the accelerometer, an
object's motion in Cartesian coordinate space (i, j, k) may be
sensed, and the direction of gravity may be sensed to estimate an
object's roll and pitch. The gyroscope may be used to measure the
rate of rotation about (i, j, k), i.e., roll (.theta.) and pitch
(.phi.) and yaw, which may also be referred to as azimuth or
"heading" (.psi.). Of course, IMU 270 merely represents on example,
and the various degrees of observability are also merely examples.
The scope of claimed subject matter is not limited to these
specific examples. Also, IMU 270 may comprise a relatively accurate
measurement unit with a relatively high cost, or may comprise a
less accurate measurement unit that may provide cost savings and
perhaps smaller, simpler designs. The scope of claimed subject
matter is not limited to any particular sensors and/or IMU, and a
range of levels of accuracy for the sensors and/or IMU may be
specified for a range of possible implementations in accordance
with claimed subject matter.
[0078] In one example implementation of a technique for determining
position information for an access point within a building where no
SPS signals are available to help with position fix operations, a
mobile station equipped with one or more sensors may be utilized.
Such sensors may comprise, for example, an accelerometer and/or a
gyroscope, to name merely two examples. The mobile station may
track latitude, longitude, and altitude displacement information to
and/or from a reference point such as a spot with the building
where the mobile station observes the access point. The mobile
station may utilize the displacement information to estimate a
position for the access point based at least in part on a position
fix performed with the aid of SPS signals or performed in some
other manner that may provide the mobile station with a relatively
accurate position fix. Base station almanac information may be
updated with the estimated position of the access point so that in
the future, the identity and position of the access point may be
utilized by other mobile stations to perform position fix
operations. Without relatively accurate position information for
the access point, position fix operations for a mobile station may
not be successfully completed. In another aspect, in order to
increase the accuracy of the position estimate for the access
point, an individual mobile station may calculate a number of
estimated positions for the access point as the mobile station
revisits the area of the access point. Further, a number of mobile
stations may perform one or more position estimates for the access
point in the manner described herein, and the various estimates may
be used to calculate a more accurate estimate. In another aspect,
individual mobile stations may utilize the more accurate position
estimate to determine a bias in the mobile station's sensors so
that future tracking operations may provide more accurate
displacement values.
[0079] As discussed previously, position fix information may be
gathered by a number of mobile stations, and such information may
be provided to a network. The network may utilize the gathered
information to update base station almanac information, and at
least a portion of such updated information may be provided to one
or more mobile stations to enable the mobile stations to perform
more efficient and accurate position fixes. In an aspect, the
gathered position fix information may include access point
estimated location information determined through the use of
sensors and displacement tracking as described herein. In this
manner, the large numbers of access points that are located within
buildings where SPS signals and/or other signals may not be
available for position fix operations may be identified and their
estimated locations included in base station almanac information
provided to mobile stations from the network. Sensor systems,
including discrete sensors and/or IMUs, used in displacement
tracking operations in an aspect need not be highly accurate in at
least some example implementations since information from a number
of mobile stations may be collectively utilized to estimate a
position of an access point and to update the base station almanac
database. Also, a number of estimates may be performed by an
individual mobile station, and the various estimates may be used to
determine a more accurate estimate and also to determine a bias for
the sensors so that future tracking operations may yield more
accurate displacement values. Less accurate sensor systems may have
the potential advantages of lower cost and smaller, simpler
designs. Base station almanac databases that may be updated and/or
maintained through the example techniques described herein may
include, but are not limited to, cellular network databases and
Wi-Fi/WLAN network databases. Of course, the scope of claimed
subject matter is not limited in this respect, and the example
processes described herein may be utilized to update and/or
maintain databases related to any type of transmitter for any type
of wireless network.
