EP1493284A1

EP1493284A1 - Methods, configuration and computer program having program code means and computer program product for determining a position of a mobile communications device within a communications network

Info

Publication number: EP1493284A1
Application number: EP03729823A
Authority: EP
Inventors: Uwe Hanebeck; Werner Hauptmann; Kai Heesche; Joachim Horn; Konrad Riegel
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2002-04-09
Filing date: 2003-04-08
Publication date: 2005-01-05
Also published as: WO2003086005A1; JP2005522918A; CN1568634A; US20060234722A1

Abstract

The aim of the invention is to determine a position of a mobile communications device within a communications network (localization). To this end, possible location areas for the mobile communications device are determined from communications signals of the mobile communications device by using base stations located within the communications network, and these possible location areas are superimposed to form a common location area while using a non-linear quantity-based filter. The position of the mobile communications device is then determined while using the common location area.

Description

description

Method and arrangement as well as computer program with program code means and computer program product for determining a position of a mobile communication device in a communication network

The invention relates to a determination of a position of a mobile communication device in a communication network (localization).

With the increasing spread of mobile communication, the demand for additional services, so-called "services", in mobile radio systems also increases.

"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. The runtime-based position determination method known from [2] is used for a mobile telephone, generally a mobile station, in a GSM communications network (= Global System for Mobile Communications) ([7], [8], - [9]) according to a TDMA - Cellular technology (Time Division Multiple Access cellular) carried out.

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.

At this time, 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.

However, this requires precise synchronization between the mobile station and base station. This synchronization is made even more difficult by the mobility of a user because the mobile station is now changing Distances to the base station and their communication signals have different transit times.

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.

64 levels are available for the TA, which are coded with values 0 to 63 (bit) and represent the runtime.

Since positions of base stations are known, 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 μs, which corresponds to a simple path length of approximately 554 m.

A determination of the position of a mobile communication device in a UMTS network (= Universal Mobile Telecommunication System network) is known from [3].

In the corresponding UMTS mobile radio standard, on which the UMTS network is based, 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).

From [4], [5] and [6], further methods for localizing a mobile communication device in a communication network are known. A non-linear, quantity-based filter is known from [10].

With this nonlinear set-based filter, complex areas of uncertainty of an N-dimensional original space are transformed into an L-dimensional hyperspace, in which they can be easily represented and processed as ellipsoids.

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.

These tasks are solved by the method and the arrangement as well as by the computer program with program code means and the computer program product for determining a position of a mobile communication device in a communication network with the features according to the respective independent patent claim. In the method for determining a position of a mobile communication device in a communication network with at least one 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, 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 advantage of this procedure is that in the hyperspace the possible location areas transformed there can be simply described and edited, in this case combined, using predefinable bodies.

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 abovementioned areas of residence or distances or areas of residence - and no exact distances or distances - result because the parameters relevant to the distance are inaccuracies, such as measurement and calculation inaccuracies or model errors, and therefore uncertainties which occur in the "unsharp" areas mentioned , so-called uncertainty areas, result.

To reduce the uncertainties or the areas of uncertainty to a lower total uncertainty or to a smaller total uncertainty area than possible The location of the mobile station is then overlaid on the individual areas of uncertainty.

For this purpose, a means from control technology, where several measurements with uncertainties have to be taken into account for state estimates, namely a non-linear, quantity-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.

Finally, the mobile station is suspected in this overall uncertainty area.

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.

Preferred developments of the invention result from the dependent claims.

The further developments described below relate both to the method and to the arrangement.

The invention and the further developments described below can be implemented both in software and in hardware, for example using a special electrical circuit. Furthermore, an implementation of the invention or a further development described below is possible by means of a computer-readable storage medium on which the computer program with program code means which carries out the invention or further development is stored.

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.

When communicating in a communication network between a mobile communication device (mobile station), for example a mobile phone, and 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.

Based on ^'the or using the transmitted communication signals or signal packets, various distance-related parameters can be determined, which in turn can be used as a basis for determining the possible residence or Entfernungsbebieten.

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). 64 coding levels (quantization levels) can be available for the TA, which can be coded with values 0 to 63 (bit) and represent the runtime.

As a result of the quantization, the measurement accuracy in determining the signal propagation time is one bit duration, for example in GSM 48/13 μs, which corresponds to a simple path length of approximately 554 m.

Accordingly, 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.

