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Patent 2884732 Summary

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Claims and Abstract availability

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(12) Patent Application: (11) CA 2884732
(54) English Title: TIME AND POWER BASED WIRELESS LOCATION AND METHOD OF SELECTING LOCATION ESTIMATE SOLUTION
(54) French Title: LOCALISATION SANS FIL BASEE SUR TEMPS ET PUISSANCE ET PROCEDE DE SELECTION DE SOLUTION D'ESTIMATION DE LOCALISATION
Status: Dead
Bibliographic Data
(51) International Patent Classification (IPC):
  • G01S 5/02 (2010.01)
  • H04W 24/00 (2009.01)
  • H04W 64/00 (2009.01)
  • H04B 17/327 (2015.01)
(72) Inventors :
  • SOMA, PITCHAIAH (United States of America)
  • BOYER, PETE A. (United States of America)
  • MIA, RASHIDUS S. (United States of America)
(73) Owners :
  • TRUEPOSITION, INC. (United States of America)
(71) Applicants :
  • TRUEPOSITION, INC. (United States of America)
(74) Agent: CASSAN MACLEAN
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 2013-09-19
(87) Open to Public Inspection: 2014-03-27
Examination requested: 2015-03-12
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US2013/060719
(87) International Publication Number: WO2014/047352
(85) National Entry: 2015-03-12

(30) Application Priority Data:
Application No. Country/Territory Date
13/624,654 United States of America 2012-09-21

Abstracts

English Abstract

Disclosed is a method for processing readily available radio network, timing and power information about cellular networks and typical measurements made by the mobile device and network. A probabilistic method is disclosed that uses both time (i.e., range) and power differences with known downlink transmitter antenna characteristics to locate mobiles with accuracy better than cell-ID with ranging, with high capacity, and without the need for field calibration.


French Abstract

La présente invention porte sur un procédé pour traiter un réseau radio rapidement disponible, des informations de temps et de puissance concernant des réseaux cellulaires et des mesures typiques réalisées par le dispositif mobile et le réseau. Un procédé probabiliste est décrit qui utilise des différences de temps (c'est-à-dire, plage) et de puissance avec des caractéristiques d'antenne d'émetteur de liaison descendante connues pour localiser des mobiles avec une précision meilleure qu'une ID de cellule avec télémétrie, avec une capacité élevée, et sans le besoin d'un étalonnage de champ.

Claims

Note: Claims are shown in the official language in which they were submitted.


We claim:
1. A method for use in locating a mobile device, comprising:
causing the mobile device to receive beacon signals from a serving base
transceiver
station (BTS) and one or more adjacent BTSs, wherein each BTS is located at a
cell site and
each beacon signal includes cell identification (CID) information;
detecting a number of sibling pairs based on the received beacon signals,
wherein a
sibling pair comprises two downlink transmission antennae that are co-sited
sectors of a
multi-sector cell site; and
selecting a predefined location method based on the number of sibling pairs
detected.
2. A method as recited in claim 1, wherein the number of sibling pairs
detected is one,
and in response thereto one of either a single site location method or an
adjacent site location
method is selected.
3. A method as recited in claim 2, wherein the single site location method
is selected in
response to determining that the sibling pair is with a serving site; and
wherein the single site
location method comprises determining both an angular sector relative to a
serving cell and a
range from the serving cell to the mobile device.
4. A method as recited in claim 1, wherein the method is employed to
geolocate a
mobile device operating in a sectored wireless communications network (WCN)
with
medium accuracy using information about the WCN that is stored in a database
in
combination with measurements made by the mobile device in the network in the
course of
supporting mobility.
5. A method as recited in claim 4, wherein the information stored in the
database
includes the geographic locations of cell sites, the spatial response of
sectored antennae,
including their geographic and downtilt orientation, and sector identifiers
that are broadcast
by each BTS.
6. A method as recited in claim 4, wherein the mobile device measures
broadcast beacon
power received from each of a number of cell sites and reports the power
measured and
identity of cell site sectors that have the largest measured powers, as well
as a timing advance

- 39 -

(TA) value determined by the network and relayed to the mobile device, wherein
the TA
value serves as a range measurement from a serving cell sector to the mobile
device.
7. A method as recited in claim 4, wherein a bearing/angle from a sectored
cell site to
the mobile device is determined from power measurements from a pair of
adjacent sectors
(siblings) and knowledge of the spatial response and orientation of sector
antennae.
8. A method as recited in claim 7, wherein a timing range or power-derived
range value
from a serving cell with power difference measurements between siblings with
the largest
measured powers from one or more cell sites is employed to determine a
location estimate of
the mobile device.
9. A system configured to locate a mobile device, the system comprising at
least one
processor and at least one storage medium communicatively coupled to said at
least one
processor, the storage medium having stored therein computer-executable
instructions for
instructing the processor in causing the following steps:
causing the mobile device to receive beacon signals from a serving base
transceiver
station (BTS) and one or more adjacent BTSs, wherein each BTS is located at a
cell site and
each beacon signal includes cell identification (CID) information;
detecting a number of sibling pairs based on the received beacon signals,
wherein a
sibling pair comprises two downlink transmission antennae that are co-sited
sectors of a
multi-sector cell site; and
selecting a predefined location method based on the number of sibling pairs
detected.
10. A system as recited in claim 9, wherein the number of sibling pairs
detected is one,
and in response thereto one of either a single site location method or an
adjacent site location
method is selected.
11. A system as recited in claim 10, wherein the single site location
method is selected in
response to determining that the sibling pair is with a serving site; and
wherein the single site
location method comprises determining both an angular sector relative to a
serving cell and a
range from the serving cell to the mobile device.

- 40 -

12. A system as recited in claim 9, wherein the method is employed to
geolocate a mobile
device operating in a sectored wireless communications network (WCN) with
medium
accuracy using information about the WCN that is stored in a database in
combination with
measurements made by the mobile device in the network in the course of
supporting
mobility.
13. A system as recited in claim 12, wherein the information stored in the
database
includes the geographic locations of cell sites, the spatial response of
sectored antennae,
including their geographic and downtilt orientation, and sector identifiers
that are broadcast
by each BTS.
14. A system as recited in claim 12, wherein the mobile device measures
broadcast
beacon power received from each of a number of cell sites and reports the
power measured
and identity of cell site sectors that have the largest measured powers, as
well as a timing
advance (TA) value determined by the network and relayed to the mobile device,
wherein the
TA value serves as a range measurement from a serving cell sector to the
mobile device.
15. A system as recited in claim 12, wherein a bearing/angle from a
sectored cell site to
the mobile device is determined from power measurements from a pair of
adjacent sectors
(siblings) and knowledge of the spatial response and orientation of sector
antennae.
16. A system as recited in claim 15, wherein a timing range or power-
derived range value
from a serving cell with power difference measurements between siblings with
the largest
measured powers from one or more cell sites is employed to determine a
location estimate of
the mobile device.
17. A non-transitory computer readable storage medium storing thereon
computer
executable instructions for locating a mobile device, said computer executable
instructions
comprising:
instructions for causing the mobile device to receive beacon signals from a
serving
base transceiver station (BTS) and one or more adjacent BTSs, wherein each BTS
is located
at a cell site and each beacon signal includes cell identification (CID)
information;

- 41 -

instructions for detecting a number of sibling pairs based on the received
beacon
signals, wherein a sibling pair comprises two downlink transmission antennae
that are co-
sited sectors of a multi-sector cell site; and
instructions for selecting a predefined location method based on the number of
sibling
pairs detected.
18. A computer readable storage medium as recited in claim 17, wherein the
number of
sibling pairs detected is one, and in response thereto one of either a single
site location
method or an adjacent site location method is selected.
19. A computer readable storage medium as recited in claim 18, wherein the
single site
location method is selected in response to determining that the sibling pair
is with a serving
site; and wherein the single site location method comprises determining both
an angular
sector relative to a serving cell and a range from the serving cell to the
mobile device.
20. A computer readable storage medium as recited in claim 17, wherein the
method is
employed to geolocate a mobile device operating in a sectored wireless
communications
network (WCN) with medium accuracy using information about the WCN that is
stored in a
database in combination with measurements made by the mobile device in the
network in the
course of supporting mobility.
21. A computer readable storage medium as recited in claim 20, wherein the
information
stored in the database includes the geographic locations of cell sites, the
spatial response of
sectored antennae, including their geographic and downtilt orientation, and
sector identifiers
that are broadcast by each BTS.
22. A computer readable storage medium as recited in claim 20, wherein the
mobile
device measures broadcast beacon power received from each of a number of cell
sites and
reports the power measured and identity of cell site sectors that have the
largest measured
powers, as well as a timing advance (TA) value determined by the network and
relayed to the
mobile device, wherein the TA value serves as a range measurement from a
serving cell
sector to the mobile device.

- 42 -

23. A computer readable storage medium as recited in claim 20, wherein a
bearing/angle
from a sectored cell site to the mobile device is determined from power
measurements from a
pair of adjacent sectors (siblings) and knowledge of the spatial response and
orientation of
sector antennae.
24. A computer readable storage medium as recited in claim 23, wherein a
timing range
or power-derived range value from a serving cell with power difference
measurements
between siblings with the largest measured powers from one or more cell sites
is employed to
determine a location estimate of the mobile device.
25. A mobile device configured to detect location measurements, the mobile
device
comprising:
means for receiving beacon signals from a serving base transceiver station
(BTS) and
one or more adjacent BTSs, wherein each BTS is located at a cell site and each
beacon signal
includes cell identification (CID) information; and
means for detecting a number of sibling pairs based on the received beacon
signals,
wherein a sibling pair comprises two downlink transmission antennae that are
co-sited sectors
of a multi-sector cell site.
26. A mobile device as recited in claim 25, further comprising means for
selecting a
predefined location method based on the number of sibling pairs detected.
27. A mobile device as recited in claim 26, further comprising means for
selecting one of
either a single site location method or an adjacent site location method when
the number of
sibling pairs detected is one.
28. A mobile device as recited in claim 27, wherein the single site
location method is
selected in response to determining that the sibling pair is with a serving
site.
29. A mobile device as recited in claim 28, wherein the single site
location method
comprises determining both an angular sector relative to a serving cell and a
range from the
serving cell to the mobile device.

- 43 -

30. A mobile device as recited in claim 25, wherein the mobile device is
configured to
operate in a sectored wireless communications network (WCN) and the method is
employed
to geolocate the mobile device with medium accuracy using measurements made by
the
mobile device in the network in the course of supporting mobility and
information about the
WCN accessible from a database.
31. A mobile device as recited in claim 30, wherein the information in the
database
includes the geographic locations of cell sites, the spatial response of
sectored antennae,
including their geographic and downtilt orientation, and sector identifiers
that are broadcast
by each BTS.
32. A mobile device as recited in claim 30, wherein the mobile device
further comprises
means for measuring broadcast beacon power received from each of a number of
cell sites
and means for determining the power measured and identity of cell site sectors
that have the
largest measured powers, as well as a timing advance (TA) value determined by
the network
and relayed to the mobile device, wherein the TA value serves as a range
measurement from
a serving cell sector to the mobile device.
33. A mobile device as recited in claim 30, wherein a bearing/angle from a
sectored cell
site to the mobile device is determined from power measurements from a pair of
adjacent
sectors (siblings) and knowledge of the spatial response and orientation of
sector antennae.
34. A mobile device as recited in claim 33, wherein a timing range or power-
derived
range value from a serving cell with power difference measurements between
siblings with
the largest measured powers from one or more cell sites is employed to
determine a location
estimate of the mobile device.
35. A location server for use in locating a mobile device, the location
server comprising at
least one processor and at least one storage medium communicatively coupled to
said at least
one processor, the storage medium having stored therein computer-executable
instructions for
instructing the processor in causing the following steps:
detecting a number of sibling pairs based on beacon signal information
received from
the mobile device based on beacon signals from a serving base transceiver
station (BTS) and

- 44 -

one or more adjacent BTSs, wherein each BTS is located at a cell site and each
beacon signal
includes cell identification (CID) information, wherein a sibling pair
comprises two downlink
transmission antennae that are co-sited sectors of a multi-sector cell site;
and
selecting a predefined location method based on the number of sibling pairs
detected.
36. A location server as recited in claim 35, wherein the number of sibling
pairs detected
is one, and in response thereto one of either a single site location method or
an adjacent site
location method is selected.
37. A location server as recited in claim 35, wherein the single site
location method is
selected in response to determining that the sibling pair is with a serving
site.
38. A location server as recited in claim 37, wherein the single site
location method
comprises determining both an angular sector relative to a serving cell and a
range from the
serving cell to the mobile device.
39. A location server as recited in claim 35, wherein the method is
employed to geolocate
a mobile device operating in a sectored wireless communications network (WCN)
with
medium accuracy using information about the WCN that is stored in a database
in
combination with measurements made by the mobile device in the network in the
course of
supporting mobility.
40. A location server as recited in claim 39, wherein the information
stored in the
database includes the geographic locations of cell sites, the spatial response
of sectored
antennae, including their geographic and downtilt orientation, and sector
identifiers that are
broadcast by each BTS.
41. A location server as recited in claim 39, wherein the mobile device
measures
broadcast beacon power received from each of a number of cell sites and
reports the power
measured and identity of cell site sectors that have the largest measured
powers, as well as a
timing advance (TA) value determined by the network and relayed to the mobile
device,
wherein the TA value serves as a range measurement from a serving cell sector
to the mobile
device.

