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
  • G01S5/0252—Radio frequency fingerprinting
  • G01S5/02521—Radio frequency fingerprinting using a radio-map
  • G01S5/02523—Details of interaction of receiver with radio-map
• • 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
  • G01S5/01—Determining conditions which influence positioning, e.g. radio environment, state of motion or energy consumption
  • G01S5/011—Identifying the radio environment
• • 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
  • G01S5/10—Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements, e.g. omega or decca systems

Definitions

• the present invention relates to a method of geographically positioning a mobile terminal in a mobile network and a network to enable the method.
• WO 01/95659 Cellpoint Systems AB
• WO 02/35875 Motorola Inc.
• TDOA time difference of arrival measurements
• WO 01/95659 defines measuring the real time difference (RTD) information between base stations during handovers.
• RTD real time difference
• WO 02/35875 detects a measurable signal type and compares it with a stored signal operable to calculate the TDOA, to determine the mobile terminals position.
• US 5394158 describes storing a set of ordered pairs corresponding to distance and signal characteristics associated with a particular location and comparing currently measured distance and signal characteristics with the stored information to determine the position of a mobile terminal.
• US publication 2002/0193941 discloses a self locating devices capable of receiving signals, which defines its location by identifying the base stations from the GSM signals it receives.
• the base stations are identified from the common channel identifiers that are associated with the GSM signals sent from them.
• GNSS global navigation satellite system
• GPS global positioning system
• A-GPS Assisted Global Positioning System
• Cell_ID Cell_ID
• the present invention provides a method of generating a database of values indicative of a first characteristic of a plurality of pairs of base stations, comprising the steps of: establishing the position of a mobile terminal using global navigation satellite systems(GNSS) measuring a first timing difference, indicative of the position of said mobile terminal with respect to a pair of base stations; calculating a first value indicative of a first characteristic for said pair of base stations from said established position of said mobile terminal and said first timing difference; and repeating the above steps for a plurality of mobile terminals and for a plurality of pairs of base stations and storing the results.
• GNSS global navigation satellite systems
• a database of values can be built up which can then be used to determine the position of a mobile terminal in a second aspect of the present invention.
• the mobile terminal is a A-GPS enabled mobile which can establish its own position and the database of values is a database of random time differences between the system frames of pairs of cells (T ran dom delay u)-
• the first timing difference is an SFN-SFN (System frame number) timing difference measurement.
• SFN is a common identifier allocated to each data frame.
• SFN-SFN type 1 measurements may be used for CELL_FACH
• Type 1 measurements require the UE (user equipment) to read the Broadcast channels (BCH) of neighbouring cells. However this reading cannot be reported until the UE enters a CELL_FACH connection. Therefore the signals needed for type 1 are not always strong enough to ascertain time difference form multiple base stations.
• BCH Broadcast channels
• SFN-SFN type 2 measurements can be used in both intra and inter-frequency for CELL_FACH and CELLJDCH.
• type 2 measurements are used in the invention since the signals required for SFN-SFN type 2 observed time difference measurements are strong enough to ascertain time difference from multiple base stations.
• SFN-SFN type 1 measurements may be used in limited situations depending on signal strength.
• the present invention provides a method wherein said step of calculating a said first value comprises a step of calculating a theoretical value indicative of the position of said mobile terminal with respect to a said pair of base stations on the basis of said established position of said mobile terminal and a step of calculating a said fist value on the basis of said theoretical value and said first timing difference.
• the theoretical value is the theoretical path delay time difference between two cells (Theoretical T p d ⁇ ).
• the T ran i om de l ay t-i c is calculated according to the equations given in the detailed description of the invention.
• the present invention provides a method of establishing the position of a mobile terminal in a mobile communications network using the database of first values indicative of a first characteristic of each of a plurality of pairs of base stations established in the first aspect of the invention, comprising the steps of: measuring a second timing difference, indicative of the position of said mobile terminal with respect to a pair of base stations; and determining the position of said mobile terminal from said second timing difference and a first value corresponding to said pair of base stations.
• the position of a mobile terminal can be calculated using the database, which has been established, and values which have been already measured.
• the position is calculated without the use of A-GPS in the mobile terminals for which the position is being calculated.
• the first values are random time differences between the system frames of pairs of cells (T random de la y t- k ) which are calculated using A-GPS and System Frame Number (SFN) -SFN timing difference measurements, which are provided simultaneously by A-GPS enabled mobile terminals.
