(12) United States Patent
`Stilp
`
`USOO6492944B1
`(10) Patent No.:
`US 6,492,944 B1
`(45) Date of Patent:
`*Dec. 10, 2002
`
`INTERNAL CALIBRATION METHOD FOR
`RECEIVER SYSTEM OF A WIRELESS
`LOCATION SYSTEM
`Inventor: Louis A. Stilp, Berwyn, PA (US)
`Assignee: TruePosition, Inc., King of Prussia, PA
`(US)
`
`- - -
`Notice:
`
`Subject to any disclaimer, the term of this
`past iss adjusted under 35
`S.C. 154
`y 0 days.
`
`This patent is Subject to a terminal dis-
`claimer.
`
`Appl. No.: 09/635,703
`Filed:
`Aug. 10, 2000
`Related U.S. Application Data
`Division of application No. 09/227,764, filed on Jan. 8,
`1999, now Pat. No. 6,184,829.
`7
`Int. Cl." .................................................. G01S 1/24
`U.S. Cl. ............
`... 342/387; 342/174
`Field of Search ................................. 342/165, 174,
`342/385, 387, 450, 457
`s
`s
`s
`
`(54)
`
`(75)
`(73)
`
`(21)
`(22)
`
`(62)
`
`(51)
`(52)
`(58)
`
`(56)
`
`2Y-4-2
`
`Sa ...
`
`- - -
`
`
`
`2/1997 Williams .................... 375/219
`5,606,575 A
`s: A : 3.E. SE et al. ................. 35E,
`5,668,837. A
`9/1997 Dent .......................... 375/316
`5,786.790 A
`7/1998 Abbott .....
`... 342/357
`5,812,609 A
`9/1998 McLochlin ..
`... 375/340
`5,844,522 A 12/1998 Sheffer et al. ...
`... 342/457
`5,861,842 A * 1/1999 Hitch et al. .....
`... 342/357
`5,874,916 A
`2/1999 DesJardins .................. 342/378
`5,890,068 A
`3/1999 Fattouche et al. .......... 455/456
`5.936,571 A
`8/1999 DesJardins ............
`... 342/357
`5,973,643 A * 10/1999 Hawkes et al. ............. 342/457
`6,014,102 A
`1/2000 Mitzlaff et al. ............. 342/457
`OTHER PUBLICATIONS
`66
`Chester, D.B. et al., VLSI Implementation of a Wide Band,
`High Dynamic Range Digital Drop Receiver, IEEE, 1991,
`1605-1608.
`* cited by examiner
`Primary Examiner Dao Phan
`(74) Attorney, Agent, or Firm Woodcock Washburn LLP
`(57)
`ABSTRACT
`Methods and apparatus for calibrating a WireleSS Location
`System to enable the system to make highly accurate TDOA
`and FDOA measurements are disclosed. An external cali
`bration method in accordance with the present invention
`comprises the Steps of transmitting a first reference Signal
`from a reference transmitter; receiving the first reference
`ignal at first and Second receiver SVStems; determining a
`References Cited
`SIgna
`y
`2
`9.
`first error value by comparing a measured TDOA (or FDOA)
`U.S. PATENT DOCUMENTS
`value with a theoretical TDOA (or FDOA) value associated
`with the known locations of the receiver Systems and the
`3,921,076 A 11/1975 Currie ........................ 325/321
`known location of the reference transmitter; and utilizing the
`RE g E. S. et al.
`".56
`first error value to correct subsequent TDOA measurements
`4800117. A * 2/1990 V Cll .....
`3. 1/3
`associated with a mobile transmitter to be located. An
`5155,590 A 10/1992 Beyers, i? et al. ... 358/86
`internal calibration method in accordance with the present
`5.1913 42 A 3/1993 Alsup et al...
`342/465
`invention comprises the steps of injecting a comb Signal into
`5,251,232 A 10/1993 Nonami ......................... 375/5
`the first receiver System; utilizing the comb signal to obtain
`5,327,144. A
`7/1994 Stilp et al. ........
`... 342/387
`an estimate of the manner in which the transfer function
`5,402,347 A
`3/1995 McBurney et al. ......... 364/443
`varies across the bandwidth of the first receiver system; and
`5,428,667 A
`6/1995 Easterling et al. ............ 379/59
`utilizing the estimate to mitigate the effects of the variation
`5.
`A : : Eh - - - - - - - - - - - - - - - - - - - - - - 342/387
`of the first transfer function on the time measurements made
`3.
`A 9/1996 E. al.
`- - - E. by the first receiver system.
`5570,000 A 10/1996 DesJardins.
`... 342/378
`5,577,087. A 11/1996 Furuya ....................... 375/377
`
`8 Claims, 27 Drawing Sheets
`
`TEMPORARILY.
`LCTRON-CALLY
`oscowNext AmTENNAUSED :
`BYRCWERSYSTEM
`
`S-20
`- -
`IMCTNTERNALLY
`GENERATED WIDE BAND
`SisnAL WITHKNOWNSTABE
`SGNALCHARACTERISTICS
`INTo First RECEIVERSYSTEM
`S-2
`
`use GNRATEd WideBAND
`SNAL TO OETANESTIMATE
`FXFRFUNCONWARIATION
`Across sandwiDTH OF FIRST!
`RECEIVER
`
`S-22
`
`JS ESTIMATE TOMTIGATE
`FFECTS WARIATION OF
`FIRST TRANSFERFUNCTION
`ON TIME AND FREQUENCY
`MEASUREMENTS MADE BY
`first RCWR
`
`S-23
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 1 of 27
`
`US 6,492,944 B1
`
`POWER, SO DATA
`RF DATA, ETC.
`
`
`
`
`
`
`
`SCS(s) 10
`
`LOCATION RECS,
`STATUS, ALARMS,
`MAINTENANCE
`
`TLP(s) 12
`
`TDOA REQS, RX
`SYNC, ETC.
