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
  • G01S5/14—Determining absolute distances from a plurality of spaced points of known location

Definitions

• the invention relates to a determination of a position of a mobile communication device in a communication network (localization).
• “Location Based Services” are understood to mean additional services provided by mobile operators, which users of the mobile radio systems are location-specific, i.e. depending on a position or a location of the respective user, are offered or made available, for example location or distance-dependent usage tariffs or orientation aids for rescue operations or search services.
• the basis for a "location-based service” is therefore a localization or position determination of the respective user or his mobile communication device.
• Various techniques are known for such a localization of mobile communication devices in communication networks, for example determining a position on the basis of a running time determination or running time measurement of communication signals from a mobile communication device to a base station of a communication network ([1], [2]) or localization by means of satellite-based systems like a GPS.
• An individual mobile station that has registered with a fixed base station (call-carrying base station) is allocated a currently free time position in a TDMA frame.
• the communication signals intended for the mobile station in question originate in signal packets, so-called bursts, with a length of 15 / 26ms from the base station, or the communication signals or bursts sent by the mobile station must arrive at the base station.
• the communication signals emitted by the base station find their way to the mobile station due to scattering over different paths (multiple propagations), being attenuated as a function of frequency.
• a reception field strength of the communication signals received by the mobile station is therefore not only dependent on the distance of the mobile station from the base station, but also on the frequency and topographical conditions between the mobile station and base station.
• the individual data packets are therefore sent on different carrier frequencies, which means that selective interference of one frequency can be distributed to several participants.
• the mobile station In order to compensate for the different transit times and to be able to supply the base station with frame-synchronous data, the mobile station measures the signal transit time to the base station and thereby corrects the start of transmission of its bursts.
• the signal transit time is encoded in a so-called "ti ing advance” (TA) and is dependent on the distance between the mobile station and the base station carrying the call.
• TA ti ing advance
• 64 levels are available for the TA, which are coded with values 0 to 63 (bit) and represent the runtime.
• the position of the mobile station can be inferred from a TA or from the signal transit time.
• Measurement accuracy in the run time determination is one bit duration, i.e. in GSM 48/13 ⁇ s, which corresponds to a simple path length of approximately 554 m.
• a position determination of a mobile radio device is already explicitly included in the standard or is required by this (TS 25.305 V3.1.0: stage 2 "Functional Specification of Location Services in UTRAN "(release 99), 3GPP TSG-RAN-WG2, 2000).
• a back transformation of the processed uncertainty areas from hyperspace into the original space enables an analytical description of processed uncertainty areas also in the original space.
• the localization methods mentioned have the disadvantages, among other things, that the positions of the mobile communication devices determined by them are imprecise and consequently involve great uncertainties. However, more precise methods require complex additional devices and costly modifications to the communication network and communication devices.
• the invention is therefore based on the object of making it possible to locate a mobile communication device in a communication network precisely and with as little uncertainty as possible, which can be implemented as simply and inexpensively as possible.
• a first communication signal is used the first communication determines a first possible location area of the mobile communication device from the first base station, using a second communication signal of the second communication determines a second possible location area of the mobile communication device from the second base station, the first possible location area and the second possible location area using a non-linear quantity-based filter combined, with a common location of the mobile communication device to the e rsten and the second base station is determined, and the position of the mobile communication device is determined using the common location area.
• the arrangement for determining a position of a mobile communication device in a communication network with at least a first base station, set up for a first communication with the mobile communication device, and a second base station, set up for a second communication with the mobile communication device also has a first location determination unit which a first possible location area of the mobile communication device can be determined by the first base station using a first communication signal of the first communication, a second location determination unit with which a second possible location area of the mobile communication device can be determined by the second base station using a second communication signal, a location overlay unit with which the first possible location area and the second possible location area can be combined using a nonlinear quantity-based filter , wherein a common location area of the mobile communication device to the first and the second base station can be determined, and a position determination unit with which the position of the mobile communication device can be determined using the common location area.
• the nonlinear quantity-based filtering in the invention is generally to be understood as follows: the possible areas of residence are transformed into a combination from an original space into a hyperspace, in this hyperspace the possible areas of residence are combined to form the common area, then the common area Residence area transformed back from hyperspace into the original space.
