(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2006/0009235 A1
`Sheynblat et al.
`(43) Pub. Date:
`Jan. 12, 2006
`
`US 2006.0009235A1
`
`(54) METHOD AND APPARATUS FOR
`DETERMINING LOCATION OFA BASE
`STATION USING A PLURALITY OF MOBILE
`STATIONS IN A WIRELESS MOBILE
`NETWORK
`(76) Inventors: Leonid Sheynblat, Hillsborough, CA
`(US); Thomas Wrappe, Los Gatos, CA
`(US)
`Correspondence Address:
`QUALCOMM, INC
`5775 MOREHOUSE DR.
`SAN DIEGO, CA 92121 (US)
`(21) Appl. No.:
`10/971,591
`(22) Filed:
`Oct. 21, 2004
`Related U.S. Application Data
`(60) Provisional application No. 60/580,929, filed on Jun.
`18, 2004.
`
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`H04O 7/20
`(52) U.S. Cl. .......................................................... 455/456.1
`(57)
`ABSTRACT
`A method and apparatus for determining a position of a base
`Station in a wireleSS communication network that includes a
`mobile station in communication with base stations. ABTS
`calibration server is networked with the base stations. ABTS
`calibration program is programmed into a group of mobile
`Stations that have position location capabilities. Using the
`BTS calibration program, calibration information may be
`requested by the BTS calibration server, or a session may be
`initiated by the mobile station. The BTS calibration program
`also provides privacy features that allow user of the mobile
`Station to prevent it from being used for base Station loca
`tion. If authorized, the BTS calibration program determines
`the position of the mobile Station, and provides calibration
`information, Such as position and base Station phase mea
`Surements, to the Server. The calibration information may be
`used to calibrate the base Station almanac.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`BTS CALIBRATION
`SERVER (BISCS)
`
`MOBILETERMINATED CALIBRATION EXAMPLE
`ORIGINATING FROMBTSCS)
`
`7
`
`COMMUNICATION ESTABLISHED
`
`37
`
`
`
`BTS CALIBRATION
`PROGRAM
`
`
`
`
`
`REQUEST CALIBRATION
`INFORMATION
`
`FXPOSITION OFMS, MAKE
`PPMMEASUREMENTS
`
`TRANSMIT MSPOSITION
`INFORMATION TO BTSCS
`
`
`
`
`
`TRANSMT BASE STATION PPM
`MEASUREMENTS TO BSCS
`
`CLOSE COMMUNICATION
`
`POSITION
`LOCATION
`SYSTEM(S)
`
`
`
`Page 1 of 18
`
`SAMSUNG EX-1201
`
`

`

`Patent Application Publication Jan. 12, 2006 Sheet 1 of 6
`
`US 2006/0009235 A1
`
`12
`
`2
`
`f
`i.
`N
`
`12
`
`13
`N
`e1
`
`NSN
`
`Ob
`1
`
`i4a
`'S 1
`\\
`
`13
`N
`NSN s
`s1&
`1
`
`3.
`
`(S$
`14b.
`Y1
`NA
`&
`
`4d
`Še 1
`\\
`
`14
`s
`& 1 C
`R
`
`2
`Oa -
`NSN
`s
`s is
`
`13
`- - As
`---
`10C
`1
`
`BASE STATIONS 10
`
`WAP'S 20
`
`15a
`
`CELLULAR INFRASTRUCTURE NETWORK
`
`
`
`
`
`15b.
`
`WIRELESS ACCESSPOINT NETWORK(S)
`
`INTERNET (OPTIONAL)
`
`16
`
`PHONE
`SYSTEM
`
`
`
`
`
`17
`
`COMPUTER
`NETWORK(S)
`(E.G.INTERNET)
`
`
`
`POSITION DETERMINATION
`ENTITY (PDE)
`
`BTS CALIBRATION
`SERVER
`FIG. 1
`
`Page 2 of 18
`
`