Very often there are several antennas at a base station, which emit in certain directions and one of which is in communication with the mobile station. With 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.

Like the signal propagation time, 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.

Assuming an unimpeded propagation of signals in such a model, 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.

Here, too, 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.

If 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.

So it makes sense to use the communication between the mobile station and the base station carrying the call for a signal propagation time determination and to determine the corresponding area of uncertainty, the circular ring sector. In addition, other base stations that can best be received by the mobile station can each be used for a field strength measurement and the respective uncertainty area, the circle or the circle segment can be determined in each case.

According to the invention, a non-linear, quantity-based filter is used to combine all the areas of uncertainty.

With this nonlinear set-based filter, complex areas of uncertainty of an N-dimensional original space are transformed into an L-dimensional hyperspace, in which they are represented and processed simply, e.g. by an ellipsoid. can be combined.

In order to do justice to all areas of uncertainty, it makes sense to form an intersection of all areas of uncertainty, in this case in hyperspace.

As a result of the intersection formation, 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 subsequent reverse transformation of the envelope ellipsoid from hyperspace into the original space enables an analytical description of the intersection of the areas of uncertainty in the original space as well. It should be noted that bodies other than ellipsoids can also be used to describe the transformed areas of uncertainty in hyperspace.

It is also possible to apply the nonlinear quantity-based filter successively or step-wise, i.e. two uncertainty areas are always cut one after the other.

Alternatively, 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.

For this purpose, for example, 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.

When using the invention, only the data available to the mobile phone will be used, and there are no costly changes to be made to the GSM network or to mobile stations in the GSM network.

For example, 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.

For the signal propagation time, 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.

In addition, 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 °.

These areas result from the individual

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.

In the figures, an embodiment of the invention is shown, which is explained in more detail below.

Show it

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

GSM network architecture of the GSM cellular network

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.

Several base stations are controlled jointly by a base station controller (BSC) 105.

The calls from mobile stations (MS) 106 are bundled together for their cells 102 by a switching node, the Mobile Switching Center (MSC) 107.

For the localization of the mobile station (MS) 106, the communication between base 104 and mobile station 106 is particularly important.

In order to be able to serve as many participants as possible with their mobile stations (MS) 106 at the same time, 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.

Furthermore, the 25 MHz bandwidth available to a network operator is divided into 124 individual channels (carrier frequencies). Finally, 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.

For this reason, the individual data packets are sent on different carrier frequencies, whereby selective interference of one frequency can be distributed to several participants. However, this requires precise synchronization between the mobile and base station.

This synchronization is made even more difficult by the mobility of the subscribers because the mobile stations are now at different distances from the base station and their signals therefore have different transit times.

In order to compensate for this and to be able to deliver frame-synchronous data to the 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.

Since the coordinates of the base stations are known, the position of the mobile station can be concluded from this.

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.

In order to be able to select the right base station with the best conditions regarding the quality of the connection, 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.

If it were a pure expansion of free space, the received power could be calculated using the equation

describe, where 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 and f is the carrier frequency.

Due to the multipath propagation due to reflections on the earth's surface and reflections from obstacles or damping, for example in buildings, this decrease is no longer proportional to the square of the distance as in vacuum, but can reach values up to a factor of 5,

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.

To do this, 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).

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.

From this RTD and the associated OTD, 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. However, this second TA value is only available at the time of the handover and can therefore generally not be used for localization.

Localization parameters in the GSM mobile radio network and their areas of uncertainty

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.

For the RxLev value, one can also use the prediction maps available to the network operators, which contain the expected field strength for a 25m grid.

Tirrting Advance (TA)

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. A bit time of 3.69μs corresponds to a distance of

d = --3.69μs -3-10 ⁸ - = 553.46m (3)

2 s

between BTS and MS.

This allows a maximum distance of around 35km to be compensated for over the available range of values.

Because of the rounding in the bit-wise specification of the TA value, the distance r between the MS and the call-carrying BTS is therefore in the quantization interval

iΛ

553.46m TA <r <553.46m TA + - lλ, TA> 0 2 /

0 <r <276.73m, TA = 0 (4)

From the TA value, 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.

RxLev value

However, so that the call-carrying BTS can select another BTS for handover, the MS informs it of the field strengths of the six best received neighboring BTS.

These field strengths are coded in the so-called 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.

These 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.

