Description
Title of Invention: POSITION ESTIMATING APPARATUS,
POSITION ESTIMATING METHOD, AND COMPUTER
PROGRAM PRODUCT
Technical Field
[0001] The present disclosure relates to a position estimating apparatus, a position e s
timating method, and a computer program product.
Background Art
[0002] Recently, receiver apparatuses capable of receiving wireless signals transmitted from
satellites have been installed in moving bodies such as vehicles, mobile telephones,
and the like. By using GPS (Global Positioning System) positioning, it is possible to
estimate the position of the moving body in which the receiver apparatus is installed.
Such position estimating technology that uses a receiver apparatus is an important base
technology in a wide range of fields such as navigation, security and entertainment.
However, position estimating technology based on GPS positioning requires a long
time at startup for supplementary synchronization and is difficult to use inside
buildings and underground that are out of range for the wireless signals from satellites.
[0003] Also, as disclosed in Japanese Laid-Open Patent Publication No. 2008-104029 for
example, a method of estimating the position of a wireless terminal based on the signal
strength at the wireless terminal of wireless signals transmitted from base stations on a
wireless LAN (Local Area Network) has been proposed. More specifically, it is
possible to estimate the position of the wireless terminal based on position information
of respective base stations registered in advance and the distances between the base
stations and the wireless terminal calculated from the respective signal strengths of the
wireless signals. Since base stations on a wireless LAN are also set up inside buildings
and underground, by using this method of estimating, it is possible to carry out position
estimation inside buildings and underground which has been difficult for position e s
timating technology based on GPS positioning.
[0004]
Citation List
Patent Literature
[0005] PTL 1: JP 2008-104029A
Summary
Technical Problem
[0006] However, a case can be imagined where, due to movement of the base station or the
like, the registered base station position information is erroneous. If position estimation
is carried out based on such erroneous base station position information, the precision
of the position estimation will fall. Such concern has significantly increased in recent
years due to the spread of mobile base stations that are carried by the user.
[0007] The present disclosure aims to provide a novel and improved position estimating
apparatus, position estimating method, and computer program product that are capable
of suppressing a fall in the precision of position estimation.
Solution to Problem
[0008] According to one embodiment, a position estimation apparatus includes
a reference area determining unit determines a reference area that includes a position
of a mobile communications station, and
a position estimation unit that estimates the position of the mobile communication
station based on position information of a plurality of transmitters within the reference
area.
[0009] One aspect of the apparatus is that the reference area determining unit determines the
reference area by combining an estimated move distance of the apparatus with a prede
termined communication range of at least one of the plurality of transmitters.
[0010] Another aspect is that the apparatus includes a movement detector that estimates the
estimated move distance of the apparatus.
[001 1] Another aspect is that the movement detector being an accelerometer.
[0012] According to a different aspect, the apparatus includes
a GPS-based location device that detects location information based on wireless
satellite transmissions, wherein
the reference area determining unit determines the reference area by combining a
GPS uncertainty amount with a predetermined communication range of at least one of
the plurality of transmitters.
[0013] According to another aspect, the device includes
a computer readable storage device that stores a previous position estimation result
for the apparatus in association with time, wherein
and the reference area determining unit determines the reference area by using the
previous position estimation result as a standard.
[0014] According to another aspect, the reference area determining unit determines the
reference area by calculating the estimated move distance.
[0015] According to another aspect the position estimation unit estimates the move distance
by measuring a propagation distance from the plurality of transmitters.
[0016] According to another aspect the position estimation unit excludes from consideration
transmitters outside of the reference area based on signal information from respective
of the plurality of transmitters.
According to another aspect the position estimation unit estimates the position of the
mobile communication station by calculation of
(Mathematical Formula 1)
1
Wi =
distS(0,Ai)
(Mathematical Formula 2)
(Mathematical Formula 3)
, wherein
O being a position, A being position information of an ith transmitter, and W being
a weighting coefficient.
[0018] According to another aspect the apparatus also includes a computer readable storage
unit that stores transmitter reliability information regarding whether a particular
transmitter has been detected as having a low reliability with at least a predetermined
frequency of occurrence, and
the position estimation unit excludes transmitters having a stored reliability below a
predetermined threshold when estimating the position of the mobile communication
station.
[0019] According to another aspect, the position estimation unit excludes transmitters
having a received signal characteristic indicating the transmitter is outside of the
reference area.
[0020] The apparatus may also include a communications interface that receives transmitter
signal information and reference area information from the mobile communication
station, and sends an estimate of the position of the mobile communication station to
the mobile communication station.
[0021] Optionally, the apparatus includes the mobile communication station.
[0022] In a process based embodiment, the method includes
determining with a processing device a reference area including a position of a
mobile communications station; and
estimating the position of the mobile communication station based on position in
formation of a plurality of transmitters within the reference area.
[0023] According to a computer readable storage device embodiment, the device has
computer readable instructions that when executed by a processing device perform a
position estimation method comprising:
determining with the processing device a reference area including a position of a
mobile communications station; and
estimating the position of the mobile communication station based on position in
formation of a plurality of transmitters within the reference area.
[0024] In a mobile commuications device embodiment, the device includes
a receiver that receives transmissions from a plurality of transmitters;
a reference area determining unit that determines a reference area that includes
therein a position of the mobile communications station; and
a communication interface that sends
signal information from the transmissions of the plurality of transmitters, and
the reference area to a remote device,
and receives from the remote device an estimated position of the mobile commu
nication station after the remote device used the signal information and reference area
to estimate the position of the mobile communication station by using transmissions
from a subset of the plurality of transmitters located within the reference area and
excluding transmissions from a subset of the plurality of transmitters located outside of
the reference area.
[0025] In an apparatus-centric embodiment, that communications with a remote device, op
tionally available as a cloud resource, the method includes
receiving transmissions from a plurality of transmitters;
determining with a processing device a reference area that includes therein a position
of the mobile communications station;
sending signal information from the transmissions of the plurality of transmitters to a
remote device;
sending the reference area to the remote device; and
receiving from the remote device an estimated position of the mobile communication
station after the remote device used the signal information and reference area to
estimate the position of the mobile communication station by using transmissions from
a subset of the plurality of transmitters located within the reference area and excluding
transmissions from a subset of the plurality of transmitters located outside of the
reference area.
[0026] In an apparatus-centric embodiment, that communications with a remote device, op
tionally available as a cloud resource, instructions are stored on a computer readable
medium that when executed by a processing device perform a position estimation
method comprising:
receiving transmissions from a plurality of transmitters;
determining with a processing device a reference area that includes therein a position
of the mobile communications station;
sending signal information from the transmissions of the plurality of transmitters to a
remote device;
sending the reference area to the remote device; and
receiving from the remote device an estimated position of the mobile communication
station after the remote device used the signal information and reference area to
estimate the position of the mobile communication station by using transmissions from
a subset of the plurality of transmitters located within the reference area and excluding
transmission from a subset of the plurality of transmitters located outside of the
reference area.