[0080] In an aspect, if a mobile phone attempts to perform a
position fix using a Wi-Fi/WLAN network and observes an access
point that is not included in a Wi-Fi/WLAN network database, the
mobile station may attempt to update the Wi-Fi/WLAN network
database with that access point's identification and mobile
station's current location. However, if the mobile station tries to
use the Wi-Fi/WLAN network for a position fix in a location where
there is no SPS coverage and if the Wi-Fi/WLAN network database
does not include a record for the observed access point, the
position fix using the Wi-Fi/WLAN network will fail to give the
mobile station its current location, and the position fix operation
initiated by the mobile station will fail. However, if the
Wi-Fi/WLAN network database is updated with a record mapping this
access point and its estimated position, future attempts to use the
Wi-Fi/WLAN network to perform position fixes for mobile stations at
this location will result in successful position fixes. FIGS. 9 and
10 depict example processes for updating a Wi-Fi/WLAN network
database and/or another base station almanac database with missing
or outdated access point identification and position information in
situations where the mobile station may be in an area without SPS
coverage and/or without other means to perform relatively accurate
position fixes.
[0081] FIG. 9 depicts an example process for estimating a position
of an access point in a building where SPS signals may not be
available to a mobile station. At block 905, a mobile station may
observe a WLAN/Wi-Fi access point. That is, the mobile station may
receive a beacon signal from the access point. The mobile station
may identify the access point via the beacon signal, and may
determine whether base station almanac information is available for
the access point. If no geographic information related to the
access point is included in the base station almanac database, or
if the database includes information related to the access point
with a lesser degree of confidence that the information is
sufficiently accurate, the mobile station may store the access
point identification information as depicted at block 910, and the
process may proceed to block 915. At block 915, the mobile station
may initiate a sensor subsystem with displacement values of zero
for latitude, longitude, and altitude. Thus, the mobile station may
track its movements from the location at which the access point was
observed by the mobile station and the current position of the
mobile station may serve as the reference point for the
displacement tracking operations. The tracking of the movements of
the mobile station may be accomplished using one or more sensors
incorporated into the mobile station. Information with respect to
the accumulated displacements in latitude, longitude, and altitude
may be stored in a memory in the mobile station and may be
continually updated as the mobile station moves within the
building. For example, at block 920 a determination may be made
based on sensor data as to whether the mobile station has moved
from mobile stations last position, which initially is the location
at which the mobile station observed the access point. As depicted
at block 920, if movement of the mobile station is detected, the
process proceeds to block 925. At block 925, a determination may be
made as to whether the mobile station moved closer to the access
point. The determination of whether the mobile station has moved
closer to the access point may be made, in one aspect, by observing
the signal strengths for signals received from the access point.
For example, if a beacon signal from the access point received by
the mobile station at its current position is determined to have a
greater signal strength than a beacon signal received by the mobile
station at the current access point observation position at an
earlier point in time, the access point may be assumed to have
moved closer to the access point. If it is indeed determined that
the mobile station has moved closer to the access point, the
process returns to block 915 where the displacement values are
reset to zero, and the current location of the mobile station acts
as the new access point observation position. The closer the mobile
station is to the access point at the beginning of the tracking
operations, the more accurate the end result will be for the
estimated position of the access point.
[0082] Continuing with the example process depicted in FIG. 9, if
at block 925 it is determined that the mobile station has not moved
closer to the access point, the latitude, longitude, and altitude
displacement is tracked from the access point observation position,
also referred to as the reference position. At block 935, a
determination may be made as to whether the mobile station has
entered an area with SPS coverage. For example, the mobile station
may be carried outside of the building or to an area of the
building where SPS signals may be received. If there is no SPS
coverage at the current position of the mobile station, the process
returns to block 920 where the determination is made again as to
whether the mobile station has moved from its last position. If so,
the determination is made again at block 925 as to whether the
mobile station has moved closer to the access point.
[0083] For the period of time in which the mobile station does not
move closer to the access point and in which there is no SPS
coverage, the process cycles through blocks 920, 925, 930, and 935.
