DE102009049673A1 - Apparatus and method for generating reference data for a radio-based location system - Google Patents

Abstract

A device (30) is described for generating a reference reference position (RRP) associated with the geographical reference position, a reference transmitter (MAC _j ) of a radio transmitter and an electromagnetic reference signal characteristic of the radio transmitter at least near the geographical reference position of a mobile Terminal can be received at a measurement time, from a plurality of measurement packets (GMP _n ), each of the measurement packets having a transmitter identifier and an electromagnetic signal property of a radio transmitter, which is receivable at a geographic position at a measurement time. The device (30) comprises for this purpose a device (32) for selecting measurement packages (GMP _i ) from the plurality of measurement packages (GMP _n ) according to a similarity criterion, means (34) for determining coordinates (RRP.x; RRP.y RRP.z) of the geographical reference position based on coordinates of the selected measurement packages (GMP _i ) associated geographical positions, means (36) for determining the at least one reference end identifier (MAC _j ) associated electromagnetic reference signal _property (RRP.RSSI _MACj ) based on the reference end detection (MAC _j ) associated electromagnetic signal characteristics of the selected measurement packets (GMP _i ), and means (38) for generating the reference measurement packet (RRP) from the determined coordinates (RRP.x; RRP.y;

Description

The present invention relates to a concept for generating reference data for a reference database for a radio-based location system.

For a localization of mobile devices different locating technologies are available. Probably the best known system for localization and navigation in the outdoor area is the satellite-based Global Positioning System (GPS). For the localization or navigation within buildings or in an indoor area, various approaches are known, such as infrared systems, RFID systems (Radio Frequency Identification) or field strength evaluations of IEEE 802.11 WLAN networks (WLAN = Wireless Local Area Network). The GPS system is currently only available for outdoor use. Recent enhancements, such as highly sensitive receivers or the so-called A-GPS (Assisted GPS) represent attempts to make the technology usable within buildings. A-GPS combines the satellite-based GPS system with a reception of so-called assistance information from cellular mobile networks. At present, however, these technologies do not yet have the desired mean accuracies. Infrared and RFID systems are generally not available across the board and are subject to specific conditions.

For the wireless network connection of portable devices, the Wi-Fi standard has IEEE 802.11 can establish. This is being continuously developed, both in terms of data rate and range. Established standards, as well as standards still in the design phase, enable broadband data transmission at high data rates and are characterized by a high level of integration, which enables low-cost hardware. In current PDAs (Personal Digital Assistents) and smartphones, wireless interfaces such as the mentioned WLAN are usually integrated. In addition, often Bluetooth will be used, and in the future possibly WiMAX.

In the case of WLAN, commercial public WLAN access points (so-called hotspots) are now available in many places with high visitor frequency. In addition, the proliferation of broadband Internet connections (eg via DSL) has also promoted the proliferation of WLAN as a cheap home networking technology in the private sector. Several studies have shown that inner-city areas in many places are already being provided with WLAN almost everywhere, or even over-covered. Especially places of daily life and of tourist interest are well equipped in this regard. At the moment it therefore makes sense to use WLAN as a basic technology for the location of mobile devices. In the future, other technologies will certainly be used, to which the described inventive concept can also be applied.

Location of mobile terminals in WLAN networks can be done in principle by evaluating the received from a mobile terminal base stations (hotspots or access points), for example, their respective signal strength received on the terminal is evaluated. However, WLAN signals are strongly shielded by structures and other obstructions, with no ideal free-field conditions usually prevailing in areas with extensive Wi-Fi coverage, as these are located in the urban area. Thus it can not be concluded directly from the measured signal strength or field strength on the distance from a mobile terminal to a base station or another communication partner.

In the case of WLAN-based location systems, a so-called "received-signal-strength fingerprinting" is often used as the basic method. This radio fingerprinting method is based on the assumption that signal strengths of radio signals of several radio stations received or receivable at a current location uniquely characterize the current location or the current position. If there is a reference data base which contains transmitter identifications of radio stations received or receivable there at reference times for a number of reference locations or reference positions, as well as the signal strengths of the corresponding radio signals, then from a set of current measured values (transmitter identifications and associated signal strength values) to the current position of the be closed by a comparison between currently measured values and the reference values of the database. This matching, also called matching, evaluates, for each reference point, how similar the previously recorded measured values or reference values are to the current measured values of the current position. The or the most similar reference points then form a basis for an estimate for the current location of the mobile terminal.