Advantageous Effects of Invention
[0027] According to embodiments of the present disclosure described above, it is possible to
suppress a fall in the precision of position estimation.
Brief Description of Drawings
[0028] [fig.l]
[0029] Fig. 1 is a diagram useful in explaining the configuration of a position estimating
system according to embodiments of the present disclosure.
[fig.2]
[0030] Fig. 2 is a diagram useful in explaining specific examples of position information of
base stations stored by a wireless terminal.
[fig.3]
[0031] Fig. 3 is a diagram useful in explaining specific examples of measurement in
formation.
[fig.4]
[0032] Fig. 4 is a diagram useful in showing examples of estimation results for different e s
timation methods.
[fig.5]
[0033] Fig. 5 is a functional block diagram showing the configuration of a wireless terminal
according to a first embodiment of the present disclosure.
[fig.6]
[0034] Fig. 6 is a diagram useful in explaining specific examples of position estimation
results stored by an estimation result storage unit.
[fig.7]
[0035] Fig. 7 is a diagram useful in explaining a specific example of a reference area.
[fig.8]
[0036] Fig. 8 is a flowchart showing the operation of the wireless terminal according to the
first embodiment.
[fig.9]
[0037] Fig. 9 is a functional block diagram showing the configuration of a wireless terminal
according to a second embodiment of the present disclosure
[fig. 10]
[0038] Fig. 10 is a diagram useful in explaining a specific example of a reference area
[fig. 11]
[0039] Fig. 11 is a flowchart showing the operation of the wireless terminal according to the
second embodiment
[fig. 12]
[0040] Fig. 12 is a functional block diagram showing the configuration of a wireless
terminal according to a third embodiment of the present disclosure
[fig. 13]
[0041] Fig. 13 is a diagram useful in showing specific examples of low reliability base
station information stored by a low reliability base station information storage unit
[fig. 14]
[0042] Fig. 14 is a diagram useful in showing specific examples of mobile base station in
formation stored by a mobile base station information storage unit
[fig. 15]
[0043] Fig. 15 is a flowchart showing an example operation of the wireless terminal
according to the third embodiment
[fig. 16]
[0044] Fig. 16 is a flowchart showing an example operation of the wireless terminal
according to the third embodiment
[fig. 17]
[0045] Fig. 17 is a diagram useful in explaining the configuration of a position estimating
system according to a fourth embodiment.
[fig.18]
[0046] Fig. 18 is a functional block diagram showing the configuration of a position e s
timating apparatus according to the fourth embodiment
[fig. 19]
[0047] Fig. 19 is a sequence chart showing the operation of the position estimating system
according to the fourth embodiment.
Description of Embodiments
[0048] Hereinafter, preferred embodiments of the present disclosure will be described in
detail with reference to the appended drawings. Note that, in this specification and the
appended drawings, structural elements that have substantially the same function and
structure are denoted with the same reference numerals, and repeated explanation of
these structural elements is omitted.
[0049] Also, in the present specification and drawings, in some cases a plurality of structural
elements that have effectively the same functional configuration are distinguished from
one another by appending different letters to the same reference numeral. For example,
a plurality of structural elements with effectively the same functional configuration are
distinguished as necessary as the "base stations 30A, 30B, and 30C". However, when it
is not especially necessary to distinguish between the plurality of structural elements
with effectively the same functional configuration, the same reference numeral is used.
For example, the base stations 30A, 30B, and 30C are referred to simply as the "base
station 30" when it is not especially necessary to distinguish between them.
[0050] Embodiments of the present disclosure will now be described in the order indicated
below.
[0051] 1. Fundamental Configuration of Position Estimating System
[0052] 2. First Embodiment
[0053] 2-1. Configuration of Wireless Terminal According to First Embodiment
[0054] 2-2. Operation of Wireless Terminal According to First Embodiment
[0055] 3. Second Embodiment
[0056] 3-1. Configuration of Wireless Terminal According to Second Embodiment
[0057] 3-2. Operation of Wireless Terminal According to Second Embodiment
[0058] 4. Third Embodiment
[0059] 4-1. Configuration of Wireless Terminal According to Third Embodiment
[0060] 4-2. Operation of Wireless Terminal According to Third Embodiment
[0061] 5. Fourth Embodiment
[0062] 5-1. Configuration of Position Estimating System According to Fourth Embodiment
[0063] 5-2. Configuration of Position Estimating Apparatus According to Fourth Em
bodiment
[0064] 5-3. Operation of Position Estimating System According to Fourth Embodiment
[0065] 6. Conclusion
[0066] 1. Fundamental Configuration of Position Estimating System
[0067] As described in detail below in the "2. First Embodiment" to "5. Fourth Em
bodiment" sections for example, the present disclosure has a variety of possible imple
mentations. The "position estimating apparatus 20" or "wireless terminal 40" according
to such embodiments includes:
[0068] (1) a base station information storage unit (216, 416) that stores position information
for base stations; and
[0069] (2) a position estimating unit (236, 436) that estimates measurement information of
wireless signals based on the position information of base stations whose position in
formation stored in the base station information storage unit is in a limited range and
measurement information for the signal strengths of wireless signals transmitted from
such base stations.
[0070] First, the fundamental configuration that is common to the respective embodiments
will be described with reference to Figs. 1 to 3.
[0071] Fig. 1 is a diagram useful in explaining the configuration of a position estimating
system 1 according to the embodiments of the present disclosure. As shown in Fig. 1,
the position estimating system 1 according to the embodiments of the present
disclosure includes a plurality of base stations 30 and a wireless terminal 40.
[0072] Each base station 30 controls communication between communication apparatuses
that are spatially distributed. As examples, the base stations 30 are capable of con
trolling wireless communication between the wireless terminal 40 and another wireless
terminal (not shown) that are both located in the respective signal ranges of the base
stations 30 and/or controlling communication between the wireless terminal 40 and a
communication apparatus that is connected by wires to a base station 30. More
specifically, the base stations 30 may be base stations on a wireless LAN (Local Area
Network) based on WiFi (Wireless Fidelity) Standard, LTE (Long Term Evolution)
base stations, GSM (Global System for Mobile Communications) base stations, or
BLUETOOTH (registered trademark) base stations.