- 45 -

42. A location server as recited in claim 39, wherein a bearing/angle from
a sectored cell
site to the mobile device is determined from power measurements from a pair of
adjacent
sectors (siblings) and knowledge of the spatial response and orientation of
sector antennae.
43. A location server as recited in claim 42, wherein a timing range or
power-derived
range value from a serving cell with power difference measurements between
siblings with
the largest measured powers from one or more cell sites is employed to
determine a location
estimate of the mobile device.
44. A method for selecting a location estimate solution in a wireless
location system,
comprising:
collecting network measurement report (NMR) data over a duration of time (STEP
1101);
pre-processing the NMR data (STEP 1102);
determining from the pre-processed NMR data whether cells are present with
valid
timing measurements (STEP 1103);
determining from the pre-processed NMR data whether cells are present with
valid
power measurements (STEPS 1104, 1109); and
activating a scenario for selecting a location estimate solution based at
least on a
result of determining whether cells are present with valid timing and/or power
measurements.
45. The method recited in claim 44, further comprising:
determining that no cells are present with valid timing measurements;
determining that no cells are present with valid power measurements; and
activating a scenario (LES1) for selecting a location estimate solution when
only cell
identifier information is available (STEP 1105).
46. The method recited in claim 45, wherein the LES1 scenario comprises:
determining whether only a single serving cell identifier is reported, and if
so
computing the location estimate as the centroid of the serving cell's serving
geographic area;
determining whether two or more serving cell identifiers are reported, and if
so
computing the location estimate as the centroid of a common region with a
highest number of
overlapping serving geographic areas of the reported serving cells;

- 46 -

determining whether one or more neighbor cell identifiers are reported without
any
serving cell information, and if so computing the location estimate as the
centroid of a
common region with a highest number of overlapping neighbor geographic areas
of the
reported neighbor cells; and
determining whether one or more neighbor cells are reported in addition to one
or
more serving cells, and if so computing the location estimate as the centroid
of a common
region of various serving geographic areas of the reported serving cells with
a highest number
of cells overlapping, wherein the computed location estimate and is biased
towards the
direction of the centroid of the maximum overlapping of neighbor geographic
areas of the
additional reported neighbor cells.
47. The method recited in claim 44, further comprising:
determining that at least one cell is present with valid timing measurements;
determining that no cells are present with valid power measurements; and
activating a scenario (LES2) for selecting a location estimate solution when
only cell
identifier and time information is available (STEP 1110).
48. The method recited in claim 47, wherein the LES2 scenario comprises:
determining whether timing information for a single serving cell is reported
during a
period of NMR data collection time, and if so computing the location estimate
as the centroid
of the serving cell sector's timing based range band along a radial direction
over associated
range uncertainty and along an angular direction within the serving area of
the serving cell;
determining whether timing information for two or more serving cells are
reported
over a period of NMR data collection time, and if so computing the location
estimate as the
centroid of a common region of various serving cell sector's timing based
range bands along
a radial direction over an associated range uncertainty and along an angular
direction within
serving areas of the reported serving cells, wherein a final location estimate
is restricted to be
within the primary serving cell's distance range band along the direction of a
common
region's centroid from the primary serving cell location;
determining whether one or more serving cell identifiers are also reported
without any
timing information in addition to one or more serving cells with valid timing
information, and
if so computing the location estimate as the centroid of a timing information
based common
region and further biased towards a direction of maximum overlapping of
serving cell
geographic areas of the additional reported serving cells, wherein a final
location estimate is

- 47 -

restricted to be within the primary serving cell's distance range band along a
direction of a
previous best location estimate from the primary serving cell location; and
determining whether one or more neighbor cell identifiers are reported without
any
power information in addition to one or more serving cells with timing
information, and if so
computing the location estimate as the centroid of the timing information
based common
region and biased further towards a direction of maximum overlapping of
neighbor
geographic areas of the additional reported neighbor cells, wherein a final
location estimate is
restricted to be within the primary serving cell's distance range band along
the direction of a
previous best location estimate from the primary serving cell location.
49. The method recited in claim 44, further comprising:
determining that no cells are present with valid timing measurements;
determining that at least one cell is present with valid power measurements;
determining that no sibling pairs are present (STEP 1106); and
activating a scenario (LES3) for selecting a location estimate solution when
only cell
identifiers and power information is available for one or more serving and/or
neighbor cells
without any sibling pairs (STEP 1107).
50. The method recited in claim 49, wherein the LES3 scenario comprises:
determining whether only power information for one or more serving cells is
reported
during a period of NMR data collection time, and if so computing the location
estimate as the
centroid of the region with highest number of overlapping of various serving
cell serving
areas and reported power based range bands along a radial direction over
associated range
uncertainty;
determining whether only power information for one or more neighbor cells is
reported during a period of NMR data collection time, and if so computing the
location
estimate as the centroid of the region with highest number of overlapping of
various neighbor
cell neighbor areas and reported power based range bands along a radial
direction over
associated range uncertainty; and
determining whether power information for two or more serving and/or neighbor
cells
is reported during a period of NMR data collection time, and if so computing
the location
estimate as the centroid of a common region of various serving and/or neighbor
areas and
reported power based range bands along radial and angular directions over
associated range
uncertainty.

- 48 -

51. The method recited in claim 44, further comprising:
determining that no cells are present with valid timing measurements;
determining that at least one cell is present with valid power measurements;
determining that at least one sibling pair is present (STEP 1106); and
activating a scenario (LES4) for selecting a location estimate solution when
cell
identifier and power information is available for two or more serving and/or
neighbor cells
with one or more sibling pairs (STEP 1108).
52. The method recited in claim 51, wherein the LES4 scenario comprises:
determining whether only a single sibling pair is reported in the NMR data,
and if so
computing the location estimate as the centroid of a common region between an
estimated
azimuth angular band with associated uncertainty from the sibling cell tower
location based
on relative power, power based distance bands along radial and azimuthal
directions over an
associated range uncertainty and serving and/or neighbor areas of all reported
cells, wherein a
final location estimate is restricted to be within a sibling pair based
azimuth band; and
determining whether two or more sibling pairs are reported in the NMR data,
and if so
computing a preliminary search area as a common region of corresponding
azimuth bands
estimated from each sibling pair tower location based on their relative power.
53. The method recited in claim 52, wherein the preliminary search area is
further
reduced by using a maximum overlapped area of serving and/or neighbor areas as
well as
power based distance bands along radial and azimuthal directions over an
associated range
uncertainty of the reported cells, and wherein a final location estimate is
computed as the
centroid of the reduced preliminary search area and is restricted to be within
the sibling pairs
relative power based preliminary search area.
54. The method recited in claim 44, further comprising:
determining that at least one cell is present with valid timing measurements;
determining that at least one cell is present with valid power measurements;
determining that no sibling pairs are present (STEP 1111); and
activating a scenario (LESS) for selecting a location estimate solution when
cell
identifier, time and/or power information is available for one or more serving
and/or neighbor
cells without any sibling pairs (STEP 1113).

- 49 -

55. The method recited in claim 54, wherein the LESS scenario comprises:
determining whether timing information for one or more serving cells are
reported
over a period of NMR data collection time, and if so a preliminary search area
is computed as
a common region of various serving cell sector's timing based range bands
along radial and
angular directions over associated range uncertainty; and
reducing the timing based preliminary search area by using power based
distance
bands along radial and azimuthal directions over an associated range
uncertainty, serving and
neighbor areas of all reported serving and neighbor cells, wherein a final
location estimate is
computed as the centroid of a final search area and is restricted to be within
the timing based
preliminary search area.
56. The method recited in claim 44, further comprising:
determining that at least one cell is present with valid timing measurements;
determining that at least one cell is present with valid power measurements
(STEP
1109);
determining that at least one sibling pair is present (STEP 1111); and
activating a scenario (LES6) for selecting a location estimate solution when
cell
identifier, time and/or power information is available for one or more serving
and neighbor
cells with one or more sibling pairs (STEP 1112).
57. The method recited in claim 56, wherein the LES6 scenario comprises:
determining whether timing information for one or more serving cells are
reported
over a period of NMR data collection time, and if so a preliminary search area
is computed as
a common region of various serving cell sector's timing based range bands
along radial and
angular directions over associated range uncertainty;
reducing the serving cells timing based search area by taking a maximum
overlapping
region of estimated azimuth bands from the one or more sibling cell towers
based on sibling
pairs relative power; and
further reducing the timing and sibling pair relative power based preliminary
search
area by using power based distance bands along radial and azimuthal directions
over an
associated range uncertainty, serving and neighbor areas of all the reported
serving and
neighbor cells, wherein a final location estimate is computed as the centroid
of the final
search area and is restricted to be within the timing and sibling pair
relative power based
preliminary search area.

- 50 -

58. The method recited in claim 44, wherein a location estimate is computed
in real time.
59. The method recited in claim 44, wherein a location estimate is loaded
from a pre-
established location mapping table database created and maintained offline for
each
individual serving or neighbor cell or multiple serving and/or neighbor cells
combinations
within a specific location service area (LSA).
60. A wireless location system (WLS) configured to select a location estimate
solution using
network measurement report (NMR) data collected over a duration of time,
wherein the
system is configured to:
pre-process the NMR data;
determine from the pre-processed NMR data whether cells are present with valid

timing measurements;
determine from the pre-processed NMR data whether cells are present with valid

power measurements; ; and
activate a scenario for selecting a location estimate solution based at least
on a result
of determining whether cells are present with valid timing and/or power
measurements.
61. The system recited in claim 60, wherein the system is further
configured to:
determining that no cells are present with valid timing measurements;
determining that no cells are present with valid power measurements; and
activate a scenario (LES1) for selecting a location estimate solution when
only cell
identifier information is available (STEP 1105).
62. The system recited in claim 61, wherein the LES1 scenario comprises:
determining whether only a single serving cell identifier is reported, and if
so
computing the location estimate as the centroid of the serving cell's serving
geographic area;
determining whether two or more serving cell identifiers are reported, and if
so
computing the location estimate as the centroid of a common region with a
highest number of
overlapping serving geographic areas of the reported serving cells;
determining whether one or more neighbor cell identifiers are reported without
any
serving cell information, and if so computing the location estimate as the
centroid of a
common region with a highest number of overlapping neighbor geographic areas
of the
reported neighbor cells; and

- 51 -

determining whether one or more neighbor cells are reported in addition to one
or
more serving cells, and if so computing the location estimate as the centroid
of a common
region of various serving geographic areas of the reported serving cells with
a highest number
of cells overlapping, wherein the computed location estimate and is biased
towards the
direction of the centroid of the maximum overlapping of neighbor geographic
areas of the
additional reported neighbor cells.
63. The system recited in claim 60, wherein the system is further
configured to:
determine that at least one cell is present with valid timing measurements;
determine that no cells are present with valid power measurements; and
activate a scenario (LES2) for selecting a location estimate solution when
only cell
identifier and time information is available (STEP 1110).
64. The system recited in claim 63, wherein the LES2 scenario comprises:
determining whether timing information for a single serving cell is reported
during a
period of NMR data collection time, and if so computing the location estimate
as the centroid
of the serving cell sector's timing based range band along a radial direction
over associated
range uncertainty and along an angular direction within the serving area of
the serving cell;
determining whether timing information for two or more serving cells are
reported
over a period of NMR data collection time, and if so computing the location
estimate as the
centroid of a common region of various serving cell sector's timing based
range bands along
a radial direction over an associated range uncertainty and along an angular
direction within
serving areas of the reported serving cells, wherein a final location estimate
is restricted to be
within the primary serving cell's distance range band along the direction of a
common
region's centroid from the primary serving cell location;
determining whether one or more serving cell identifiers are also reported
without any
timing information in addition to one or more serving cells with valid timing
information, and
if so computing the location estimate as the centroid of a timing information
based common
region and further biased towards a direction of maximum overlapping of
serving cell
geographic areas of the additional reported serving cells, wherein a final
location estimate is
restricted to be within the primary serving cell's distance range band along a
direction of a
previous best location estimate from the primary serving cell location; and
determining whether one or more neighbor cell identifiers are reported without
any
power information in addition to one or more serving cells with timing
information, and if so

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computing the location estimate as the centroid of the timing information
based common
region and biased further towards a direction of maximum overlapping of
neighbor
geographic areas of the additional reported neighbor cells, wherein a final
location estimate is
restricted to be within the primary serving cell's distance range band along
the direction of a
previous best location estimate from the primary serving cell location.
65. The system recited in claim 60, wherein the system is further
configured to:
determine that no cells are present with valid timing measurements;
determine that at least one cell is present with valid power measurements;
determine that no sibling pairs are present (STEP 1106); and
activate a scenario (LES3) for selecting a location estimate solution when
only cell
identifiers and power information is available for one or more serving and/or
neighbor cells
without any sibling pairs (STEP 1107).
66. The system recited in claim 65, wherein the LES3 scenario comprises:
determining whether only power information for one or more serving cells is
reported
during a period of NMR data collection time, and if so computing the location
estimate as the
centroid of the region with highest number of overlapping of various serving
cell serving
areas and reported power based range bands along a radial direction over
associated range
uncertainty;
determining whether only power information for one or more neighbor cells is
reported during a period of NMR data collection time, and if so computing the
location
estimate as the centroid of the region with highest number of overlapping of
various neighbor
cell neighbor areas and reported power based range bands along a radial
direction over
associated range uncertainty; and
determining whether power information for two or more serving and/or neighbor
cells
is reported during a period of NMR data collection time, and if so computing
the location
estimate as the centroid of a common region of various serving and/or neighbor
areas and
reported power based range bands along radial and angular directions over
associated range
uncertainty.
67. The system recited in claim 60, wherein the system is further
configured to:
determine that no cells are present with valid timing measurements;
determine that at least one cell is present with valid power measurements;