`

`Patent Application Publication Jan. 12, 2006 Sheet 2 of 6
`
`US 2006/0009235 A1
`
`10
`
`BASE STATION
`
`
`
`
`
`MOBILE SWITCHING
`CENTER (MSC)
`
`24
`
`IWF/PDSN
`
`
`
`
`
`22
`
`IPNETWORK
`
`
`
`MOBILE POSITONING
`CENTER (MPC)
`
`POSITION DETERMINING
`ENTITY (PDE)
`
`BTS CALIBRATION
`SERVER (BTSCS)
`
`TO/FROM
`TELEPHONE
`LINES
`
`
`
`25
`
`
`
`TO/FROM
`PROCESSORS AND
`PROCESSORS IN
`LA
`CELLU A. ETWORK
`EXTERNAL LOCATION
`SERVICESCLIENTS
`
`27
`
`
`
`
`
`
`
`
`
`
`
`BASE STATION
`ALMANAC (BSA)
`
`
`
`BASE STATION
`ALMANACDATABASE
`SERVER
`
`FIG. 2
`
`Page 3 of 18
`
`

`

`Patent Application Publication Jan. 12, 2006 Sheet 3 of 6
`
`US 2006/0009235 A1
`
`i3
`-/
`
`31
`
`14
`
`12
`N--
`
`38 A/
`
`
`
`
`
`
`
`TWO-WAY COMMUNICATIONSYSTEM(S)
`(E.G. CELLULAR, AND/OR WIRELESS
`LAN)
`
`
`
`POSITION LOCATIONSYSTEM(S)
`39
`
`GPS RECEIVER
`
`V
`Y
`
`33
`
`
`
`
`
`LAN POSITIONING SYSTEM
`
`WANTDOA (AFLT) SYSTEM
`
`MOBILE DEVICE CONTROL SYSTEM
`
`SOFTWARE APPLICATIONS
`
`MICROPROCESSOR
`
`37
`
`
`
`BTS CALIBRATION
`APPLICATION
`
`MEMORY
`
`SYSTEM
`
`HARDWARE
`
`FIRMWARE
`
`
`
`
`
`
`
`EXTERNAL
`INTERFACE(S)
`(E.G. USB, IEEE
`1394)
`
`
`
`
`
`
`
`
`
`
`
`
`
`MICROPHONE/
`SPEAKER
`
`USER INTERFACE
`
`KEYPAD
`
`VISUAL
`DISPLAY
`
`Page 4 of 18
`
`

`

`Patent Application Publication Jan. 12, 2006 Sheet 4 of 6
`
`US 2006/0009235 A1
`
`42
`
`INSTALLED INTO MS:
`E.G. DOWNLOADABLE, PRE
`INSTALLED
`
`
`
`RESTRICTED
`ACCESS
`
`
`
`43
`
`
`
`OPERATION:
`ONGOING, CAN RUN IN
`BACKGROUND
`
`BTS CALIBRATION
`PROGRAM
`
`Cameras)
`
`48
`
`COMMUNICATIONS
`WITH BTSCS 19
`
`46
`
`
`
`
`
`SECURE ACCESS: USER
`IDENTITY NOT DISCLOSED
`
`47
`
`
`
`CONSENT OF
`OWNER OF MS:
`PRIVACY SETTINGS
`
`
`
`
`
`
`
`INTERFACE WITH
`POSITION LOCATION
`SYSTEMS 34
`
`FIG. 4
`
`Page 5 of 18
`
`

`

`Patent Application Publication Jan. 12, 2006 Sheet 5 of 6
`
`US 2006/0009235 A1
`
`CALIBRATE ABASE STATION LOCATION
`
`50
`PROGRAM A GROUP OF MOBILESTATIONS WITHBS CALIBRATION
`PROGRAM
`
`5
`
`COMMUNICATE BETWEENTARGET BASE STATION ANDAT LEAST ONE OF
`CALIBRATION-ENABLED MOBILE STATIONS
`
`REQUEST CALEBRATION INFORMATION FROM CALIBRATION-ENABLED MOBILE
`STATION IN COMMUNICATION WITH TARGET BASE STATION
`
`53
`
`CHECKPRIVACY SETTINGS OF MOBILE STATION
`
`53b
`
`
`
`*5ged NO
`AUTHORIZED?
`YES
`
`54
`
`DETERMINE POSTION OF MOBILESTATION
`
`EXIT, DO NOT ALLOW
`COMMUNICATION OF
`INFORMATION
`
`MEASURE PHASE OF BASE STATION(S
`) TO
`MOBILE STATION
`
`-
`
`55
`
`56
`
`TRANSMIT CALIBRATION INFORMATION FROM
`MOBILE STATION TO BTSCS
`
`52
`
`57
`
`RESPONSIVE TO CALIBRATION INFORMATION, CALCULATE DISTANCE FROMMOBILE
`STATION TOBASE STATION, AND (OPTIONALLY) POSITION OF BASE STATION(S)
`
`58
`
`-
`
`COMPARE CALCULATED BASE STATION
`POSITION WITH POSITION STORED IN BSA
`
`59
`
`UPDATESTORED POSITION IN BSA ASAPPROPRIATE
`
`FIG. 5
`
`Page 6 of 18
`
`