[0073] In addition, the base stations 30 form a wireless network by regularly transmitting a
beacon signal, for example. Here, the expression "beacon signal" includes a beacon
signal including a base station ID identifying each base station 30. This means that it is
possible for the wireless terminal 40 to specify the base station 30 that transmitted a
beacon signal that has been received from the base station ID included in the beacon
signal.
[0074] The wireless terminal 40 is capable of wirelessly transmitting and receiving various
data in accordance with control by the base stations 30. For example, the wireless
terminal 40 is capable of receiving content data from a content distribution server (not
shown) and/or transmitting and receiving electronic mail to or from another wireless
terminal via the base stations 30. Note that various data, for example, audio data (such
as music, a performance, or a radio program), image data (such as a movie, a television
program, a video program, photographs, artwork, or drawings), games, and software,
can be given as examples of the content data.
[0075] As examples, the wireless terminal 40 may be an information processing apparatus
such as a PC (personal computer), a home video processing apparatus (a DVD
recorder, video deck, or the like), a mobile telephone, a PHS (Personal Handyphone
System), a mobile music player, a mobile video processing apparatus, a PDA (Personal
Digital Assistant), a home game console, a mobile game console, or a home appliance.
[0076] When a wireless signal (for example, a beacon signal) transmitted from a base station
30 is received, the wireless terminal 40 is also capable of measuring the signal strength
of such wireless signal. The wireless terminal 40 also stores position information for
the respective base stations 30 and is capable of estimating the position of the wireless
terminal 40 based on the position information of the respective base stations 30 and the
measurement information for the wireless signals. Specific examples of the position in
formation of the respective base stations 30 stored by the wireless terminal 40 and the
measurement information will now be described.
[0077] Fig. 2 is a diagram useful in explaining specific examples of the position information
of the base stations 30 stored by the wireless terminal 40. As shown in Fig. 2, the
wireless terminal 40 stores base station information of a plurality of base stations 30
made up of base station IDs and position information. Note that in the present speci
fication, for ease of explanation, it is assumed that the code assigned to each base
station and the base station ID are the same.
[0078] Although the position information is shown in simplified form as "position in
formation A" and "position information B" in Fig. 2, the position information may be
expressed by a format using latitude and longitude, a format using x and y coordinates,
a format using absolute coordinates, a format using vectors, or the like.
[0079] Fig. 3 is a diagram useful in showing specific examples of the measurement in
formation. As shown in Fig. 3, the measurement information includes signal strength
information for each base station 30. For example, in the example shown in Fig. 3, the
signal strength at the wireless terminal 40 of a wireless signal transmitted from the
base station 30A is "-90dBm".
[0080] The wireless terminal 40 according to the embodiments of the present disclosure
estimates the position information of the wireless terminal 40 based on the mea
surement information described earlier and the position information for each base
station 30. For example, the wireless terminal 40 estimates a position O of the wireless
terminal 40 in accordance with the mathematical formulas shown below.
(Mathematical Formula 1)
Wi =
distS(0,Ai)
(Mathematical Formula 2)
i
(Mathematical Formula 3)
[0081] Note that "Ai" in Formula 1 shows the position information of the ith base station
registered in the wireless terminal 40. Accordingly, when the position information of a
base station is expressed by longitude and latitude, the wireless terminal 40 applies
Formula 1 to both the longitude and the latitude. Also, as shown in Formula 2, "Wi" is
a weighting coefficient obtained based on distS (0,Ai) showing the distance between
the wireless terminal 40 and the ith base station estimated from the signal strength. As
shown in Formula 3,W is the sum of the weighting coefficients Wi.
[0082] Note that the method of estimating the position of the wireless terminal 40 is not
limited to a method using Formula 1 given above and the wireless terminal 40 may for
example use the position of the base station 30 that transmitted the signal with the
highest signal strength received by the wireless terminal 40 as an estimate of the
position of the wireless terminal 40. Alternatively, the wireless terminal 40 may use a
position at the center of the base stations 30 that have transmitted signals received with
a signal strength of a specified value or higher by the wireless terminal 40 as an
estimate of the position of the wireless terminal 40. It is also possible to realize highly
robust estimation of the position by applying a least-squares method.
[0083] However, a case can be imagined where, due to movement of a base station 30 or the
like, the position information registered for the base station 30 is erroneous. If position
estimation is carried out based on such erroneous position information, the precision of
the position estimation will fall. This will now be described in detail with reference to
Fig. 4.
[0084] Fig. 4 is a diagram useful in showing examples of estimation results for different e s
timation methods. In Fig. 4, a situation is imagined where "position information A" to
"position information C" and "position information X" showing positions A to C and
position X have been registered as the position information of the base station 30A to
the base station 30C and the base station 30X. In this situation, a case is considered
where a wireless terminal 40 located at position U receives wireless signals from the
base station 30A to the base station 30C and the base station 30X and carries out
position estimation of the wireless terminal 40 based on the signal strength information
of the respective wireless signals.
[0085] Note that the signal strength of the wireless signal transmitted by a base station 30
falls in accordance with a specified rule as the distance from the base station 30
increases. That is, the signal strength of the wireless signal at the wireless terminal 40
can be converted into the distance between the base station 30 that transmitted such
wireless signal and the wireless terminal 40. For this reason, in Fig. 4, converted
distance values of the signal strengths are shown inside parentheses. Also, the base
station 30X is assumed to not be present at the position X in reality and to have moved
to the position X'.
[0086] Here, when the wireless terminal 40 provisionally uses the center of gravity of the
registered positions of the base stations 30A to 30C and the base station 30X as an
estimate of the position of the wireless terminal 40, the wireless terminal 40 will use
the position S as the estimate of the position of the wireless terminal 40 in spite of the
wireless terminal 40 being actually located at the position U. Also, by using a robust
median method that is less affected by errors, the wireless terminal 40 is capable of
obtaining a position T, for example that is closer to the actual position U of the
wireless terminal 40 than the position S.
[0087] However, if position estimation for the wireless terminal 40 is carried out using the
position information of the base station 30X, it is expected that the position estimation
result will be distant from the actual position regardless of the estimation method used.
Here, although it would be conceivably possible to carry out position estimation
without using the position information of the base station 30X that is distant from the
base station 30A to the base station 30C, in reality, a case where the position in
formation of the base station 30X is correct and the position information of the base
station 30A to the base station 30C is erroneous can also be imagined. For this reason,
it would not be appropriate to carry out position estimation without using the position
information of the base station 30X based only on the fact that the base station 30X is
very distant from the other base stations 30.
[0088] By focusing on the situation described above, the embodiments of the present
disclosure were conceived. By carrying out position estimation using position in
formation of highly reliable base stations 30, the wireless terminal 40 or the position
estimating apparatus 20 according to the embodiments of the present disclosure are
capable of suppressing a drop in the precision of position estimation. Such em
bodiments of the present disclosure will now be described in detail.