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determine that at least one sibling pair is present (STEP 1106); and
activate a scenario (LES4) for selecting a location estimate solution when
cell
identifier and power information is available for two or more serving and/or
neighbor cells
with one or more sibling pairs (STEP 1108).
68. The system recited in claim 67, wherein the LES4 scenario comprises:
determining whether only a single sibling pair is reported in the NMR data,
and if so
computing the location estimate as the centroid of a common region between an
estimated
azimuth angular band with associated uncertainty from the sibling cell tower
location based
on relative power, power based distance bands along radial and azimuthal
directions over an
associated range uncertainty and serving and/or neighbor areas of all reported
cells, wherein a
final location estimate is restricted to be within a sibling pair based
azimuth band; and
determining whether two or more sibling pairs are reported in the NMR data,
and if so
computing a preliminary search area as a common region of corresponding
azimuth bands
estimated from each sibling pair tower location based on their relative power.
69. The system recited in claim 68, wherein the preliminary search area is
further reduced
by using a maximum overlapped area of serving and/or neighbor areas as well as
power
based distance bands along radial and azimuthal directions over an associated
range
uncertainty of the reported cells, and wherein a final location estimate is
computed as the
centroid of the reduced preliminary search area and is restricted to be within
the sibling pairs
relative power based preliminary search area.
70. The system recited in claim 60, wherein the system is further
configured to:
determine that at least one cell is present with valid timing measurements;
determine that at least one cell is present with valid power measurements;
determine that no sibling pairs are present (STEP 1111); and
activate a scenario (LESS) for selecting a location estimate solution when
cell
identifier, time and/or power information is available for one or more serving
and/or neighbor
cells without any sibling pairs (STEP 1113).
71. The system recited in claim 70, wherein the LESS scenario comprises:
determining whether timing information for one or more serving cells are
reported
over a period of NMR data collection time, and if so a preliminary search area
is computed as

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a common region of various serving cell sector's timing based range bands
along radial and
angular directions over associated range uncertainty; and
reducing the timing based preliminary search area by using power based
distance
bands along radial and azimuthal directions over an associated range
uncertainty, serving and
neighbor areas of all reported serving and neighbor cells, wherein a final
location estimate is
computed as the centroid of a final search area and is restricted to be within
the timing based
preliminary search area.
72. The system recited in claim 60, wherein the system is further
configured to:
determining that at least one cell is present with valid timing measurements;
determining that at least one cell is present with valid power measurements
(STEP
1109);
determining that at least one sibling pair is present (STEP 1111); and
activate a scenario (LES6) for selecting a location estimate solution when
cell
identifier, time and/or power information is available for one or more serving
and neighbor
cells with one or more sibling pairs (STEP 1112).
73. The system recited in claim 72, wherein the LES6 scenario comprises:
determining whether timing information for one or more serving cells are
reported
over a period of NMR data collection time, and if so a preliminary search area
is computed as
a common region of various serving cell sector's timing based range bands
along radial and
angular directions over associated range uncertainty;
reducing the serving cells timing based search area by taking a maximum
overlapping
region of estimated azimuth bands from the one or more sibling cell towers
based on sibling
pairs relative power; and
further reducing the timing and sibling pair relative power based preliminary
search
area by using power based distance bands along radial and azimuthal directions
over an
associated range uncertainty, serving and neighbor areas of all the reported
serving and
neighbor cells, wherein a final location estimate is computed as the centroid
of the final
search area and is restricted to be within the timing and sibling pair
relative power based
preliminary search area.
74. The system recited in claim 60, wherein a location estimate is computed
in real time.

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75. The
system recited in claim 60, wherein a location estimate is loaded from a pre-
established location mapping table database created and maintained offline for
each
individual serving or neighbor cell or multiple serving and/or neighbor cells
combinations
within a specific location service area (LSA).

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Description

Note: Descriptions are shown in the official language in which they were submitted.


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TIME AND POWER BASED WIRELESS LOCATION AND METHOD OF SELECTING
LOCATION ESTIMATE SOLUTION
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Patent Application
No. 13/624,654, filed September 21, 2012, which is a continuation-in-part of
United States
Patent No. 8315647, filed December 28, 2010, the content of which are
incorporated herein
by reference in their entireties.
TECHNICAL FIELD
[0002] The present invention relates generally to methods and apparatus for
locating
wireless devices, also called mobile stations (MS), such as those used in
analog or digital
cellular systems, personal communications systems (PCS), enhanced specialized
mobile
radios (ESMRs), and other types of wireless communications systems. More
particularly, but
not exclusively, the present invention relates to the position of mobile
devices using pre-
existing wireless infrastructure data.
BACKGROUND
[0003] Wireless communications networks (WCN) manage mobility of a wireless
mobile device by collecting radio information about the network. From the
advent of
location-based services, this radio information has been used to provide low
and medium
accuracy location estimates.
[0004] In non-soft handoff systems, the location of every active mobile in the

network is known to the nearest serving cell and sector. The identification of
the serving cell
and serving sector can be converted to a location estimate by simple
translation to a pre-
established latitude and longitude for the serving cell and/or sector.
[0005] Inclusion of the WCN measured time or mobile measured power based range

estimate from the serving cell to the mobile position provides a method for
refining the basic
serving cell identifier based location estimate with minimal additional
calculations.
[0006] A further refinement of the cell/sector identifier plus ranging method
using
the mobile-collected network information from one or more potential handover
neighboring
cells is generally known as Enhanced Cell-ID (ECID). The ECID technique relies
on the
mobile unit's ability to record the power levels from the beacons (also known
as pilots) of
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multiple potential handover candidate/neighbor cells. This technique adds
absolute power
based and/or power-difference-of-arrival (PDOA) based measurements to improve
the
serving cell ranging location estimate.
[0007] Since typically the received signal power of various nearby
transmitting cell
sectors measured by the active mobile device is known by the WCN, the PDOA for
ECID
value is based on the received signal levels measured by the mobile for the
serving cell's
and/or one or more potential handover candidate/neighboring cell's beacons.
Since the PDOA
data collection requires visibility to two or more neighbor cell sites,
location yield will be less
than 100%. The effects of RF multipath, mobile receiver quality, and
granularity of the
measurement all act to reduce location accuracy for ECID.
ECID in GSM, UMTS and LTE
[0008] In GSM, ECID is also known as Network Measurement Report (NMR)
location. The NMR is generated by the mobile to provide the WCN with
information
regarding the serving and neighboring cells to facilitate handover as
described in GSM/3GPP
Technical Standard 05.08, "Radio subsystem link control" section 3 (Handover).
[0009] The Enhanced Cell ID positioning technique is standardized as "Timing
Advance" positioning in 3GPP TS 43.059 , "Functional stage 2 description of
Location
Services (LCS) in GERAN" section, section 4.2.1. In LTE networks the "enhanced
cell ID
method" is described in 3GPP TS 36.305, "Stage 2 functional specification of
User
Equipment (UE) positioning in E-UTRAN" Section 4.3.3.
[0010] In the example GSM system, the NMR contains the mobile generated
Measurement Results. The purpose of the Measurement Results information
element is to
provide the results of the measurements made by the mobile station regarding
the serving cell
and the neighbor cells. The Measurement Results information element is coded
as shown in
GSM/3GPP Technical Specification 04.08, "Mobile radio interface layer 3
specification"
section 10.5.2.20 (Measurement Report).
[0011] The mobile location center (MLC) uses NMR delivered serving cell-id (in

GSM the Cell-Global-Identity (CGI) gives the cell and sector) to consider the
cell site's
geographical location as the reference point. The reported timing advance (TA)
value of the
current serving cell allows computation of the range from the reference point.
The Received
Signal Strength Indicator (RSSI) of the serving cell is corrected with the
current mobile
dynamic power control settings, when received on traffic control channel
instead of broadcast
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control channel. The corrected RSSI value of serving cell is then normalized
with its known
value of broadcast effective radiated power (ERP). The Reception Level (RxLev)
values of
the reported neighboring cells over Broadcast Control Channel (BCCH) beacons
are then
normalized against their known value of broadcast effective radiated power
(ERP). Using the
serving cell's antenna position, the TA-derived range, and the PDOA from three
or more
sites, a location estimate can be calculated.
[0012] Since ECID can use PDOA multi-lateration, the geographic layout of the
neighbor cells also affects the quality of the location through geographic
dilution of precision
(GDOP). The limitation of only up to six neighbor cell RxLev measurements
present in the
NMR limits accuracy, when NMR data is not collected over a sufficient amount
of the time
interval by limiting potential GDOP reduction though receiver site selection.
[0013] Since the PDOA measurement requires averaging over multiple samples to
nullify the received signal fast fading effects (the GSM NMR is transmitted by
the mobile
station periodically during an active call), latency is much higher than for
other cell-ID based
techniques.
[0014] Since the RSSI measurement for only the serving cell, when the mobile
is in
active mode is based on the variable power settings for the BTS, normalization
of the serving
cell RSSI before inclusion into the PDOA calculation requires knowledge of the
BTS forward
(downlink) power control settings from the GSM WCN.
[0015] Calibration may be used improve accuracy in ECID location systems. ECID

Calibration can include the use of predictive RF propagation mapping and
extensive drive
testing to create a grid of CGI/RxLev "fingerprints". By mapping the neighbor
list and
received signal levels over the coverage area, it is possible to achieve
medium accuracy
results within the range of 200-500 meters in networks having relatively high
BTS density.
[0016] In United States Patent No. 7,434,233, a single site ECID location
system is
taught where the power measurements from a single 3-sector Base Transceiver
Station (BTS)
with a serving sector and two co-sited sectors allow the formation of a sector
limited timing
range band and a directional angle from the BTS cell site.
[0017] The inventive techniques and concepts described herein apply to time
and
frequency division multiplexed (TDMA/FDMA) radio communications systems
including the
widely used IS-136 (TDMA), GSM, and Orthogonal Frequency Division Multiplexed
(OFDM) wireless systems such as LTE, LTE-Advanced and IEEE 802.16
(WiMAN/WiMAX). The Global System for Mobile Communications (GSM) model
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discussed is an exemplary but not exclusive environment in which the present
invention may
be used.
SUMMARY
[0018] Disclosed herein is a method for processing readily available radio
network,
timing and power information about cellular networks and typical measurements
made by the
mobile device and network. Different methods are disclosed that uses both time
(i.e. range)
and power differences to locate mobiles with accuracy better than cell-ID with
ranging, with
high capacity and without the need for calibration. In addition, we disclosed
improved,
computer-implemented methods for selecting a location estimate solution in a
wireless
location system.
[0019] One illustrative embodiment of the present invention provides for a
method
for use in locating a mobile device. This embodiment of the inventive method
includes the
step of causing a mobile device to receive beacon signals from a serving base
transceiver
station (BTS) and one or more adjacent BTS. Each BTS is located at a cell site
and each
beacon signal includes cell identification (CID) information. A number of
sibling pairs based
on the received beacon signals are detected. A sibling pair comprises two
downlink
transmission antennae of a multi-sector cell site, which are located
relatively close to one
another (for instance, within 100 meters) and their antenna pattern main beams
pointing to
different directions.. Next, a predefined location method is selected based on
the number of
sibling pairs detected. The mobile device measures broadcast beacon power
received from
each of a number of cell sites and reports the power measured and identity of
cell site sectors
that have the largest measured powers, as well as a timing advance (TA) value
determined by
the network and relayed to the mobile device. The TA value serves as a range
measurement
from the serving cell sector to the mobile device
[0020] In the illustrative embodiments, when the number of sibling pairs
detected is
zero, a power-difference-of-arrival with ranging (PDOA) location method is
selected. When
the number of sibling pairs detected is one, either a single site location
method or an adjacent
site location method is selected. When the number of sibling pairs detected is
greater than
one, one of either a power angle-of-arrival (AoA) location method or a power
AoA with
ranging location method is selected.
[0021] In the illustrative embodiments, the method may be employed to
geolocate a
mobile device operating in a sectored wireless communications network (WCN)
with
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medium accuracy using information about the WCN that is stored in a database
in
combination with measurements made by the mobile device in the network in the
course of
supporting mobility. In this regard, a bearing/angle from a sectored cell site
to the mobile
device may be determined from power measurements from a pair of adjacent
sectors
(siblings) and knowledge of the spatial response and orientation of the sector
antennas. Next,
a timing range or power-derived range value from the serving cell with power
difference
measurements between siblings with the largest measured powers from one or
more cell sites
may be employed to determine a location estimate of the mobile device
[0022] In the embodiments recounted above, the power AoA location method or
power AoA with ranging location method comprises a probabilistic method for
geolocation
of mobile devices using sibling pairs. Timing (Timing Advance (TA) in GSM)
information
and power information from the wireless network is derived by creating a model
of the
timing advance and power difference between siblings of neighbor cells over
the range band.
[0023] As mentioned, we also disclose methods for selecting a location
estimate
solution in a wireless location system. In one inventive embodiment, a method
for selecting a
location estimate solution comprises collecting network measurement report
(NMR) data
over a duration of time. (This is represented as STEP 1101 in Figure 11.)
Next, the NMR data
are pre-processed (STEP 1102), and then the method involves determining from
the pre-
processed NMR data whether cells are present with valid timing measurements
(STEP 1103).
From here, various "scenarios" may be activated as described below. These are
enumerated
as scenarios LES1, LES2, LES3, LES4, LESS and LES6 in the illustrative
embodiments.
[0024] Additional features and aspects of the present invention are described
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The foregoing summary as well as the following detailed description are

better understood when read in conjunction with the appended drawings. For the
purpose of
illustrating the invention, there is shown in the drawings exemplary
constructions of the
invention; however, the invention is not limited to the specific methods and
instrumentalities
disclosed. In the drawings:
[0026] Figure la schematically depicts initial signal collection and analysis.