`

`Patent Application Publication Jan. 12, 2006 Sheet 6 of 6
`
`US 2006/0009235 A1
`
`MOBILE-ORIGINATED CALIBRATION EXAMPLE
`
`6
`
`62
`
`ESTABLISH COMMUNICATION
`
`COMMUNICATION ESTABLISHED
`
`BTS CALIBRATION
`PROGRAM
`
`CALIBRATION REQUEST?
`
`FIXPOSITION OFMS, MAKE
`PPM MEASUREMENTS
`
`BTS CALIBRATION
`SERVER (BTSCS)
`
`TRANSMITMSPOSITION
`NFORMATION TO BTSCS
`
`POSITION
`LOCATION
`SYSTEM(S)
`
`TRANSMITBASE STATION PPM
`MEASUREMENTS TO BTSCS
`
`68
`
`CLOSE COMMUNICATION
`
`MOBILETERMINATED CALIBRATION EXAMPLE
`(ORIGINATING FROMBTSCS)
`
`71
`
`COMMUNICATION ESTABLISHED
`
`REQUEST CALIBRATION
`INFORMATION
`
`FIXPOSITION OFMS, MAKE
`PPMMEASUREMENTS
`
`73
`
`
`
`4 7
`
`TRANSMIT MSPOSITION
`NFORMATION TO BTSCS
`
`TRANSMTBASE STATION PPM
`MEASUREMENTS TO BTSCS
`
`
`
`CLOSE COMMUNICATION
`
`
`
`
`
`37
`
`BTS CALIBRATION
`PROGRAM
`
`
`
`
`
`POSITION
`LOCATION
`SYSTEM (S)
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`19
`
`BTS CALIBRATION
`SERVER (BTSCS)
`
`
`
`
`
`
`
`Page 7 of 18
`
`