[0089] 2. First Embodiment
[0090] 2-1. Configuration of Wireless Terminal According to First Embodiment
[0091] Fig. 5 is a functional block diagram showing the configuration of a wireless terminal
40-1 according to a first embodiment of the present disclosure. As shown in Fig. 5, the
wireless terminal 40- 1 according to the first embodiment includes a communication
unit 412, a measurement unit 414, a base station information storage unit 416, an accelerometer
420, a moved distance calculating unit 424, an estimation result storage
unit 428, a reference area determining unit 432, and a position estimating unit 436.
Although described in detail later, the wireless terminal 40- 1 according to the first em
bodiment encompasses a function as a position estimating apparatus that estimates the
position of the wireless terminal 40-1.
[0092] The communication unit 412 is an interface for base stations 30 in the periphery of
the wireless terminal 40-1 and functions as a reception unit that receives wireless
signals transmitted from the base stations 30 and as a transmission unit that transmits
wireless signals to the base stations 30.
[0093] The measurement unit 414 measures the signal strength of wireless signals received
by the communication unit 412 from the respective base stations 30 separately for each
transmitting base station 30. By measuring signal strength using the measurement unit
414, as one example measurement information such as that described with reference to
Fig. 3 is obtained.
[0094] As described with reference to Fig. 2 for example, the base station information
storage unit 416 stores base station information made up of base station IDs and
position information of the respective base stations 30. Note that as examples, the base
station information storage unit 416 may be a storage medium such as a nonvolatile
memory, a magnetic disk, an optical disc, or an MO (Magneto Optical) disc. Here,
EEPROM (Electrically Erasable Programmable Read-Only Memory) and EPROM
(Erasable Programmable ROM) can be given as examples of nonvolatile memory. A
hard disk, a disk-shaped magnetic disk, and the like can be given as examples of a
magnetic disk. A CD (Compact Disc), a DVD-R (Digital Versatile Disc - Recordable),
and a BD (Blu-Ray Disc (Registered Trademark)) and the like can be given as
examples of an optical disc. Also, although the base station information storage unit
416 and the estimation result storage unit 428 are shown as different functional blocks
in Fig. 5, the functions of both storage units may be provided by the same storage
medium or by different storage media.
[0095] The accelerometer 420 functions as a motion detection unit that detects acceleration
(movement) of the wireless terminal 40-1. The moved distance calculating unit 424
calculates the movement speed of the wireless terminal 40- 1 in a given period from the
history of the acceleration of the wireless terminal 40- 1 obtained by the accelerometer
420. The moved distance calculating unit 424 is also capable of calculating the moved
distance by integrating the movement speed during a given period. Note that the ac
celerometer 420 is described above merely as one example of a motion detection unit
and a "motion detection unit" for the present disclosure is not limited to the accelerometer
420. For example, it is possible to use a compass, a gyrosensor or other
type of sensor as the motion detection unit.
[0096] The estimation result storage unit 428 stores previous position estimation results for
the wireless terminal 40-1 produced by the position estimating unit 436. Specific
examples of the position estimation results stored by the estimation result storage unit
428 will now be described with reference to Fig. 6.
[0097] Fig. 6 is a diagram useful in explaining specific examples of position estimation
results stored by the estimation result storage unit 428. As shown in Fig. 6, the e s
timation result storage unit 428 stores position information of the wireless terminal
40-1 estimated in the past by the position estimating unit 436 in association with the
time at which such estimates were made.
[0098] The reference area determining unit (limited range determining unit) 432 reads the
previous estimated position information from the estimation result storage unit 428 and
determines a reference area (limited range) that uses a position shown by the estimated
position information as a standard. The position estimating unit 436 estimates the
position of the wireless terminal 40-1 based on the position information of the base
stations 30 whose position information stored in the base station information storage
unit 416 is inside the reference area and the signal strength information of wireless
signals transmitted from such base stations 30. The reference area will now be
described in detail with reference to Fig. 7.
[0099] Fig. 7 is a diagram useful in explaining a specific example of the reference area. The
position N shown in Fig. 7 is the previous position estimation result. The wireless
terminal 40- 1 is thought to be located in a range (the range shown by the broken line in
Fig. 7) that is within the estimated distance moved by the wireless terminal 40 from the
time of the previous position estimation calculated by the moved distance calculating
unit 424 from the position N.
[0100] Accordingly, base stations that transmit wireless signals that can be received by the
wireless terminal 40- 1 at the present time are thought to be located in a region that is
centered on the position N and has a sum of the estimated moved distance and the
signal range of the base stations 30 as a radius. For this reason, if the typical signal
range (area range) of a base station 30 is 300m, as shown in Fig. 7, the reference area
determining unit 432 determines, as the reference area, a region that is centered on the
position N and has a value produced by adding the estimated moved distance and
300m as a radius.
[0101] In this case, the position A to the position C are inside the reference area and the
position X is outside the reference area. For this reason, the position estimating unit
436 estimates the position U of the wireless terminal 40-1 according to Formula 1
described above, for example, based on the position information A to position information
C of the base stations 30A to 30C showing the position A to the position C
stored in the base station information storage unit 416 and the signal strength in
formation of the wireless signals transmitted from the base stations 30A to 30C.
[0102] Meanwhile, the position estimating unit 436 does not use the position information X
of the base station 30X showing the position X stored in the base station information
storage unit 416 and the signal strength information of the wireless signal transmitted
from the base station 30X in position estimation for the wireless terminal 40-1. In this
way, according to the first embodiment of the present disclosure, by not using the
position information of a base station 30 that has a high probability of being erroneous
and the signal strength information of the wireless signal from such base station 30 in
position estimation, it is possible to suppress a drop in the precision of the position e s
timation.
[0103] 2-2: Operation of Wireless Terminal According to First Embodiment
[0104] The configuration of the wireless terminal 40-1 according to the first embodiment of
the present disclosure has been described above. Next, the operation of the wireless
terminal 40- 1 according to the first embodiment will be described with reference to
Fig. 8.
[0105] Fig. 8 is a flowchart showing the operation of the wireless terminal 40-1 according to
the first embodiment. As shown in Fig. 8, first, the measurement unit 414 of the
wireless terminal 40- 1 measures the signal strengths of the wireless signals received by
the communication unit 412 from the base stations 30 in the periphery (S304).
[0106] Also, the reference area determining unit 432 searches the estimation result storage
unit 428 for the most recent position estimation result of the wireless terminal 40-1
(S308) and the moved distance calculating unit 424 calculates the moved distance of
the wireless terminal 40-1 from the most recent time at which position estimation was
carried out (S3 12).