• the computer program with program code means is set up to carry out all the steps according to the method according to the invention for determining a position, ie the localization method according to the invention, when the program is executed on a computer.
• the computer program product with program code means stored on a machine-readable carrier is set up to carry out all steps according to the localization method according to the invention when the program is executed on a computer.
• the arrangement and the computer program with program code means, set up to carry out all steps according to the inventive localization method when the program is executed on a computer, and the computer program product with program code means stored on a machine-readable medium, set up all steps according to the Performing localization methods according to the invention when the program is executed on a computer are particularly suitable for carrying out the localization method according to the invention or one of its further developments explained below.
• the inventive localization method is based on the idea of obtaining distance-relevant parameters and geographic information, in this case possible areas of residence or distance or location of the mobile station, from available communication signals between at least two base stations and a mobile station.
• the location of the mobile station is then overlaid on the individual areas of uncertainty.
• the nonlinear set-based filter When the areas of uncertainty are overlaid by the nonlinear set-based filter, the individual areas of uncertainty are reduced to a common intersection, the overall area of uncertainty.
• a particular advantage of the invention lies in the fact that the localization is carried out on the basis of communication signals and known positions of base stations which are incurred during normal operation in a mobile radio system and are available there. As a result, complex changes and expansions as well as additional measurements of existing mobile radio systems or existing mobile radio systems can be dispensed with.
• the invention or any further development described below can also be implemented by a computer program product which has a storage medium on which the computer program with program code means which carries out the invention or further development is stored.
• a mobile communication device for example a mobile phone
• a base station for example a omnidirectional antenna or an omnidirectional antenna or one or more sectoral antennas
• data, the (first and the second) communication signals in Signal packets, so-called bursts, transmitted.
• various distance-related parameters can be determined, which in turn can be used as a basis for determining the possible residence or remplibieten.
• Such a distance-relevant, i.e. Distance-dependent parameter is, for example, a signal runtime of a signal packet between the mobile station and the base station.
• the signal delay has a natural dependence on the distance between the mobile station and the (conversation-leading) base station and consequently provides information about a possible location area or distance area (uncertainty area) of the mobile station.
• the signal transit time can be measured by a mobile station (or also by a base station) and encoded in a so-called timing advance (TA).
• TA timing advance
• 64 coding levels quantization levels
• 64 bits can be available for the TA, which can be coded with values 0 to 63 (bit) and represent the runtime.
• the measurement accuracy in determining the signal propagation time is one bit duration, for example in GSM 48/13 ⁇ s, which corresponds to a simple path length of approximately 554 m.
• a measured and thus coded signal transit time leads to a possible area of uncertainty in the form of a circular ring around the base station with a width that corresponds to a bit duration, for example a circular ring with the width of 554 m for GSM.
• the annulus can be restricted to one sector if a directional emission characteristic of the base station is taken into account.
• antennas at a base station which emit in certain directions and one of which is in communication with the mobile station.
• three antennas for example, there is a sector of 120 ° on which the circular ring can be restricted.
• Another parameter relevant to distance is, for example, a field strength of a signal packet.
• the field strength has a natural dependence on the distance between the mobile station and the (talking) base station and consequently provides information about a possible location area or distance area (uncertainty area) of the mobile station. This relationship between field strength and distance can be described by physical models that describe the propagation behavior of signals.
• this model provides a maximum distance for a given or a measured field strength.
• the field strength of a signal packet received by a base station can thus be measured by the mobile station and a maximum distance of the mobile station from the base station can be estimated therefrom using a propagation model.
• This maximum distance can be described by an area of uncertainty in the form of a circle with a corresponding radius around the base station.
• this circle can be limited to one sector if a directional emission characteristic of the base station is taken into account. As a result, there is an area of uncertainty in the form of a circular sector.
• a mobile station is now in communication with a plurality of base stations or receives from them or exchanges signal packets with them, several such areas of uncertainty can be determined in each case with respect to the corresponding base station.
• a non-linear, quantity-based filter is used to combine all the areas of uncertainty.
• the nonlinear set-based filter in turn provides an easy-to-describe body, such as an ellipsoid, referred to as an envelope lipoid, in hyperspace.
• This envelope ellipsoid fulfills the following conditions: a) it is analytically describable by an ellipsoid body which contains the intersection, b) it lies entirely in a • union of the areas of uncertainty.