`
`FIGURE 1
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 2 of 27
`
`US 6,492,944 B1
`
`
`
`SCS REGION 1
`
`
`
`
`
`ROUTER
`
`
`
`NOC 16A
`
`NOC 16B
`
`FIGURE 1A
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 3 of 27
`
`US 6,492,944 B1
`
`10-1 (1-6 ANTENNAS)
`
`
`
`
`
`
`
`
`
`
`
`REEER
`
`DSP
`10-4 (BUS
`MODULE(S) —? (BUS)
`1O-3A
`
`
`
`CTRL 10 MHz
`
`CTRL
`
`CTRL
`
`
`
`
`
`RECEIVER
`1O-2B
`
`
`
`CTRL 10 MHz
`
`DSP
`MODULE(S)
`1O-3B
`
`C
`
`
`
`
`
`RECEIVER
`10-2C
`
`CTRL 10 MHz
`
`DSP
`MODULE(S)
`1O-3C
`
`CONTROL & T1/E-
`COMM'S 10-5
`
`10
`
`SERIAL 1P
`PS
`Hz
`
`10 MHz
`
`
`
`1 PPS
`
`10 MHz 1 PPS
`
`FIGURE 2
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 4 of 27
`
`US 6,492,944 B1
`
`SCS RECEIVER MODULE 10-2
`
`RF TUNER SECTION 10-2-1
`
`B
`
`-RF INPUT
`
`MUTE
`WITCH
`
`LOCK
`STATUS
`
`PHASE
`LOCKED
`
`
`
`
`
`PREAMP LONEO
`BAS #1
`
`i
`
`control
`Lo INPUT:
`
`
`
`
`
`-RF NPUT
`s
`
`ON/OFF
`
`LOINPUT
`
`TUNER #2
`
`SAMPLED
`OUPU
`
`
`
`SAMPLE CLK
`DTHER
`s
`CIRCUIT
`60 MHz
`CLKSAMPLE CLK
`i
`come PL-LOCK STATUS:-
`
`-
`60 MHz
`SAMPLE CLK
`
`SAMPLED
`OUPUT
`
`.
`
`DATA IN
`
`
`
`
`
`TEMP.
`
`TEMP.
`SENSOR
`
`BAS #2
`
`ON/OFF
`
`DATA OUT
`
`a sm sm am m) m am am am am am am am am am am am am m
`
`
`
`
`
`
`
`DATA INTERFACE 8,
`CONTROL. 10-2-2
`
`A
`
`FRAME
`SYNC
`
`DATA DATA
`CKN or
`
`FIGURE 2A
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 5 of 27
`
`US 6,492,944 B1
`
`RF
`SPLITTER
`
`
`
`BASE
`STATION
`RECEIVERS
`
`SCS
`RECEIVERS
`10-2
`
`
`
`
`
`FIGURE 2B
`
`
`
`
`
`
`
`
`
`
`
`
`
`WDE BAND
`BPF
`(A AND B
`
`RF
`SPLITTER
`
`
`
`RF
`SPLTTER
`
`BASE
`STATION
`RECEIVERS
`
`
`
`
`
`
`
`
`
`SCS
`RECEIVERS
`10-2
`
`FIGURE 2C
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 6 of 27
`
`US 6,492,944 B1
`
`LOCATION PROCESSING ON
`RECEIVED RF DATA
`COMMENCES
`
`WLS AGAIN DETERMINES
`CELL SITE, SECTOR, RF
`CHANNEL TIMESLOT, MASK
`AND ENCRYPTION KEY
`CURRENTLY IN USEBY 1ST
`TRANSMITTER
`
`iF CELL SITE, SECTOR, RF
`CHANNEL TIMESLOT, MASK
`AND ENCRYPTION KEY
`CURRENTLY IN USE BY 1ST
`TRANSMITTER HAS
`CHANGED BETWEEN
`QUERIES, WLS CEASES
`LOCATION PROCESSING,
`CAUSESAER MESSAGE
`AND RE-TRIGGERS ENTRE
`PROCESS
`
`LOCATION PROCESSING ON
`RECEIVED RF DATA
`COMPLETES
`
`FIRST WIRELESS
`TRANSMITTER ENGAGED
`IN TRANSMITTING ONA
`PARTICULAR RF CHANNEL
`
`WLS TRIGGERS ON
`MAKING ALOCATION
`ESTMATE OF FIRST
`WIRELESS TRANSMITTER
`
`WLS DETERMINES CELL
`SITE, SECTOR, RF
`CHANNEL, TIMESLOT,
`MASK AND ENCRYPTION
`KEY CURRENTLY IN USE
`BY FIRST WIRELESS
`TRANSMITTER
`
`WLS TUNES FIRST
`NARROWBAND RECEIVER
`AT FIRST SCS 10 TO RF
`CHANNEL AND TIMESLOT
`AT DESIGNATED CELL
`SITE AND SECTOR
`
`FIRST SCS RECEIVES
`TIME SEGMENT OF RF
`DATA AND EVALUATES
`POWER, SNRAND
`MODULATION
`CHARACTERISTICS, AND,
`IF POWER OR SNRS
`BELOW PREDETERMINED
`THRESHOLD, WLS WAITS
`PREDETERMINED TIME
`AND RETURNS TO 3RD
`STEP
`
`IF TRANSMISSIONS AMPS
`VOICE CHANNEL
`TRANSMISSION AND
`MODULATION IS BELOW
`THRESHOLD, THEN WLS
`COMMANDS THE
`WRELESS SYSTEM TO
`SEND COMMAND TO FIRST
`WIRELESS TRANSMTER
`TO CAUSE"BLANK AND
`BURST ON FRST