[0107] Next, the reference area determining unit 432 determines the reference area based on
the most recent position estimation result for the wireless terminal 40- 1 and the moved
distance calculated by the moved distance calculating unit 424 (S3 16).
[0108] After this, the position estimating unit 436 searches the base station information
storage unit 416 for position information of the base stations that transmitted the
wireless signals whose signal strengths have been measured by the measurement unit
414 (S320). The position estimating unit 436 then determines outliers that are position
information outside the reference area out of the pieces of position information that
have been found (S324). Next, the position estimating unit 436 estimates the position
information of the wireless terminal 40- 1 based on the position information of the base
stations 30 inside the reference area (S328).
[0109] 3. Second Embodiment
[0110] The first embodiment of the present disclosure has been described above. Next, a
second embodiment of the present disclosure will be described. As described in detail
below, the second embodiment of the present disclosure differs to the first embodiment
in that the reference area is determined in accordance with a position determination
result produced by a different method to the position estimating unit 436.
[0111] 3-1: Configuration of Wireless Terminal According to Second Embodiment
Fig. 9 is a functional block diagram showing the configuration of a wireless terminal
40-2 according to the second embodiment of the present disclosure. As shown in Fig.
9, the wireless terminal 40-2 according to the second embodiment includes the com
munication unit 412, the measurement unit 414, the base station information storage
unit 416, a GPS positioning unit 440, and a reference area determining unit 444. Note
that since functional blocks such as the communication unit 412, the measurement unit
414, and the base station information storage unit 416 are the same as those described
in the first embodiment, detailed description thereof is omitted here.
[01 12] The GPS positioning unit 440 receives navigation messages from satellites and
calculates the present position of the wireless terminal 40-2 from ephemeris in
formation included in the navigation messages. Note that the GPS positioning unit 440
is merely one example of a position determining unit that determines a position
according to a different method to the position estimating unit 436 and such "position
determining unit" can be realized by a variety of implementations.
[0113] The reference area determining unit 444 (limited range determining unit) determines
the reference area with the present position of the wireless terminal 40-2 calculated by
the GPS positioning unit 440 as a standard. The position estimating unit 436 estimates
the position of the wireless terminal 40-2 based on the position information of the base
stations 30 whose position information stored in the base station information storage
unit 416 is inside the reference area and signal strength information for the wireless
signals transmitted from such base stations 30. The reference area will now be
described in more detail with reference to Fig. 10.
[0114] Fig. 10 is a diagram showing a specific example of the reference area. The position O
shown in Fig. 10 is the positioning result produced by the GPS positioning unit 440.
The wireless terminal 40-2 is believed to be located in a region that is within the range
of the GPS positioning error from the position O (i.e., in the region shown by the
broken line shown in Fig. 10).
[0115] Accordingly, the base stations that transmitted the wireless signals that can be
received at the present time by the wireless terminal 40-2 are believed to be located in
a region that is centered on the position O and has the sum of the GPS positioning error
and the signal range of a base station 30 as a radius. For this reason, if the typical
signal range (area range) of a base station 30 is 300m, as shown in Fig. 10, the
reference area determining unit 444 determines, as the reference area, a region that is
centered on the position O and has a value produced by adding the GPS positioning
error and 300m as a radius.
[0116] In this case, the position A to the position C are inside the reference area and the
position X is outside the reference area. For this reason, the position estimating unit
436 estimates the position U of the wireless terminal 40-2 according to Formula 1
described above, for example, based on the position information A to position in
formation C of the base stations 30A to 30C showing the position A to the position C
stored in the base station information storage unit 416 and the signal strength in
formation of the wireless signals transmitted from the base stations 30A to 30C.
[01 17] Meanwhile, the position estimating unit 436 does not use the position information X
of the base station 30X showing the position X stored in the base station information
storage unit 416 and the signal strength information of the wireless signal transmitted
from the base station 30X in position estimation of the wireless terminal 40-2. In this
way, according to the second embodiment of the present disclosure, in the same way as
the first embodiment, by not using the position information of a base station 30 that has
a high probability of being erroneous and the signal strength information of the
wireless signal from such base station 30 in position estimation, it is possible to
suppress a drop in the precision of the position estimation.
[0118] 3-2: Operation of Wireless Terminal According to the Second Embodiment
The configuration of the wireless terminal 40-2 according to the second embodiment
of the present disclosure has been described above. Next, the operation of the wireless
terminal 40-2 according to the second embodiment will be described with reference to
Fig. 11.
[0119] Fig. 11 is a flowchart showing the operation of the wireless terminal 40-2 according
to the second embodiment. As shown in Fig. 11, first, the measurement unit 414 of the
wireless terminal 40-2 measures the signal strengths of the wireless signals received by
the communication unit 412 from the base stations 30 in the periphery (S344). Also,
the GPS positioning unit 440 calculates the present position of the wireless terminal
40-2 (S348). Note that the processing in S344 and S348 may be implemented in
parallel.
[0120] The reference area determining unit 444 then determines the reference area based on
the positioning result produced by the GPS positioning unit 440 (S352). After this, the
position estimating unit 436 searches the base station information storage unit 416 for
position information of the base stations that transmitted the wireless signals whose
signal strengths have been measured by the measurement unit 414 (S356).
[0121] Next, the position estimating unit 436 determines outliers that are position in
formation outside the reference area out of the pieces of position information that have
been found (S360). The position estimating unit 436 then estimates the position in
formation of the wireless terminal 40-2 based on the position information of the base
stations 30 inside the reference area (S364).
[0 122] 4. Third Embodiment
[0123] The second embodiment of the present disclosure has been described above. Next, a
wireless terminal 40-3 according to a third embodiment of the present disclosure will
be described in detail with reference to Figs. 12 to 16.
[0124] 4-1: Configuration of Wireless Terminal According to Third Embodiment
Fig. 12 is a functional block diagram showing the configuration of the wireless
terminal 40-3 according to the third embodiment of the present disclosure. As shown in
Fig. 12, the wireless terminal 40-3 according to the third embodiment includes the
communication unit 412, the measurement unit 414, the base station information
storage unit 416, the GPS positioning unit 440, the reference area determining unit
444, a low reliability base station information storage unit 448, a mobile base station
determining unit 452, and a mobile base station information storage unit 456.
[0125] Note that since functional blocks such as the communication unit 412, the mea
surement unit 414, the base station information storage unit 416, the GPS positioning
unit 440, and the reference area determining unit 444 are the same as those described
in the second embodiment, detailed description thereof is omitted here.