[0027] Figure lb illustrates a location process for the no sibling sector
case.
[0028] Figure lc illustrates a location process for a single sibling pair
scenario.
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[0029] Figure ld illustrates a location process for when two or more sibling
pairs
are detected.
[0030] Figure 2 graphically depicts a location scenario for a single sibling
pair in an
adjacent cell site.
[0031] Figure 3 graphically depicts a location scenario for when two sibling
pairs
exist in two adjacent cell sites.
[0032] Figure 4 illustrates graphically depicts a location scenario for when
two
sibling pairs exist in two adjacent cell sites and no timing range from the
serving cell is
available.
[0033] Figure 5 illustrates graphically depicts a location scenario for when
three
sibling pairs exist in three cell sites and no timing range from the serving
cell is available.
[0034] Figure 6 graphically depicts a mobile-based collection of downlink
signals in
a radio access network.
[0035] Figure 7a illustrates a probabilistic time and power-based location
determination algorithm geometrically.
[0036] Figure 7b details geographic differences between the measured and
modeled
azimuths.
[0037] Figure 8 illustrates spatial responses of the sibling sector antennas
lines of
constant power differences in forming azimuths.
[0038] Figure 9 illustrates radiation patterns of representative directional
antenna
using the half power beamwidth and front to back lobe ratio (FBR) values.
[0039] Figure 10 illustrates a use of sibling pairs of antenna in the
generation of an
azimuth through relative gain with 120 degree directional antenna.
[0040] Figure 11 sequentially shows a solution flow for the fall-forward
technique
for localization.
[0041] Figure 12 graphically depicts location estimation based on the service
area of
a cell-ID.
[0042] Figure 13 graphically depicts location estimation based neighbor area
of two
sibling cells.
[0043] Figure 14 graphically depicts location estimation based on the neighbor
area
of two non-sibling cells.
[0044] Figure 15 graphically depicts location estimation based on the neighbor
area
of three cells with common region.
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[0045] Figure 16 graphically depicts location estimation based on the neighbor
area
of three cells without common region.
[0046] Figure 17 graphically depicts location estimation based on a
combination of
timing range and service areas from 3 cells.
[0047] Figure 18 graphically depicts location estimation based on a
combination of
timing ranges and service areas from 3 cells.
[0048] Figure 19 graphically depicts location estimation based on power
ranging
from the serving cell and at least two neighboring cells.
[0049] Figure 20 graphically depicts location estimation based on power
ranging
from the serving cell and service areas of at least two neighboring cells.
[0050] Figure 21 graphically depicts location estimation based on power
ranging
from the serving cell and a sibling neighbor cell.
[0051] Figure 22 graphically depicts location estimation using power ranging
between sibling cells and the service area of at least one additional neighbor
cell.
[0052] Figure 23 graphically depicts location estimation using power ranging
between sibling cells and the power range from one additional neighbor cell.
[0053] Figure 24 graphically depicts location estimation using cell
identifier, time
and/or power information as available for one or more serving and/or neighbor
cells without
any sibling pair.
[0054] Figure 25 graphically depicts location estimation using cell
identifier, time
and/or power information as available for one or more serving and neighbor
cells with one or
more sibling pairs.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0055] We will now describe illustrative embodiments of the present invention.

First, we provide a detailed overview of the problem and then a more detailed
description of
example embodiments of the present invention.
Overview
[0056] Determining the location of a mobile station transmitter is commonly
achieved by measuring characteristics of the mobile station transmitter's
uplink signal at a
number of known receiving antenna locations. Also the location of a mobile
station receiver
is determined by measuring characteristics of the mobile station's serving
cell site
transmitter's and/or nearby potential handover/neighboring cell site
transmitter's downlink
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signals by the mobile station. Typical characteristics measured include signal
power (RSSI),
time-of-arrival (TOA), angle-of-arrival (AoA), or any combination thereof. GSM
mobiles
may be geolocated in sectored GSM networks with medium accuracy using
information
about the network that is readily available and measurements typically made by
the Mobile
Station (MS) in the network during course of supporting mobility.
[0057] The readily available network information includes the geographic
location
of the cell sites, the spatial response of the sectored antennas including
their main beam
pointing azimuthal and downtilt orientation, broadcast control channel(BCCH),
base station
color code (BSIC), effective radiated power (ERP) on broadcast control
channel, and the
unique sector identifiers that are broadcasted by each sector. For instance,
GSM mobiles
measure the broadcast beacon power received from each of a number of cell
sites and report
the power measured and identity (BCCH and BSIC) of up to six cell site sectors
that have the
largest measured powers to the network approximately at a rate of twice per
second.
Additionally, in GSM, a timing advance(TA) value is determined by the network
and relayed
to the mobile to permit the mobile to transmit over its entire time slot. The
TA value also
serves as a range measurement from the serving cell sector (CGI in GSM) to the
mobile.
[0058] During the course of experimentation with Enhanced Cell-ID (ECID)
location technology, it was determined that the power difference measurements
between
sectors of the base BTS possess minimum variability because path loss between
the sectors
and the mobile are cancelled out as the wireless channel between the two
sectors and the
mobile is fairly similar. With the ability to reject common bias from beacons
of sectors of the
same cell, the bearing, or angle, from a sectored cell site to the mobile
transmitter can be
determined from the power measurements from a pair of adjacent sectors, i.e.
siblings, and
knowledge of the spatial response and orientation of the sector antennas.
Coupling the timing
range (e.g. TA, RTT) or a power-derived range value from the serving cell with
the power
difference measurements between two sectors with the largest measured powers
from one or
more cell sites provide sufficient measurements to determine a location
estimate of the
mobile with accuracy better than cell-ID location with ranging. The Cell-ID
with ranging
location technique is well known (e.g., in GSM - CGI+TA, in UMTS - CID+RTT, or
in LTE
- PCI+TALTE).
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Figure la
[0059] Figure la illustrates the initial steps in the mobile-assisted, network-
based
determination of location in accordance with the present invention. As shown,
the mobile
device collects the downlink beacon signal strengths and identifiers 101. The
mobile
transmits these signals to the Radio Access Network (RAN). This collection and
transmission
from the mobile device is performed by the mobile in the normal course of
operation as part
of the Mobile-Assisted-Handoff (MAHO) technique typically used by modern
cellular
systems.
[0060] The downlink beacon signal strengths and identifiers are forwarded by
the
RAN to the Serving Mobile Location Center (SMLC) or passively monitored and
sent to the
SMLC. Examples of passive monitoring triggering platforms are described in US
Patent No.
6,782,225, "Monitoring of Call Information in a Wireless Location System" and
US Patent
No. 7,783,299; "Advanced Triggers for Location Based Service Applications in a
Wireless
Location System," both incorporated herein by reference.
[0061] The SMLC, part of the WLS, contains or has access to a database of
beacon
identifiers, transmitter antenna geographic locations, transmitter signal
powers and radio base
station downlink (transmit) antenna gain patterns. This database is deemed the
cell-ID
database 102. Using the cell-ID database and the collected signal information,
the received
signals are then sorted by cell (cell/sector) identifier and any sibling pairs
identified 103. A
sibling pair is two downlink transmission antennae of a multi-sector cell site
that are located
geographically close (e.g. separated by less than 100 meters) to each other
and their
horizontal antenna pattern main beams are pointing to different directions.
Further
processing, shown by the marker "A", is dependent on the number of sibling
pairs detected.
Figure lb
[0062] Figure lb depicts the case where no sibling pairs were detected 104.
Since
no siblings are available, only a power-difference-of-arrival with ranging
calculation can be
performed 105. Since only a classic enhanced-cell ID (ECID) location can be
reported
106,the location accuracy will vary widely based on the cell structure and
coverage areas.
[0063] With ECID, the cell-ID (CGI) component will allow determination of the
latitude and longitude of the serving tower or sector antenna while the Timing
Advance (TA)
determined ranging from serving cell site location allows for reduction of the
location error
radius in radial direction from serving cell site to a band approximately 554
meters wide,
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when there are no measurement errors in reported TA exist in the case of
sectored cells. But
the location error radius in azimuth angular direction increases proportional
to the increased
TA value or distance from serving cell. If sufficient (three or more) neighbor
cells are
available via the mobile device beacon collection and if the cell geometry
does not result in
extremely high geometric dilution of precision, the added PDOA-based location
measurement can significantly improve location accuracy along azimuth angular
direction,
especially at larger TA values over that of a CGI+TA location estimate.
Figure lc
[0064] If a sibling pair is detected 107 from the analysis 103 of the mobile
collected
signal data 102, then a power-based angle of arrival technique can be used to
improve the
classic ECID location.
[0065] The sibling pair is further analyzed to determine if the sibling pair
is
associated with the serving cell 108. If yes, then a single site location 109
will be performed
as detailed in U.S. Patent No. 7,434,233. If the sibling pair is found to be
associated with an
adjacent cell site 110, then Adjacent Site Location 111 is performed.
Figure id
[0066] If more than one sibling pair is detected 112 from the analysis 103 of
the
mobile collected signal data 102, then a power-based angle of arrival
technique can be used
to improve the classic ECID location. Availability of two or more sibling
pairs also allows for
location even if the time or power based ranging is not available or not
granular enough (for
instance in GSM, the timing range band increments in 554 meter steps) to allow
a precise
location. With each sibling pair allowing a power-based Angle of Arrival (AoA)
to be
determined, this technique has been deemed "power AoA".
[0067] If serving site ranging is available 113, then a power AoA with ranging

calculation is possible 115. If serving site ranging is not available, a
purely power AoA
calculation 114 is still possible.
Power-based Angle of Arrival
[0068] The angle-of-arrival (AoA), or line-of-bearing (LOB), of a signal can
be
determined from a common site location to the mobile position to be estimated
by receiving
the signals from two antennas that are co-sited or located in close geographic
proximity (e.g.,
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spaced 10's of meters from each other) and pointed in different directions.
The decibel
power, i.e. dBm, of the signal received from each antenna is averaged over a
period of time to
mitigate the effect of fast fading. The decibel difference in the averaged
signals from the two
antennas is determined. The AoA of the signal at mobile station can then be
determined from
this decibel difference and knowledge of their antennas spatial responses,
operating
frequencies and ERP values.
[0069] Many wireless communications systems break the 360 degree
omnidirectional coverage into three overlapping sectors to increase their
communications
capacity through frequency reuse. A coverage area is defined as the area
illuminated by the
downlink beacon radio signal. Typically, the 360 degree, omnidirectional,
coverage region is
split into three 120 degree sectors through the use of directional antennas.
Ideally, each sector
antenna will cover only its 120 degree region and none of its adjacent
sectors' regions.
Practically, this would require a very large antenna so smaller antennas are
utilized that
overlap. Other sectorization plans (e.g. two 90 degree sectors, six 60 degree
sectors) are
supported.
[0070] Characterizing sector antennas in a generic fashion makes it easy to
determine the AoA from the decibel power differences between two sibling
antennas without
collecting and maintaining large number of various manufactured antenna
pattern data files in
different file formats to be processed and then derive the appropriate pattern
fitting model to
be used in the closed form solution to estimate the azimuth angle of mobile
station from the
sibling pair cellsite. Antennas can be characterized by their half-power-
beamwidth (HPBW)
in the vertical dimension, their HPBW in their horizontal dimension, and their
front-to-back
ratio (FBR). The HPBW of an antenna that is symmetric about its boresite is
defined as the
angular separation from a point on the left side of the antenna where its
power response is 3
dB below its peak response at boresite to the point on the right side of the
antenna where its
power response is 3 dB below its peak response. The FBR of an antenna is
defined as the
decibel difference between the antenna's maximum decibel power response at its
boresite to
its decibel power response 180 degrees away from its boresite.
[0071] Antennas are often characterized in a normalized fashion by setting
their
maximum decibel power response to 0 dB. A generic model for the normalized,
horizontal
plane, decibel power response of an antenna can be expressed mathematically
as:
G dB (6) Qh (1 ¨[0.5 0.5 cos(0)]a )
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where the antenna pattern model parameter a is derived based upon the
corresponding
horizontal HPBW, eh and front to back lobe ratio (FBR) in dB Kli, as:
a = 1og10(1+3/f2h)/1og10(0.5+0.5cos(Oh /2))
[0072] Plots of normalized antenna patterns for three different HPBW for two
different FBR values are shown in Figure 9.
[0073] Similarly, a plot of the decibel power difference between two 120
degree
HPBW antennas with boresites at 0 degrees and 120 degrees are shown in Figure
10 for the
entire 360 degrees omnidirectional response of both antennas. Note that
between the two
antennas boresites the power difference will vary from +12 dB to -12 dB in a
linear fashion
with a negative slope of -0.2 dB per degree. Also note that the decibel power
difference is not
single valued over the entire omnidirectional 360 degree range. Another
duplicate value
occurs outside the angular range between the two antennas' boresites. Thus
when
determining the AoA utilizing the power difference between these two antennas,
two angles
will result. One AoA is the correct one and the other is an ambiguous one.
These types of
ambiguous AoAs can be resolved using serving cell physical site information
such as
location, antenna boresite angle and TA information or when solving for the
location of the
mobile within a pre-defined search area of the primary serving cell TA band in
a probabilistic
manner.
Model Based Location Estimation Utilizing Sibling Sector Power Differences and