• the second timing difference is an SFN-SFN timing difference measurement.
• the present invention provides a method wherein said step of calculating the position comprises a step of calculating a third timing difference indicative of the position of said mobile terminal with respect to said pair of base stations on the basis of said second timing difference and a first value corresponding to said pair of base stations and a step of calculating the position of said mobile terminal on the basis of said third timing difference.
• the third timing difference is the path delay time difference between two cells (T pd Wc ) which is calculated using the equations shown below in the detailed description.
• At least two T pd t . k values are used to determine the position of the mobile terminal by using for example, the known positions of the base stations and hyperbolic equations as shown below.
• the accuracy of this method would be between Cell_ID and A-GPS.
• the present invention provides a mobile communications system, comprising a plurality of base stations arranged to communicate with a plurality of mobile terminals, the system comprising: a database of first values indicative of a first characteristic of each of a plurality of pairs of base stations; first value means for calculating said first values on the basis of established positions of said mobile terminals and intermediate values indicative of positions of said mobile terminals with respect to pairs of base stations; and position means for calculating the position a said mobile terminal on the basis of the intermediate values indicative of the position of said mobile terminal with respect to said pair of base stations and a said first value corresponding to said pair of base stations.
• Figure 1 shows a procedure diagram of an embodiment of the present invention
• Figure 2 show an example of hyperbolic positioning in an embodiment of the present invention
• Figure 3 shows a database structure for T random de ⁇ ay t . k values between each pair of four cells in an embodiment of the present invention. Detailed description of the preferred embodiments
• Figure 1 shows a procedure diagram of an embodiment of the present invention. The procedure will be described below.
• the Mobile switching centre (MSC) in 3 G core networks is responsible for maintaining databases for location registration, allocation resources, handover management, paging etc.
• the location of all mobile terminals that are present in the area served by an MSC is registered in databases maintained in the MSC.
• the latest location of a particular mobile terminal is stored in a Visitor location register (VLR).
• VLR Visitor location register
• HLR Home location register
• This register contains subscriber information of mobile users registered with a particular MSC.
• the data from the HLR of a mobile terminal is copied onto a VLR when a mobile enters (or switches ON) its home MSC or another MSC.
• the VLR When a mobile terminal enters the area served by a new MSC, the VLR is updated and the location information in the VLR is communicated to the HLR of the mobile terminal.
• the location may be updated in the VLR based on the quality of signal strength each time the mobile terminal requests a service.
• a temporary mobile subscriber identifier is allocated to the mobile terminal by the VLR for tracking its changes.
• the location updates in the VLR and HLR enhances the paging procedure for a mobile terminal, since its latest location is known from the VLR, and the call may be easily routed.
• a location application server may be integrated into the structure of the MSC, for deploying a particular logic function.
• This server may be configured in a desired fashion to perform and record location updates . Therefore if more precise database is required, the LAS may be configured to poll the different mobile units at regular intervals to provide their location information, which is registered at in a database.
• the LAS can also support GNSS services. The LAS may then be configured to perform predefined computation on the location data that it receives.
• mobile terminals report their A-GPS measurements to the Location Application Server (LAS) at regular intervals. Since the location of the mobile terminal is known from the A-GPS measurements, and the location of the base stations is known from a database in the LAS, the distance of the mobile terminal from each of two base stations i and k can be calculated. From these values it is possible to calculate the theoretical path delay from the mobile terminal to each of the two base stations i and k. The difference between these to path delays is the theoretical path delay time difference between two base stations i and k (theoretical T pdi-k ).
• the LAS receives the A-GPS measurements and calculates the theoretical T pd i_ k using the base station locations in the LAS's database and A-GPS measurements as follows:
• the coordinates of the mobile terminal could be calculated, for example by using hyperbolic positioning.
• the equation has two solutions for the coordinates X AGPS and y AG p S , and two values of T pd i-k are therefore required. This can be achieved by using three base stations (a, b and c) instead of two.
• Tpd i- 2> T pd2-3 and T pd 1-3 there is a path delay time difference between each of the three pairs of base stations and the mobile terminal.
• Tpd i- 2> T pd2-3 and T pd 1-3 shows an example of hyperbolic positioning and is for illustrative purposes only.
• Two T pd uk could be used to solve the following hyperbolic equations to estimate the mobile terminal position (x m , V 1n ):