`WIRELESSTRANSMITTER
`
`WLS REQUESTS WIRELESS
`SYSTEM TO PREVENT HAND
`OFF OF WIRELESS
`TRANSMITTER TO ANOTHER
`RF CHANNEL FOR
`PREDETERMINED PERIOD
`
`WLS RECEIVES RESPONSE
`INDICATING TIME PERIOD
`DURING WHICH 1S
`TRANSMER WILL BE
`PREVENTED FROM HANDING
`OFF AND, IF COMMANDED,
`TIME PERIOD DURING WHICH
`SYSTEM WILL SEND
`COMMAND TO 1ST
`TRANSMTTER TO CAUSE
`"BLANKAND BURST"
`
`WLS DETERMINES LST OF
`ANTENNAS HAT WILL BE
`USED IN LOCATION
`PROCESSING
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`WLS DETERMINES EARLIEST
`TIMESTAMPAT WHICH
`NARROWEAND RECEIVERS
`AREAVAILABLE TO BEGIN
`COLLECTING RF DATA
`
`WS COMMANDS
`NARROWBAND RECEIVERS
`TO TUNE TO CELL SITE,
`SECTOR AND RF CHANNEL
`CURRENTLY NUSE BY 1ST
`TRANSMITTER AND TO
`RECEIVERF DATA FOR
`PREDETERMINED DWELL
`TME
`
`RF DATA RECEIVED BY
`NARROWBAND RECEIVERS
`SWRITTEN INTO DUAL PORT
`MEMORY
`
`FIGURE 2C-1
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 7 of 27
`
`US 6,492,944 B1
`
`scs DSP MODULE 10-3
`
`St At
`TEST
`Y SRC
`1. 0-3-2
`
`A- 10-3-3
`
`SERIAL
`PARALLEL
`
`DSP CLK
`
`PARTY y
`DSP + RAM
`(DETECT)
`10-3-5
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`DRAM
`(Digitized
`IF)
`
`DRAM
`(Digitized
`IF)
`
`DRAM
`(Digitized
`IF)
`
`DRAM
`(Digitized
`IF)
`
`PAR.
`TO
`
`FIFO 7
`
`SERIAL E.
`
`OKHZAND 200
`KHZ CHANNELS
`
`DSP + RAM
`(DEMOD.)
`10-3-6
`
`(NORM)
`10-3-7
`
`TO CONTR
`& COMM.
`MODULE 10-5
`
`
`
`
`
`ADDRESS GENERATORICONTROL. 10-3-8
`
`FIGURE 2D
`
`
`
`125MHz
`o- to Mux
`
`MEASURE
`AGC
`(1ST LINK)
`
`TOBACKPLANE
`
`1.25MHz
`to Mux
`
`
`
`1.25MHz
`to Mux
`
`SIP
`
`
`
`DRAM
`(Digitized
`IF)
`
`1.6 sec.
`
`DRAM
`(Digitized
`IF)
`
`1.6 sec.
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 8 of 27
`
`US 6,492,944 B1
`
`RECEIVE DIGITAL DATA
`STREAM
`
`S1
`
`EXTRACT BLOCK OF
`CHANNES
`
`S2
`
`DETECT PWRN
`CHANNELS AND RPT TO
`TLP
`
`S3
`
`STORE BLOCKS INDUAL
`PORT MEMORY
`
`
`
`S4
`
`READ DATA FROM
`MEMORY AND EXTRACT
`BASEBAND DATA
`
`S5
`
`DETECT ACTIVE
`CHANNELS (SEE FIG.2E-1)
`
`S6
`
`
`
`PERFORM
`DEMODULATION
`
`S7
`
`PERFORMLOCATION
`PROCESSING
`
`S8
`
`FIGURE 2E
`
`
`
`MAINTAN ACTIVE
`CHANNEL MAP
`
`S9
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 9 of 27
`
`US 6,492,944 B1
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FOREACH POSSIBLE CONTROL AND/OR VOICE CHANNEL WHICH MAYBE USED IN THE COVERAGE
`AREA OF THE SCS, ESTABLISH PEG COUNTERS
`
`S7-1
`
`AT THE START OF A DETECTION PERIOD, RESET ALL PEG COUNTERS TO ZERO
`
`S7-2
`
`EACHTIMEA TRANSMISSION OCCURS IN A SPECIFED RF CHANNEL AND THE RECEIVED POWER
`LEVELISABOVE PRE-SET THRESHOLD, INCREMENT PEG COUNTER FOR THAT CHANNEL
`
`
`
`S7-3
`
`—
`
`EACHTIMEA TRANSMISSION OCCURS INASPECIFIED RF CHANNEL AND THE RECEIVED POWER
`LEVELISABOVE SECOND PRE-SET THRESHOLD, ATTEMPT TO DEMODULATE A PORTION OF THE
`TRANSMISSIONUSINGA FIRST PREFERRED PROTOCOL
`
`S7-4
`
`IF DEMODULATION ISSUCCESSFUL, INCREMENT SECOND PEG COUNTER FOR THAT CHANNEL
`
`S7-5
`
`F DEMODULATION IS UNSUCCESSFULATTEMPT TO DEMODULATE A PORTION OF THE
`TRANSMISSIONUSING ASECOND PREFERRED PROTOCOL.
