(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2006/0089153 A1
`Sheynblat
`(43) Pub. Date:
`Apr. 27, 2006
`
`US 2006.00891.53A1
`
`(54) LOCATION-SENSITIVE CALIBRATION
`DATA
`
`(76) Inventor: Leonid Sheynblat, Hillsborough, CA
`(US)
`Correspondence Address:
`QUALCOMM, INC
`S775 MOREHOUSE DR.
`SAN DIEGO, CA 92121 (US)
`
`(21) Appl. No.:
`22) Filed:
`(22) File
`
`11/000,702
`Nov. 30, 2004
`OV. 5U,
`Related U.S. Application Data
`
`(60) Provisional application No. 60/622,884, filed on Oct.
`27, 2004.
`
`
`
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`H04O 7/20
`(52) U.S. Cl. .......................................................... 455/4.56.1
`
`(57)
`
`ABSTRACT
`
`A system, method and device are provided for determining
`the position of a mobile station through the identification of
`an approximate position of the mobile station. Thereafter
`received signal strength (RSSI) fingerprint data for the
`approximate position is requested and retrieved. The finger
`print data and received signal strength data collected at the
`mobile station are compared in connection with fixing the
`position of the mobile station.
`
`Page 1 of 9
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`SAMSUNG EX-1071
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`Patent Application Publication Apr. 27, 2006 Sheet 1 of 4
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`US 2006/0089.153 A1
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`Fig. 1
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`Page 2 of 9
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`Patent Application Publication Apr. 27, 2006 Sheet 2 of 4
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`US 2006/00891.53 A1
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`MOBILE STATION
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`LOCATION
`APPROX.
`30
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`DATABASE
`8
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`11
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`Fig. 2
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`MEMORY
`42
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`40 ase
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`Page 3 of 9
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`Patent Application Publication Apr. 27, 2006 Sheet 3 of 4
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`US 2006/0089.153 A1
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`RSS
`INDICATOR
`51
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`LOCATION
`ESTIMATOR
`46
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`FINGERPRINT
`REGUESTOR
`48
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`FINGERPRINT
`COMPARATOR
`50
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`NETWORK
`54
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`Fig. 4
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`LOCATION
`DISPLAY
`52
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`TOWER
`TOWER TOWER INTES
`on RSSITOKEN LOCATION
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`8
`Fig. 5
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`Page 4 of 9
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`Patent Application Publication Apr. 27, 2006 Sheet 4 of 4
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`US 2006/00891.53 A1
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`76
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`60
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`COLLECT RSS
`DATA ATMS
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`62
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`DETERMINE APPROXIMATE
`MSLOCATION
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`64
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`SELECT LOOK-UP TOKEN ON
`THE BASIS OF APPROXIMATE
`MSLOCATION
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`COMPARE LOOK-UP TOKEN
`DATA TO RSS
`DATA COLLECTED
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`FIND CORRELATION OF
`RSS DATA WITH
`LOOK-UPDATA
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`70
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`SELECT TOKEN WITH
`HIGHEST CORRELATION
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`CORRELATION
`ABOVE A SET
`THRESHOLD
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`Fig. 6
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`74
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`SELECT
`POSITION
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`Page 5 of 9
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`US 2006/0O891.53 A1
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`Apr. 27, 2006
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`LOCATION-SENSITIVE CALIBRATION DATA
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`0001. This application claims priority from copending
`provisional patent application 60/622,884, filed Oct. 27.
`2004.
`
`BACKGROUND
`0002 Locating people, vehicles employees, etc. has
`become a matter of increased importance over the last
`several years, especially through the medium of a mobile
`phone. Much interest in determining mobile phone position
`was prompted by the Federal Communications Commission
`(FCC) through its edict to create the wireless Enhanced 911
`system (E911) by November 2005.
`0003. Several technologies are available and have been
`proposed for mobile station (e.g. mobile phone, personal
`digital assistant (PDA) with telecommunications capability,
`portable computer with telecommunications capability,
`pager etc.) position determination ranging from use of the
`global positioning systems (GPS) to phone network-based
`Solutions. Fingerprinting provides another approach to
`determining the position of a mobile station.