Of course, for the present example process, if the mobile station
is determined to have moved closer to the access point than the
current access point observation position, the process returns to
block 915 wherein the latitude, longitude, and altitude
displacement tracking operations begin anew, with the displacement
values being nulled or cleared to values of zero. At some point in
time, the mobile station may have access to an SPS system, for
example if the mobile station exits the building, and the mobile
station may perform a position fix utilizing SPS signals, as
depicted at blocks 935 and 940. At block 940, the SPS position fix
may be performed for the mobile station, and the tracked
displacement values for latitude, longitude, and altitude from the
access point observation position may be utilized to calculate an
estimated position for the access point. In an aspect, the
latitude, longitude, and altitude displacement values may be
subtracted from the latitude, longitude, and altitude values from
the SPS position fix for the mobile station. The calculated
position for the access point may be used to update a base station
almanac database. In another aspect, the base station almanac may
further be updated with the access point identification information
previously stored in memory in the mobile station. The scope of
claimed subject matter may include all of, less than, or more than
boxes 905-945 depicted in FIG. 9. Also, the order of boxes of
905-945 is merely an example order, and the scope of claimed
subject matter is not limited in this respect.
[0084] FIG. 10 depicts an additional example process for estimating
a position of an access point in a building where SPS signals may
not be available to a mobile station. For this example process, a
reference point may be established by performing a position fix,
perhaps using SPS signals or other technique for providing a
relatively accurate position fix. In response to the position fix
and the establishment of the reference position, the mobile station
may track the latitude, longitude, and altitude displacements from
the reference point until the mobile station observes an access
point. In response to the observation of the access point, the
tracked latitude, longitude, and altitude displacement values may
be utilized to calculate an estimated position for the access
point.
[0085] With respect to the example process depicted in FIG. 10, a
position fix may be performed by a mobile station at block 1005. In
an aspect, the position fix may comprise a relatively accurate
position fix. In another aspect, the position fix may be based, at
least in part, on one or more signals received from an SPS system.
At block 1010, the result of the position fix operation from block
1005 may be stored in a memory in the mobile station. The position
fix may be referred to as the last known successful position fix
for this example process. At block 1015, the mobile station may
initiate a sensor subsystem within the mobile station with
displacement values of zero for latitude, longitude, and altitude.
Thus, the mobile station may track its movements from the location
indicated by the last known successful position fix. The last known
successful position fix location may serve as the reference point
for the displacement tracking operations. The tracking of the
movements of the mobile station may be accomplished using one or
more sensors incorporated into the mobile station. Information with
respect to the accumulated displacements in latitude, longitude,
and altitude may be stored in a memory in the mobile station and
may be continually updated as the mobile station moves within the
building. For example, at block 1020 a determination may be made
based on sensor data as to whether the mobile station has moved
from mobile station's last position, which initially is the
location indicated by the last known successful position fix. If
movement of the mobile station is detected, the process moves to
block 1025.
[0086] At block 1025, a determination may be made as to whether the
mobile station has gained the ability to perform a position fix.
For example, the mobile station may have moved to a location where
SPS signals may be received. If it is determined that the mobile
station has the ability to perform a position fix, the process
moves back to block 1005. As indicated at block 1005, a new
position fix is obtained for the mobile station, and the new
position fix is stored as the last known successful position fix at
block 1010. As depicted at block 1015, the last known successful
position fix location is used as the reference position for the
displacement operations that begin anew, with the latitude,
longitude and altitude displacement values being nulled or cleared
to a value of zero. If at block 1025 it is determined that the
mobile station is not capable of performing a position fix, the
process moves to block 1030 where the latitude, longitude, and
altitude displacement tracking operations are depicted.
[0087] In an aspect of the present example process, the operations
of blocks 1020, 1025, 1030, and 1035 may be repeated in a cycle
that may be broken either by the mobile station gaining the ability
to perform a position fix at block 1025 or the mobile station
observing an access point with either no geographical mapping
information in the base station almanac database or with
geographical mapping information with a lesser degree of confidence
of sufficient accuracy in the base station almanac database, as
depicted at block 1035. If an access point is observed by the
mobile station, the tracked latitude, longitude, and altitude
displacements may be utilized to calculate an estimated position of
the access point. For example, the displacement values may be added
to the position coordinates for the last known successful position
fix to obtain the estimated position of the access point. Of
course, the closer the mobile station is to the access point when
the tracking operations are ceased, the more accurate the estimated
position for the access point will be.
[0088] At least in part in response to calculating the estimated
position for the observed access point, a database may be updated
at block 1045 with the calculated position of the access point. The
database may further be updated with identification information for
the access point. The scope of claimed subject matter may include
all of, less than, or more than boxes 1005-1045 depicted in FIG.