• V(*2 - ⁇ . ⁇ + (yi -y m ? - V(*i -*.) a + ( ⁇ - ⁇ ,,) 2 c ⁇ pdl2 (2)
• T pd i-k can not be measured directly. All mobile terminals do however measure the SFN-SFN timing difference between two base stations i and k. SFN-SFN timing difference measurements are performed in the mobile terminal to identify the frame time difference between two geographically separated sites. The present invention utilises these measurements as follows to enhance positioning accuracy.
• the measured SFN-SFN time difference has three components as described below:
• T 1n t . k T pd u k + T rmdom de ⁇ ay ,. / .; (5)
• T pdi _ k is the path delay time difference between two cells i and k; T r an d om dela y i- k is random time difference between the System Frames of two cells i and k; and Offset is a number between 0 and 255 set by the operator.
• T m ;-fo has two components. The first one is a random delay due to asynchronous nature of network, T random de ⁇ ay ⁇ , and the second one is the path delay, T pd i _ k , which, as described above enables the location of a mobile terminal to be calculated.
• T m uk can be calculated.
• T pd uk can be used as described above to calculate the mobiles position.
• T random de ⁇ ay t . k we need to know T random de ⁇ ay t . k . In order to work this value out, mobile terminals with A-GPS must be used.
• the LAS regularly sends measurement requests to mobile terminals with A- GPS capabilities for the following:
• T random delay i-k can be calculated by the LAS as follows:
• Trandom delay i-k Measured T m uk - Theoretical T pd t _ k (6)
• Theoretical T pd t . k is calculated from the A-GPS measurements as shown above in relation to equation one.
• Measured T m uk is calculated from the SFN-SFN timing difference measurements as shown above in relation to equation four.
• the LAS can calculate a database for the T random de ⁇ ay t - k between each pair of cells i and k using above procedure.
• An example database is shown in Figure 3.
• T random de]ay i-k database in the LAS as shown in figure 3.
• the random delays between two system frames are expected to be stable. If any change is observed then the database would automatically update itself.
• the LAS uses the T random de i ay ⁇ database when a location fix is requested by the user, in accordance with the following procedure:
• the user requests a location service
• the network requests the last measured SFN-SFN measurement from that mobile terminal
• the mobile terminal sends the SFN-SFN timing difference measurement report to the LAS;
• the LAS calculates the T m uk using equation (4);
• the LAS calculates T pd t . k using equation (5);
• the LAS can calculate the position of the mobile terminal, for example using hyperbolic positioning as shown above in relation to equations 2 and 3.
• the present invention provides a mechanism which utilises measurements from mobile terminals with A-GPS capabilities, to enable the position of mobiles without A-GPS capabilities to be calculated.
• Hyperbolic positioning has been described above as a method of calculating the mobile terminals position from the calculated T pd t . k .
• other techniques including other triangulation techniques, may be used as will be appreciated by one skilled in the art. It will also be appreciated that although the above technique has been described on the basis of obtaining two values for T pd ;-fo the accuracy of the technique could be increased by obtaining three or more values of T pd ⁇ .
• the present invention could be used with other radio information in order to triangulate the position of the terminal.
• the mobile terminal can only receive signals form two base stations, then the present invention may only allow the position the terminal to be calculated along one hyperbola.
• other methods known to the person skilled in the art may can help calculate position along the hyperbola. For example, looking at the intersection of the hyperbola with known sections of each of the cells of the respective base stations or the intersection of the hyperbola with ranging estimates based on radio power. Other techniques will be apparent to the person skilled in the art for establishing the position of a mobile terminal along a single hyperbola.
• the second aspect of the present invention has been described above in relation to mobile terminals with A-GPS capabilities. While these mobile terminals may be mobile phones, it will be appreciated that alternative terminals may be used in accordance with the present invention.
• the network operator may wish to improve the database of T random delay t . k itself. This could be done by moving test equipment round the area covered by the network. The equipment must be capable of taking SFN-SFN timing difference measurements and measuring its location, by using GPS for example.
• the database of T random de ⁇ ay t _ k is then established in accordance with the method described above.

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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)
• Position Fixing By Use Of Radio Waves (AREA)
• Mobile Radio Communication Systems (AREA)

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• 2005
  • 2005-05-10 GB GBGB0509498.2A patent/GB0509498D0/en not_active Ceased
• 2006
  • 2006-05-10 AU AU2006245486A patent/AU2006245486A1/en not_active Abandoned
  • 2006-05-10 EP EP06727074A patent/EP1880567A2/de not_active Withdrawn
  • 2006-05-10 WO PCT/GB2006/001722 patent/WO2006120447A2/en not_active Application Discontinuation
• 2007
  • 2007-11-06 NO NO20075633A patent/NO20075633L/no not_active Application Discontinuation
  • 2007-11-08 IL IL187255A patent/IL187255A0/en unknown

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