`0004 Radio frequency signal characteristics associated
`with various regions in a signal transmission area are
`collected in a database. Each grouping of signal character
`istics for a region is known as a fingerprint. Typically, the
`position of a mobile station is determined by comparing a
`RF data sample collected by the mobile station to fingerprint
`data in the database. The mobile stations position is deter
`mined to lie in the area corresponding to a fingerprint data
`point of highest correlation to the RF data sample.
`0005 The comparison is made by a server holding the
`fingerprint data. If the comparison were to be accomplished
`at a mobile station, in accordance with conventional prac
`tices, a significant amount of data would have to be down
`loaded from a network-based database to the mobile station.
`Fingerprinting requires multiple measurements to be taken
`from different base stations or cell sites, e.g., base station
`transceivers (BTSs), at different times of day to capture
`short-term signal variation (Rayleigh fading, etc.) and varia
`tions in network load (capacity) in an effort to capture each
`fingerprint calibration point for a fingerprint database. Con
`sequently, downloading the fingerprint database to the
`mobile station would likely be infeasible.
`0006 Received signal strength indicator (RSSI) has been
`used in connection with network planning and fingerprinting
`by Ekahau, Inc. Radio network sample points are collected
`from different site locations. Each sample point contains
`RSSI data together with related map coordinates which are
`stored in a database for position tracking of persons, assets,
`equipment, etc. within a Wi-Fi network (802.11a/b/g).
`0007. However, this Wi-Fi based Ekahau system is for
`Small applications wherein a program run on a server
`calculates position determinations and interacts with a client
`device (i.e., laptop computer, personal digital assistant
`(PDA), Wi-Fi Tag, etc.) in connection with an application
`program for recording field data (e.g., RSSI data). The
`position determination data returned can include the speed,
`heading, building floor and grid location of client device.
`
`For larger scale applications, several U.S. wireless carriers
`determine a mobile phone's location using RSSI measure
`ments made from and by nearby BTSs.
`0008 Triangulation techniques can result in duplicative
`calculations at a network server which can unnecessarily
`burden the system, especially in heavily trafficked networks.
`While not subject to many of the problems associated with
`other position identifying technologies, fingerprinting
`requires Substantial work in data collection and is most
`feasible in highly populated, highly concentrated metropoli
`tan areas. However, fingerprinting benefits from the collec
`tion of multi-path signal data which arises through indirect
`signal paths from transmitter to receiver. A need exists to
`seize on the benefits of fingerprinting in a manner that
`improves current RSSI position measurement techniques.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0009 FIG. 1 is a diagram of a mobile station and several
`BTSS organized in a grid, with each grid division being
`assigned a token look-up, indicated by a Subscripted
`0010 FIG. 2 is a block diagram of an embodiment of a
`communication system.
`FIG. 3 is a block diagram of mobile station.
`0.011)
`0012 FIG. 4 illustrates a functional block diagram of a
`mobile station position location system.
`0013 FIG. 5 is a chart illustrating the type of data which
`can be maintained in fingerprint database.
`0014 FIG. 6 is a flowchart of a method for determining
`a position of a mobile station.
`
`DETAILED DESCRIPTION
`0015. An improved position determination method, sys
`tem, and device are provided for a mobile station, especially
`for use in highly populated areas exhibiting multi-path
`signal patterns. Familiar locations having such multi-path
`signal patterns include, for example, the Chicago, Manhat
`tan, or San-Francisco financial districts.
`0016.
`In one position determination aspect, fingerprint
`data is stored in a network database, and relevant portions of
`the database are downloaded to the mobile station in con
`nection with identifying an approximate signal reception
`area in which the mobile station lies. The fingerprint data
`base includes RSSI data.
`0017. With reference to FIG. 1, which illustrates a dia
`gram including mobile station 2 (Suggesting a car phone)
`and several transmitting receiving sites, such as BTSS orga
`nized in grid 5, each grid division is assigned a token
`look-up indicated by a subscripted “T”. The subscripts refer
`to the row and column of grid 5.