`

`US 2006/0009235 A1
`
`Jan. 12, 2006
`
`METHOD AND APPARATUS FOR DETERMINING
`LOCATION OFA BASE STATION USINGA
`PLURALITY OF MOBILE STATIONS INA
`WIRELESS MOBILE NETWORK
`
`RELATED APPLICATIONS
`0001. This applications claims priority to U.S. Provi
`sional Application No. 60/580,929, filed on Jun. 18, 2004.
`
`BACKGROUND
`
`0002) 1. Field
`0003. The present invention generally relates to wireless
`communications Systems in which a base Station communi
`cates with a number of mobile Stations that have position
`location capabilities, and more particularly to the determi
`nation of the position of a base Station in a mobile commu
`nication network.
`0004 2. Description of Related Art
`0005. In wireless communication networks, one or more
`base Stations communicate wirelessly with a number of
`mobile Stations (e.g., wireless devices Such as cell phones).
`Mobile Stations usually provide Standard Voice and/or data
`communication; as an additional feature, Some mobile Sta
`tions have positioning capabilities, which allow the user of
`the mobile station to determine his or her position. Such
`position determination capabilities are becoming increas
`ingly useful and important; for example, the regulatory
`requirements of a jurisdiction may require a network opera
`tor to report the location of a mobile station when the mobile
`Station places a call to an emergency Service, Such as a 911
`call in the United States. Or a user may simply want to know
`his or her position for purposes of locating a nearby restau
`rant or movie theater.
`0006. One well-known type of position location system
`utilizes Satellites in earth orbit to trilaterate a position of the
`mobile station. One example of such a system is the Global
`Positioning Satellite (GPS) system currently in operation.
`Another type of position location System utilizes radio
`Signals from base Stations whose locations are known. For
`example, in one communication network-a Code Division
`Multiple Access (CDMA) digital cellular network-the
`position location capability can be provided by Advanced
`Forward Link Trilateration (AFLT), a technique that com
`putes the location of the mobile station (MS) from the
`mobile Station's measured time of arrival of radio signals
`from the cellular base stations. An AFLT-enabled wireless
`mobile station makes pilot phase measurements (PPMs) of
`the radio Signals from the base Stations with which it is
`communicating, and uses these measurements to determine
`the mobile Station's position. A more advanced technique is
`hybrid position location, where the mobile Station also
`employs a GPS receiver and the position is computed based
`on both AFLT and GPS measurements.
`0007 Message protocols and formats for CDMA position
`location employing AFLT, GPS, and hybrid receivers, appli
`cable to both the MS-based and MS-assisted cases, have
`been published in TIA/EIA standard IS-801-1 2001, Position
`Determination Service Standard for Dual-Mode Spread
`Spectrum Systems-Addendum. Pages 4-41 through 4-44 of
`this Standard Specify that each base Station shall transmit a
`base Station almanac message among other elements con
`
`taining the locations of the base Station antennae transmit
`ting the CDMA pilot pseudorandom (PN) sequence.
`0008 Thus, in wireless communication systems with
`AFIT capabilities, the wireleSS base Stations can be used as
`reference points to assist in fixing the location of a mobile
`Station. However, one prerequisite to using a base Station as
`a reference is precise knowledge of the position of the base
`Station antennae. Timing information regarding the base
`Station is also important. Once known, the base Station's
`antenna position and timing information may be recorded in
`a base station almanac (BSA) database for use by a position
`determining entity (PDE). However, acquiring the base
`Stations antenna precise location and timing information
`can be tedious and expensive.
`0009. To further elaborate on the position determination
`System, data concerning calibration or re-calibration of a
`base Station time offset, base Station antenna location and
`other parameters are typically Stored in what is called a
`“base Station almanac.' The base Station almanac database
`provides information for determining an initial position
`estimate of the mobile station to seed GPS pseudorange
`Searching. Due to PN reuse, the base Station almanac data
`base provides information for resolving ambiguities about
`which observed pseudorandom noise Sequences (PNs) cor
`respond to which physical sectors of a CDMA network base
`Station. The base Station almanac database provides the
`cellular base Station Sector antenna position from which
`Signals emerge. AFLT range measurements are made to
`these antenna positions.
`0010. In some instances the position of a base station
`antenna may change Slightly or by a larger distance, and in
`that instance the corresponding almanac information must
`be updated. For example a base Station antenna may be
`relocated, or a base Station transceiver may be repaired or
`replaced, a new cable may be placed between a transceiver
`and an antenna causing a change in the base Station antenna
`position or timing information. In another example, a base
`Station can be logically (but not physically) moved, when,
`for example, two physical base Stations Swap their identifi
`cation information, and in Such a circumstance, the two
`Stations would appear to have Swapped locations although
`neither base Station physically moves.
`0011. In such situations, if not updated, the corresponding
`information in the database can become erroneous, therefore
`the almanac database must be updated before resuming
`Service from the base Station. However, updating the alma
`nac database using conventional techniques can be time
`consuming and expensive: for example conventionally the
`antenna location may be determined by a Survey or with
`reference to coordinates read from a map, and if the antenna
`coordinates are entered manually into the database then the
`possibility of human error arises. The base Station timing
`information is also Subject to human error in cases where
`custom hardware is used to measure the timing information,
`and timing offsets are entered manually into the database.
`0012. In Local Area Networks the significant number of
`base stations (several million), the deployment practices and
`the ease of moving the portable base Station from one
`physical location to another make it impossible to locate and
`maintain the base Station almanac using conventional Sur
`Veying techniques.
`0013 In summary, deployment of base station time dif
`ference of arrival ranging Solutions Such as AFLT or hybrid
`
`Page 8 of 18
`
`