10. Also, the order of boxes of 1005-1045 is merely an example
order, and the scope of claimed subject matter is not limited in
this respect.
[0089] In another aspect, in order to obtain a relatively accurate
position estimate for the access point, the access point may be
observed by the mobile station at multiple locations. The mobile
station may determine which of the observation locations is likely
to be closest to the access point, and may obtain estimated
positions for the individual observation locations. At least in
part in response to the mobile station determining which
information from which observation point is likely to provide the
most accurate result, the mobile station may transmit the position
fix information to a network entity and the database may be
updated. By waiting until the mobile station has found an
observation point that seems to be closest to the transmitter,
multiple write operations to the database may be avoided.
[0090] In another aspect, rather than updating the appropriate
database in response to an estimation of a position of an access
point from a single mobile station, a network entity, perhaps a
database server such as BSA database server 180 depicted in FIG. 1,
may gather several samples for that particular access point, and
after receiving a selectable number of position estimations for the
access point, the database server may determine position
information with which to update the database. In one aspect, the
server may average the position estimates, or may use a weighted
average of the various position estimates, with more recent
position estimates receiving more weight than estimates received
earlier. In another aspect, the server may simply select a position
estimate for the access point that appears to be the more accurate,
based on any of a range of criteria.
[0091] In another aspect, mobile stations implemented with SPS
position fix capabilities and sensor-based displacement tracking
capabilities may provide advantages related to database efficiency.
For example, accurate position fixes performed using SPS signals
may be combined with latitude, longitude, and altitude displacement
tracking information provided at least in part by sensors of a
mobile station to provide position fixes for the mobile station in
areas where no SPS signals are available. For this example, no
Wi-Fi access point signals are utilized to perform the position
fix. Therefore, in an example implementation, it may not be
necessary to gather and store information related to Wi-Fi access
points in a base station almanac, because such information would
not be required by mobile stations supporting SPS/sensor position
fix operations in order to perform such operations. By eliminating
or reducing the amount of information related to Wi-Fi access
points gathered for a base station almanac, for example, the effort
involved in creating the almanac is reduced, along with the size of
the almanac. Of course, these are merely examples of how sensor
data may be used advantageously in conjunction with position fix
operations, and the scope of claimed subject matter is not limited
in these respects.
[0092] FIG. 11 is a block diagram illustrating another example of
mobile station 1100 that may be adapted to perform any of the
example techniques described herein in connection with FIGS. 1-10.
One or more radio transceivers 1170 may be adapted to modulate an
RF carrier signal with baseband information, such as voice or data,
onto an RF carrier, and demodulate a modulated RF carrier to obtain
such baseband information. An antenna 1172 may be adapted to
transmit a modulated RF carrier over a wireless communications link
and receive a modulated RF carrier over a wireless communications
link.
[0093] A baseband processor 1160 may be adapted to provide baseband
information from a central processing unit (CPU) 1120 to
transceiver 1170 for transmission over a wireless communications
link. Here, CPU 1120 may obtain such baseband information from an
input device within a user interface 1110. Baseband processor 1160
may also be adapted to provide baseband information from
transceiver 1170 to CPU 1120 for transmission through an output
device within user interface 1110.
[0094] In another aspect, for this example implementation, mobile
station 1100 may comprise an inertial measurement unit (IMU) 1190.
IMU 1190 may comprise one or more sensors. Example types of sensors
that may be incorporated into IMU 1190 include, but are not limited
to, an accelerator and a gyroscope, although claimed subject matter
is not limited in this respect.
[0095] User interface 1110 may comprise a plurality of devices for
inputting or outputting user information such as voice or data.
Such devices may include, by way of non-limiting examples, a
keyboard, a display screen, a microphone, and a speaker.