`0018. The embodiments can be used in conjunction with
`several different radio access channel systems, including, for
`example, code division multiple access (CDMA), time divi
`sion multiple access (TDMA), frequency division multiple
`access (FDMA), space division multiple access (SDMA), or
`like systems.
`0019. In the case of CDMA systems, signals are spread
`over a frequency and coded. Such characteristics contribute
`to signal properties allowing privacy and jamming resis
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`US 2006/0O891.53 A1
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`Apr. 27, 2006
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`tance. Coding is accomplished using code resembling noise,
`which is referred to as pseudorandom scrambling code or
`pseudo noise. Whereas other mobile systems regard multi
`path signal characteristics as being undesirable, with
`CDMA, a multipath signal has some desirable aspects in that
`the multi-path signals can be used to increase the quality of
`a signal. This is made possible because the wideband nature
`of CDMA signals. Each BTS site 4 transmits a pseudo noise
`(PN) code having a unique code sequence, (including a base
`station identification (BASE-ID) which mobile station 2 can
`distinguish in the BTS's pilot signal on the forward link
`(communication from a BTS to mobile station) pilot chan
`nel. The pilot channel constantly transmits signal 7 which
`mobile station 2 uses to acquire the communication system.
`After mobile station 2 has acquired the system, pilot signal
`7 is used for signal strength measurement.
`0020. The strength of the pilot signal from a BTS to a
`mobile station is used to determine the power required to
`properly adjust the strength of a mobile station's signal
`transmission. Additionally, according to one aspect, the pilot
`signal strength can be used to identify transmitting BTSS in
`an effort to define relevant look-up tokens from a network
`database (not shown) which contains pertinent RSSI data
`base information for comparison with the RSSI data mea
`sured at mobile station 2.
`0021. The relevant look-up token information can be
`determined from a single BTS. For instance, BTS 4A can be
`circumscribed within circle 12 (shown partially) defining a
`transmitting radius 10. Look-up token data within circle 12
`of a given radius 10 can be downloaded to mobile station 2.
`Radius 10 can be of a predetermined length, a parameter
`selection characteristic that is especially suitable for multi
`path signal environments. Alternatively, the length of radius
`10 can be tailored as a function of pilot signal strength. For
`instance, the stronger the signal, the Smaller the radius
`length needed since a closer proximity to a BTS may be
`inferred and a fewer number of look-up tokens analyzed.
`0022 Mobile station 2 compares the downloaded look-up
`token information based on a single BTS 4 with RSSI data
`measured at its position to assess its location. Since each
`look-up token T corresponds to a mapped location, choosing
`the look-up token with closest correlation to the measured
`RSSI data allows a position fix at location corresponding to
`that look-up token. As can be judged from FIG. 1's grid 5
`of look-up tokens, more look-up tokens over a given area
`will allow tighter grid spacing and thus provide a better basis
`for a more accurate position determination.
`0023. In an alternative embodiment, the pilot signals
`from two BTSs are used to determine the relevant look-up
`token data for analysis. As shown in FIG. 1, intersecting
`radii 10 from BTSs 4A and 4C, respectively, define a region
`of intersection 6 on grid 5. Consequently, the affected areas
`in region 6 relate to look-up tokens which include T.T.,
`T.I.T.s, and T2. The look-up tokens within the region of
`intersection 6 are downloaded to mobile station 2. By using
`two BTSs to define the relevant look-up tokens, fewer
`look-up tokens may have to be analyzed as compared with
`look-up tokens within a transmission radius of a single BTS
`4. As with the previous embodiment, radius 10 can be of a
`predetermined length or it can be tailored to represent a
`function of pilot signal strength from each BTS. Accord
`ingly, each radius 10 associated with a given BTS 4 need not
`be the same length.
`
`0024. In another alternative embodiment, other methods
`of determining the relevant look-up token data for analysis,
`and therefore an approximate location for the mobile station,
`may be used. For instance the pilot signal from yet a third
`BTS, BTS 4B, can be used to establish another intersecting
`circle (not shown) in a manner employing advanced forward
`link trilateration (AFLT). With AFLT, the mobile station
`takes RSSI measurements of signals from nearby cellular
`base stations (towers) in addition to the relative times of
`arrival (TOA) measurements, and uses these readings to
`trilaterate an approximate location of the handset.