`

`US 2006/0009235 A1
`
`Jan. 12, 2006
`
`AFLT requires accurate base Station almanac (BSA) infor
`mation including base Station antennae locations and
`forward link calibration parameterS Such as time corrections,
`which are key components of the BSA information. Today,
`population of the BSA parameters is done individually for
`each base Station, which is a manual, laborious and expen
`Sive process, and therefore hinders the deployment and
`proliferation of LBS services. It would be an advantage to
`provide a practical System that can update the BSA param
`eters in real time using data from mobile devices that are in
`the area to compute base Station locations and forward link
`calibration parameters.
`
`SUMMARY
`0.014) A method and apparatus for determining a position
`of a base Station in a wireleSS communication network that
`includes a plurality of mobile Stations in communication
`with one or more base stations is disclosed. The method
`comprises programming a group of mobile Stations with a
`BTS calibration program, thereby providing a plurality of
`calibration-enabled mobile stations, and providing a BTS
`calibration server networked with the base station. Calibra
`tion information is requested from at least one of the
`calibration-enabled mobile Stations in communication with a
`base Station, and the position of the calibration-enabled
`mobile Station(s) is determined. A signal from the base
`Station is received at the mobile Station(s), and this signal
`may be used to measure the time of travel of the Signal from
`the base station to the mobile station, for example it may
`measure path delays of the Signals transmitted between the
`base Station and the mobile Stations to determine distances
`between the base Station and the mobile Stations, and may
`include measuring a relative time of arrival in a TDOA
`system, or a round trip delay in an RTD system. If autho
`rized, calibration information indicative of the position is
`transmitted from the mobile station(s) to the BTS calibration
`server. In the BTS calibration server, the calibration infor
`mation is compared with base Station almanac information
`asSociated with the base Station, and the position and timing
`of the base Station may be calibrated responsive thereto.
`0.015. In order to provide the user of the mobile station a
`way to prevent it from being used for base Station location,
`the mobile station calibration software may determine if it is
`authorized to communicate calibration information. If there
`is no authorization then operation is exited any time before
`transmitting calibration information, otherwise operation is
`completed. For example, the users of the calibration-enabled
`mobile phones may utilize the BTS calibration program to
`create privacy Settings to indicate authorization to provide
`calibration information, and the Step of determining if the
`mobile Station is authorized to communicate calibration
`information further comprises checking the privacy Settings
`to verify that the mobile station is authorized to provide
`calibration information.
`0016 Calibration information may be requested by the
`BTS calibration server, or by the mobile station, triggered
`upon a particular event. For example, the calibration request
`may be initiated by the BTS calibration software when in
`communication with the target base Station. AS another
`example, the BTSCS may select a target base Station, and the
`BTS calibration server requests calibration information from
`at least one of the Software-enabled mobile Stations in
`communication with the target base Station. In yet another
`
`example, the BTSCS may provide the identity of a target
`base station to the mobile stations for the BTS calibration
`Software processing.
`0017. The position of the mobile stations is determined
`by any suitable method. For example if the mobile stations
`have global Satellite receivers, the positions of the mobile
`Stations may be determined from Signals received by the
`mobile Stations from global Satellites. Alternatively, or in
`addition to GPS, the positions of the mobile stations may be
`determined by Advanced Forward Link Trilateration (AFLT)
`of each mobile Station from base Stations having accurately
`known positions. The mobile Stations may comprise hybrid
`telephone handsets including global Satellite receivers, the
`positions of the mobile Stations may be determined from
`Signals received by the mobile Stations from global Satel
`lites, and the position of the base Station may be determined
`from the positions of the mobile Stations using time differ
`ence of arrival, time of arrival or round trip delay Systems.
`0018) A variety of embodiments are disclosed. The
`mobile Stations may comprise hybrid telephone handsets
`including global Satellite receivers. The positions of the
`mobile Stations may be determined from Signals received by
`the mobile Stations from global Satellites, and/or the base
`Stations comprise at least one WireleSS LAN base Station,
`and/or the position of the Wireless LAN base station (such
`as a WiFi access point) may be determined from the posi
`tions of the mobile Stations in communication with the
`Wireless LAN base station, using Wireless LAN signals.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0019 For a more complete understanding, reference is
`now made to the following detailed description of the
`embodiments as illustrated in the accompanying drawing,
`wherein:
`0020 FIG. 1 is a perspective view of a plurality of
`cellular base Stations, GPS Satellites, and a user holding a
`wireleSS mobile device Such as a cell phone,
`0021
`FIG. 2 is a block diagram of one example of the
`Stationary components that reside in the cellular network
`shown in FIG. 1;
`0022 FIG. 3 is a block diagram of one embodiment of
`the mobile device that incorporates communication and
`position location Systems;
`0023 FIG. 4 is a diagram of BTS calibration program,
`illustrating features of one embodiment;
`0024 FIG. 5 is a flow chart of operations to calibrate a
`base Station location;
`0025 FIG. 6 is a flow chart of an example of a mobile
`originated calibration process, and
`0026 FIG. 7 is a flow chart of an example of a mobile
`terminated calibration process, which differs from FIG. 6 in
`that the request originates in the BTSCS.
`
`DETAILED DESCRIPTION
`0027. In the drawing, like numbers are used to denote like
`or Similar elements.
`
`Page 9 of 18
`
`