[0096] A receiver 1180 may be adapted to receive and demodulate
transmissions from an SPS, and provide demodulated information to
correlator 1140. Correlator 1140 may be adapted to derive
correlation functions from the information provided by receiver
1180. Correlator 1140 may also be adapted to derive pilot-related
correlation functions from information relating to pilot signals
provided by transceiver 1170. This information may be used by a
mobile station to acquire wireless communications services. Channel
decoder 1150 may be adapted to decode channel symbols received from
baseband processor 1160 into underlying source bits. In one example
where channel symbols comprise convolutionally encoded symbols,
such a channel decoder may comprise a Viterbi decoder. In a second
example, where channel symbols comprise serial or parallel
concatenations of convolutional codes, channel decoder 1150 may
comprise a turbo decoder.
[0097] A memory 1130 may be adapted to store machine-readable
instructions which are executable to perform one or more of
processes, implementations, or examples thereof which are described
or suggested herein. CPU 1120 may be adapted to access and execute
such machine-readable instructions. Memory 1130 for this example
may also be adapted to store one or more of a fix database, a cell
database, or base station almanac information.
[0098] FIG. 12 is a schematic diagram illustrating an example
computing and communications environment 1200 that may include one
or more devices configurable to implement techniques and/or
processes described above, for example, in connection with example
techniques for requesting and transmitting BSA information and/or
fix and cell database information depicted in FIGS. 1-10. System
1200 may include, for example, a first device 1202, a second device
1204, and a third device 1206, which may be operatively coupled
together through a network 1208.
[0099] First device 1202, second device 1204 and third device 1206,
as shown in FIG. 12, may be representative of any device, appliance
or machine that may be configurable to exchange data over wireless
communications network 1208. By way of example but not limitation,
any of first device 1202, second device 1204, or third device 1206
may include: one or more computing devices and/or platforms, such
as, e.g., a desktop computer, a laptop computer, a workstation, a
server device, or the like; one or more personal computing or
communication devices or appliances, such as, e.g., a personal
digital assistant, mobile communication device, or the like; a
computing system and/or associated service provider capability,
such as, e.g., a database or data storage service provider/system,
a network service provider/system, an Internet or intranet service
provider/system, a portal and/or search engine service
provider/system, a wireless communication service provider/system;
and/or any combination thereof. Any of the first, second, and third
devices 1202, 1204, and 1206, respectively, may comprise one or
more of a base station almanac database server, a base station,
and/or a mobile station in accordance with the examples described
herein.
[0100] Similarly, network 1208, as shown in FIG. 12, is
representative of one or more communication links, processes,
and/or resources configurable to support the exchange of data
between at least two of first device 1202, second device 1204, and
third device 1206. By way of example but not limitation, network
1208 may include wireless and/or wired communication links,
telephone or telecommunications systems, data buses or channels,
optical fibers, terrestrial or space vehicle resources, local area
networks, wide area networks, intranets, the Internet, routers or
switches, and the like, or any combination thereof. As illustrated,
for example, by the dashed lined box illustrated as being partially
obscured of third device 1206, there may be additional like devices
operatively coupled to network 1208.
[0101] It is recognized that all or part of the various devices and
networks shown in system 1200, and the processes and methods as
further described herein, may be implemented using or otherwise
including hardware, firmware, software, or any combination
thereof.
[0102] Thus, by way of example but not limitation, second device
1204 may include at least one processing unit 1220 that is
operatively coupled to a memory 1222 through a bus 1228.
[0103] Processing unit 1220 is representative of one or more
circuits configurable to perform at least a portion of a data
computing procedure or process. By way of example but not
limitation, processing unit 1220 may include one or more
processors, controllers, microprocessors, microcontrollers,
application specific integrated circuits, digital signal
processors, programmable logic devices, field programmable gate
arrays, and the like, or any combination thereof.
[0104] Memory 1222 is representative of any data storage mechanism.
Memory 1222 may include, for example, a primary memory 1224 and/or
a secondary memory 1226. Primary memory 1224 may include, for
example, a random access memory, read only memory, etc. While
illustrated in this example as being separate from processing unit
1220, it should be understood that all or part of primary memory
1224 may be provided within or otherwise co-located/coupled with
processing unit 1220.
[0105] Secondary memory 1226 may include, for example, the same or
similar type of memory as primary memory and/or one or more data
storage devices or systems, such as, for example, a disk drive, an
optical disc drive, a tape drive, a solid state memory drive, etc.