• the nonlinear set-based filter can also be used for the simultaneous intersection formation of several uncertainty areas in a single step.
• the position of the mobile station can then be determined using the cut, back-transformed common uncertainty area.
• a characteristic value of the common area of uncertainty can be determined, such as a center of gravity or an expected value, which is then used as an estimate for the position of the mobile station.
• the invention is particularly suitable for use in the environment of a digital, cellular mobile radio system, such as a GSM network, for example for localizing a GSM telephone (mobile phone) there.
• a digital, cellular mobile radio system such as a GSM network
• GSM telephone mobile phone
• the positions of the individual base stations and their antennas and their characteristics, which provide information about the coverage area of the respective antenna, are known from a GSM network.
• Prediction maps of expected tendency field strengths are determined from environmental models and are also available.
• the mobile phone for its part, is always in contact with the receivable antennas for a correct connection in order to be assigned the antenna best suited for a call from the network. To do this, it measures, among other things, the reception field strength of the receivable antennas and determines signal propagation times, which are then also known.
• the cell phone is then located on the basis of this available information.
• a distance range of the mobile phone from its leading antenna resulting from a quantization and a maximum possible distance are derived from the field strength measurements.
• this distance specification can still be limited to a specific area around the antenna, since it is often directed antennas that, for example, only supply a sector of 120 °.
• Measurements are then reduced with a nonlinear quantity-based filter to the common intersection in which the telephone can be accepted according to the 'model.
• FIG. 1 shows a sketch of a GSM network architecture of a GSM mobile radio network
• FIG. 2 shows a sketch of a TA uncertainty area (TA segment)
• FIG. 3 shows a sketch of field strength uncertainty ranges (RxLev ranges);
• FIG. 4 shows a sketch with an overlay of a TA segment with several RxLev areas
• FIG. 5 shows a sketch of a TA segment generated by a nonlinear quantity-based filter
• FIG. 6 shows a sketch of an RxLev range generated by a nonlinear, quantity-based filter
• FIG. 7 shows a sketch of an intersection formation of a TA segment with RxLev areas by means of a non-linear, quantity-based filter.
• Exemplary embodiment Localization of a mobile phone in a GSM mobile radio network
• FIG. 1 shows a network architecture 101 of a GSM mobile radio network 100.
• This mobile radio network 100 is a digital, cellular mobile radio system ([7], [8], [9]) with a hierarchical structure of a GSM system architecture 101 shown in FIG.
• An area 103 supplied by an antenna 103 is referred to as cell 102 and is dimensioned according to the expected number of participants.
• a base station (BTS) 104 always manages a location at which, however, several sectional antennas 103 can be positioned. If there is only one antenna 103 in a BTS 104 that supplies its entire environment, this is referred to as an omnidirectional antenna.
• BSC base station controller
• the calls from mobile stations (MS) 106 are bundled together for their cells 102 by a switching node, the Mobile Switching Center (MSC) 107.
• MSC Mobile Switching Center
• the communication between base 104 and mobile station 106 is particularly important.
• the GSM network 100 is cellular, which enables frequency band repetition since only immediately adjacent radio cells 102 are not allowed to work with the same frequency groups.
• the 25 MHz bandwidth available to a network operator is divided into 124 individual channels (carrier frequencies).
• eight time-shifted conversation channels are accommodated in it and served by multiple time access. In this way, up to 1000 participants can be supplied in one area without repeating the frequency band.
• the data transmission takes place within a time slot in signal packets, the so-called bursts, with a length of 15/26 ms.
• the signals emitted by the base station (BTS) 104 find their way to the mobile station (MS) 106 due to scattering over different paths (multipath propagation), and are attenuated as a function of frequency.
• the reception field strength of the mobile station (MS) 106 is therefore not only dependent on its distance from the base station (BTS) 104, but also on its frequency and the topographical conditions between the transmitter and receiver.
• the individual data packets are sent on different carrier frequencies, whereby selective interference of one frequency can be distributed to several participants.
• this requires precise synchronization between the mobile and base station.
• the mobile station measures the signal transit time to the base station and thereby corrects the start of transmission of its data packets.
• the signal propagation time is encoded in the so-called timing advance (TA) and, of course, is dependent on the distance between the mobile station and the base station carrying the call.