`

`US 2006/0009235 A1
`
`Jan. 12, 2006
`
`0028 Glossary of Terms and Acronyms
`0029. The following terms and acronyms are used in the
`detailed description:
`0030 AFLT (Advanced Forward Link Trilateration): a
`technique, implemented in CDMA Systems, that computes
`the location of a mobile station (MS) from the mobile
`Station's measured time difference of arrival of radio signals
`from the base Stations.
`0031 BSA (Base Station Almanac): An almanac that
`includes location information and time correction informa
`tion, among other information, for one or more base Stations.
`0032 BSA message: The BSA message (e.g., the Provide
`Base Station Almanac message of the IS-801-1 protocol)
`includes fields that describe a BTS including its location and
`time correction values, among other information. The BSA
`message is typically Sent to an MS upon request by the MS.
`0033 BTS (Base Station Transceiver Subsystem): (a/k/a
`base Station or cell site): A fixed-position station that
`includes a transmitter and receiver (transceiver) for com
`municating with mobile Stations. Includes antennas for
`transmitting and receiving wireleSS communication signals
`from mobile stations.
`0034). BTSCS (BTS Calibration Server) A server con
`nected to the network of base stations (BTS's). The BTSCS
`provides Services related to calibration of base Station loca
`tion and timing using one or more mobile phones in com
`munication with the base Station.
`0035 CDMA (Code Division Multiple Access): a high
`capacity digital wireleSS technology that was pioneered and
`commercially developed by QUALCOMMTM Incorporated.
`0.036
`Calibration-enabled Mobile Station: a mobile sta
`tion that has an installed, operating BTS calibration pro
`gram.
`0037 Cellular: A type of communication service in which
`an MS communicates with one or more base Stations in a
`cellular network, each in a different Wireless Wide Area
`Network or Wireless Local Area Network “cell” that covers
`a relatively small area. As the MS moves from one cell to
`another, there is a “handoff from cell to cell. “Cellular” is
`used herein in its broadest Sense to include at least digital
`and/or analog systems.
`0038 GPS fix: the end result of a process of satellite
`measurements and Subsequent computations by which the
`location of the MS (GPS user) is determined.
`0039 GPS (Global Positioning System): Although the
`term GPS is often used to refer to the U.S. Global Position
`ing System, the meaning of this term includes other Satellite
`based global positioning Systems, Such as the Russian Glo
`nasS System and the planned European Galileo System.
`004.0 GSM (Global System for Mobile): a widely-used
`digital wireless communication technology.
`0041) MS (Mobile Station) a portable electronic device
`Such as a cell phone, PDA or a laptop that has a means (Such
`as a modem) for communicating with one or more base
`Stations. Sometimes referred as a mobile handheld unit,
`portables, mobiles, handhelds, personal Stations, wireleSS
`devices, Subscriber units, mobile terminals, or user termi
`
`nals, for example. MS's referenced in this disclosure have
`position determining capabilities.