`0025 Additionally, pertinent RSSI fingerprint data for
`download to the mobile station can also be based on a
`cell-ID (cellular identifiers) information, or enhanced cell
`ID through the identification of cellular base station masts
`proximate the mobile station. Enhanced Cell-ID is a network
`technology that combines cell-ID with one or more addi
`tional technologies. The level of accuracy is increased over
`basic cell-ID. For example, in GSM networks, the additional
`technologies for combination can include Timing Advance
`(which measures handset range from the base station,
`including whether or not the handset is connected to the
`nearest cell) and RSSI.
`0026 Table 1 below summarizes the expected perfor
`mance in terms of average accuracies of position determi
`nation according to the method indicated to obtain a location
`approximation. The accuracies define the search regions for
`RSSI matching and reduce significantly the number of grids
`to be provided to and examined by the mobile station.
`
`TABLE 1.
`
`Location Approximation
`Method
`
`AFLT
`
`Enhanced
`Cell-ID
`
`Cell-ID
`
`Average Accuracy of
`Position Determination
`
`1OO to 200 m 150 to 1000 m 750 m to
`3–5 km
`
`0027 FIG. 2 is a block diagram showing a system in
`which the interaction of mobile station 2 with BTS 4 and
`database 8 can be located remotely from mobile station 2
`and BTS 4. Interaction is such that a request, denoted by the
`outgoing end of double arrow 16, to a BTS 4 (having the
`strongest pilot signal strength indication), for selected look
`up tokens can be made by mobile station 2 in connection
`with analyzing signal strength data received from BTSs.
`Look-up token information can be received by the same
`BTS 4 from database 8 in connection with a request to a
`server 11 at which the database is resident. Alternatively,
`database 8 information can be forwarded to mobile station 2
`through another BTS (not shown) as indicated by dotted
`lined arrow 20.
`0028. In an alternative embodiment, other unique cellular
`identifiers in addition to the base station identification
`(BASE-ID) can be used to identify an area of interest in
`connection with downloading the pertinent fingerprint data.
`These identifiers include the system identification (SID)/
`network identification (NID)/BASE-ID and SID/mobile
`switching center identification (MSC-ID)/BASE-ID.
`0029 FIG. 3 is a block diagram of mobile station 2. As
`shown, mobile station 2 includes a location approximation
`identifier section 30 which identifies the pertinent portion of
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`the fingerprint database to download to mobile station 2 in
`accordance with one of the location approximation methods
`discussed herein, i.e. AFLT, enhanced Cell-ID, etc. RSSI
`section 32 determines RSSI measurements at mobile station
`2 working in conjunction with a radio frequency commu
`nication section 34 for providing mobile communications
`and processor 36 for processing data within mobile station
`2. The RSSI measurements, request for pertinent fingerprint
`data and determination of mobile station position occur in
`connection with software 42 held in memory 40.
`0030 FIG. 4 is a functional block diagram of a mobile
`station position location system. As shown, location estima
`tor 46 identifies an approximate location of the mobile
`station according to one of methods discussed herein. Alter
`natively, location estimator can be implemented in the
`network 54. Fingerprint requestor 48 requests and obtains
`the pertinent fingerprint data for the approximate location
`identified by location estimator 46. Fingerprint comparator
`50 compares the measured RSSI data as determined by RSSI
`indicator 51 with the fingerprint data received from network
`54 through fingerprint requestor 48 in connection with
`requestor 48’s fingerprint request.
`0031. A mobile station's position is determined by fin
`gerprint comparator 50 in connection with choosing a look
`up token with highest correlation to the RSSI data measured
`by RSSI indicator 51. The area corresponding to the look-up
`token is chosen as the position of the mobile station. The
`mobile stations location is displayed on location display 52.
`The location can be displayed in terms of latitude and
`longitude readings. Additionally, or alternatively, the loca
`tion can include a representative street address. Alterna
`tively, location display step may entail mapping and dis
`playing location on the digital map. In yet another
`embodiment the location can be provided to an application
`internal or external to the mobile station for further process
`ing and display.