[0126] As described above in the second embodiment and the like, the position estimating
unit 436 searches the base station information storage unit 416 for position information
of the base stations that transmitted the wireless signals whose signal strengths have
been measured by the measurement unit 414 and determines outliers that are position
information outside the reference area out of the pieces of position information that
have been found.
[0127] Here, the position information determined by the position estimating unit 436 to be
an outlier is believed to be position information of a base station 30 that has moved
after registration in the base station information storage unit 416. This means that there
is the possibility that a base station 30 with position information determined to be an
outlier by the position estimating unit 436 is a mobile base station carried by the user.
However, there are also cases where even a home base station will move due to
movement of the user. For this reason, in the present embodiment, it is specified
whether the base station 30 is a mobile base station based on the frequency with which,
or the number of times that, the position information has been determined to be an
outlier. This is described in detail below.
[0128] The low reliability base station information storage unit 448 stores the base station
IDs of base stations with position information that has been determined by the position
estimating unit 436 to be an outlier. Specific examples of the low reliability base
station information stored by the low reliability base station information storage unit
448 will now be described with reference to Fig. 13.
[0129] Fig. 13 is a diagram useful in showing specific examples of the low reliability base
station information stored by the low reliability base station information storage unit
448. As shown in Fig. 13, the low reliability base station information storage unit 448
stores base station IDs showing low reliability base stations in association with report
times showing when such base stations were reported (added) as low reliability base
stations. For example, in Fig. 13, it is shown that the base station 30X was reported as
a low reliability base station at "2010/7/14 10:34:56". In this way, the low reliability
base station information storage unit 448 functions as a history information storage
unit that stores history information for each piece of low reliability base station in
formation that has been reported.
[0130] The mobile base station determining unit 452 refers to the low reliability base station
information storage unit 448 and determines that a base station 30 that has been
reported as a low reliability base station with high frequency is a mobile base station.
For example, the mobile base station determining unit 452 may determine that a base
station 30 that has been reported as a low reliability base station more than a set
number of times, such as twice, five times, or ten times within a specified period, such
as one week, one month, or three months, is a mobile base station.
[0131] In more detail, for the example shown in Fig. 13, since the base station 30X has been
reported as a low reliability base station four times in the period from "2010/7/14" to
"2010/7/18", the mobile base station determining unit 452 may determine that the base
station 30X is a mobile base station.
[0132] Information on the base station 30 determined by the mobile base station determining
unit 452 to be a mobile base station is added to the mobile base station information
storage unit 456. For example, when the base station 30X has been determined to be a
mobile base station by the mobile base station determining unit 452, as shown in Fig.
14, the base station ID of the base station 30X is added to the mobile base station in
formation storage unit 456. Note that the base station ID may be added to the mobile
base station information storage unit 456 in an offline manner based on a base station
ID reported by the user and/or information reported from a vendor or carrier.
[0133] The information on the base station 30 determined by the mobile base station de
termining unit 452 to be a mobile base station may be deleted from the base station in
formation storage unit 416. For example, when the base station 30X has been de
termined by the mobile base station determining unit 452 to be a mobile base station,
the base station information, such as the position information and the like, of the base
station 30X may be deleted from the base station information storage unit 416.
[0134] Since a mobile base station is not present at a fixed location as described above, if information
on such a mobile base station were used when estimating the position of the
wireless terminal 40-3, there would be the risk of a fall in the precision of the position
estimation.
[0135] For this reason, the position estimating unit 436 of the wireless terminal 40-3 may
estimate the position of the wireless terminal 40-3 by selectively using signal strength
information of base stations 30 whose position information show positions in the
reference area and that are not stored in the mobile base station information storage
unit 456 as mobile base stations, and also the position information of such base stations
30. According to this configuration, it is possible to improve the precision of position
estimation for a wireless terminal 40.
[0136] 4-2: Operation of Wireless Terminal According to Third Embodiment
The configuration of the wireless terminal 40-3 according to the third embodiment of
the present disclosure has been described above. Next, the operation of the wireless
terminal 40-3 according to the third embodiment will be described with reference to
Figs. 15 and 16.
[0137] Figs. 15 and 16 are flowcharts showing an example operation of the wireless terminal
40-3 according to the third embodiment. As shown in Fig. 15, first, when measurement
information for wireless signals has been acquired by the measurement unit 414 of the
wireless terminal 40-3, the position estimating unit 436 acquires, from the base station
information storage unit 416, the base station information of the base stations that
transmitted such wireless signals (S504).
[0138] After this, the wireless terminal 40-3 carries out the processing in S508 to S520 for
each piece of base station information S acquired in S504. More specifically, the
position estimating unit 436 refers to the mobile base station information storage unit
456 and determines whether the base station information S is base station information
of a base station 30 registered as a mobile base station (S508).
[0139] Also, the position estimating unit 436 determines whether the position information
included in the base station information S is inside the reference area (S512). After
this, if it has been determined that the position information included in the base station
information S is outside the reference area, the wireless terminal 40-3 adds the base
station information S to the low reliability base station information storage unit 448
(S516) and excludes such base station information S from use in position estimation
(S520). Also, if it has been determined in S508 that the base station information S is
base station information of a base station 30 registered as a mobile base station, the
wireless terminal 40-3 excludes such base station information S from use in position
estimation (S520).
[0140] The position estimating unit 436 then uses the remaining base station information
and measurement information to estimate the position information of the wireless
terminal 40-3 (S524).
[0141] Meanwhile, the mobile base station determining unit 452 executes the processing in
S528 to S536 shown in Fig. 16 at arbitrary timing, such as when a specified interval
has passed or when new information has been added to the low reliability base station
information storage unit 448.
[0142] More specifically, the mobile base station determining unit 452 refers to the low r e
liability base station information storage unit 448 (S528) and determines whether a
base station 30 has been reported as a low reliability base station with high frequency
(S532). After this, the mobile base station determining unit 452 adds information
relating to a base station 30 that has been reported as a low reliability base station with
high frequency to the mobile base station information storage unit 456 (S536). Note
that the mobile base station determining unit 452 may delete information relating to the
base station 30 that has been reported as a low reliability base station with high
frequency from the base station information storage unit 416.
[0143] 5. Fourth Embodiment
[0144] The first to third embodiments of the present disclosure have been described above.
In the first to third embodiments of the present disclosure, examples have been
described where a function for determining outliers among the base stations 30, a
position estimating function, a function for determining mobile base stations, and the
like have been implemented in a wireless terminal 40. However, as described below as
the fourth embodiment, it is also possible to implement such functions in a position e s
timating apparatus 20.
[0145] 5-1. Configuration of Position Estimating System According to Fourth Embodiment
[0146] Fig. 17 is a diagram useful in showing the configuration of a position estimating
system 2 according to the fourth embodiment. As shown in Fig. 17, the position e s
timating system 2 according to the fourth embodiment includes a position estimating
apparatus 20, a plurality of base stations 30, and a wireless terminal 40.