`
`IF DEMODULATION S SUCCESSFUL, INCREMENT THIRD PEG COUNTER FOR THAT CHANNEL
`
`S7-7
`
`AT THE END OF A DETECTION PERIOD, READ ALL PEG COUNTERS
`
`S7-8
`
`AUTOMATICALLY ASSIGN PRIMARY CHANNELS BASED UPON PEG COUNTERS
`
`
`
`S7-9
`
`FIGURE 2E-1
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 10 of 27
`
`US 6,492,944 B1
`
`CONTROL & COMM. MODULE 10-5
`
`MEMORY
`
`10-5-3
`
`T1/E1 TO TLP 12
`
`DATA
`BUFFERS
`TO DSP
`MODULES
`
`10-5-1
`
`
`
`
`
`CONTROL
`TO ALL
`MODULES
`
`10-5-2
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIGURE 2F
`
`Y
`Y
`- 1
`Y
`
`e1 1
`- 1
`1
`
`A-B
`
`Y
`
`CAL
`c 20A
`
`N/
`
`N
`N
`N
`
`Ne1
`N
`Y
`
`11
`
`1
`
`- 1é4
`- 1
`
`N
`N
`N
`- 1
`YD1
`
`1
`
`N
`N
`w
`- 1
`
`SCS
`10B
`
`scs
`10A
`
`- 1
`1
`-
`w
`Y
`
`w
`Y
`
`e3N
`
`CAL
`
`2OB
`
`FIGURE 2G
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 11 of 27
`
`US 6,492,944 B1
`
`TEMPORARILY,
`ELECTRONICALLY
`DISCONNECT ANTENNAUSED
`BY RECEIVERSYSTEM
`
`S-20
`
`NJECT INTERNALLY
`GENERATED WIDE BAND
`SIGNAL WITH KNOWN STABLE
`SIGNAL CHARACTERISTICS
`NTO FIRST RECEIVER SYSTEM
`
`S-21
`
`USE GENERATED WIDE BAND
`SIGNAL TO OBTAIN ESTMATE
`OFXFER FUNCTION VARATION
`ACROSS BANDWIDTH OF FIRST
`RECEIVER
`
`S-22
`
`USE ESTIMATE TO MITIGATE
`EFFECTS OF WARIATION OF
`FIRST TRANSFER FUNCTION
`ON TIME AND FREOUENCY
`MEASUREMENTS MADE BY
`FIRST RECEIVER
`
`
`
`
`
`
`
`S-23
`
`
`
`
`
`
`
`FIGURE 2H
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 12 of 27
`
`US 6,492,944 B1
`
`
`
`|
`
`|
`
`|
`
`| |
`
`|
`
`|
`
`|
`
`|
`
`|
`
`|
`|
`|
`|
`315 KHZ
`
`|
`
`|
`
`|
`
`|
`
`|
`
`|
`
`|
`
`| -
`
`FIGURE 2
`
`A
`AMPLITUDE
`
`21 CHANNELS
`
`FREQUENCY 630 KHZ
`
`FIGURE 2
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 13 of 27
`
`US 6,492,944 B1
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`PLACE STANDARD WIRELESS
`TRANSMITTERS A VARIOUS
`POINTS WITHIN WLS
`COVERAGE AREA
`
`S30
`
`
`
`SURVEY POINTS AT WHICH
`FIXED PHONES HAVE BEEN
`PLACED TO DETERMINE
`THER LOCATION TO WITHN
`PREDETERMINED DISTANCE
`
`S31
`
`STORE SURVEYED
`LOCATIONS IN TABLE NAP
`
`S32
`
`PERMIT FIXED PHONESTO
`REGISTERATRATE AND
`INTERVAL SET BY THE
`WIRELESS SYSTEM
`
`S33
`
`ATEACH REGISTRATION
`TRANSMISSION BY FIXED
`PHONE, LOCATE PHONE
`USING NORMAL LOCATION
`PROCESSING
`
`
`
`S34
`
`
`
`COMPUTE ERROR BETWEEN
`CALCULATED LOCATION
`DETERMINED BY LOCATION
`PROCESSING AND STORED
`LOCATION DETERMINED BY
`SURVEY
`
`
`
`S35
`
`STORE LOCATION, ERROR
`VALUE AND OTHER
`MEASURED PARAMETERS
`ALONG WITH TIME STAMP IN
`APDATABASE
`
`S36 — - V - -
`
`MONITOR INSTANTERROR
`AND OTHER MEASURED
`PARAMETERS (EXTENDED
`LOCATION RECORD) AND
`COMPUTE STATISTICAL
`VALUES OF ERROR(S) AND
`OTHER MEASURED
`PARAMETERS
`
`
`
`S37
`
`IF ANY ERROR OR OTHER
`VALUE EXCEEDS PRE
`DETERMINED THRESHOLD
`OR HISTORICAL STATISTICAL
`VALUE, SIGNALALARM TO
`WLS OPERATOR
`
`S38
`
`FIGURE 2K
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 14 of 27
`
`US 6,492,944 B1
`
`
`
`
`
`
`
`
`
`
`
`
`
`SURVEY TEST POINTS IN
`COVERAGE AREA OF WLS
`
`S40
`
`ASSGN EACH TEST POINTA
`CODE COMPRISING" OR
`"#" AND SEOUENCE NO.
`
`S41
`
`STORE CODE AND
`SURVEYED LOCATION FOR
`EACH TEST POINT
`
`S42
`
`DIAL CODES
`
`
`
`S43
`
`LOCATE WRELESS
`TRANSMITTERS USING
`NORMAL LOCATION
`PROCESSING
`
`S44
`
`COMPUTE ERROR BETWEEN
`CALCULATED LOCATION AND
`STORED LOCATION DETERMINED
`BY SURVEY
`
`S45
`
`
`
`
`
`
`
`
`
`
`
`
`
`STORE LOCATION AND ERROR
`VALUE ALONG WITH TIME STAMP
`NAPDATABASE
`
`S46
`
`MONITOR INSTANTERROR AND
`HISTORICAL STATESTICAL VALUES
`OF ERROR AND, IF ERROR VALUES
`EXCEED PRE-DETERMINED
`THRESHOLD OR A HISTORICAL
`STATISTICAL VALUE, SIGNAL
`ALARM TO WLS OPERATOR
`
`S47
`
`FIGURE 2L
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 15 Of 27
`
`US 6,492,944 B1
`
`DSP MODULES
`
`12-1
`
`
`
`
`
`
`
`CONTROLLER
`
`12-3
`
`ETHERNET
`
`OCAL MANTENANCE
`
`
`
`-a-
`
`---
`
`
`
`Network Map
`
`Table of interest
`MIN, Mobile Station
`ID, ESN, dialed
`digits, Sys. D, RF
`channel no, Cell site
`no. Or Sector no.,
`transmission type,
`etc.