For a reference database, reference measurements can be used to experimentally determine the signal strength from a radio transmitter receivable to a reference measurement instant at a reference position. This creates a database that contains a list of radio transmitters (access points) for each geographic reference position with the respectively assigned reception field strength and quality. This list associated with a reference position can also be referred to as reference measurement package or reference package (RP). For example, in a WLAN implementation, such a reference database might look like this: RID MAC RSSI PGS X Y Z MAPNR CREATED 1 00.0D.54.9E.17.81 46530 100 5795 15627 150 0 12:03:07 12:42 1 00.0D.54.9E.1A.BA 67260 90 5795 15627 150 0 12:03:07 12:42 1 00.0D.54.9E.1D.64 72002 88 5795 15627 150 0 12:03:07 12:42 1 00.0E.6A.D3.B9.8B 59531 100 5795 15627 150 0 12:03:07 12:42 1 00.0F.A3.10.07.6C 46464 96 5795 15627 150 0 12:03:07 12:42 1 00.0F.A3.10.07.FB 74488 94 5795 15627 150 0 12:03:07 12:42 1 00.0F.A3.10.09.SF 72375 97 5795 15627 150 0 12:03:07 12:42 2 00.0D.54.9E.17.81 54138 100 14399 15451 150 0 12:03:07 12:43 2 00.0D.54.9E.18.1D 76560 11 14399 15451 150 0 12:03:07 12:43 2 00.0D.54.9E.1A.BA 62318 94 14399 15451 150 0 12:03:07 12:43 2 00.0D.54.9E.1D.64 71348 96 14399 15451 150 0 12:03:07 12:43 2 00.0E.6A.D3.B9.8B 45393 100 14399 15451 150 0 12:03:07 12:43 2 00.0F.A3.10.07.6C 66853 96 14399 15451 150 0 12:03:07 12:43 2 00.0F.A3.10.07.FB 72251 100 14399 15451 150 0 12:03:07 12:43 2 00.0F.A3.10.09.5F 70990 90 14399 15451 150 0 12:03:07 12:43 3 00.0D.54.9E.17.81 58291 100 24583 15627 150 0 12:03:07 12:43 3 00.0D.54.9E.18.1D 78610 68 24583 15627 150 0 12:03:07 12:43 3 00.0D.54.9E.1A.BA 62153 98 24583 15627 150 0 12:03:07 12:43 3 00.0D.54.9E.1D.64 64187 90 24583 15627 150 0 12:03:07 12:43 3 00.0E.6A.D3.B9.8B 32851 100 24583 15627 150 0 12:03:07 12:43 3 00.0F.A3.10.07.6C 69006 96 24583 15627 150 0 12:03:07 12:43 3 00.0F.A3.10.07.FB 71749 92 24583 15627 150 0 12:03:07 12:43 3 00.0F.A3.10.09.5F 71482 83 24583 15627 150 0 12:03:07 12:43 3 00.0F.A3.10.09.80 71000 40 24583 15627 150 0 12:03:07 12:43

• • Referenzposition-Identifikation (ID) (hier: 1, 2, 3),
• • MAC-Adressen der an der jeweiligen Referenzposition empfangenen Funksender,
• • die Empfangsfeldstärken der an der Referenzposition empfangbaren Funksender (RSSI = Received Signal Strength Indicator; 46,56 bedeutet beispielsweise –46,56 dBm),
• • die Referenzposition in kartesischen, metrischen Koordinaten (x, y, z), sowie
• • den Zeitpunkt bzw. Zeitstempel der Messwertaufnahme.

The table contains the following information:

• • reference position identification (ID) (here: 1, 2, 3),
• • MAC addresses of the radio transmitters received at the respective reference position,
• The reception field strengths of the radio receivers receivable at the reference position (RSSI = Received Signal Strength Indicator; 46.56 means -46.56 dBm, for example),
• • the reference position in Cartesian, metric coordinates (x, y, z), as well as
• • the time or timestamp of the measured value recording.

The optional values PGS ("Percentage seen") indicate how often the respective station was seen as a percentage during the measurement recording (ie PGS = 90 means that on average the station was measured in 9 out of 10 measurements).