In certain implementations, secondary memory 1226 may be
operatively receptive of, or otherwise configurable to couple to, a
computer-readable medium 1240. Computer-readable medium 1240 may
include, for example, any medium that can carry and/or make
accessible data, code and/or instructions for one or more of the
devices in system 1200. Computer readable medium 1240 may also be
referred to as a storage medium.
[0106] Second device 1204 may include, for example, a communication
interface 1230 that provides for or otherwise supports the
operative coupling of second device 1204 to at least network 1208.
By way of example but not limitation, communication interface 1230
may include a network interface device or card, a modem, a router,
a switch, a transceiver, and the like.
[0107] Second device 1204 may include, for example, an input/output
1232. Input/output 1232 is representative of one or more devices or
features that may be configurable to accept or otherwise introduce
human and/or machine inputs, and/or one or more devices or features
that may be configurable to deliver or otherwise provide for human
and/or machine outputs. By way of example but not limitation,
input/output device 1232 may include an operatively configured
display, speaker, keyboard, mouse, trackball, touch screen, data
port, etc.
[0108] The methodologies described herein may be implemented by
various means depending upon applications according to particular
examples. For example, such methodologies may be implemented in
hardware, firmware, software, and/or combinations thereof. In a
hardware implementation, for example, a processing unit may be
implemented within one or more application specific integrated
circuits (ASICs), digital signal processors (DSPs), digital signal
processing devices (DSPDs), programmable logic devices (PLDs),
field programmable gate arrays (FPGAs), processors, controllers,
micro-controllers, microprocessors, electronic devices, other
devices units designed to perform the functions described herein,
and/or combinations thereof.
[0109] "Instructions" as referred to herein relate to expressions
which represent one or more logical operations. For example,
instructions may be "machine-readable" by being interpretable by a
machine for executing one or more operations on one or more data
objects. However, this is merely an example of instructions and
claimed subject matter is not limited in this respect. In another
example, instructions as referred to herein may relate to encoded
commands which are executable by a processing circuit having a
command set which includes the encoded commands. Such an
instruction may be encoded in the form of a machine language
understood by the processing circuit. Again, these are merely
examples of an instruction and claimed subject matter is not
limited in this respect.
[0110] "Storage medium" as referred to herein relates to media
capable of maintaining expressions which are perceivable by one or
more machines. For example, a storage medium may comprise one or
more storage devices for storing machine-readable instructions
and/or information. Such storage devices may comprise any one of
several media types including, for example, magnetic, optical or
semiconductor storage media. Such storage devices may also comprise
any type of long term, short term, volatile or non-volatile memory
devices. However, these are merely examples of a storage medium,
and claimed subject matter is not limited in these respects.
[0111] Some portions of the detailed description included herein
are presented in terms of algorithms or symbolic representations of
operations on binary digital signals stored within a memory of a
specific apparatus or special purpose computing device or platform.
In the context of this particular specification, the term specific
apparatus or the like includes a general purpose computer once it
is programmed to perform particular operations pursuant to
instructions from program software. Algorithmic descriptions or
symbolic representations are examples of techniques used by those
of ordinary skill in the signal processing or related arts to
convey the substance of their work to others skilled in the art. An
algorithm is here, and generally, is considered to be a
self-consistent sequence of operations or similar signal processing
leading to a desired result. In this context, operations or
processing involve physical manipulation of physical quantities.
Typically, although not necessarily, such quantities may take the
form of electrical or magnetic signals capable of being stored,
transferred, combined, compared or otherwise manipulated. It has
proven convenient at times, principally for reasons of common
usage, to refer to such signals as bits, data, values, elements,
symbols, characters, terms, numbers, numerals, or the like. It
should be understood, however, that all of these or similar terms
are to be associated with appropriate physical quantities and are
merely convenient labels. Unless specifically stated otherwise, as
apparent from the following discussion, it is appreciated that
throughout this specification discussions utilizing terms such as
"processing," "computing," "calculating," "determining" or the like
refer to actions or processes of a specific apparatus, such as a
special purpose computer or a similar special purpose electronic
computing device. In the context of this specification, therefore,
a special purpose computer or a similar special purpose electronic
computing device is capable of manipulating or transforming
signals, typically represented as physical electronic or magnetic
quantities within memories, registers, or other information storage
devices, transmission devices, or display devices of the special
purpose computer or similar special purpose electronic computing
device.