`
`FIGURE 3
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 16 0f 27
`
`US 6,492,944 B1
`
`SECTORED ANTENNAS
`- - - -
`gamma
`alpha
`
`-C
`
`
`
`
`
`N/2
`
`
`
`- 1 N.
`
`e
`
`-beta
`Ge
`
`Y
`
`w
`
`N11
`(TLP-N, SCS-1)
`
`NETWORK MAP
`
`
`
`N/32
`
`DYNAMIC COOPERATION
`TABLE
`
`Best Antenna Port
`
`
`
`1
`
`TLP 1/SCS 1
`
`1 2 3 4 5 6
`
`32
`
`N/K 5 6
`
`FIGURE 3A
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 17 of 27
`
`US 6,492,944 B1
`
`Location
`DB
`
`Loc. Info.
`
`
`
`Tasking info.
`
`TLP 12A
`
`
`
`
`
`
`
`
`
`
`
`
`
`Location info.
`Tasking
`info. to
`ApDbSend
`
`AP COre Processes
`Tasking & Task ID info.
`
`y
`
`AP Redundant Mode
`-
`Processes
`
`r
`
`ApTaskSync
`
`ApTaskSync
`
`
`
`
`
`ApWatchDog
`
`
`
`AplocSync
`
`
`
`AplocSync
`
`ApDbRecvLoc
`
`Loc. Seq. No. Info.
`
`ApMnDsptch
`
`
`
`ApConfigSync
`
`ApConfigSync
`
`
`
`LOC. Info.
`
`FIGURE 4
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 18 of 27
`
`US 6,492,944 B1
`
`
`
`
`
`TLP 12A
`
`Tasking info.
`
`
`
`Location
`info.
`
`Location
`info.
`
`Tasking info.
`
`
`
`
`
`
`
`
`
`
`
`AP COre
`Processes
`
`Loc. Sync.
`
`Failover info.
`
`
`
`A
`
`AP Core
`Processes
`
`
`
`
`
`Location, Tasking
`& Config. Info.
`
`\ onfiguration Requests/
`Replies
`
`Location, Tasking
`& Config. Info.
`
`
`
`
`
`
`
`Location,
`Tasking &
`Config. Info.
`
`14A-2
`
`NOC 16A
`
`
`
`Location,
`Tasking &
`Config. Info.
`
`14B-2
`
`-Configuration info.
`
`FIGURE 4A
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 19 of 27
`
`US 6,492,944 B1
`
`
`
`WRELESS TRANSMITTER
`INITIATES TRANSMISSION
`ON CONTROL CHANNELOR
`VOICE CHANNEL
`
`S50
`
`TRANSMISSION RECEIVED
`AT MULTIPLE ANTENNAS
`AND AT MULTIPLE SCS'S
`
`S51
`
`TRANSMISSION CONVERTED TO
`DIGITAL FORMAT IN RECEIVER
`CONNECTED TO EACH ANTENNA
`
`S52
`
`DIGITAL DATA STORED IN
`MEMORY
`
`S53
`
`TRANSMISSIONS
`DEMODULATED
`
`S54
`
`WLS DETERMINES
`WHETHER TO BEGIN
`LOCATION PROCESSING
`
`S55
`
`IF TRIGGERED, TLP REQUESTS
`COPES OF DIGITAL DATA
`FROMMEMORY AT MULTIPLE
`SCS'S
`
`S56
`
`DIGITAL DATA SENT FROM
`MULTIPLE SCS'STO
`SINGLE TLP
`
`S57
`
`TLP PERFORMS TDOA,
`FDOA AND MULTIPATH
`MTIGATION ON DIGITAL
`DATA FROM PARS OF
`ANTENNAS
`
`S58
`
`TLP PERFORMS POSITION AND
`SPEED DETERMINATION USING
`TDOA DATA, AND
`CREATES LOCATION RECORD
`AND FORWARDS IT TO AP
`
`S59
`
`FIGURE 5
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 20 of 27
`
`US 6,492,944 B1
`
`
`
`IF TRIGGERED, FIRST SCS
`DEMODULATES
`TRANSMISSION AND
`DETERMINES
`APPROPRIATE PHASE
`CORRECTION INTERVAL
`
`S66
`
`FOREACH PHASE
`CORRECT. INTERVAL,
`FIRST SCS CALCULATES
`PHASE CORRECTION &
`AMP. CORRECTION, AND
`ENCODES PHASE AND AMP.
`CORRECTION
`PARAMETERSALONG WITH
`DEMODULATED DATA
`
`FIRST SCS AND EACH
`SECOND SCS CREATE
`FIRST RE-MODULATED
`SIGNAL AND PHASE
`CORRECTION AND
`AMPLITUDE CORRECTION
`PARAMETERS
`
`S71
`
`FIRST SCS AND EACH
`SECOND SCS PERFORM
`TDOA, FDOA & MULTIPATH
`MITIGATION USNG DATA
`STORED IN MEMORY 8.