`0032 FIG. 5 is a chart illustrating the type of data which
`can be maintained in fingerprint database 8 that is used to
`determine the position of the mobile station. As shown,
`database 8 can hold tower entries indicating the identity of
`towers for defining the areas of look-up token interest. FIG.
`5 show an example of two tower entries. However, more
`tower entries can be used to define a look-up token area. For
`further refinement of the look-up token area, the intersecting
`areas between two towers can be documented as determined
`by a specified radius, defining BTS antenna coverage or
`antenna range, out from each BTS. Note, however, that it is
`useful to maintain single tower entries in database 8 to
`account for circumstances where a single tower is Sufficient
`to define the look-up token area and where only a single
`tower reception is relevant. RSSI tokens as defined by the
`tower intersection area or single tower, can be maintained in
`database 8. Location as defined by latitude and longitude
`readings, among other measures, can also be maintained in
`database 8.
`0033 FIG. 6 is a flowchart showing a method for posi
`tion determination of a mobile station. As shown, RSSI data
`is collected by the mobile station, 60. Thereafter, an approxi
`mate location of the mobile station is determined, 62. The
`approximate location of the mobile station can be deter
`mined according to one of the foregoing discussed tech
`niques. For instance, in one aspect, the mobile station
`
`determines the nearest BTS site based on pilot signal
`strength from the transmitted pilot signal on the received
`pilot channel. A second and next nearest BTS tower is
`identified based on the 2" and next strongest pilot signal.
`Based on the intersection of overlapping reception areas
`from the two or more identified BTS sites, an area of interest
`of relevant look-up tokens is defined and supplied to the
`mobile station.
`0034. In another aspect, look-up token data is defined
`corresponding to an area identified as being proximate to the
`mobile station, 64. These look-up tokens are compared,
`preferably at a server holding the look-up token database,
`with the RSSI data collected by the mobile station, 66. A
`correlation is calculated between each look-up token data
`point in the defined area of interest, 68. The look-up token
`with the highest correlation to the collected RSSI data is
`selected, 70, and compared with a predetermined correlation
`threshold, 72. For instance, should an 80% correlation
`between the look-up token and collected RSSI data be
`Sufficient then the selected look-up token is chosen indica
`tive of a corresponding position location (street address,
`longitudinal and latitudinal indication, etc.) of the mobile
`station, 74. If the selected look-up token of highest corre
`lation fails to meet the threshold value, the method is
`restarted, starting with collection of RSSI data by the mobile
`station, 60, in an effort to obtain a position fix for the mobile
`station. The use of many known algorithms related to nearest
`neighbor search and signal pattern matching is also contem
`plated herein. These techniques can be employed to further
`refine the location estimate.
`0035 Although a description has been given with refer
`ence to particular embodiments, it is to be understood that
`these embodiments are merely illustrative of the principles
`and applications. It is therefore to be understood that numer
`ous modifications may be made to the illustrative embodi
`ments and that other arrangements may be devised without
`departing from the spirit and scope as defined by the
`appended claims.
`1. A system for determining the position of a mobile
`station comprising:
`a location estimator for identifying an approximate posi
`tion of the mobile station;
`a fingerprint requestor for requesting and obtaining,
`through radio channel access, pertinent location finger
`print data from a fingerprint database remote from said
`mobile station, said pertinent location fingerprint data
`being indicative of the approximate position of the
`mobile station; and
`a fingerprint comparator for comparing measured RSSI
`data at said mobile station with said pertinent location
`fingerprint data in order to determine the position of
`said mobile station.
`2. A system for determining the position of a mobile
`station as recited in claim 1 further comprising a display,
`said displaying being operable to indicate the position of the
`mobile station.
`3. A system for determining the position of a mobile
`station as recited in claim 1 wherein said radio channel
`access is provided through a technique selected from the
`group of radio-channel access schemes consisting of
`CDMA, TDMA, FDMA, SDMA and a combination thereof.
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`4. A system for determining the position of a mobile
`station as recited in claim 1 wherein said remote fingerprint
`database contains RSSI data.