Serving Sector Timing Advance
[0074] Location estimation of mobiles operating on a wireless network can be
achieved with measurements that are commonly made by the mobiles as well as
timing
measurements made by the network. Specifically, mobiles make power
measurements of
nearby cell sectors to assist in handoff to those sectors as they move about
the coverage area.
Networks make range timing measurements from the serving cell/sector site to
the mobile to
time synchronize the mobile to the network for proper operation. The decibel
difference in
the power between measurements of two adjacent sectors of a cell site, i.e.
sibling pair,
provides a robust indication of the direction the mobile with respect to the
cell site.
Practically, power difference measurements have two important advantages.
First, common
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biases in the mobile's power measurement are cancelled, providing a more
accurate
measurement. Second, the wireless channel between the mobile and each of the
two adjacent
sectors will be similar, resulting in less variation between them which
results in less variation
in location estimates. Power difference measurements from two or more cell
sites can be
compared with a model over the coverage area to determine potential locations
of the mobile.
A range measurement from the serving cell site/sector can be used to limit the
search range
for locating a mobile, typically providing a unique location.
[0075] In an illustrative example, a transmitter and receiver are separated by
a
distance r and there is a direct path from the transmitter to the receiver and
no multipath
present, i.e. the definition of free space propagation. The transmitter has
effective radiated
power of PT and with a normalized antenna gain pattern of GTO where 0
represents the
spatial variation of the antenna's gain in azimuth plane. The received power
is given as the
transmitter power multiplied by the gains of the transmit antenna in the
direction of the
receiver 00, multiplied by the effective area of the receive antenna '1,0 in
the direction of the
transmitter 00. Additionally, we divide this quantity by the area of a sphere
of radius r to
account for the reduction in the power density of the RF signal at a distance
r from the
transmitter, or source, due to spherical spreading of the radio wave as it
propagates from the
transmitter to the receiver. This is written as:
P

TT
P G (19 )A,(19 )
=
42-cr 2
The effective area of the receive antenna is related to the gain of the
receive antenna as:
G4
R(19) 2rAe ()
0
where X is the wavelength of the RF signal. Combining these two equations
yields:
PT GT o)GR o)
p
=
[0076] The product of the wavelength of the signal, k, and its frequency, f,
is equal
to the speed of light, c, as:
c =f2.
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[0077] The speed of light is equal to 3x108 meters per second. The wavelength
can
be expressed in terms of the frequency of the signal in MegaHertz (MHz) as:
A 300
= ____________ .
fmHz
Substituting results in:
p
PT GT (19,)R G (19, )3002
R \2 =
(471f mHzr 1
[0078] The above equation indicates that with all other parameters constant,
the
received power will vary as the inverse of the square of the distance from the
transmitter.
This is accurate for free space propagation; however, for the land mobile
radio propagation
channel the 1/r2 factor needs to be substituted by 1/Kra, where a is typically
between 2 and 4,
to model the received power correctly. Therefore, the power received for a
land mobile
propagation scenario is expressed as:
PT GT (19 , )GR (19, )3002
p
R=
(4 ;If mHz)2 Kra
[0079] Taking 10 times the base 10 logarithm of the above equation yields the
power in dBm as:
r 300
PBa. = PTdB. G Ta (0 ,) G Ba (0 )+ 20 log10 ¨ ¨ 2010 g io (fA/Hz )¨ K dB ¨
10a log10 (r)
47-/- i
=
[0080] In reality, various complex radio wave propagation mechanisms such as
reflection, diffraction, and blockage of LOS path due to hilly terrain,
manmade obstructions
or foliage can cause an excess loss (Lex) along the radio propagation path.
Modeling such
complex propagation mechanisms to achieve low prediction error require state
of the art
modeling expertise as well as an expensive GIS database for modeling the
environment along
with good amount of field data collection to calibrate the propagation model.
So the predicted
received power can be expressed as:
r 300
PRdB. = PTdB. +G Ta (0 ,) G Ba (0 ,) 20 logio ¨ ¨ 2010 gio (f )¨ K dB ¨
10a logio (r)+ Lex
47-/- y
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[0081] The difference in power received by the mobile between two sibling
sectors
at the same cell site will yield an equation that is mainly dependent upon the
difference in the
gains of the two sector antennas cancelling out all the common complex radio
waves
propagation mechanism between transmitting antenna and mobile station. So the
sibling pair
only based solution reduces system complexity and costs by avoiding
sophisticated modeling
techniques, GIS database and field data collection requirements.. All other
parameters cancel
in the differencing operation. This is written as:
( i
AF'dB (9) (PRldB PT1) (PR2dB,, PT2) +20 log10 = GT1aB(0)¨ GT2aB(0).
j2)
[0082] Therefore, with this model and with knowledge of the spatial responses
of
the sector antennas, the azimuth angle from the cell site to the unknown
mobile position can
be estimated. The spatial response can be manufacturer specified or derived
based on an
empirical model using antenna pattern characteristics such as main beam
pointing direction,
half power beamwidth (HPBW) and Front-to-back lobe ratio (FBR). Lines in the
direction of
estimated azimuth angle and the angular uncertainty associated with estimated
angle can be
drawn from two cell sites as shown in Figure 8. The powers from these sectors
can be
measured and their differences taken and compared to the model to find where
the two or
more lines along the estimated angles from two or more cell sites intersect
for a unique
location. In case, when a unique intersection point is not found based on the
estimated
azimuth angle, the common intersection region of two or more angular bands
associated with
uncertainty from two or more cell sites is used to estimate the mobile
location. When the TA
information is available for one or more reported serving cells, the common
intersection
region is further reduced as the overlapped region of TA based angular bands
and sibling pair
relative RSSI based angular bands to compute the final location estimate,
[0083] The range of a mobile from its serving cell is typically known by the
wireless network because the mobile must be time synchronized to its serving
cell to some
level for proper operation. Typically, the distance of the mobile from its
serving sector is
known over a band of ranges because of quantization of the time
synchronization.
Additionally, for sectored cell sites, the spatial response of the serving
sector's antenna will
limit the range band over an angular range. This information can be
incorporated in the
location determining process for increased accuracy and efficiency.
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[0084] Figure 8 geographically illustrates this concept where the search for
the
intersection of the two lines of power differences that best match those
measured by the
mobile is limited to the range band of the serving sector. In the Figure 8
scenario, three cell
sites 801 802 803, each with three sectors, are shown. Using the beacon signal
strengths and
identifiers sent by the mobile device, two sets of sibling pairs are found,
one pair associated
with the first adjacent cell site 802 and one pair associated with the second
adjacent cell site
803. The serving cell 801 determines a timing or power-based range shown by
the range band
804.
[0085] Using the sibling pair technique, lines of constant power difference
805 can
be shown from the first adjacent cell site 802. Similarly, lines of constant
power difference
806 can be shown from the second adjacent cell site 803.
[0086] The overlap between the line of bearings formed by the lines of
constant
power difference 805 806 and the range band 804 allow for determination of a
most likely
location 807 and an error range 808.
Figure 7a
[0087] Figure 7a graphically depicts a probabilistic method for power AoA
using
sibling pairs. A serving cell 701, a first adjacent cell 707 and a second
adjacent cell 708 are
involved in this location estimation example of the Power AoA or Adjacent
Sector technique.
The serving cell site 701 has a serving sector 702. The serving sector 702 has
a reported (by
the mobile) range band 703. The joint area of the serving sector 702 and range
band 703 is
subdivided radially into 2 or more divisions based on the cell size. On reach
radial 705, 1-to-n
"pixels" 704 are placed to generate a uniform coverage within the range band
703.
[0088] In the Figure 7a example, two sibling pairs of sector downlink transmit

antenna have been discovered at the first 707 and second 708 adjacent cell
sites. Using the
normalized reported downlink power for each sibling pair, a first 706 and
second 709
measured azimuth can be plotted.
[0089] Then for each pixel 704, a first 710 and second 711 theoretical azimuth
is
created for each pixel 704 using the pixel location, the previously determined
antenna
characteristics, and the normalized reported downlink power. The difference
between the
first measured azimuth 706 and the first theoretical azimuth 710 is determined
for each pixel
704. The difference between the second measured azimuth 709 and the second
theoretical
azimuth 711 is also then determined for each pixel 704. These differences
between the
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measured and theoretical model allow weighting of the pixel's location as a
probability.
Pixels showing minimal measured vs. modeled differences are granted a high
weight.
[0090] Once computation and weighting is concluded, a final location estimate
is
computed as the weighted average of the K pixels with the smallest geographic
differences
between the modeled and measured.
Figure 7b
[0091] Figure 7b illustrates geometrically the determination of the
differences
which generate the probability weighting for a single pixel 704. The first
measured 706 and
the first modeled 710 azimuth for first adjacent cell 707 are shown. The first
modeled
azimuth 710 passes through the pixel 704. The difference between the first
measured 706 and
the first modeled 710 azimuth is shown geographically 712.
[0092] If a second sibling pair exists, then the second measured 709 and the
second
modeled 711 azimuth are shown. The second modeled azimuth 711 passes through
the pixel
704. The geographic difference 713 between the second measured 709 and the
second
modeled 711 azimuth is shown.
[0093] Mathematically, a probabilistic approach for geolocation of mobiles
using
timing (Timing Advance (TA) in GSM) information and power information from the
wireless
network can be derived by creating a model of the timing advance and power
difference
between siblings of neighbor cells over the range band. These parameters are
assumed to
possess a Gaussian distribution with a known variance and a mean value equal
to the model,
or predicted value. Gaussian like normalized weights are defined as:
(measured ¨ predcited)2
W=e 2a2
for each of the parameters. The weights are evaluated over the range band for
all of the
parameters. This is accomplished by evaluating the weights at a number of
points or "pixels"
uniformly distributed about the range band as shown in Figure 7a. At each
"pixel" the
weights are combined in some fashion, i.e. multiplied and/or added for a final
result at each
pixel's location. The final location estimate is computed as the weighted
average of the K
pixels with the largest effective weights.
[0094] The effective weight at each pixel is given as:
W ¨ WRSSI * W *TA WAZ =
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[0095] WRSSI represents a weight based on modeled relative RSSI compared to
the
reported sibling cell sectors relative RSSI, WTA represents a weight based on
pixel distance
from reported serving cells TA based distance and WAz represents a weight
based on pixel
angle from reported primary serving cell's antenna main beam pointing
direction, which has
least TA value.
[0096] The effective weight of cumulative relative power matching error of all
the
reported cell sites at each pixel is given by one of the following two methods
(sum or product
of individual weights),
W RSSI nw-n* W RSSIn or W RSSI Eirn * W RSSIn
n=1 n=1
[0097] WRSSIn represents a normalized Gaussian weight as:
IRPineas RPpredl A PSS1 y.,
20-2
=
RSSIn
[0098] RP meas is the measured relative power in dB between sibling sectors at
cell
site n, RP pred _s i the model of the relative power, i.e. the predicted
value, in dB between sibling
sectors at cell site n at the pixel and aRssr2 is the known a priori variance
of the relative
powers over the coverage area. This weight value is only used when the
magnitude of the
difference between RP meas and RP pred _s i greater than ArssidB. When the
magnitude is less than
or equal to ArsszdB WRSSIn is set equal to 1.
[0099] Wn is a reliability weight of RF modeling as a function of measured
RSSI
difference and is given by:
)2
26,2
Wn =
when the magnitude of the measured relative power in dB at cell site n, i.e.
RP
- meas,
is greater
than 6measdB. Otherwise, Wn is given a value of 1.
[0100] When measurements from one or more serving cell sectors are available,
the
effective weight at each pixel is calculated over the primary serving cell TA
band as follows:
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S
W TA n WIAn =
s=1
[0101] S is the total number of reported serving cells, WTA i the TA distance
error
n .s
based weight for the nth reported serving cell and is given by the following
normal
distribution:
A y
WTA n =e ' 2,4
where dTA is the measured TA distance, d is the distance of the pixel, and o-
TA2 is the known a
priori variance. This weight value is only used when the magnitude of the
difference between
dTA and d is greater than Ad. When the magnitude is less than or equal to Ad
5W TAn is set equal
to 1.
[0102] The server probability weight as a function of azimuth angle from the
bore
site direction is given by:
1
W Az = ( [0.5+0.5 lefoosr( ,00: HBW
[0.5 + 0.5 cos(HB WA ] 4
for d HBW
01
Again, the effective weight for a pixel is the product of the above three
weights.
[0103] The final step of the location estimation involves sorting weights for
all of
pixels from largest to smallest and then choosing the K largest ones within
some pre-defined
percentage of the maximum weight and calculating a location that is the
weighted sum of the
pixel locations associated with these K weights. Mathematically, this is
written as:
K K
E wi xi E WiYi
Xest ¨ 1 Ki and yõt = 1=K1
E wi E wi
Illustrative Embodiments
1. Power AoA with 3-Sectored Serving and Adjacent Site(s)
[0104] In Figure 2, the location of a mobile device 202 using information from
an
omni-directional serving cell 201 and a neighboring sectored cell 203 is
shown. The serving
cell site 201 has a single serving sector (a CGI in GSM terminology or PCI in
LTE) with a
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range band 207. The size and width of range band 207 is based on the value of
the Timing
Advance (TA) and the precision of the Timing Advance value (a TA width is 554
meters in
GSM and 156 meters in LTE). The mobile device (e.g., an MS or UE) 202 must be
active to
allow production of measurement reports, but can be in a control channel
transaction or
traffic channel transaction while active. The active MS/UE 202 has a
bidirectional radio link
with the serving cell 201 and periodically scans and receives the beacon
broadcasts from the
sectors 204 205 of the adjacent cell 203.
[0105] Using the normalized received power and antenna models, bearing angles
206 209 corresponding to a standard deviation on either side of the mean
bearing angle
estimate originating from each sector 204 205 transmit antenna can be
calculated. By
combining the angle information standard deviations 206 209 and the range band
207, a
location estimate 208 for the mobile device can be calculated. This location
estimate 208 is
superior in accuracy as compared to a conventional cell-ID based location in
an
omnidirectional cell (the latitude and longitude of the serving cell 201). The
estimated
location error here can be calculated as the area encompassed by the range
band 207 and the
standard deviation of the bearing angles 206 209.
2. Power AoA with Omnidirectional Serving and Sectored Adjacent Site(s)
[0106] In Figure 3, the location of a mobile device 302 using an omni-
directional
serving site 301 and 3-sectored adjacent cell sites 305306 is shown. In the
serving cell/sector
301, a range band 304 is shown based on the value of the Timing Advance and
the precision
of the Timing Advance value. The mobile device 302 must be active to allow
production of
measurement reports, but can be in a control channel transaction or traffic
channel transaction
while active. The active MS/UE 302 has a bidirectional radio link 303 with the
serving cell
301 and periodically scans and receives the beacon broadcasts from sectors 307
308 of cell
305 and from sectors 309 310 from cell 306.
[0107] Using the normalized receive power and antenna models, a set of bearing