Additionally, a reference packet may include orientation information that includes spatial orientation information of a mobile terminal with which the corresponding reference packet was recorded. That is, the orientation information stores information about which direction a mobile terminal was held in measuring the reference point or in which direction the mobile terminal was moved when measuring the reference point. This is especially interesting when the mobile device such. B. a WLAN-enabled device, is held directly in front of the body of a user, so that it can come through the body to shading effects. Even without these body-related shadowing effects, additional orientation information may be useful since virtually every antenna has a directional characteristic. Therefore, by orientation, for example, the spatial orientation of the main lobe of an antenna of a mobile terminal can be understood.

The described reference data or reference packets can now be collected in different ways:
The simplest but most elaborate method is the manual generation of a single reference point or reference packet. Here are the calibration after specifying a certain coordinate (x, y, z), which is provided for example by a high-precision GPS device available over a certain Einmesszeitraum across several WLAN measurements performed on the same reference position. The result is then a kind of averaging of the received signal strength values and a generation of certain additional information, which are stored, for example, in a special data format ("reference point") together with the location information in the reference database.

Another method is to generate reference data from a moving measurement. In other words, individual measurements are carried out in a continuous motion process, which are enriched at the same time or subsequently with location information. It should be noted that due to the movement in principle, each individual measurement can be assigned a different location. Thus, first of all, a large number of raw measured values arise, from which an optimal reference data carpet is to be subsequently generated. In comparison to the (time-) consuming method described above, the raw measurement values are obtained relatively quickly, since it is not necessary to dwell on a reference position for each reference point for a calibration period of several seconds.

Accordingly, the object of the present invention is to generate reference points or reference packets for a database from a plurality of individual measurements with respective location information.

This object is achieved by a device for generating a reference measurement packet having the features of claim 1 and a method according to claim 17.

The finding of the present invention is that a reference packet can be obtained by combining a plurality of suitable single measurements recorded at different measuring positions. The individual measurements come from a previously described moving measurement, wherein their measurement positions are within a certain predetermined spatial or geographical area. A reference position associated geographic reference position and an electromagnetic reference signal property of a receivable at the reference position radio transmitter result according to embodiments by weighted averaging corresponding values of a suitably assembled set of individual measurements. According to the same principle, even more information, such. As orientation and / or quality indicators are obtained.

In accordance with embodiments of the present invention, there is provided a device for generating a reference measurement position associated with a reference measurement packet, the reference measurement packet assigning the reference reference position and a reference electromagnetic property of at least one radio transmitter to the reference end identifier, the radio transmitter at least in the vicinity of the reference geographical position a reference measurement time is receivable / was. In this case, the reference measurement packet is generated from a plurality of measurement packets, wherein each of the measurement packets has the transmitter identifier and an electromagnetic signal property of the wireless transmitter with which the wireless transmitter can be received at a corresponding measurement packet geographic measurement position at a measurement time / was. For this purpose, the device for generating the reference measurement packet has a device for selecting measurement packets from the plurality of measurement packets according to a similarity criterion. In addition, means are provided for determining coordinates of the geographical reference position based on coordinates of the geographical measurement positions associated with the selected measurement packages. The apparatus also comprises a device for determining the electromagnetic reference signal property of the radio transmitter based on the electromagnetic signal properties of the radio transmitter of the selected measurement packets. Finally, a device for generating the reference measurement packet is provided in order to generate the reference measurement packet from the determined coordinates of the geographical reference position and the electromagnetic reference signal property.

According to embodiments, the electromagnetic signal characteristics are each signal properties related to a reception field strength, such as received signal strength indicator (RSSI) values, a received power spectrum, or a signal-to-noise power ratio.

According to one exemplary embodiment, each of the plurality of measurement packages is also assigned a spatial orientation with which the respective measurement package was measured at its geographical measurement position or in which a mobile terminal was held during calibration. The orientations can be distinguished, for example, according to the cardinal directions (north, west, south, east). With existing orientation information of the measurement packets, the means for selecting the measurement packets may be configured to select measurement packets according to their associated spatial orientations such that the spatial orientations are within a predefined tolerance range around a default value (eg, north).