The determination of the distance information from the field strength values according to [11] leads to a distance r between the mobile and base station

ΔP (dB) = 10 • α • log f-fλ - 10 • ß • log (4πr), (5)

VC j

where ΔP is the decrease in field strength, f is the carrier frequency, c is the speed of light, α is a frequency-dependent and ß is a terrain-dependent factor.

The received power increases with the power ß Distance from.

Another applicable approximation for gaining distance is described in [12].

Alternatively, a model for determining the distance can be derived from field strength measurements.

A linear dependency in the form of a straight line between the RxLev values and the distances MS-BTS is chosen as an approximation.

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. For the maximum distance r_max 304 it follows

r_max = offset + slope * RxLev (6)

the parameters offset and slope come from an antenna-specific database or can also be obtained from the prediction maps.

Furthermore, it is assumed that the signals spread circularly despite all obstacles (FIG. 3), the distance previously derived from the RxLev values serving as the radius of the circles 301, 302, 303.

In the ideal case, circles 301, 302, 303 result as equipotential lines, which represent the maximum possible distance for the received field strengths (cf. FIG. 3).

In addition, as with the TA value, 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.

Consideration and combination of TA and RxLev information

Furthermore, 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).

Due to the very simple linear distance model of the field strength, however, the TA segment 401 should be the basis of this combination 407, i.e. Intersection of the individual areas act.

Filtering or overlaying the uncertainty areas using a non-linear, quantity-based filter

The intersection formation 407 of the areas 401, 402, 403 (FIG. 4) takes place using a non-linear, quantity-based filter. Such 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. 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.

In order to apply the nonlinear quantity-based filter from [10] to the above localization problem, 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.

Basics

The idea behind this non-linear set-based filter is to simply represent the complicated areas of uncertainty of the original N-dimensional space in an L-dimensional hyperspace with L> N.

To do this, 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

^A _ι ^Λ

X = {x: [xx] ^x (C) ¹ [x - x] <1}, (7)

can be displayed. Here 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

R ² <(x - a _x ) ² + (y - a _y ) ² <R ² _a = (x - a.) ² + (y - a _v ) ² + v (8)

with Ri as the inner radius, Ra as the outer radius, a _x a _y as the coordinates of the antenna and v as the uncertainty of the measurement in a hyperspace (index *) with state vector

, ^x 5j (9)

in linear form

-2a _x x _x 2a _y x ₂ + x "+ x _κ + a; + a „+ v (10)

The uncertainty v * = v of the transformed measurement is limited to the interval

Generalized for the measurement equation (10) follows in state variables

(al + a) + v

'12 ^'

z * = H * x * + cf + v *, and ultimately z * = H * x * + v *,

through the area

is restricted.

H * is the transmission matrix in hyperspace, x * the state vector and 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

(14) with

: ^s '* = xP' * + λ CP '<(H) ^τ v' + λ H c ^Pr (H r H x ¥ ι (15)

he '= d P ^& ' (16)

, JL. -_ Λ. I JL,] -J

, ^s , _ λ _C ^p 'JH H * Cp, * (17)

d = 1 + λ - λ * (z * - H * χP ' ^* ) ^T j _V * + λ cP' * ( _H *) ^T | 'z - H x'

(18)

The parameter λ 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

In order to limit the TA ring 501 thus generated to a 120 sector as in FIG. 2, in the next filter step Xs '* becomes the prediction area X ^p ' and this again with two uncertain measurements in the form of pairs of lines 503, 504, one Include an angle of 120 °, cut. This creates the segment 502 recursively in Fig. 5.

The resulting pseudo-ellipsoid X '502 approximates the extent of the ring very well, but has a significant error in the sector constraint.

For this reason, the ellipsoid should either be narrowed further in an even higher dimensional hyperspace or corrected by reducing the angle between the pairs of lines.

However, the exact solution to the expansion of hyperspace has the disadvantage of a disproportionately increasing computing time. With the variation of the angle that the two pairs of lines enclose, the sector can be approximated better, but this is not rewarded by the results. Obviously not all measurements are in the segment assumed by the model, so that a somewhat larger angular range is more appropriate for the measurements.

For this reason, the approximation in Fig. 5 is retained for the calculations and the measurement uncertainties are therefore partially included in the set theory TA model.

To include the model of field strength measurements on the To adapt the radiation characteristics of the antennas and thus limit the direction-independent propagation of the signals to the irradiated antenna sector, another virtual measurement is introduced as an approximation, which must then be taken into account recursively via the filter.