angles 311 312 313 314 corresponding to the standard deviation of the bearing
angle
estimates can be plotted for each reported sector 309 310 307 308 transmit
antenna. By
combining the angle information from bearing angles 311 312 313 314 and the
serving cell
301 range band 304, a location estimate 315 for the mobile device can be
calculated. This
location estimate 315 is superior in accuracy as compared to a conventional
cell-ID based
location in an omnidirectional cell (the latitude and longitude of the serving
cell 301). The
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estimated location error here can be calculated as the area encompassed by the
range band
304 and the standard deviations of the bearing estimates 311 312 313 314.
3. Power AoA with Two Nearby Sectored Sites
[0108] In Figure 4, the location of a mobile device 403 using nearby sectored
cell
sites 401 402 is shown. In this scenario, no serving cell power or timing
range band is
needed. The mobile device 403 need not be registered, active, or engaged in
duplex
communications with the wireless system providing the downlink beacons.
[0109] The mobile device 403 scans and receives the downlink beacon broadcasts

from the sectors 404 405 of cell 401 and from sectors 406 407 from cell 407.
Using the
normalized receive power and antenna models, a set of bearing angles 408 409
410 411
corresponding to the standard deviation of the bearing angle estimates can be
plotted for each
received sector 404 405 406 407 transmit antenna. By combining the angle
information from
bearing angles 408 409 410 411, a location 412 for the mobile device 403 can
be calculated.
The information needed for calculation of the mobile location 412 (the
transmission antenna
broadcast power, the antenna models, and the location of each downlink
transmission
antenna) may be broadcast by the wireless network, recorded locally on the
mobile device
403, or received from an alternative radio network. In some scenarios, the
mobile device 403
may collect the downlink signals and transmit over alternative means to a
landside server for
location calculation.
4. Power AoA with Three Nearby Sectored Sites
[0110] In Figure 5, the location of a mobile device 504 using nearby sectored
cell
sites 501 502 503 is shown. In this scenario, no serving cell power or timing
range band is
needed. The mobile device 504 need not be registered, active, or engaged in
duplex
communications with the wireless system providing the downlink beacons.
[0111] The mobile device 504 scans and receives the downlink beacon broadcasts

from sectors 505 506 of cell 501, sectors 507 508 of cell 502, and sectors 509
510 of cell 503.
Using the normalized receive power and antenna models, a set of bearing angles
511 512 513
514 515 516 corresponding to the standard deviation of the bearing angle
estimates can be
plotted for each received sector 505 506 507 508 509 510 transmit antenna. By
combining the
angle information from bearing angles 511 512 513 514 515 516, a location 517
for the
mobile device 504 can be calculated. The information needed for calculation of
the mobile
location 517 (the transmission antenna broadcast power, the antenna models,
and the location
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of each downlink transmission antenna) may be broadcast by the wireless
network, recorded
locally on the mobile device 517, or received from an alternative radio
network. In some
scenarios, the mobile device 504 may collect the downlink signals and transmit
over
alternative means to a landside server for location calculation.
Figure 6
[0112] Figure 6 depicts a Wireless Communications Network (WCN) for voice and
data communications. The WCN is comprised of the Radio Access Network (RAN)
602 and
the Core Network 609. A Wireless Location System (WLS) 610 is deployed to
support
location services.
[0113] The RAN 602 is comprised of a distributed network of radio transceiver
stations and antennae (RTS). Also known as Base Transceiver Stations, Radio
Base Stations,
Base Stations, NodeB's and Enhanced NodeB's, the RTS 603 604 605 come in a
variety of
different sizes, providing differing coverage areas and load capabilities. In
this example the
RTS are further described by their roles and proximity with respect to the
mobile station/User
Equipment (MS/UE) 601. The serving RTS 603 establishes and maintains the radio
link 606
with the MS/UE 601. The adjacent RTSs 605 and proximate RTSs 604 are potential
handover
candidates and the radio broadcast beacons from each RTS may be scanned by the
MS/UE
601 in accordance with the beacon allocation list present in the serving RTS
603 downlink
beacon.
[0114] Each RTS 603 604 605 connects with the core network 609 via a wired or
wireless data link 608. In a GSM system, BTS are interconnected to a Base
Station Controller
(BSC)/Packet Control Unit (PCU) while in an LTE system, the eNodeB are
interconnected to
a Mobility Management Entity (MME).
[0115] In the GSM example, the BTS 603 604 605 are connected to the BSC/PCU
611 by the Abis interface 609. The BSC/PCU 611 connects to the Mobile
Switching Center
(MSC) 613 via the A interface 612. The MSC typically also serves as the
Visitor Location
Register (VLR) where subscriber profiles from the HLR 615 are downloaded via
the SS7
network 614 as needed.
[0116] In an LTE network, the Core Network 609 is replaced by the System
Architecture Evolution (SAE) which takes advantage of the all-internet
protocol (IP) packet
routing area networks and increased microprocessor performance to create a
cheaper, scalable
core network. The four main components (not shown in the Figure 6 example) of
the SAE are
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the Mobility Management Entity (MME), Serving Gateway (SGW), the PDN Gateway
(PGW), and the Policy and Charging Rules Function (PCRF).
[0117] A Wireless Location System 610 for GSM is shown. The Serving Mobile
Location Center (SMLC) 619 interconnects with the BSC/PCU 611 via the 3GPP-
defined Lb
interface 616. The SMLC in turn interconnects (normally via intermediary
interfaces and
nodes) to the Gateway Mobile Location Center GMLC 617 via the Lg interface
618.
[0118] Not shown in this example illustration is the WLS for an LTE network.
The
LTE WLS is comprised of the E-SMLC (Evolved SMLC for LTE) which connects to
the
MME as described in 3GPP Technical Specification 36.305 v9.3, "Stage 2
functional
specification of User Equipment (UE) positioning in E-UTRAN".
Alternative Embodiments
User Plane
[0119] A user-plane approach (where the handset and a landside server interact
with
the WCN transparently providing a data connection) to the present invention is
possible using
the Subscriber Identity Module (SIM) toolkit (STK). The STK was originally
defined in the
European Telecommunications Standards Institute (ETSI) GSM 11.14 Technical
Standard
(TS) 11.14, "Specification of the SIM Application Toolkit (SAT) for the
Subscriber Identity
Module - Mobile Equipment (SIM-ME) interface." An updated toolkit standard for
the GSM,
UMTS, and LTE networks and the Universal Subscriber Identity Module (USIM) can
be
found in the 3'd Generation Partnership Program (3GPP) TS 31.111 "Universal
Subscriber
Identity Module (USIM) Application Toolkit (USAT)." The STK defined command
set allows
direct access of the MS/UE network, timing and power measurements by a
landside server.
Using the STK, the SMLC can request the network measurements without
interaction with
the WCN control nodes.
LMU-assisted system
[0120] Location Measurement Units (LMUs) are radio receivers typically co-
located with the wireless network's base stations normally installed to
facilitate uplink time-
difference-of-arrival (U-TDOA) and/or angle-of-arrival (AoA) location
techniques. The
primary advantage of using an LMU based system with Power AoA location is the
ability of
an LMU to measure the received downlink beacon identifiers and signal
strengths from
surrounding sectors resulting in an overlay system that, when coupled with the
SIM toolkit,
provide location services outside the control of the wireless communications
system operator.
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The combination of U-TDOA with ECID for calibration of the ECID location was
previously
taught in U.S. Application No. 11/736,950, filed April 18, 2007, "Sparsed U-
TDOA Wireless
Location Networks."
Method of Selecting Appropriate Location Estimate Solution
[0121] A wireless device location estimate solution (LES) comprises a means to

provide the probable location estimate and the associated uncertainty region
around the
location estimate for a specified confidence level of location estimate being
within the
uncertainty region. Herein is presented a fall-forward method of selecting an
appropriate
wireless device location estimate solution depending on the available input
information such
as number of cells with valid cell identifiers, cell type such as serving or
neighbor cell,
number of cells with valid time value, number of cells with valid power value
and number of
sibling pairs with valid power values in the input NMR (Network Measurement
Report) data
collected over a pre-defined period of time. The term NMR is used inclusively
and
encompasses technology dependent measurement reports examples include the CDMA

system's Reported Pilot Level (RPL) measurement, the UMTS Measurement Report
and LTE
system's Measurement Report,
[0122] Each cell sector in the cellular network can be assigned with a unique
numeric identifier associated with a combination of broadcast control channel
[for example:
BCCH (Broadcast Control Channel) in GSM, uARFCN (UMTS Terrestrial Radio Access