`FIRST RE-MODULATED
`SGNAL
`
`S67
`
`S72
`
`DEMODULATED DATA AND
`PHASE CORRECTION AND
`AMPLITUDE CORRECTION
`PARAMETERS SENT FROM
`FIRST SCS TO TLP
`
`S68
`
`TDOA, FDOA, AND
`MULTIPATH MITIGATION
`DATA SENT FROM FIRST
`SCS AND EACH SECOND
`SCS TO TLP
`
`S73
`
`WRELESS TRANSMITTER
`NITATES TRANSMISSION
`ONETHER CONTROL
`CHANNEL OR VOICE
`CHANNEL
`
`S60
`
`TRANSMISSION RECEIVED
`AT MULTIPLE ANTENNAS
`AND MULTIPLE SCS'S
`
`S61
`
`TRANSMISSION
`CONVERTED INTO DIGITAL
`FORMAT IN RECEIVER
`CONNECTED TO EACH
`ANTENNA
`
`S62
`
`DIGITAL DATA STORED IN
`MEMORY IN SCS
`
`S63
`
`TLP PERFORMS POSITION
`AND SPEED
`DETERMINATION USING
`TDOA DATA
`
`S74
`
`TLP CREATES LOCATION
`RECORD, AND FORWARDS
`LOCATION RECORD TO AP
`
`S75
`
`TRANSMISSION
`DEMODULATED
`
`S64
`
`TLP DETERMINES SCS'S
`AND RECEIVING ANTENNAS
`TO USE IN LOCATION
`PROCESSING
`
`S69
`
`WLS DETERMINES
`WHETHER TO BEGIN
`LOCATION PROCESSING
`
`S65
`
`TLP SENDS DEMODULATED
`DATA AND PHASE
`CORRECTION AND
`AMPLITUDE CORRECTION
`PARAMETERS TO EACH
`SECOND SCS THAT WILL BE
`USED IN LOCATION
`PROCESSENG
`
`S70
`
`FIGURE 6
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 21 of 27
`
`US 6,492,944 B1
`
`
`
`WIRELESS TRANSMITTER INITIATES
`TRANSMISSION ON CONTROL CHANNELOR
`VOICE CHANNEL
`
`S80
`
`TRANSMISSION RECEIVEDAT FIRST SCS
`
`S81
`
`TRANSMISSION CONVERTED TO DIGITAL
`FORMAT IN RECEIVER CONNECTED TO
`EACHANTENNA
`
`S82
`
`BEGIN LOCATION PROCESSING?
`
`S83
`
`IF TRIGGERED, FIRST SCS DEMODULATES
`TRANSMISSION AND ESTMATES PHASE
`CORRECTION INTERVAL AND NUMBER OF
`BITS TO ENCODE PHASE AND AMPLITUDE
`CORRECTION PARAMETERS
`
`S84
`
`BASED ON NUMBER OF BITS RECURED
`FOREACH METHOD, SCS ORTLP
`DETERMINE WHETHER TO USE CENTRAL
`BASED PROCESSING OR STATION BASED
`LOCATION PROCESSING
`
`S85
`
`FIGURE 7
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 22 of 27
`
`US 6,492,944 B1
`
`
`
`WIRELESS TRANSMITTER INITIATES
`TRANSMISSION ON CONTROL CHANNEL
`OR VOICE CHANNEL
`
`PRIMARY SCS DETERMINES
`TIMESTAMPASSOCIATED WITH
`DEMODULATED DATA
`
`S90
`
`S96
`
`TRANSMISSION RECEIVEDAT
`MULTIPLE ANTENNAS AND AT
`MULTIPLE SCSS
`
`WLS DETERMINES WHETHER TO BEGIN
`LOCATION PROCESSING FOR THE
`TRANSMISSION
`
`S91
`
`S97
`
`TRANSMISSION CONVERTED TO
`DGITAL FORMAT IN RECEIVER
`CONNECTED TO EACH ANTENNA
`
`S92
`
`F LOCATION PROCESSING IS
`TRIGGERED, WLS DETERMINES
`CANOIDATE LIST OF SCS'S AND
`ANTENNAS TO USE IN LOCATION
`PROCESSING
`
`S98
`
`DIGITAL DATA STORED IN MEMORY IN
`EACH SCS
`
`S93
`
`TRANSMISSION DEMODULATED ATAT
`LEAST ONE SCS AND CHANNEL
`NUMBER ON WHICH TRANSMISSION
`OCCURRED AND CELL SITE AND
`SECTOR SERVING THE WIRELESS
`TRANSMITTER IS DETERMINED
`
`S94
`
`BASED ON SERVING CEL SITE AND
`SECTOR, ONE SCS DESIGNATED AS
`PRIMARY SCS FOR PROCESSING THAT
`TRANSMISSION
`
`S95
`
`EACH CANDDATE SCSIANTENNA
`MEASURES AND REPORTS RECEIVED
`SNR IN THE CHANNEL NUMBER OF
`TRANSMISSION AND AT TIME OF
`TIMESAMP DETERMINED BY PRIMARY
`SCS
`
`S99
`
`WLS ORDERS CANDDATE SCSI
`ANTENNAS USING SPECIFED CRITERA
`AND SELECTS PROCESSENGLIST OF
`SCS/ANTENNAS TO USEN LOCATION
`PROCESSING
`
`S1 OO
`
`WLS PROCEEDS WITH LOCATION
`PROCESSING USING DATA FROM
`PROCESSING LIST OF SCSIANTENNAS
`
`S101
`
`FIGURE 8
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 23 Of 27
`
`US 6,492,944 B1
`
`
`
`max radius from primary
`
`FIGURE 9
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 24 of 27
`
`US 6,492,944 B1
`
`
`
`
`
`
`
`
`
`USER WISHES TO BE
`LOCATED2
`
`DISPATCHER SENDS MSG TO
`WLS
`
`WLS CRUERIES MTSO/MSC AND
`SENDS CONFIRMATION TO
`DISPATCHER
`
`DSPATCHER INSTRUCTS
`CALLER TODAL 9-DIGIT
`NUMBER AND PRESS "SEND"
`
`WLS MONITORS BANDWIDTH
`
`BW a THRESHOLD?