In the TA segment, this is done via two pairs of lines 503, 504, ie two further measurements.

Another way of approximating the restriction to a sector is to introduce a second circular measurement, as shown in Fig. 6.

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.

The circular equation of the shifted circle is 602

R _v ² = (x - (a _x + R _v cos φ)) ² + (y - (a _y + R _v sin φ)) ² (20)

with R _v as radius

R _v ² = _j ? (21)

2 cos (α / 2)

and (a _x , a _y ) as coordinates and φ as the angle between the x-axis and the main radiation direction of the antenna.

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.

One filter step can be saved compared to the TA segment. Of course, it would also be a good idea to create the TA segment in the same way using the cut with a shifted circle, but that gave a slightly worse result Result. For the RxLev segment, on the other hand, the approximation of the sector is the better choice, which may be due to the measurement uncertainties.

With the non-linear, quantity-based filter, both the TA and the RxLev model for directional antennas can be approximately limited to one sector according to their radiation characteristics.

However, the main task of the filter is still to collect several measurements with their local restrictions.

Starting from the TA circle, which may be reduced to one sector, the other circles of the

Now take the RxLev measurements recursively into account and determine a pseudo-ellipsoid Xs' * enclosing the intersection.

Using the example of an antenna constellation with a talk-leading 120 ° antenna (TA ring segment) and an omnidirectional antenna or a 120 "antenna (RxLev measurements), 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.

In the first cut (FIG. 7b), the sectoral TA segment 704 with a circle 708 as the area of uncertainty (still without taking into account the directional characteristic) of the second approach tenne cut, which leads to a reduced cutting area 705.

In the next section (FIG. 7c), the directional characteristic of the second antenna 702 is taken into account. This is done by a shifted circle 709 as described in the above. Area 706 results as a further reduced intersection area.

In the last cut (FIG. 7d), 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.

location

The aim of the localization is to estimate the position of the mobile phone from its measurements as accurately as possible.

For this purpose, areas of residence are derived from the measurements, in which a uniform distribution is assumed.

Of these areas, the nonlinear set-based filter determines an ellipsoid that includes the intersection of all areas.

From this (Fig. 7d, 707) it is now necessary to determine a point that minimizes the mean distance over the entire pseudo-ellipsoid of the end region.

This can be achieved approximately using a grid by selecting the point (x, y) of the grid that is the sum

minimized over all N grid points which lie within the final pseudo-ellipsoid and which are obtained by numerically evaluating equation (14).

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.

For this purpose, 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.

For this purpose, the closer environment of the mean value over the points of the grid lying within the segment lends itself, which is also a numerical approximation for the expected value and which minimizes the quadratic distance.

The expected value for the TA segment alone can also be determined analytically without going through a grid.

If the TA segment is placed symmetrically about the x axis with a suitable transformation in the origin of the coordinate system as in FIG. 2, the expected value is calculated as the position of the mobile station

_η sin (α / 2) 12 • (TA) ² +1

_E = 2 • d ^ '- ■ γX—' - ^ -, TA> 0 α (12 • TA)

_Λ , "sin (α / 2)

E _x = 2/3 • d * -, TA = 0 (23) α

E _y = 0. The following writings are cited in this document:

[1] Rappaport T.S., Reed J.H. et al., "Position Location Using Wireless Communications on Highways of the Future", IEEE Communication Magazine, pp. 33-41, Oct. 1996.

[2] DE 198 36 778 AI

[3] TS 25.305 V3.1.0: stage 2 "Functional Specification of Location Services in ÜTRAN" (release 99), 3GPP TSG-RAN-WG2, 2000

[4] United States Patent, Patent Number 5,883,598

[5] United States Patent, Patent Number 6,094,168

[6] United States Patent, Patent Number 6,108,553

[7] Eberspächer, J.; Vögel, H.-J .: GSM. Global system for

Mobile communication. Stuttgart, Leipzig: Teubner, 1999

[8] Young. P.: Analysis and design of digital mobile radio systems. Stuttgart, Leipzig: Teubner, 1997

[9] Kennemann, 0 .: Localization of mobile stations based on their radio measurement data. Number 11 in Aachen's contributions to mobile and telecommunications. Aachen: Verlag der Augustinus Buchhandlung, 1997.