`0.042 MTSO (Mobile Telephone Switching Office): Pro
`vides control and commands to the mobile Stations. Also
`provides connectivity to the PSTN.
`0.043 PDE (Position Determination Entity): A system
`resource (e.g., a server) typically within the CDMA network,
`working in conjunction with one or more GPS reference
`receivers, which is capable of exchanging location informa
`tion with an MS. For example, in an MS-Assisted A-GPS
`session, the PDE can send GPS and/or cellular assistance
`data to the MS to enhance the satellite and base station
`pseudorange Signal acquisition process. The MS returns
`pseudorange measurements back to the PDE, which is then
`capable of computing the position of the MS. Alternatively,
`in an MS-Based A-GPS session, the MS sends back com
`puted position results to the PDE. The PDE can also provide
`assistance data regarding other networked entities, Such as
`the identifying information, position information and type of
`wireless base stations (access points) that may be in the
`vicinity of the MS.
`0044) PSTN (Public Switched Telephone Network): Pro
`vides connection to wireline telephones in homes and busi
`nesses, for example.
`0.045 RSSI (Received Signal Strength Indicator): A
`parameter indicating Strength of a wireleSS Signal between a
`base Station and a mobile Station.
`004.6 RTD (Round Trip Delay): A method of measuring
`distance by measuring a two-way travel time (distance)
`between a base Station and a mobile Station, e.g., a base
`Station Sends a signal to a mobile Station, which is returned
`to the base Station, and the base Station then measures the
`time between transmitting the Signal and receiving the return
`Signal, which can then be divided by two to provide an
`indication of the distance between the base Station and the
`mobile station. Alternatively, the RTD can be measured by
`the mobile station.
`0047 QoS (Quality of Service): A measure of a desired
`Service parameter Such as the accuracy of position location
`information.
`0.048 SV (Satellite Vehicle): One major element of the
`Global Positioning System is the set of SVs orbiting the
`Earth, broadcasting uniquely identifiable Signals.
`0049 TDOA (Time Difference of Arrival): A system that
`measures distance by measuring the relative times of arrival
`of radio Signals from the base Stations, e.g., for example, in
`CDMA networks AFLT systems use TDOA to provide PPM
`measurements, the time difference of arrival is indicated by
`a pilot phase measurement that is relative to the reference
`pilot used to Set the mobile Station's time base. Another
`example of a TDOA system is an Uplink TDOA system,
`which uses the time difference between transmission of a
`mobile Station signal and reception by base Stations.
`0050 TOA (Time of Arrival): A system which measures
`the time of arrival of a one-way Signal; e.g., for example, a
`GPS system which measures the time of arrival of a satellite
`Signal.
`0051 WLAN (Wireless Local Area Network): a limited
`range wireleSS communication network, examples include
`WiFi, WiMAX, Bluetooth, etc.
`
`Page 10 of 18
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`