`
`
`
`
`
`
`
`
`
`
`
`
`
`USER WISHES TO BE
`LOCATED
`
`DISPATCHER SENDS MSG TO
`WLS
`
`WLS OUERIES MTSO/MSC AND
`SENDS CONFIRMATION TO
`DISPATCHER
`
`WLS AUDITS MOBILE PHONE
`
`WLS MONITORS BANOWIOTH
`
`BW > THRESHOLD?
`
`WLS INITIATES LOCATION
`PROCESSING
`
`WLS INITIATES LOCATION
`PROCESSING
`
`FIGURE 10A
`
`FIGURE 10B
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 25 Of 27
`
`US 6,492,944 B1
`
`ORIGINATION
`OOOOOO.o
`MSC
`
`PHONE MSC
`
`PHONE
`
`MSC
`
`PHONE
`
`PAGE
`
`AUDIT
`
`ORIGINATE
`
`RVCASSIGN.
`ORDER CONF.
`
`PAGE
`
`PAGE RESP.
`RVCASSIGN.
`
`ORDER CONF.
`
`AUDT
`
`AUDIT RESP.
`
`FIGURE 11A
`
`FIGURE 11B
`
`FIGURE 11C
`
`
`
`
`
`
`
`MAKE 1ST
`LOCATION
`ESTIMATE
`
`AUDIT AND HANG
`UP OR CALL BACK
`
`Yes
`
`MORE
`ESTIMATES
`
`COMBINE MULTIPLE
`STATISTICALLY
`INDEPENDENT
`ESTIMATES
`
`FIGURE 11D
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 26 of 27
`
`US 6,492,944 B1
`
`--------------------------------------
`
`SCS 10A
`
`4
`
`v.
`
`Wireless Xmitter
`
`Calibration Xmitter
`
`SCS 10B
`
`
`
`
`
`WIRELESS
`COMM.
`SYSTEM
`
`BW
`SYNTHESIS
`MEANS
`
`FIGURE 12A
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 27 of 27
`
`US 6,492,944 B1
`
`
`
`Channel
`
`1
`
`2 3 4 5 6 7 8 9
`
`FIGURE 12B
`
`

`

`US 6,492,944 B1
`
`1
`INTERNAL CALIBRATION METHOD FOR
`RECEIVER SYSTEM OF A WIRELESS
`LOCATION SYSTEM
`
`This is a divisional of U.S. patent application Ser. No.
`09/227,764 filed Jan. 8, 1999, now U.S. Pat. No. 6,184.829
`issued Feb. 6, 2001.
`
`5
`
`FIELD OF THE INVENTION
`The present invention relates generally to methods and
`apparatus for locating wireleSS transmitters, Such as those
`used in analog or digital cellular Systems, personal commu
`nications Systems (PCS), enhanced specialized mobile
`radios (ESMRs), and other types of wireless communica
`tions Systems. This field is now generally known as wireleSS
`location, and has application for Wireless E9-1-1, fleet
`management, RF optimization, and other valuable applica
`tions.
`
`15
`
`2
`proposed for locating wireleSS telephones. Indeed, as of
`December, 1998, no other wireless location system has been
`installed anywhere else in the world that is capable of
`locating live 9-1-1 callers. The innovation of the Wireless
`Location System disclosed herein has been acknowledged in
`the wireleSS industry by the extensive amount of media
`coverage given to the System's capabilities, as well as by
`awards. For example, the prestigious WireleSS Happy Award
`was granted to the system by the Cellular Telephone Indus
`try Association in October, 1997, and the Christopher
`Columbus Fellowship Foundation and Discover Magazine
`found the Wireless Location System to be one of the top 4
`innovations of 1998 out of 4,000 nominations Submitted.
`The value and importance of the Wireless Location Sys
`tem has been acknowledged by the wireleSS communications
`industry. In June 1996, the Federal Communications Com
`mission issued requirements for the wireleSS communica
`tions industry to deploy location Systems for use in locating
`wireless 9-1-1 callers, with a deadline of October 2001. The
`location of wireleSS E9-1-1 callers will Save response time,
`Save lives, and Save enormous costs because of reduced use
`of emergency responses resources. In addition, numerous
`Surveys and Studies have concluded that various wireleSS
`applications, Such as location Sensitive billing, fleet
`management, and others, will have great commercial values
`in the coming years.
`Background on Wireless Communications Systems
`There are many different types of air interface protocols
`used for wireleSS communications Systems. These protocols
`are used in different frequency bands, both in the U.S. and
`internationally. The frequency band does not impact the
`Wireless Location System's effectiveness at locating wire
`leSS telephones.
`All air interface protocols use two types of “channels'.
`The first type includes control channels that are used for
`conveying information about the wireleSS telephone or
`transmitter, for initiating or terminating calls, or for trans
`ferring bursty data. For example, Some types of short
`messaging Services transfer data over the control channel. In
`different air interfaces, control channels are known by
`different terminology, but the use of the control channels in
`each air interface is similar. Control channels generally have
`identifying information about the wireleSS telephone or
`transmitter contained in the transmission.
`The Second type includes voice channels that are typically
`used for conveying voice communications over the air
`interface. These channels are only used after a call has been
`Set up using the control channels. Voice channels will
`typically use dedicated resources within the wireleSS com
`munications System whereas control channels will use
`shared resources. This distinction will generally make the
`use of control channels for wireleSS location purposes more
`cost effective than the use of Voice channels, although there
`are Some applications for which regular location on the
`Voice channel is desired. Voice channels generally do not
`have identifying information about the wireleSS telephone or
`transmitter in the transmission. Some of the differences in
`the air interface protocols are discussed below: AMPS
`This is the original air interface protocol used for cellular
`communications in the U.S. In the AMPS system, separate
`dedicated channels are assigned for use by control channels
`(RCC). According to the TLAIEIA Standard IS-553A, every
`control channel block must begin at cellular channel 333 or
`334, but the block may be of variable length. In the U.S., by
`convention, the AMPS control channel block is 21 channels
`wide, but the use of a 26-channel block is also known. A
`reverse voice channel (RVC) may occupy any channel that
`
`BACKGROUND OF THE INVENTION
`Early work relating to the present invention has been
`described in U.S. Pat. No. 5,327,144, Jul. 5, 1994, “Cellular
`Telephone Location System,” which discloses a system for
`locating cellular telephones using novel time difference of
`arrival (TDOA) techniques. Further enhancements of the
`system disclosed in the 144 patent are disclosed in U.S. Pat.