In a moving measurement, the plurality of measurement packages, as described above, are typically recorded in chronological succession at different measurement positions along a path (trail) in order to receive radio signals from radio receivers (access points) receivable there at the different measurement positions. In order to obtain spatially or geographically adjacent measurement packages, the device for selecting the measurement packages according to an exemplary embodiment is designed to select the measurement packages according to their measurement times, such that the measurement times of the measurement packages lie in a predefined tolerance range or time window. Alternatively or additionally, the means for selecting the measurement packets may also be designed to select the measurement packets according to their assigned measurement positions, such that the measurement positions of the measurement packets lie in a predefined tolerance range or in a predefined spatial range around a default value for the geographic reference position.

The means for determining the coordinates of the reference geographical position of the reference packet is configured according to embodiments to determine each of the coordinates (x, y, z) of the reference position based on averaging of the corresponding coordinates of the geographical measurement positions associated with the selected measurement packets. In a preferred exemplary embodiment, these are, in particular, a weighted averaging of the respective coordinates.

Accordingly, according to embodiments, the means for determining the electromagnetic signal characteristic is also configured to determine the electromagnetic reference signal property based on an averaging of the corresponding electromagnetic signal properties of the selected measurement packets. According to a preferred embodiment, this is a weighted averaging of RSSI values of different individual measurements at different measurement positions assigned to the radio transmitter.

With the concept according to the invention, measurement packages or individual measurements determined by a preceding movement measurement can be combined or clustered to form a reference measurement package. As a result, due to the susceptibility of z. B. WLAN signals relatively low reliability of the individual measurements improved. Furthermore, by combining the individual measurements, a data amount stored in a reference database can be significantly reduced. Also, a redundant growth of reference data by multiple collection of measurements at the same or similar locations can be avoided by the inventive concept. Geographical locations or positions with multiple reference packages are avoided. In other words, for each geographic reference position, there is exactly one reference measurement packet in the reference database, so that there can not be an unwanted revaluation of locations with multiple reference packets in a position calculation to a radio fingerprint.

In addition to generating a reference measurement packet, embodiments of the present invention may also be used to perform update actions on a database with already existing reference measurement packets.

Embodiments of the present invention will be explained in more detail below with reference to the accompanying figures. Show it:

1a Schematic representations of various types of data according to the invention for describing individual measurements or measurement packages;

2 a schematic representation of generated measurement packages in an exhibition hall;

3 a schematic representation of an apparatus for generating a Referenzmesspakets according to an embodiment of the present invention;

4a a schematic representation of a device for selecting a group of measurement packages according to an embodiment of the present invention;

4b a schematic representation of a device for selecting a group of measurement packets according to another embodiment of the present invention;

4c Obtaining individual measurements from selected measurement packets and integration of the individual measurements into a reference measurement packet according to an embodiment of the present invention;

5a a schematic representation of a device for selecting a group of reference measuring packets according to an embodiment of the present invention;

5b a schematic representation of a device for selecting a group of reference measuring packets according to another embodiment of the present invention;

5c Obtaining individual measurements from selected reference measurement packets and integrating the individual measurements into a new reference measurement packet according to an exemplary embodiment of the present invention;

6 a schematic representation of a geo-clustering according to the invention; and

7a , b is a schematic representation of reference measurement packets generated according to the invention from the measurement packets according to FIG 2 ,

For a better understanding of the present invention will be hereinafter with reference to the 1a First, by way of example, individual measurements and measurement packages or reference packages are assigned Described data types, which will be used in the course of the following description of the invention.

1a shows a schematic representation of a possible structure of a data type GM to a geo-referenced single measurement (Geo-referenced Measurement).