[0112] Wireless communication techniques described herein may be in
connection with various wireless communication networks such as a
wireless wide area network (WWAN), a wireless local area network
(WLAN), a wireless personal area network (WPAN), and so on. The
term "network" and "system" may be used interchangeably herein. A
WWAN may be a Code Division Multiple Access (CDMA) network, a Time
Division Multiple Access (TDMA) network, a Frequency Division
Multiple Access (FDMA) network, an Orthogonal Frequency Division
Multiple Access (OFDMA) network, a Single-Carrier Frequency
Division Multiple Access (SC-FDMA) network, or any combination of
the above networks, and so on. A CDMA network may implement one or
more radio access technologies (RATs) such as cdma2000,
Wideband-CDMA (W-CDMA), to name just a few radio technologies.
Here, cdma2000 may include technologies implemented according to
IS-95, IS-2000, and IS-856 standards. A TDMA network may implement
Global System for Mobile Communications (GSM), Digital Advanced
Mobile Phone System (D-AMPS), or some other RAT. GSM and W-CDMA are
described in documents from a consortium named "3rd Generation
Partnership Project" (3GPP). Cdma2000 is described in documents
from a consortium named "3rd Generation Partnership Project 2"
(3GPP2). 3GPP and 3GPP2 documents are publicly available. A WLAN
may comprise an IEEE 802.11x network, and a WPAN may comprise a
Bluetooth network, an IEEE 802.15x, for example. Wireless
communication implementations described herein may also be used in
connection with any combination of WWAN, WLAN and/or WPAN.
[0113] Techniques described herein may be used with any one or more
of several SPS, including the aforementioned SPS, for example.
Furthermore, such techniques may be used with positioning
determination systems that utilize pseudolites or a combination of
satellites and pseudolites. Pseudolites may comprise ground-based
transmitters that broadcast a PRN code or other ranging code (e.g.,
similar to a GPS or CDMA cellular signal) modulated on an L-band
(or other frequency) carrier signal, which may be synchronized with
GPS time. Such a transmitter may be assigned a unique PRN code so
as to permit identification by a remote receiver. Pseudolites may
be useful in situations where SPS signals from an orbiting
satellite might be unavailable, such as in tunnels, mines,
buildings, urban canyons or other enclosed areas. Another
implementation of pseudolites is known as radio-beacons. The term
"satellite", as used herein, is intended to include pseudolites,
equivalents of pseudolites, and possibly others. The term "SPS
signals", as used herein, is intended to include SPS-like signals
from pseudolites or equivalents of pseudolites.
[0114] The terms, "and," "and/or," and "or" as used herein may
include a variety of meanings that will depend at least in part
upon the context in which it is used. Typically, "and/or" as well
as "or" if used to associate a list, such as A, B or C, is intended
to mean A, B, and C, here used in the inclusive sense, as well as
A, B or C, here used in the exclusive sense. Reference throughout
this specification to "one example" or "an example" means that a
particular feature, structure, or characteristic described in
connection with the example is included in at least one example of
claimed subject matter. Thus, the appearances of the phrase "in one
example" or "an example" in various places throughout this
specification are not necessarily all referring to the same
example. Furthermore, the particular features, structures, or
characteristics may be combined in one or more examples. Examples
described herein may include machines, devices, engines, or
apparatuses that operate using digital signals. Such signals may
comprise electronic signals, optical signals, electromagnetic
signals, or any form of energy that provides information between
locations.
[0115] While there has been illustrated and described what are
presently considered to be example features, it will be understood
by those skilled in the art that various other modifications may be
made, and equivalents may be substituted, without departing from
claimed subject matter. Additionally, many modifications may be
made to adapt a particular situation to the teachings of claimed
subject matter without departing from the central concept described
herein. Therefore, it is intended that claimed subject matter not
be limited to the particular examples disclosed, but that such
claimed subject matter may also include all aspects falling within
the scope of the appended claims, and equivalents thereof.
* * * * *