Absolute RF Channel Number) in UMTS or LTE] and base station identification
code [for
example: BSIC (Base Station Identity Code) in GSM, pSC (Pilot scrambling code)
in UMTS
or LTE] which are presented for the serving or neighbor cells in MR/NMR
(Measurement
Report/Network Measurement Report) data reported by mobile station back to the
network.
The network measured timing (for example: TA (Timing Advance) in GSM or LTE,
Pd
(Propagation delay) or RTT (Round-Trip-Time) in UMTS) information and/or the
mobile
station measured power [for example: RSSI (Received Signal Strength Indicator)
in GSM,
RSCP (Received Signal Code Power) in UMTS, RSRP (Reference Signal Received
Power)
in LTE] are available for each of the reported cells in the input NMR data.
The primary cell is
defined as the cell closest to the MS with least timing information value,
when one or more
reported cells have timing values or strongest power value, when none of the
cells have
reported timing information, but have reported power values.
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[0123] Various location estimate solutions applicable for different input NMR
data
information are presented to provide a location estimate based on a closed
form approximate
solution to a more accurate detailed solution based on a sophisticated radio
propagation
prediction model with low prediction errors and cellular network functionality
concepts of
defining a serving area for a serving cell and neighbor area for a neighbor or
a potential
handover cell. The shape of various geographic areas representing the timing
based distance
range band, power based distance range band, serving and neighbor areas could
be defined by
approximate closed form equations or a set of well-known shapes such as a
circle or rectangle
enclosing a complex shape of the geographic areas based on a sophisticated
radio propagation
prediction modeling.
[0124] The uncertainty region specification along with the location estimate
is
equally important to understand the error associated with the probable
location estimate. The
probable search area where the mobile may be located could be derived using
different
location estimation techniques presented in subsequent sections based on the
available input
information. The most probable location estimate could be computed as the
weighted average
of all or part of this search area based on the associated weights and the
corresponding
uncertainty region will be defined accordingly based on the quality as well as
the
combination of available input information for a specified confidence level of
being the
location estimate inside the provided uncertainty region.
[0125] Since the range of the available input information in NMR data is
limited to
be within certain known limits, each location solution could have an offline
generated ready
to use mapping table of available input information associated with the
corresponding
location estimate as well as the uncertainty region specification. This
approach can able to
achieve high location throughput yet keeping the real time system simple to
meet the
demands of various accuracy requirements as well as the complexity and cost of
the
associated deployment and maintenance.
[0126] For example when the flat file based proprietary location solution
database is
used, just the knowledge of the primary cell, its timing or power information
and the solution
type to be used limits the searching of database only to match the remaining
input
information against the contents of a specific file tagged with the solution
type, primary cell
identifier and the associated timing or power value. The contents of this file
include all the
possible combinations of other input information for the reported cells. In
this way, location
solution could be provided quickly even for a large sized cellular network of
tens of
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thousands of cell sites to achieve higher throughput yet keeping real time
system simple by
separating the underlying location technology and maintenance.
Figure 11
[0127] A high level overview of the appropriate location estimate solution
selection
process based on the available input information is shown in Figure 11. Using
the fall-
forward method, the database containing cell-level parameters (e.g. cell-ID,
cell service areas,
neighbor lists) is already established in the SMLC or location server. The
mobile collects
NMR data in the normal course of operations and this data is sent to the
Wireless
Communications Network (WCN) over the air interface. The NMR data is collected
by the
Wireless Location System (WLS) over duration 1101. This duration will vary
according to
the radio air interface technology and the WCN settings. The NMR data
collected will then
be pre-processed 1102 against the databased cell site and network information.
Validity of the
collected data will be ascertained by its correspondence to the possible
ranges or values held
in the databased information.
[0128] If in the collected NMR data, cells are found with valid timing 1103
(that is
within the limitations established from the databased cell site and network
information), then
a test for cells with valid power is performed 1109. If no valid power
measurements are
found in the collected NMR data, then scenario LES2 1110 (LES2: When only cell
Identifier
and time information is available) is activated. If instead valid power
measurements are
found in the collected NMR data, then a check for sibling pairs is performed
1111. If sibling
pair(s) are found, then then scenario LES6 1112 (LES6: When cell Identifier,
time and/or
power information is available for one or more serving and neighbor cells with
one or more
sibling pairs) is activated. If no sibling pair(s) are found in the collected
NMR data, then
scenario LESS 1113 (LESS: When cell Identifier, time and/or power information
is available
for one or more serving and/or neighbor cells without any sibling pair) is
activated.
[0129] If the collected NMR data, when tested for cells with valid timing
1103, does
not contain valid timing measurements, then that NMR data is tested for valid
power
measurements 1104. If no valid power measurements are found, the scenario LES1
1105
(LES1: When only cell Identifier information is available) is activated. If
instead valid power
measurements are found in the collected NMR data, then a check for sibling
pairs is
performed 1106. If sibling pair(s) are found, then then scenario LES4 1108
(LES4: When cell
Identifier and power information is available for two or more serving and/or
neighbor cells
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with one or more sibling pairs) is activated. If no sibling pair(s) is found
in the collected
NMR data, then scenario LES3 1107 (LES3: When only cell Identifiers and power
information is available for one or more serving and/or neighbor cells without
any sibling
pair) is activated.
[0130] The details of each scenario 1-6 introduced in Figure 11 are described
in the
subsequent sections. Depending on the complexity level of the solution and
throughput
requirements, it can be computed in real time or just use the readily
available mapping table
generated and maintained offline. The Universal Geographical Area Description
(as defined
in 3GPP Technical Specification No. 23.032; "Universal Geographical Area
Description
(GAD)" is used to describe all reported location estimates and error areas. In
many low-
accuracy location techniques, the reported location is the merely the center
or centroid of an
area of equal location probability.
1) LE51 : WHEN ONLY CELL IDENTIFIER INFORMATION IS AVAILABLE
[0131] When only one or more cell identifiers are reported during the period
of
NMR data collection time, a location estimation method is presented, which
could be better
than or equal to the standard available CID solution, which reports the cell
site location of the
primary serving cell.
[0132] When a single serving cell identifier is only reported the location
estimate is
computed as the centroid of serving cell's serving geographic area.
[0133] When two or more serving cell identifiers are only reported, the
location
estimate is computed as the centroid of the common region with highest number
of
overlapping of the serving geographic areas of the reported serving cells. For
example, when
three serving cells are reported and no common region is found among the
serving areas of all
three serving cells, then the common region overlapping with the serving areas
of only two
serving cells is selected instead.
[0134] When one or more neighbor cell identifiers are only reported without
any
serving cell information, the location estimate is computed as the centroid of
the common
region with highest number of overlapping of the neighbor geographic areas of
the reported
neighbor cells.
[0135] When one or more neighbor cells are reported in addition to one or more

serving cells, the location estimate is computed as the centroid of the common
region of
various serving geographic areas of the reported serving cells with highest
number of cells
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overlapping and is further biased towards the direction of the centroid of the
maximum
overlapping of neighbor geographic areas of the additional reported neighbor
cells. The
location estimate for the single or multiple reported serving cell identifier
combinations
availability over the NMR data collection time could be computed in real time
or loaded from
a pre-established location mapping table database created and maintained
offline for each
individual serving cell or multiple serving cells combinations within a
specific location
service area (LSA).
Figure 12
[0136] Figure 12 graphically depicts location estimation based on the service
area of
a cell-ID. A latitude 1201 and longitude 1202 map is used to help depict cell-
ID location. For
an omnidirectional cell centered on the base station antenna 1204, the
reported location is that
of the base station antenna 1204 with an error probability equal to the
service area 1203. For
a 120 degree (3-sectored) cell using a directional base station antenna, the
reported location
1206 is placed at the center of mass of the service area 1205. For a 60 degree
(6-sectored) cell
using a directional base station antenna, the reported location 1208 is placed
at the center of
mass of the service area 1207.
[0137] Improvements, based on the acquisition and use of historical location
data,
can be used to modify the reported location and location error as described in
U.S. Patent
Application 12/870,564; "Location Accuracy Improvement Using a priori
Probabilities"
Figure 13
[0138] Figure 13 graphically depicts location estimation based neighbor area
of two
sibling cells. Plotted on a latitude 1301 and longitude map, the sibling cells
are each sectors
on the same base station 1303. The serving sector's service area 1304 and the
neighboring
sector's service area 1305 are used to determine the location estimate 1306
and error area
based on the overlap between service areas.
Figure 14
[0139] Figure 14 graphically depicts location estimation based on the neighbor
area
of two non-sibling cells. Shown on the latitude 1401 and longitude 1402 map,
the serving and
neighbor cells (shown as sectors in this example) are based on two different
base stations
1403 1404. The service area of the serving cell 1405 and the service area of
the neighbor cell
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1406 overlap. The center of area 1407 of the overlap area 1408 is reported as
the estimated
location while the dimensions of the overlap area 1408 are used to describe
the error area.
Figure 15
[0140] Figure 15 graphically depicts location estimation based on the neighbor
area
of three cells with common region. As shown on the Latitude 1501 and Longitude
1502 plot,
three base stations 1503 1504 1505 have a cells with service areas 1506 1507
1508 that all
overlap. The centroid 1509 of the overlapping area 1510 is reported as the
location estimate
and the geographical area description of the overlapping area 1510 is reported
as the error
estimate.
Figure 16
[0141] Figure 16 graphically depicts location estimation based on the neighbor
areas
of three cells without a single/common, overlapping service area. In this
example, plotted on
a latitude 1601 and longitude 1602 map, three base stations 1603 1604 1605 are
sectorized.
The service areas 1606 1607 1608 do not share a common overlap area, however;
two service
areas 1606 1607 do overlap creating a partially common service area 1610.
Rather than
discard the information gleaned from the existence of the non-included service
area 1608, the
reported location estimate 1609 is offset from the center of the partially
common area 1610 in
direction of the non-included service area 1608 basestation 1605. The offset
is determined
from the relative power received from basestation 1605 versus those of the
other base stations
1603 1604.
2) LES2: WHEN ONLY CELL IDENTIFIER AND TIME INFORMATION IS AVAILABLE
[0142] When one or more serving cells with valid timing information are
reported
during the period of NMR data collection time, a location estimation method is
presented,
which could be better than or equal to the standard available Cell ID +Timing
Range (e.g.
CGI+TA in GSM) location of the primary serving cell. The primary serving cell
is the
closest cell to the MS with the least timing information value, when one or
more serving cells
report timing values.
[0143] A distance estimate along with the associated range uncertainty from a
reported serving cell site location can be computed from the network measured
timing
information. The distance range estimate for each timing value could be
defined by a simple
closed form equation or a set of well-known shapes such as a circle or
rectangle enclosing the
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complex shape of the geographic distance range area based on a sophisticated
radio
propagation prediction modeling.
[0144] When timing information for a single serving cell is reported during a
period
of NMR data collection time, the location estimate is computed as the centroid
of the serving
cell sector's timing based range band along radial direction over associated
range uncertainty
and along angular direction within the serving area of the serving cell.
[0145] When timing information for two or more serving cells are reported over
a
period of NMR data collection time, the location estimate is computed as the
centroid of the
common region of various serving cell sector's timing based range bands along
radial
direction over associated range uncertainty and along angular direction within
the serving
areas of the reported serving cells. Final location estimate is restricted to
be within the
primary serving cell's distance range band along the direction of common
region's centroid
from the primary serving cell location.
[0146] When one or more serving cell identifiers are also reported without any

timing information in addition to one or more serving cells with valid timing
information, the
location estimate is computed as the centroid of the timing information based
common region
and further biased towards the direction of the maximum overlapping of server
geographic
areas of the additional reported serving cells. Final location estimate is
restricted to be within
the primary serving cell's distance range band along the direction of the
previous best
location estimate from the primary serving cell location.
[0147] When one or more neighbor cell identifiers are reported without any
power
information in addition to one or more serving cells with timing information,
the location
estimate is computed as the centroid of the timing information based common
region and
biased further towards the direction of the maximum overlapping of neighbor
geographic
areas of the additional reported neighbor cells. Final location estimate is
restricted to be
within the primary serving cell's distance range band along the direction of
the previous best
location estimate from the primary serving cell location.
[0148] The location estimate for the single or multiple reported serving cells
timing
and power availability combinations availability over the NMR data collection
time could be
computed in real time or loaded from a pre-established location mapping table
database
created and maintained offline for each individual serving cell or multiple
serving cells
combinations within a specific location service area (LSA).
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Figure 17
[0149] Figure 17 graphically depicts location estimation based on a
combination of
timing range and service areas from 3 cells. As shown on the latitude 1701
longitude 1702
map, in this example the three base stations 1703 1704 1705 have a common area
1709. In
this example the common area 1709 is constrained by the serving areas of cells
1706 1708
and that of a timing range band 1707. The reported location estimate 1710 is
calculated as the
centroid of the common area and the error area estimate is reported using area
and shape of
the common area 1710.
Figure 18
[0150] Figure 18 graphically depicts location estimation based on a
combination of
timing ranges and service areas from 3 cells over a region defined by latitude
1801 and
longitude 1802. As shown in this example, timing range information is
available from two
base stations 1803 1804 while at least a third base station's 1805 beacon and
thus service area
1808 is acquired. A common area 1810 is formed by the intersection of the two
range bands
1806 1807 and the service area 1808. The reported location estimate 1809 is
calculated as the
centroid of the common area 1810 and the error area estimate is reported as
the dimensions of
the common area 1810.
3) LES3: WHEN ONLY CELL IDENTIFIERS AND POWER INFORMATION IS
AVAILABLE
FOR ONE OR MORE SERVING AND/OR NEIGHBOR CELLS WITHOUT ANY SIBLING PAIR
[0151] Distance estimate along with the associated range uncertainty from a
reported serving or neighbor cell site location can be computed from the
mobile measured
power information normalized to its effective radiated power (ERP) by using
the path loss
model. The distance range estimate for each power value could be defined by a
closed form
equation or a set of well-known shapes such as a circle or rectangle enclosing
the complex
shape of the geographic distance range area based on a sophisticated radio
propagation
prediction modeling.
[0152] When only power information for one or more serving cells is reported
during a period of NMR data collection time, the location estimate is computed
as the
centroid of the region with highest number of overlapping of various serving
cells serving
areas and the reported power based range bands along the radial direction over
associated
range uncertainty.
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[0153] When only power information for one or more neighbor cells is reported
during a period of NMR data collection time, the location estimate is computed
as the
centroid of the region with highest number of overlapping of various neighbor
cells neighbor
areas and the reported power based range bands along radial direction over
associated range
uncertainty.
[0154] When power information for two or more serving and/or neighbor cells is