GM is a single measurement of a mobile terminal with respect to an access point at a specific measurement time "Timestamp", at a certain measurement location or a measurement position with Cartesian coordinates (x, y, z, site), which are provided for example by a GPS system can, assigned. In this case, for example, the so-called. WGS 84 (World Geodetic System 1984) system can be used. WGS 84 is a geodetic reference system that serves as a unified basis for position information on Earth and in near-Earth space. It consists of a simple, three-dimensional reference surface, the reference ellipsoid roughly adapted to the earth's surface, a more detailed model of the earth's shape deviating from this idealized shape, the so-called geoid, twelve fundamental stations distributed across the earth, and the relationship between these models and the earth's crust is defined by specifying (time-dependent) coordinates (the so-called reference frame). Since the WGS uses 84 spherical coordinates and the formulas described here use Cartesian coordinates (x, y, z), a coordinate transformation is necessary. A site defines a Cartesian, localized three-dimensional and globally suspended coordinate system, thus providing the converter between the local and global coordinates (including WGS 84). An individual measurement GM may include an identification "MId" with regard to the mobile terminal used and / or a measurement campaign. Furthermore, a single measurement GM may have a weight "Weight" for a possible further processing. For example, the weight may range from 0 to 1 and may be selected depending on a localization technology used and / or measurement accuracy or reliability. A single measurement GM also includes a transmitter identifier, such. A MAC address, a radio transmitter or access points received at the measurement position (x, y, z, site), and information about an electromagnetic signal property of the signal received from the radio transmitter. According to exemplary embodiments, this may be a signal property related to the reception field strength, such as, for example, An RSSI value, a received power spectrum or a signal-to-noise power ratio.

A summary of all radio transmitters or access points that can be measured by a specific mobile terminal MId at a particular measurement time point "timestamp", at a measurement position (x, y, z, site) is referred to in the context of the present invention as "GMP". referenced Measurement Pack, geo-referenced measurement package). The corresponding data format is exemplary in 1b shown. Therein, MAC [] denotes an array of sender identifiers, such as a sender. As MAC addresses, from at the measurement time "Timestamp" at the measurement site (x, y, z, site) receivable by the mobile device MId radio transmitters. RSSI [] denotes a vector of corresponding electromagnetic signal properties, such as. RSSI values, the receivable radio transmitter MAC []. In addition, a measurement packet GMP may also have information regarding an orientation with which the corresponding measurement was made. By orientation is meant, for example, a direction (north, south, east, west), in which the mobile terminal was held and / or moved during the measurement. This orientation information can be provided, for example, by the use of a compass-like device when measuring a measurement package GMP.

2 shows an example of a plan 20 an exhibition hall equipped with Wi-Fi access points. Raw data, in the form of individual measurement packages, was generated in the exhibition hall by running previously defined straight-line paths. It corresponds to in 2 every point 22 a measuring package GMP determined at the respective geographical position in the exhibition hall. For recording the measurement packages GMP, the electromagnetic properties of the radio signals of the WLAN radio transmitter positioned in the exhibition hall of the WLAN radio transmitter positioned in the exhibition hall are determined at predefined time intervals ΔT (eg ΔT = 1 s) during a movement along a path or along a path. The result of such a measurement is a GMP. It should also be mentioned that the individual in 2 drawn rectilinear stretches were sometimes repeated several times and in different directions in order to obtain measurement packages according to different orientations.

The measurement packages GMP corresponding to a route can be stored, for example, in the form of a so-called trail whose data format is schematically represented in FIG 1c is shown. In a trail, for example, all GMPs from the device with the identification MId and / or the same measurement campaign can be stored. In this case, the sequence of the GMP measurement packets stored in the vector GMP corresponds to a time course of the associated GMP time stamps.

As already explained above, it is an object of the present invention, for example, to generate as reliable as possible reference measurement packets from a multiplicity of measurement packages GMP recorded during a moving measurement. For this purpose, according to embodiments, several measurement packages, z. B. a trail, combined in a grouping or clustering process to a reference measurement package, which will be discussed in more detail below. A possible data format for a reference measurement packet or a reference point "RRP" is shown schematically in FIG 1d shown.

In addition to vectors MAC [], RSSI [], a vector PGS [] can additionally be provided in order to list calculated percentage lake values of the radio transmitters registered in the vector MAC []. In conjunction with the PGS values PGS [], auxiliary quantities MaxNmbM [] can be specified, each of which specifies a maximum number of potential knife sequences for a radio transmitter. The field "Id" designates the reference point ID or the reference measurement packet ID for administration of the reference packet RRP within databases. The reference measurement package ID has global validity.

Furthermore, reference points can also be generated independently of a mobile terminal MId and / or a measurement campaign, such as by a combination of raw reference measurement packets RRP. This creates a reference measurement package or reference point "RP" reduced by the quantities "MId", "Weight", "MacNmbM []", which are used exclusively for identification purposes. An example of a data format for a reference point "RP" is in 1e shown.