• TA timing advance
• the mobility of the subscribers can also have the consequence that the mobile station leaves the coverage area of a base station and thus an adjacent base station leaves the mobile station. Station must take over. This process is called handover.
• the field strength of all receivable antennas is continuously measured by the mobile station, among other things.
• the field strengths of the six best received antennas are communicated to the base station carrying the call in the so-called RxLev values, which can make a handover decision based on the quality of the connection and the number of participants in the other base stations.
• the RxLev value contains information about the distance to the other receivable base stations 104, since the field strength decreases with the distance, and is therefore relevant for the location of the mobile station (MS) 106.
• G s and G e stand for the gain of the transmitting or receiving antenna
• c is the speed of light
• r is the distance MS-BTS
• f is the carrier frequency
• the mobile station In order to make the handover synchronous, the first data packet from the mobile station for the new call-carrying base station must arrive at the BTS in the correct time frame. For this reason, the mobile station must know the TA value of the next call base station before the actual handover.
• the MS constantly calculates the time difference between the base station on the call and the other receivable base stations. This is called the Observed Time Difference (OTD).
• OTD Observed Time Difference
• the base stations in turn always have the so-called Real Time Difference (RTD) ready for their neighbors and inform the mobile station of the RTD to the next talking base station before a handover.
• RTD Real Time Difference
• the MS can now calculate the TA value for the new call-carrying BTS, from which in turn conclusions can be drawn about the distance MS-BTS.
• this second TA value is only available at the time of the handover and can therefore generally not be used for localization.
• the timing station (TA) as a measure of the distance MS-BTS and the RxLev value as a field strength measure to a maximum of six further base stations are constantly available to the mobile station as parameters relevant to localization.
• the coordinates of the base stations and cell centers can also be called up from the GSM network. Before the TA or RxLev value can be used for localization, the dependence on the distance to the respective base station must be modeled.
• timing advance 64 stages are available for the timing advance (TA), which are coded with the values 0 to 63 and represent the runtime BTS-MS-BTS.
• TA timing advance
• a bit time of 3.69 ⁇ s corresponds to a distance of
• the distance r between the MS and the call-carrying BTS is therefore in the quantization interval
• a ring 200 with a width of 553 m 202 can be derived around the call-carrying BTS 201, in which the MS is located. Depending on the antenna, however, this ring 200 can be further restricted (to a ring segment 204). Very often there are several antennas on the mast of a BTS that emit in certain directions. These directions point to the cell center of the respective antenna. With three antennas on the same mast, for example, there is a sector 203 of 120 ° (FIG. 2).
• the location of the mobile station can now be assumed within this TA segment 204.
• the MS informs it of the field strengths of the six best received neighboring BTS.
• RxLev values which, like the TA value, are represented in the value range from 0 to 63. This corresponds to a measuring range of the reception field strength from -HOdBm to -48dBm.
• RxLev values should now be converted into a distance from the respective base station in order to be used for localization. It should be noted that the RxLev values do not only depend on the distance MS-BTS.
• ⁇ P is the decrease in field strength
• f is the carrier frequency
• c is the speed of light
• ⁇ is a frequency-dependent
• ß is a terrain-dependent factor
• the received power increases with the power ß Distance from.
• a model for determining the distance can be derived from field strength measurements.
• the linear approach is refined by defining at least one such straight line per antenna 306, 307, 308 (FIG. 3) for adaptation to its surroundings.
• r_max 304 For the maximum distance r_max 304 it follows
• the parameters offset and slope come from an antenna-specific database or can also be obtained from the prediction maps.
• circles 301, 302, 303 result as equipotential lines, which represent the maximum possible distance for the received field strengths (cf. FIG. 3).
• the directional dependence of the propagation in the sectional antennas 305, 306, 307 can now also be taken into account, and the circles 301, 302, 303 can be limited to a 120 ° segment 308, 309, 310, for example.
• the location of the mobile telephone can be assumed within the restricted circle segments 308, 309, 3010.
• both the TA segment (401, Fig. 4; Fig. 2) as the presumed location of the mobile phone and the RxLev circles (402, 403, Fig. 4; Fig. 3) as the assumed location 407 for calculating the resulting location Position of the mobile phone used.