[0147] On receiving a wireless signal transmitted from a base station 30 (for example, a
beacon signal), the wireless terminal 40 is capable of measuring the signal strength of
the wireless signal. After this, the wireless terminal 40 transmits measurement in
formation including the measured signal strength information and the base station ID
of the base station 30 to the position estimating apparatus 20. The wireless terminal 40
also transmits reference area information for enabling the position estimating apparatus
20 to specify a reference area. Note that the previous estimated position and estimated
moved distance described in the first embodiment and the positioning result produced
by GPS described in the second embodiment can be given as examples of the reference
area information.
[0148] Note that there are no particular limitations on the format for expressing the signal
strength information. As examples, the signal strength information may be expressed
in "Dbm" units or by a value, such as "40%" or "80%", that is the measured value
expressed as a proportion of a set value (for example, a saturation value for the signal
strength), or may be a converted distance value for the signal strength.
[0149] The position estimating apparatus 20 stores position information for each base station
30 and is capable of estimating the position information of a wireless terminal 40 based
on the position information of the respective base stations 30 and measurement in
formation received from the wireless terminal 40. The position estimating apparatus 20
then transmits the estimated position information to the wireless terminal 40.
[0150] Note that the position estimating apparatus 20 may communicate with the wireless
terminal 40 via a communication network that includes wired or wireless transfer
paths. More specifically, the communication network may include a public network
such as the Internet, a telephone network, or a satellite communication network,
various types of LAN (Local Area Network) including Ethernet (registered trademark),
an LTE core network, a WAN (Wide Area Network), and the like. The communication
network may also include a dedicated network such as an IP-VPN (Internet Protocol-
Virtual Private Network).
[0151] As described above, in the fourth embodiment, the position estimation for the
wireless terminal 40 is carried out by the position estimating apparatus 20. In the same
way, in the fourth embodiment, the determination of the reference area, the deter
mination of outliers, the determination of mobile base stations, and the like may also
be carried out by the position estimating apparatus 20. The configuration and operation
of the position estimating apparatus 20 according to the fourth embodiment will now
be described.
[0152] 5-2: Configuration of Position Estimating Apparatus According to Fourth Em
bodiment
[0153] Fig. 18 is a functional block diagram showing the configuration of the position e s
timating apparatus 20 according to the fourth embodiment of the present disclosure. As
shown in Fig. 18, the position estimating apparatus 20 according to the fourth em
bodiment includes a communication unit 212, a base station information storage unit
216, a position estimating unit 236, a reference area determining unit 244, a low r e
liability base station information storage unit 248, a mobile base station determining
unit 252, and a mobile base station information storage unit 256.
[0154] The communication unit 212 is an interface for transmitting and receiving in
formation to and from the wireless terminal 40. As one example, the communication
unit 212 has functions as a reception unit that receives measurement information and
reference area information from the wireless terminal 40 and as a transmission unit that
transmits a position estimation result to the wireless terminal 40.
[0155] In the same way as the base station information storage unit 416 described above in
the first to third embodiments, the base station information storage unit 216 stores base
station information made up of base station IDs and position information of the r e
spective base stations 30.
[0156] The reference area determining unit 244 determines the reference area based on the
reference area information received by the communication unit 212 from the wireless
terminal 40. Since methods of determining the reference area based on the reference
area information were described in the first and second embodiments, detailed de
scription thereof is omitted here.
[0157] However, when the position estimating apparatus 20 stores a history of the position
estimation results for each wireless terminal 40, it is possible for the reference area de
termining unit 244 to specify the reference area based on the history of position e s
timation results stored in the position estimating apparatus 20 and an estimated moved
distance received from the wireless terminal 40 as the reference area information.
[0158] Since the position estimating unit 236, the low reliability base station information
storage unit 248, the mobile base station determining unit 252, and the mobile base
station information storage unit 256 can be effectively the same configurations as the
position estimating unit 436, the low reliability base station information storage unit
448, the mobile base station determining unit 452, and the mobile base station in
formation storage unit 456 described in the third embodiment, detailed description
thereof is omitted here.
[0159] In short, base station IDs showing base stations 30 that have low reliability as fixed
base stations are recorded in the low reliability base station information storage unit
248 and the mobile base station determining unit 252 determines mobile base stations
by referring to the low reliability base station information storage unit 248. In
formation relating to a base station 30 determined by the mobile base station de
termining unit 252 to be a mobile base station is added to the mobile base station in
formation storage unit 256 and is deleted from the base station information storage unit
216.
[0160] The position estimating unit 236 estimates the position of the wireless terminal 40 by
selectively using the measurement information of base stations 30 which have position
information showing positions inside the reference area and are not stored in the
mobile base station information storage unit 256 as mobile base stations, and also
position information of such base stations 30.
[0161] 5-3: Operation of the Position Estimating System According to the Fourth Em
bodiment
[0162] The configuration of the position estimating apparatus 20 according to the fourth em
bodiment of the present disclosure has been described above. Next, the operation of the
position estimating system 2 according to the fourth embodiment will be described
with reference to Fig. 19.
[0163] Fig. 19 is a sequence chart showing the operation of the position estimating system 2
according to the fourth embodiment. As shown in Fig. 19, the wireless terminal 40 first
measures the signal strengths of the wireless signals received from the base stations 30
in the periphery (S604). The wireless terminal 40 acquires the reference area in
formation (S508) and transmits the reference area information and the measurement in
formation acquired in S604 to the position estimating apparatus 20 (S612).
[0164] After this, the position estimating unit 236 of the position estimating apparatus 20
searches the base station information storage unit 216 for base station information
relating to the measurement information received from the wireless terminal 40 (S616).
The reference area determining unit 244 determines the reference area based on
reference area information received from the wireless terminal 40 (S620).
[0165] In addition, the position estimating unit 236 determines mobile base stations and de
termines outliers as described above and estimates the position of the wireless terminal
40 using the measurement information of base stations 30 that have position in
formation showing positions inside the reference area and have not been stored in the
mobile base station information storage unit 256, and position information of such base
stations 30 (S628). After this, the communication unit 212 transmits the position in
formation of the wireless terminal 40 estimated by the position estimating unit 236 to
the wireless terminal 40 (S632).
[0166] 6. Conclusion
[0167] As described above, according to the embodiments of the present disclosure, by e s
timating the position of the wireless terminal 40 based on the position information of
the base stations 30 showing positions in the reference area, it is possible to improve
the precision of position estimation for the wireless terminal 40.