reported during a period of NMR data collection time, the location estimate is
computed as
the centroid of the common region of various serving and/or neighbor areas and
the reported
power based range bands along radial and angular directions over the
associated range
uncertainty.
[0155] The location estimate for the case of one or more reported serving
and/or
neighbor cells power availability in the absence of sibling pairs over the NMR
data collection
time could be computed in real time or loaded from a pre-established location
mapping table
database created and maintained offline for each individual serving or
neighbor cell or
multiple serving and/or neighbor cells combinations within a specific location
service area
(LSA).
Figure 19
[0156] Figure 19 graphically depicts location estimation based on power
ranging
from the serving cell and at least two neighboring cells. In this example,
three base stations
1903 1904 1905 serve a geographic region dimensioned by latitude 1901 and
longitude 1902.
Three power derived range bands 1906 1907 1908 are available for positioning.
The common
area 1910 created from the intersection of the three power range bands 1906
1907 1908 all
calculation of the centroid 1909 of the common area 1910. The centroid 1909 is
reported as
the estimated location while the common area 1910 size and shape are reported
as the error
estimate.
Figure 20
[0157] Figure 20 graphically depicts location estimation based on power
ranging
from the serving cell and service areas of at least two neighboring cells. As
shown on the
latitude 2001 longitude 2002 map, in this example the three base stations 2003
2004 2005
have a common area 2010 formed from the service areas 2006 2008 of the
neighboring cells
2035 2003 and a power range band 2007 from the serving cell 2004. Based on the
common
area 2010, the centroid 2009 is calculated. The centroid 2009 is then is
reported as the
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estimated location while the common area 2010 size and shape are reported as
the error
estimate.
4) LES4: WHEN CELL IDENTIFIER AND POWER INFORMATION IS AVAILABLE FOR
TWO OR MORE SERVING AND/OR NEIGHBOR CELLS WITH ONE OR MORE SIBLING PAIRS
[0158] A special case of using power measurements from at least one pair of
sibling
cells could simplify the overall location estimation system complexity and
deployment costs
to achieve same level of accuracy by cancelling out the complex radio
propagation path
impairments between the sibling cells and the MS. A sibling pair comprises two
downlink
transmission antennae of a multi-sector cell site, which are located within
100m from each
other and their antenna pattern main beam pointing to different directions.
[0159] When a single sibling pair is only reported in the input NMR data, the
location estimate is computed as the centroid of the common region between the
estimated
azimuth angular band with the associated uncertainty from the sibling cell
tower location
based on the relative power, the power based distance bands along radial and
azimuthal
direction over the associated range uncertainty and the serving and/or the
neighbor areas of
all the individual reported cells. The final location estimate is restricted
to be within the
sibling pair based azimuth band.
[0160] When two or more sibling pairs are reported in the input NMR data, the
preliminary search area is computed as the common region of the corresponding
azimuth
bands estimated from each sibling pair tower location based on their relative
power. The
preliminary search area is further reduced by using the maximum overlapped
area of serving
and/or neighbor areas as well as the power based distance bands along radial
and azimuthal
direction over the associated range uncertainty of the individual reported
cells, if possible.
The final location estimate is computed as the centroid of the reduced
preliminary search area
and is restricted to be within the sibling pairs relative power based
preliminary search area.
[0161] The location estimate for the case of one or more reported serving
and/or
neighbor cells power availability in the presence of sibling pairs over the
NMR data
collection time could be computed in real time or loaded from a pre-
established location
mapping table database created and maintained offline for each primary serving
cell or
multiple serving and/or neighbor cells combinations within a specific location
service area
(LSA).
Figure 21
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[0162] Figure 21 graphically depicts location estimation based on power
ranging
from the serving cell and a sibling neighbor cell. Plotted on a latitudinal
2101 and
longitudinal 2102 map, a single basestation 2103 supports at least two cells
(sectors). Known
as sibling pair prior to location calculation, the two sibling cells allow
production of two
power-based range bands 2104 2105 and an angle vector 2106. The intersection
of the power
range bands 2104 2105 and the angle vector 2106 produce an equipotential area
2108 in
which the centroid 2107 is reported as the location estimate and the
equipotential area 2108 is
reported as the error estimate.
Figure 22
[0163] Figure 22 graphically depicts location estimation using power ranging
between sibling cells and the service area of at least one additional neighbor
cell. In this
example, three base stations 2203 2204 2205 are depicted on a geographical
area defined by
latitude 2203 and longitude 2202. At least one base station 2204 has a sibling
pair set of cells
(sectors). From the sibling pair, two power-range bands 2207 2208 and an angle
vector 2210
can be determined. These measurements combined with the service areas 2206
2209 from the
nearby base stations 2203 2205 form a common area 2211 (in this example). The
centroid
2212 of the common area 2211 is reported as the location estimate and the
equipotential
common area 2211 is reported as the error estimate.
Figure 23
[0164] Figure 23 graphically depicts location estimation using power ranging
between sibling cells and the power range from one additional neighbor cell.
As shown on the
map of latitude 2301 and longitude 2302, at least two base stations 2303 2304
are
geographically proximate. One base station 2303 has a sibling pair of cells
(sectors) allowing
two power measurements and thus two power-range bands 2306 2307 to be
calculated. Also
from the two power measurements, an angle vector 2308 can be derived. Using
the power-
range band 2305 determined from the transmissions from the other basestation
2303 with the
aforementioned, a common area 2310 may be determined. The centroid 2309 of the
common
area 2310 is reported as the location estimate and the equipotential common
area 2310 is
reported as the error estimate.
5) LESS: WHEN CELL IDENTIFIER, TIME AND/OR POWER INFORMATION IS
AVAILABLE FOR ONE OR MORE SERVING AND/OR NEIGHBOR CELLS WITHOUT ANY SIBLING
PAIR
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[0165] When timing information for one or more serving cells are reported over
a
period of NMR data collection time, the preliminary search area is computed as
the common
region of various serving cell sector's timing based range bands along radial
and angular
directions over associated range uncertainty.
[0166] The timing based preliminary search area could be further reduced by
using
the power based distance bands along radial and azimuthal direction over the
associated
range uncertainty, the serving and neighbor areas of all the reported serving
and neighbor
cells. The final location estimate is computed as the centroid of the final
search area and is
restricted to be within the timing based preliminary search area.
[0167] The location estimate for the case of one or more reported serving
and/or
neighbor cells time and/or power availability in the absence of sibling pairs
over the NMR
data collection time could be computed in real time or loaded from a pre-
established location
mapping table database created and maintained offline for each primary serving
cell or
multiple serving and/or neighbor cells combinations within a specific location
service area
(LSA).
Figure 24
[0168] Figure 24 graphically depicts location estimation using cell
identifier, time
and/or power information as available for one or more serving and/or neighbor
cells without
any sibling pair(s). As shown on the map of latitude 2401 and longitude 2402,
four base
stations 2403 2404 2405 2406 are geographically proximate. In this example,
two base
stations 2404 2406 have cells with power reported and thus two power range
bands 2410
2411 can be plotted for the reporting cells (sectors). Two basestations
24032405 have both a
reporting cell (producing serving areas 2407 2409) and a timing range for each
cell 2408
2412. Combining the geographical areas of the service area(s) 2402 2409, the
power range
band(s) 2410 2411, and the timing band(s) 2408 2412 yields a common area 2413.
The
centroid 2414 of the common area 2413 is reported as the location estimate and
the
equipotential common area 2413 is reported as the error estimate.
6) LES6: WHEN CELL IDENTIFIER, TIME AND/OR POWER INFORMATION IS
AVAILABLE FOR ONE OR MORE SERVING AND NEIGHBOR CELLS WITH ONE OR MORE SIBLING

PAIRS
[0169] When timing information for one or more serving cells are reported over
a
period of NMR data collection time, the preliminary search area is computed as
the common
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region of various serving cell sector's timing based range bands along radial
and angular
directions over associated range uncertainty. The serving cells timing based
search area is
further reduced by taking the maximum overlapping region of the estimated
azimuth bands
from the one or more sibling cell towers based on the sibling pairs relative
power.
[0170] The timing and sibling pair relative power based preliminary search
area
could be further reduced by using the power based distance bands along radial
and azimuthal
direction over the associated range uncertainty, the serving and neighbor
areas of all the
reported serving and neighbor cells. The final location estimate is computed
as the centroid of
the final search area and is restricted to be within the timing and sibling
pair relative power
based preliminary search area.
[0171] The location estimate for the case of one or more reported serving
and/or
neighbor cells time and/or power availability with the presence of sibling
pairs over the NMR
data collection time could be computed in real time or loaded from a pre-
established location
mapping table database created and maintained offline for each primary serving
cell or
multiple serving and/or neighbor cells combinations within a specific location
service area
(LSA).
Figure 25
[0172] Figure 25 graphically depicts location estimation using cell
identifier, time
and/or power information as available for one or more serving and neighbor
cells with one or
more sibling pairs. As shown on the map of latitude 2501 and longitude 2502,
four base
stations 2503 2504 2505 2506 are geographically proximate in this example. Two
base
stations 2404 2406 have cells with power reported and thus two power range
bands 2507
2509 can be plotted for the reporting cells (sectors). One base station 2505
has both a
reporting cell (producing serving area 2510) and a cell with timing range
2511. A base station
2503 has two similarly equipped cells reporting power, so a sibling pair
condition exists and a
power-based angle is produced 2508. Combining the geographical areas of the
service area
2510, the power range band(s) 2507 2509, the timing band 2511 and the angle
measurement
from the sibling pair yields a common area 2512. The centroid 2513 of the
common area
2512 is reported as the location estimate and the equipotential common area
2512 is reported
as the error estimate.
[0173] Any of the above mentioned aspects can be implemented in methods,
systems, computer readable media, or any type of manufacture. It should be
understood to
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CA 02884732 2015-03-12
WO 2014/047352 PCT/US2013/060719
those skilled in the art that the various techniques described herein may be
implemented in
connection with hardware or software or, where appropriate, with a combination
of both. For
example, aspects of the invention may execute on a programmed computer. Thus,
the
methods and apparatus of the invention, or certain aspects or portions
thereof, may take the
form of program code (i.e., instructions) embodied in tangible media, such as
floppy
diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium
wherein,
when the program code is loaded into and executed by a machine, such as a
computer, the
machine becomes an apparatus for practicing the invention. In the case of
program code
execution on programmable computers, the computing device generally includes a
processor,
a storage medium readable by the processor (including volatile and non-
volatile memory
and/or storage elements), at least one input device, and at least one output
device. Such
programs are preferably implemented in a high level procedural or object
oriented
programming language to communicate with a computer system. However, the
program(s)
can be implemented in assembly or machine language, if desired. In any case,
the language
may be a compiled or interpreted language, and combined with hardware
implementations. In
example embodiments a computer readable storage media can include for example,
random
access memory (RAM), a storage device, e.g., electromechanical hard drive,
solid state hard
drive, etc., firmware, e.g., FLASH RAM or ROM, and removable storage devices
such as, for
example, CD-ROMs, floppy disks, DVDs, FLASH drives, external storage devices,
etc. It
should be appreciated by those skilled in the art that other types of computer
readable storage
media can be used such as magnetic cassettes, flash memory cards, digital
video disks,
Bernoulli cartridges, and the like. The computer readable storage media may
provide non-
volatile storage of processor executable instructions, data structures,
program modules and
other data for a computer.
Conclusion
[0174] The true scope of the present invention is not limited to the presently

preferred embodiments disclosed herein. For example, the foregoing disclosure
of methods
and systems for use in locating a mobile device and for computationally
selecting a location
estimate solution uses explanatory terms, such as wireless location system,
base transceiver
station (BTS), Network Measurement Report (NMR), timing advance (TA), cell
identifier,
scenarios (LES1, LES2, etc.), and the like, which should not be construed so
as to limit the
scope of protection of the following claims, or to otherwise imply that the
inventive aspects
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CA 02884732 2015-03-12
WO 2014/047352 PCT/US2013/060719
of the time and power based location techniques and ways of selecting a
location estimate
solution are limited to the particular methods and apparatus disclosed.
Accordingly, except as
they may be expressly so limited, the scope of protection of the following
claims is not
intended to be limited to the specific embodiments described above.
- 38 -

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date Unavailable
(86) PCT Filing Date 2013-09-19
(87) PCT Publication Date 2014-03-27
(85) National Entry 2015-03-12
Examination Requested 2015-03-12
Dead Application 2017-09-19

Abandonment History

Abandonment Date Reason Reinstatement Date
2016-09-19 FAILURE TO PAY APPLICATION MAINTENANCE FEE

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $800.00 2015-03-12
Application Fee $400.00 2015-03-12
Maintenance Fee - Application - New Act 2 2015-09-21 $100.00 2015-08-25
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
TRUEPOSITION, INC.
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Date
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Number of pages   Size of Image (KB) 
Abstract 2015-03-12 2 73
Claims 2015-03-12 18 889
Drawings 2015-03-12 19 503
Description 2015-03-12 38 2,051
Representative Drawing 2015-03-19 1 15
Cover Page 2015-04-01 1 47
Description 2016-04-26 37 2,005
Claims 2016-04-26 14 533
PCT 2015-03-12 5 284
Assignment 2015-03-12 5 189
Examiner Requisition 2015-10-26 4 258
Amendment 2016-04-26 22 790