Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0205—Details
  • G01S5/0218—Multipath in signal reception
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/12—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Definitions

• This invention generally relates to spread spectrum code division multiple
• CDMA code access
• GPS global positioning system
• NAVSTAR satellites Each satellite transmits data indicating the satellite' s identity
• the handset can triangulate
• the air interface is located within a plurality of base stations.
• the location of the mobile telephone is calculated.
• CDMA code division multiple access
• CDMA systems are more resistant to signal distortion and interfering
• TDMA time division multiple access
• frequency division multiplex frequency division multiplex
• FDMA frequency division multiple access
• the invention determines the geographic location of a subscriber unit within
• At least one base station transmits a spread
• the base station receives the subscriber unit signal and
• Figure 1 is an illustration of a simplified, prior art CDMA system.
• Figure 2 is an illustration of a prior art CDMA system.
• FIG. 3 is a block diagram of major components within a prior art CDMA
• Figure 4 is a block diagram of components within a prior art CDMA system.
• Figure 5 is an illustration of a global pilot signal and an assigned pilot signal
• FIG. 6 is a block diagram of a first embodiment of the present invention
• Figure 7 is an illustration of locating a subscriber unit using the first
• embodiment of the present invention with at least three base stations.
• Figure 8 is a block diagram of a second embodiment of the present invention.
• Figure 9 is an illustration of locating a subscriber unit using the second
• Figure 10 is an illustration of locating a subscriber unit using the second
• FIG. 11 is a detailed illustration of the third embodiment of the present
• invention having a base station with multiple antennas.
• Figure 12 is an illustration of the third embodiment having a base station with
• Figure 13 is a block diagram of components used in the third embodiment.
• Figure 14 is an illustration of multipath.
• Figure 15 is a graph of a typical impulse response of multipath components.
• Figure 16 is a block diagram of components within a fourth embodiment
• FIG. 1 Shown in Figure 1 is a simplified CDMA communication system.
• a data is shown in Figure 1 .
• random chip code sequence generator producing a digital spread spectrum signal.
• an unmodulated pilot signal is
• the pilot signal allows respective receivers to
• base stations send global pilot signals to all
• each subscriber unit sends a unique assigned pilot signal to each subscriber unit.
• FIG. 2 illustrates a CDMA communication system 30.
• Each base station 36 1; 36 2 ... 36 n is in wireless communication with a plurality of subscriber units 40 l5
• Each subscriber unit 40 ⁇ , 40 2 ... 40 n which may be fixed or mobile.
• Each subscriber unit 40 ⁇ , 40 2 ... 40 n may be fixed or mobile.
• Each base station 36 36 2 ... 36 n is in
• a local exchange 32 is at the center of the communications system 30 and
• NEUs network interface units
• Each NIU is in communication with a plurality of radio carrier stations (RCS) 38
• 36 l5 36 2 ... 36 n communicates with a plurality of subscriber units 40 l5 40 2 ... 40 n
• Figure 4 depicts a block diagram of the pertinent parts of an existing spread
• generating means 42 x generates a unique pseudo random chip code sequence.
• spectrum processing means modulates the global pilot chip code sequence up to a desired center frequency.
• the global pilot signal is transmitted to all subscriber units
• a receiver 48 x at a subscriber unit 40 x receives available signals from a
• within the subscriber unit 40 x can receive global pilot chip code sequences from a
• the subscriber unit 40 x generates a replica
• the subscriber unit 40 x also has a processor 82 x
• the subscriber unit 40 x generates an assigned pilot signal 52 x using assigned
• pilot chip code generating means 56 x and spread spectrum processing means 58 x are examples of pilot chip code generating means 56 x and spread spectrum processing means 58 x .
• the assigned pilot chip code generating means 56 x generates a pseudo random chip
• the assigned pilot signal 52 x is
• the base station 36 x receives the assigned pilot signal 52 x with the base
• the received assigned pilot 52 x travels the same distance d l
• assigned pilot signal will be delayed by ⁇ 1 with respect to the mobile unit 40 x and by
• delay, 2 ⁇ 2 can be determined by comparing the timing of the two chip code
• base station 36 x and subscriber unit 40 x can be determined by:
• the communication system has the ability to track 1/16 th of a chip, the distance d j can be
• Figure 6 is a block diagram of a first embodiment of the present invention.
• the subscriber unit 40 x is sent a signal by a base station 36 x indicating that a
• 911 call was initiated and to begin the subscriber location protocol. Upon receipt,
• the subscriber unit 40 x will sequentially synchronize its transmission chip code
• a processor 66 x within each base station 36 l5 36 2 ... 36 n is coupled to the
• the processor 66 x compares the two chip code sequences to determine the
• a processor 68 receives the
• the processor 68 uses the distances d v d 2 ... d n to determine the
• the location of the subscriber unit 40 x is determined.
• Each circle 78 x , 78 2 , 78 3 is centered around
• 36 n is represented as X n , Y n , where X n is the
• Y represents the location of the subscriber unit