[0168] In addition, according to the third and fourth embodiments of the present disclosure,
by estimating the position of the wireless terminal 40 without using the position in
formation of base stations 30 that have a high probability of being mobile base
stations, it is possible to significantly improve the precision of the position estimation.
[0169] Although preferred embodiments of the present disclosure have been described in
detail with reference to the attached drawings, the present disclosure is not limited to
the above examples. It should be understood by those skilled in the art that various
modifications, combinations, sub-combinations and alterations may occur depending
on design requirements and other factors insofar as they are within the scope of the
appended claims or the equivalents thereof.
[0170] As one example, the respective steps in the processing of the position estimating
system 2 or the wireless terminal 40 in this specification do not need to be carried out
in a time series in the order in which such steps are given in the sequence charts or
flowcharts. For example, the respective steps in the processing of the wireless terminal
40 may be carried out in a different order to the order written in the flowcharts and/or
may be carried out in parallel.
[0171] It is also possible to produce a computer program for causing hardware such as a
CPU, a ROM, and a RAM incorporated in the position estimating apparatus 20 or the
wireless terminal 40 to achieve the same functions as the respective structural elements
of the position estimating apparatus 20 or the wireless terminal 40 described earlier. A
storage medium on which such computer program is recorded may also be provided.
Reference Signs List
[0172] 20 Position estimating apparatus
30 Base station
40, 40-1, 40-2, 40-3 Wireless terminal
212, 412 Communication unit
216, 416 Base station information storage unit
236, 436 Position estimating unit
244, 432, 444 Reference area determining unit
248, 448 Low reliability base station information storage unit
252, 452 Mobile base station determining unit
256, 456 Mobile base station information storage unit
420 Accelerometer
424 Moved distance calculating unit
428 Estimation result storage unit
440 GPS positioning unit

Claims
A position estimation apparatus, comprising:
a reference area determining unit determines a reference area that
includes a position of a mobile communications station, and
a position estimation unit that estimates the position of said mobile
communication station based on position information of a plurality of
transmitters within said reference area.
The apparatus of claim 1, wherein:
said reference area determining unit determines said reference area by
combining an estimated move distance of said apparatus with a prede
termined communication range of at least one of said plurality of
transmitters.
The apparatus of claim 2, further comprising:
a movement detector that estimates the estimated move distance of said
apparatus.
The apparatus of claim 3, wherein
said movement detector being an accelerometer.
The apparatus of claim 1, further comprising:
a GPS-based location device that detects location information based on
wireless satellite transmissions, wherein
said reference area determining unit determines the reference area by
combining a GPS uncertainty amount with a predetermined commu
nication range of at least one of said plurality of transmitters.
The apparatus of claim 1, further comprising:
a computer readable storage device that stores a previous position e s
timation result for said apparatus in association with time, wherein
and said reference area determining unit determines said reference area
by using the previous position estimation result as a standard.
The apparatus of claim 6, wherein:
said reference area determining unit determines the reference area by
calculating the estimated move distance.
The apparatus of claim 6, wherein
said position estimation unit estimates the move distance by measuring
a propagation distance from the plurality of transmitters.
The apparatus of claim 1, wherein
said position estimation unit excludes from consideration transmitters
outside of the reference area based on signal information from rePCT/
JP2011/004687
spective of said plurality of transmitters.
The apparatus of claim 1, wherein
the position estimation unit estimates the position of the mobile com
munication station by calculation of
(Mathematical Formula 1)
1
Wi
distS(0,Ai)
(Mathematical Formula 2)
W= Wi
(Mathematical Formula 3)
, wherein
O being a position, A being position information of an ith transmitter,
and W being a weighting coefficient.
The apparatus of claim 9, wherein
further comprising a computer readable storage unit that stores
transmitter reliability information regarding whether a particular
transmitter has been detected as having a low reliability with at least a
predetermined frequency of occurrence, and
said position estimation unit excludes transmitters having a stored r e
liability below a predetermined threshold when estimating the position
of the mobile communication station.
The apparatus of claim 9, wherein
said position estimation unit excludes transmitters having a received
signal characteristic indicating the transmitter is outside of the
reference area.
The apparatus of claim 1, further comprising:
a communications interface that receives transmitter signal information
and reference area information from said mobile communication
station, and sends an estimate of said position of said mobile commu
nication station to said mobile communication station.
The apparatus of claim 1, further comprising:
WO 2012/032725 PCT/JP2011/004687
the mobile communication station.
[Claim 15] A position estimation method comprising:
determining with a processing device a reference area including a
position of a mobile communications station; and
estimating the position of the mobile communication station based on
position information of a plurality of transmitters within said reference
area.
[Claim 16] A computer readable storage device having computer readable in
structions that when executed by a processing device perform a
position estimation method comprising:
determining with the processing device a reference area including a
position of a mobile communications station; and
estimating the position of the mobile communication station based on
position information of a plurality of transmitters within said reference
area.
[Claim 17] A mobile communications station comprising:
a receiver that receives transmissions from a plurality of transmitters;
a reference area determining unit that determines a reference area that
includes therein a position of the mobile communications station; and
a communication interface that sends
signal information from said transmissions of said plurality of
transmitters, and
said reference area to a remote device,
and receives from said remote device an estimated position of said
mobile communication station after said remote device used said signal
information and reference area to estimate said position of said mobile
communication station by using transmissions from a subset of said
plurality of transmitters located within said reference area and
excluding transmissions from a subset of said plurality of transmitters
located outside of said reference area.
[Claim 18] A position estimation method comprising:
receiving transmissions from a plurality of transmitters;
determining with a processing device a reference area that includes
therein a position of the mobile communications station;
sending signal information from said transmissions of said plurality of
transmitters to a remote device;
sending said reference area to the remote device; and
receiving from said remote device an estimated position of said mobile
WO 2012/032725 PCT/JP2011/004687
communication station after said remote device used said signal in
formation and reference area to estimate said position of said mobile
communication station by using transmissions from a subset of said
plurality of transmitters located within said reference area and
excluding transmissions from a subset of said plurality of transmitters
located outside of said reference area.
[Claim 19] A computer readable storage device having computer readable in
structions that when executed by a processing device perform a
position estimation method comprising:
receiving transmissions from a plurality of transmitters;
determining with a processing device a reference area that includes
therein a position of the mobile communications station;
sending signal information from said transmissions of said plurality of
transmitters to a remote device;
sending said reference area to the remote device; and
receiving from said remote device an estimated position of said mobile
communication station after said remote device used said signal in
formation and reference area to estimate said position of said mobile
communication station by using transmissions from a subset of said
plurality of transmitters located within said reference area and
excluding transmission from a subset of said plurality of transmitters
located outside of said reference area.