• the TA segment 401 of the call-carrying antenna 404 is combined with up to six circles 402, 403 from the field strength measurement to the neighboring base stations 405, 406 (407, FIG. 4).
• the TA segment 401 should be the basis of this combination 407, i.e. Intersection of the individual areas act.
• intersection formation 407 of the areas 401, 402, 403 takes place using a non-linear, quantity-based filter.
• a non-linear, quantity-based filter is described in [10].
• This non-linear, quantity-based filter is a means of control engineering, where several measurements with uncertainties, which can be represented in the form of uncertainty areas, have to be taken into account for state estimates.
• uncertainties which can be represented in the form of uncertainty areas
• the non-linear set-based filter When the areas of uncertainty are overlaid by the non-linear set-based filter, the individual areas of uncertainty are reduced to a common intersection, a total area of uncertainty.
• both the TA ring segment 401 and each of the RxLev circles 402, 403 are treated as an uncertainty area of a distance measurement, and from this the total uncertainty area 407 is assumed to be assumed by the nonlinear quantity-based filtering
• the location of the mobile phone is determined.
• the points of the original space are mapped into the hyperspace using a nonlinear transformation, where the complicated areas are formed by simple ellipsoids of the shape
• x is the center point vector and C is the definition matrix of the ellipsoid.
• the non-linear measurement equation of the TA ring can be represented as
• H * is the transmission matrix in hyperspace
• x * the state vector
• cf is a constant correction factor. This should now be intersected with a prediction area (index p ) that contains all measurements. Finally, a limiting ellipsoid (index s ) can be described for the intersection
• the parameter ⁇ serves to weight the prediction and measurement and can be used to minimize the volume of the limiting ellipsoid.
• z z - cf and V * results from the square of the maximum uncertainty, so here too
• the resulting pseudo-ellipsoid X '502 approximates the extent of the ring very well, but has a significant error in the sector constraint.
• the ellipsoid should either be narrowed further in an even higher dimensional hyperspace or corrected by reducing the angle between the pairs of lines.
• the circles 601 of the maximum possible distance of the RxLev model are cut with a further circle 602 which is shifted in the direction of radiation.
• R v 2 (x - (a x + R v cos ⁇ )) 2 + (y - (a y + R v sin ⁇ )) 2 (20)
• the nonlinear set-based filter again supplies the intersection of this as a pseudo-ellipsoid 603 in the form of the gray approximation in FIG. 6 that takes into account the radiation characteristics of the antenna.
• both the TA and the RxLev model for directional antennas can be approximately limited to one sector according to their radiation characteristics.
• Fig. 7 once again illustrates the procedure of the filter and the successive reduction in the area of uncertainty (Fig. 7a to Fig.7d, 704-705-706-707).
• AI 701 is the talkative antenna with the sectoral TA segment 704 as the starting body for the intersection formation.
• A2 702 is another, second antenna or base station with a directional characteristic of 120 °.
• A3 is a third omnidirectional antenna.
• the cut is made with a further circle 710 as the unsafe area of the circular antenna A3 703. This leads to a further reduction to the unsafe area 707.
• the aim of the localization is to estimate the position of the mobile phone from its measurements as accurately as possible.
• the nonlinear set-based filter determines an ellipsoid that includes the intersection of all areas.
• the point with a minimal mean distance to the other points lying within the ellipsoid is therefore chosen as the position of the mobile station and the result of the localization.
• the mean distance for each of these points must be determined before the minimum of these mean distances is available as a result.
• the search for the minimum of the mean distances and thus the computing time can be limited somewhat by preselecting the points in question.
• the expected value for the TA segment alone can also be determined analytically without going through a grid.
• the expected value is calculated as the position of the mobile station

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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)

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• 2003
  • 2003-04-08 US US10/480,103 patent/US20060234722A1/en not_active Abandoned
  • 2003-04-08 JP JP2003583048A patent/JP2005522918A/ja not_active Withdrawn
  • 2003-04-08 EP EP03729823A patent/EP1493284A1/de not_active Withdrawn
  • 2003-04-08 CN CNA038004054A patent/CN1568634A/zh active Pending
  • 2003-04-08 WO PCT/DE2003/001160 patent/WO2003086005A1/de not_active Application Discontinuation

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