`

`US 2006/0009235 A1
`
`Jan. 12, 2006
`
`0052. Use of Mobile Stations to Determine Base Station
`Location
`0053 U.S. Patent Publication US2003/0125046A1 pub
`lished Jul. 3, 2003, entitled “Use of Mobile Stations for
`Determination of Base Station Location Parameters in a
`Wireless Mobile Communication System', discloses a sys
`tem in which a network uses known positions of one or more
`mobile Stations to Verify, update, and/or determine the
`position of a base Station, and is assigned to the same
`assignee as the present application. For example, the pub
`lication discloses a method for AFLT-enabled wireless hand
`sets to provide pilot phase measurements (PPMs) to a
`network, which can be used to determine the base Station
`locations and associated forward link calibration parameters.
`AS an example, to Solve for a base Station location an
`algorithm would require a PPM to said base stations mea
`Sured by at least three distinct geographically Separated
`mobiles each one at a known location; the knowledge of the
`mobile station location can be ascertained via GPS. One
`alternative is to manually Survey base Station antennae and
`use GPS fix to compute errors to the PPM measurements by
`collecting measurements with a dedicated base Station cali
`bration handset in the field in close proximity to the base
`Station.
`Particularly, the system disclosed in Publication
`0.054
`US2003/O12504.6 A1 describes methods that use the mobile
`Stations in communication with a base Station to determine
`the location parameters of that base station. For example, the
`positions of the mobile Stations are determined, and then the
`position of the base Station is determined from the positions
`of the mobile Stations and from Signals transmitted between
`the base Station and the mobile Stations. Despite erroneous
`base Station location parameters for at least one of the base
`Stations, it is often possible to accurately determine the
`positions of the mobile Stations from the base Station loca
`tion parameters of other base Stations, or from global Satel
`lite signals received by the mobile stations if the mobile
`Stations are equipped with global Satellite receivers.
`0055. In addition, the base station location information in
`the database can be checked during normal position location
`Sessions whenever the position of a mobile Station is deter
`mined independent of the location of a base Station in
`communication with the mobile station. This is done by
`determining the distance between the base Station and the
`mobile Station from Signals transmitted between the base
`station and the mobile station. When this distance is incon
`Sistent with the base Station location information in the
`database, the database may be modified to include corrected
`base Station location information. In this fashion, it is
`possible to find erroneous base Station information and
`discontinue its use for position location Services before the
`correct location of the base Station becomes known.
`0056 Erroneous base station location information can be
`corrected automatically once a Sufficient number of inde
`pendent distances are determined between the base Station
`and mobile stations having known positions. With a suffi
`cient number of independent distance measurements, it is
`possible to determine the base Station location with a degree
`of certainty comparable to the position of a single mobile
`Station. In this fashion, it is possible to automatically main
`tain and improve the base Station location information in the
`database. This can be done while providing regular position
`
`location Services, without any change in the communication
`protocols between the base Stations and the mobile Stations.
`0057 What is needed is a practical system and apparatus
`that would bring these base Station location concepts into
`wide use while at the same time making the Solution
`economically viable.
`0.058 Overview
`0059. The position location system described herein uti
`lizes information from calibration-enabled mobile stations
`to determine the position of a base Station, and update the
`base Station almanac on an ongoing basis. This System is
`useful for a number of reasons: for example handset-based
`information can be utilized to shorten time to commercial
`Service of new base Stations and provide ongoing improve
`ment in location performance. Advantageously, the System
`can be implemented with no hardware modification, and
`very little modification to the basic subscriber service ele
`ments; thus very little cost is required to provide this
`network preparation and improvement ability.
`0060 Each handset that is part of the system utilizes a
`calibration program to communicate with, and respond to a
`calibration Server. The calibration program can for example,
`be BREW-, Java- or similar technology-based, and can be
`downloaded or embedded in the handset.
`0061. In one example, in a CDMA system, in order to
`calibrate or re-calibrate the base station, GPS and AFLT
`position measurement data is obtained from mobile stations
`during regular position location Sessions for example when
`mobile Station users normally engage in telephone calls, or
`when field Service perSonnel drive around to Selected loca
`tions and place calls for the purpose of obtaining position
`measurement data not otherwise obtained from the regular
`position location sessions, and then sent to the BTSCS. In
`this fashion, the BTSCS may then use this information to
`compute the calibration data internally and Store the cali
`bration data in the base Station almanac database on a
`continuous basis. In addition, to alleviate any privacy con
`cerns, the regular position location Sessions may occur only
`when the user of the location-enabled mobile Station places
`or answers a wireless telephone call. In this case, the CDMA
`System does not determine the user's position without the
`user's knowledge and consent. In another example, the user
`of the mobile station (cellular phone) authorizes the use of
`the mobile Station as a calibration device, allowing the
`BTSCS to request calibration information from Such device.
`0062) Description
`0063 FIG. 1 is a perspective view of a wireless com
`munication network 10 that includes a plurality of wide area
`network base Stations 10 including first, Second, and third
`base stations 10a, 10b, and 10c respectively, a plurality of
`local area network base Stations (access points) 20 including
`first and second base stations 20a 20b respectively, GPS
`satellites shown collectively at 11, and a plurality of mobile
`Stations 14 including first, Second, third, and fourth mobile
`stations 14a, 14b, 14c, and 14d respectively. FIG. 1 is
`provided for illustrative purposes; it should be clear that in
`an actual im