[10] UD Hanebeck, "Recursive Nonlinear Set-Theoretic Estation Based on Pseudo-Ellipsoids", Proceedings of the IEEE Conference on Multisensor Fusion and Integration for Intelligent Systems, Baden-Baden, Germany, August 2001, pp. 159-164; [11] Latapy, J.-M .: GSM mobile station location. Diploma

Thesis, Oslo: Norwegian university of Science and Technology, 1996.

[12] Okumura, Y .; Ohmori, E .; Kawano, J.; Fukuda, K.: Field strength and its variability in VHF and UHF land mobile service. Review of Electrical Communication Laboratories, Volume 16, No. 9, pp. 825-873, 1968.

Claims

claims

1.Method 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, in which using a first Communication signal of the first communication, a first possible location area of the mobile communication device is determined by the first base station, in which, using a second communication signal of the second communication, a second possible location area of the mobile communication device is determined by the second base station, in which the first possible location area and the second possible location area can be combined using a nonlinear quantity-based filter, with a common location area of the mobile comm Unication device is determined to the first and the second base station, in which the position of the mobile communication device is determined using the common location area.

2.The method of claim 1, wherein the first and / or the second communication signal in

Form of data packets are transmitted.

3. The method according to claim 1 or 2, in which one and / or more distance-dependent parameters are determined or will be determined using the first and / or the second communication signal and which depend on a distance of the mobile communication device to one of the base stations or depends and under Use of which the first and / or the second possible area of residence are or will be determined.

4. The method according to claim 3, in which a signal propagation model is used in the determination of the first and / or second possible location area from the or the distance-dependent parameters.

5.The method according to any one of claims 3 to 4, wherein the distance-dependent parameter is a signal transit time of the first or the second communication signal or a field strength of the first or the second communication signal.

6.The method according to any one of claims 3 to 5, wherein the distance-dependent parameter of the mobile

Communication device is determined.

7. The method according to claim 3 to 6, in which the distance-dependent parameter is coded, in particular bit-coded.

8. The method according to claim 7, wherein the bit-coded parameter is a ti ing advance value or an RxLev value.

9. The method as claimed in one of the preceding claims, in which a radiation characteristic, in particular a directional radiation characteristic, of the first and / or second base station is taken into account when determining the first and / or second possible location area.

10.A method according to one of the preceding claims, in which the first possible area of residence is a circular ring, in particular a circular ring sector.

11.The method according to any one of the preceding claims, in which the second possible area of residence is a district, in particular a district sector.

12.The method according to any one of the preceding claims, wherein the communication network a plurality of first and / or second

Has base stations,

- Each of which is set up for communication with the mobile communication device, a possible location area being determined in each case using the corresponding communication signal of the respective communication, in which all possible location areas are combined using the nonlinear quantity-based filter, with a common location area of the mobile communication device to the base stations.

13.The method according to claim 12, in which only two possible areas are combined in succession.

14.The method according to claim 12, in which all possible areas of residence are combined with one another.

15. The method as claimed in one of the preceding claims, in which, in the case of nonlinear quantity-based filtering, the possible areas of residence are transformed from an original space into a hyperspace, in which they are described using an ellipsoidal body.

16. The method as claimed in one of the preceding claims, in which, in the case of nonlinear quantity-based filtering, the possible areas of residence are transformed from an original space into a hyperspace in which they are combined to form the common area of residence.

17. The method according to claim 15 and 16, in which the common location in the hyperspace is described using an ellipsoidal body, in particular by an envelope ellipsoid.

18.The method according to any one of the preceding claims, in which the combination of the possible areas of residence to the common area of residence is carried out by intersection formation.

19. Method according to one of the preceding claims, in which a characteristic value of the common area, in particular a focus or an expected value of the common area, is used as the position of the mobile communication device.

2O.Verfahren according to any one of the preceding claims, used to locate a mobile phone in a digital, cellular mobile network, in particular in a GSM network, wherein the mobile communication device, the mobile phone, the first base station is a talking base station and the second base station one of the mobile phone are receivable base station in the cellular network.

21. Arrangement for determining a position of a mobile communication device in a communication network with at least one 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, with a first location determination unit, with 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 of the second communication, 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 is, 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.

22. Computer program with program code means to carry out all steps according to claim 1 when the program is executed on a computer.

23. Computer program with program code means according to claim 22, which are stored on a computer-readable data carrier.

24.Computer program product with program code means stored on a machine-readable carrier in order to carry out all the steps according to claim 1 when the program is executed on a computer.