`5. A system as recited in claim 1 wherein said mobile
`station is a mobile communications device selected from the
`group consisting of a mobile phone, a personal digital
`assistant with wireless communications capability, a por
`table computer with wireless communications capability and
`a pager.
`6. A mobile station comprising:
`a location approximation identification section being
`operable to identify a pertinent portion of a remote
`fingerprint database, corresponding to a vicinity of said
`mobile station, to download to said mobile station;
`a RSSI section for making RSSI measurements at said
`mobile station;
`a memory;
`
`a processor;
`Software held in memory and run in said processor for
`determining the position of said mobile station by
`comparing said pertinent portion of said remote finger
`print database with said RSSI measurements made at
`said mobile station.
`7. A mobile station as recited in claim 6 wherein said
`location approximation identification section identifies a
`pertinent portion of a remote fingerprint database, corre
`sponding to a vicinity of said mobile station by a method of
`advanced forward link trilateration.
`8. A mobile station as recited in claim 6 wherein said
`location approximation identification section identifies a
`pertinent portion of a remote fingerprint database through
`identification of a base station site in the vicinity of said
`mobile station by measuring base station pilot signal
`strength.
`9. A mobile station as recited in claim 6 wherein said
`location approximation identification section identifies a
`pertinent portion of a remote fingerprint database, corre
`sponding to a vicinity of said mobile station by a method
`using cell-ID through the identification of a cellular base
`station located proximate said mobile station.
`10. A mobile station as recited in claim 6 wherein said
`location approximation identification section identifies a
`pertinent portion of a remote fingerprint database, corre
`sponding to a vicinity of said mobile station by a method
`using enhanced cell-ID.
`11. A system for determining the position of a mobile
`station comprising:
`a fingerprint database including RSSI data;
`a mobile station including a location estimator for iden
`tifying an approximate position of said mobile station;
`a fingerprint requestor for requesting and obtaining,
`through radio channel access, pertinent location finger
`print data from a fingerprint database remote from said
`mobile station, said pertinent location fingerprint data
`being indicative of the approximate position of the
`mobile station; and
`
`a fingerprint comparator for comparing measured RSSI
`data at said mobile station with said pertinent location
`fingerprint data in order to determine the position of
`said mobile station.
`12. A method of determining the position of a mobile
`station comprising:
`collecting RSSI data at said mobile station;
`determining the approximate location of said mobile
`station;
`selecting fingerprint look-up token data, from a database
`located remotely from said mobile station, correspond
`ing to said approximate location of said mobile station;
`comparing said fingerprint look-up token data with said
`RSSI data collected at said mobile station; and
`determining the position of said mobile station in accor
`dance with finding said fingerprint look-up token data
`of highest correlation with said RSSI data.
`13. A method of determining the position of a mobile
`station as recited in claim 12 further including determining
`whether said highest correlation meets a predetermined
`threshold.
`14. A method of determining the position of a mobile
`station as recited in claim 13 wherein said method is
`reiterated should said highest correlation fail to meet said
`predetermined threshold.
`15. A method of determining the position of a mobile
`station as recited in claim 12 wherein said fingerprint
`look-up token data includes RSSI data.
`16. A method of determining the position of a mobile
`station as recited in claim 12 wherein determining the
`approximate location of said mobile station is accomplished
`using a method of AFLT.
`17. A method of determining the position of a mobile
`station as recited in claim 12 wherein determining the
`approximate location of said mobile station is accomplished
`through identification of a base station site in the vicinity of
`said mobile station by measuring base station pilot signal
`strength.
`18. A method of determining the position of a mobile
`station as recited in claim 12 wherein determining the
`approximate location of said mobile station is accomplished
`through identification of a cellular base station antenna
`located proximate said mobile station.
`19. A method of determining the position of a mobile
`station as recited in claim 12 which further includes dis
`playing said mobile station location.
`20. A method of determining the position of a mobile
`station as recited in claim 19 wherein the display of said
`mobile station location includes longitudinal and latitudinal
`readings.
`21. A method of determining the position of a mobile
`station as recited in claim 19 wherein the display of said
`mobile station location includes Street location information.
`
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