• Equations 3, 4 and 5 cannot be solved using conventional algebra.
• stations 36 4 , 36 5 ... 36 n can be used to calculate additional distances for inclusion in
• the subscriber unit's location is sent through the communication system 30 .
• a processor 76 A processor
• the display comprises a listing of all 911 calls
• Figure 8 is a second embodiment of a location system. At least two base
• the subscriber unit 40 x receives the global pilots 52 l5 52 2 ...
• the global pilot 52 2 from a second base station 36 2 travels distance d 2 and is
• the subscriber unit 40 x recovers each base station' s global pilot chip code sequence with its global pilot chip code recovery means 54 x .
• a processor 82 x executes each base station' s global pilot chip code sequence with its global pilot chip code recovery means 54 x .
• the processor 82 x compares the chip code sequences of each
• the processor 82 x will store where within the sequence synchronization was
• synchronization process can be done sequentially (synchronizing to the first base
• the time differences ⁇ t x , ⁇ tj ... ⁇ t n are transmitted to at least one of the base
• At least one base station 36 x recovers the time difference data from the
• time difference data The time difference data
• the processor 68 determines the location of the subscriber unit 40 x using the
• time difference data ⁇ t x , ⁇ t ⁇ ... ⁇ t n and the distance data d j , d 2 ... d as follows.
• the processor uses distances d v d 2 to create two circles 78 x , 78 2 . Using the time
• a hyperbola 86 x can be constructed as follows.
• time difference At can be converted to a distance difference Adj by substituting At,
• Equation 8 By using Equation 8 with Equations 3 and 4 in a maximum likelihood
• the location of the subscriber unit 40 x can be determined.
• Figure 10 shows the invention used with three base stations 36 l5 36 2 , 36 3 .
• distances d 2 , d 2 , d 3 are used to create three circles 78 x , 78 2 , 78 3 .
• hyperbolas 86 l5 86 2 and three circles 78 x , 78 2 , 78 3 yields greater accuracy.
• the subscriber unit 40 x is required to process each
• An alternate approach removes the processing from the subscriber unit 40 x .
• the mobile unit 40 x will synchronize the assigned
• the assigned pilot 50 x is transmitted to all base
• the assigned pilot 50 x will be received at each base station
• Each base station 36 l5 36 2 ... 36 n will
• processor 68 located in a NIU 34 x or local exchange 32.
• the processor 68 will
• pilot chip code sequences Since all received assigned pilot chip code sequences are 0
• the subscriber unit 40 x can be located using hyperbolas 86 x , 86 2
• FIG. 11 Another embodiment shown in Figures 11, 12 and 13 uses a base station 36 x
• the antenna 88 2 further away from the subscriber unit 40 x receives the
• a processor 66 using the
• assigned pilot chip code recovery means 96 96 2 ... 96 n can determine the location
• the subscriber unit 40 x is located at distance d j at
• Figure 12 both received assigned pilot signals 90 x , 90 2 appear to be coincident.
• the received assigned pilot signals 90 , 90 2 are
• the angle « can be determined by the following
• the distance m can be determined by using the carrier phase difference, ⁇ ,
• the distance m equals the phase difference between the two signals, ⁇ , in radians
• the processor 68 also compares the chip code sequences of the global pilot
• the processor 66 x locates the subscriber unit 40 x using simple geometry.
• antennas may be used to improve on the accuracy of the system.
• An alternate embodiment uses more than one base station 36 x , 36 2 ... 36 n .
• processor 68 located within either a NIU 34 x or the local exchange 32 collects
• the processor 68 determines
• a fourth embodiment corrects for multipath.
• Figure 14 illustrates multipath.
• a signal such as a global pilot signal is transmitted from a base station 36 x .
• Figure 13 is a graph showing the impulse response 136 of the received
• the impulse response 106 shows the collective signal
• subscriber unit 40 x synchronizes with the line of sight multipath component 98 x
• Figure 16 is a system correcting for errors resulting from multipath.
• global pilot 50 x is sent from the base station 36 x to subscriber unit 40 x .
• subscriber unit 40 x collects all of the multipath components using a multipath
• receiver 102 x such as disclosed in U.S. Patent Application No. 08/669,769, Lomp
• the first received component 98 x is the line of sight component. If the line of
• the first received component 98 x will be the closest
• the processor 82 x compares the chip code sequence of the first received component 98 x
• MD X multipath delay
• MD 2 of the assigned pilot signal is determined. Additionally,
• multipath delay recovery means 106 x recovers the transmitted global pilot signal's
• the processor 66 x compares the
• the processor 66 x subtracts both the global pilot signal's multipath delay

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Position Fixing By Use Of Radio Waves (AREA)
• Radio Relay Systems (AREA)

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Citations (6)

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• 1999
  • 1999-03-22 US US09/274,081 patent/US6603800B1/en not_active Expired - Lifetime
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• 2000
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• 2002
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• 2005
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• 2008
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• 2010
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