`No. 5,608,410, Mar. 4, 1997, “System for Locating a Source
`of Bursty Transmissions.” Both patents are owned by the
`assignee of the current invention, and both are incorporated
`herein by reference. The present inventors have continued to
`develop significant enhancements to the original inventive
`concepts and have developed techniques to further improve
`the accuracy of Wireless Location Systems while signifi
`cantly reducing the cost of these Systems.
`Over the past few years, the cellular industry has
`increased the number of air interface protocols available for
`use by wireleSS telephones, increased the number of fre
`quency bands in which wireleSS or mobile telephones may
`operate, and expanded the number of terms that refer or
`relate to mobile telephones to include “personal communi
`cations services”, “wireless', and others. The air interface
`protocols now include AMPS, N-AMPS, TDMA, CDMA,
`GSM,TACS, ESMR, and others. The changes in terminol
`ogy and increases in the number of air interfaces do not
`change the basic principles and inventions discovered and
`enhanced by the inventors. However, in keeping with the
`current terminology of the industry, the inventors now call
`the system described herein a Wireless Location System.
`The inventors have conducted extensive experiments with
`the Wireless Location System technology disclosed herein to
`demonstrate both the viability and value of the technology.
`For example, Several experiments were conducted during
`several months of 1995 and 1996 in the cities of Philadelphia
`and Baltimore to verify the system's ability to mitigate
`multipath in large urban environments. Then, in 1996 the
`inventors constructed a System in Houston that was used to
`test the technology's effectiveness in that area and its ability
`to interface directly with E9-1-1 systems. Then, in 1997, the
`system was tested in a 350 square mile area in New Jersey
`and was used to locate real 9-1-1 calls from real people in
`trouble. Since that time, the System test has been expanded
`to include 125 cell sites covering an area of over 2,000
`Square miles. During all of these tests, techniques discussed
`and disclosed herein were tested for effectiveness and fur
`ther developed, and the System has been demonstrated to
`overcome the limitations of other approaches that have been
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`

`US 6,492,944 B1
`
`15
`
`25
`
`35
`
`40
`
`3
`is not assigned to a control channel. The control channel
`modulation is FSK (frequency shift keying), while the voice
`channels are modulated using FM (frequency modulation).
`N-AMPS This air interface is an expansion of the
`AMPS air interface protocol, and is defined in EIA/TIA
`standard IS-88. The control channels are substantially the
`same as for AMPS, however, the voice channels are differ
`ent. The voice channels occupy less than 10 KHZ of
`bandwidth, versus the 30 KHZ used for AMPS, and the
`modulation is FM.
`TDMA This interface is also known D-AMPS, and is
`defined in EIA/TIA standard IS-136. This air interface is
`characterized by the use of both frequency and time Sepa
`ration. Control channels are known as Digital Control Chan
`nels (DCCH) and are transmitted in bursts in timeslots
`assigned for use by DCCH. Unlike AMPS, DCCH may be
`assigned anywhere in the frequency band, although there are
`generally Some frequency assignments that are more attrac
`tive than others based upon the use of probability blocks.
`Voice channels are known as Digital Traffic Channels
`(DTC). DCCH and DTC may occupy the same frequency
`assignments, but not the same timeslot assignment in a given
`frequency assignment. DCCH and DTC use the same modu
`lation scheme, known as JL/4 DQPSK (differential quadra
`ture phase shift keying). In the cellular band, a carrier may
`use both the AMPS and TDMA protocols, as long as the
`frequency assignments for each protocol are kept Separated.
`CDMA This air interface is defined by EIATIA standard
`IS-95A. This air interface is characterized by the use of both
`frequency and code Separation. However, because adjacent
`cell sites may use the Same frequency Sets, CDMA is also
`characterized by very careful power control. This careful
`power control leads to a situation known to those skilled in
`the art as the near-far problem, which makes wireleSS
`location difficult for most approaches to function properly.
`Control channels are known as Access Channels, and Voice
`channels are known as Traffic Channels. Access and Traffic
`Channels may share the same frequency band, but are
`Separated by code. AcceSS and Traffic Channels use the same
`modulation scheme, known as OOPSK.
`GSM- This air interface is defined by the international
`standard Global System for Mobile Communications. Like
`TDMA, GSM is characterized by the use of both frequency
`and time separation. The channel bandwidth is 200 KHZ,
`which is wider than the 30 KHZ used for TDMA. Control
`channels are known as Standalone Dedicated Control Chan
`nels (SDCCH), and are transmitted in bursts in timeslots
`assigned for use by SDCCH. SDCCH may be assigned
`anywhere in the frequency band. Voice channels are known
`as Traffic Channels (TCH). SDCCH and TCH may occupy
`the same frequency assignments, but not the same timeslot
`assignment in a given frequency assignment. SDCCH and
`TCH use the same modulation scheme, known as GMSK.
`Within this specification the reference to any one of the air
`interfaces shall automatically refer to all of the air interfaces,
`unless Specified otherwise. Additionally, a reference to con
`trol channels or voice channels shall refer to all types of
`control or voice channels, whatever the preferred terminol
`ogy for a particular air interface. Finally, there are many
`more types of air interfaces used throughout the World, and
`there is no intent to exclude any air interface from the
`inventive concepts described within this specification.
`Indeed, those skilled in the art will recognize other interfaces
`used elsewhere are derivatives of or Similar in class to those
`describ