Having previously discussed in detail the various types of data in the context of the present invention, the inventive concept will be explained in detail below.

der Gesamtmenge aller Messpakete GMP₁, ..., GMP_N erzeugt, die beispielsweise einem zurückgelegten Einmessweg oder einem vorbestimmten geografischen Gebiet entsprechen. Diese Untermengen GMP₁, ...,

werden in erster Linie durch Ähnlichkeiten der geographischen Positionen gebildet.In addition shows 3 a schematic block diagram of a device 30 for generating a reference measurement packet RRP associated with a geographical reference position (RRP.x, RRP.y, RRP.z), which of the geographical reference position (RRP.x, RRP.y, RRP.z) has a reference end identifier MAC _{j of} at least one radio transmitter and an associated one assigns electromagnetic reference signal characteristic RSSI _{MACj receivable} at least near the reference geographical position (RRP.x, RRP.y, RRP.z) at a reference measurement time point. In this case, the reference measurement packet RRP is derived from a subset GMP ₁ ,.

of the total quantity of all measurement packets GMP ₁ ,..., GMP _N , which correspond, for example, to a traveled calibration path or a predetermined geographical area. These subsets GMP ₁ , ...,

are formed primarily by similarities of geographical positions.

aus der Mehrzahl der Messpakete GMP₁, ..., GMP_N gemäß einem Ähnlichkeitskriterium. Ferner ist eine Einrichtung 34 zum Ermitteln von Koordinaten (RRP.x, RRP.y, RRP.z) der Referenzposition vorgesehen, basierend auf Koordinaten (x_i, y_i, z_i) (i = 1, ..., M_GMP) von den ausgewählten Messpaketen GMP₁, ...,

zugeordneten geografischen Messpositionen. In einer Einrichtung 36 wird die elektromagnetische Referenzsignaleigenschaft RRP.RSSI_MACj des wenigstens einen Funksenders MAC_j, basierend auf elektromagnetischen Signaleigenschaften des Funksenders der ausgewählten Messpakete GMP_i (i = 1, ..., M_GMP) ermittelt. Um das Referenzmesspaket RRP zu erhalten, werden die ermittelte Referenzposition (RRP.x, RRP.y, RRP.z) und die ermittelte elektromagnetische Referenzsignaleigenschaft RRP.RSSI_MACj des wenigstens einen Funksenders MAC_j einer Einrichtung 38 übergeben, um basierend auf den ermittelten Koordinaten der geografischen Referenzposition und der elektromagnetischen Signaleigenschaft das Referenzpaket RRP zu erhalten.The device 30 includes a facility 32 for selecting measurement packages GMP ₁ , ...,

from the plurality of measurement packets GMP ₁ ,..., GMP _N according to a similarity criterion. There is also a device 34 for determining coordinates (RRP.x, RRP.y, RRP.z) of the reference position, based on coordinates (x _i , y _i , z _i ) (i = 1, ..., M _GMP ) of the selected measurement packets GMP ₁ , ...,

assigned geographic measurement items. In a facility 36 the electromagnetic reference signal property RRP.RSSI _{MACj of} the at least one radio transmitter MAC _j , based on electromagnetic signal properties of the radio transmitter of the selected measurement packets GMP _i (i = 1, ..., M _GMP ) is determined. In order to obtain the reference measurement packet RRP, the obtained reference position (RRP.x, RRP.y, RRP.z) and the detected electromagnetic reference signal property _{RRP.RSSI MACj of} the at least one radio transmitter MAC _{j of} a device 38 in order to obtain the reference packet RRP based on the determined coordinates of the geographical reference position and the electromagnetic signal property.

According to one exemplary embodiment of the present invention, the generation of reference packets RRP is based on a defined stream of time-sequential measurement packets or GMP objects, namely a so-called trail, and can be broken down into three different areas:
Since the individual measurement packages GMP _n (n = 1,..., N) are sorted according to their age within a trail, additional information such as eg. As an orientation can be determined. From the measurement positions (x _n , y _n , z _n ) stored in the measurement packets GMP _n (n = 1,..., N) and the corresponding measurement times T _n , a direction of movement of a specific measurement packet GMP _n (n = 1,. .., N) to the next GMP _{n + 1} , from which an orientation information can be derived.

Due to a certain amount of noise in the radio signals, it makes sense to filter the received signal waveforms, ie the RSSI values, by means of a low-pass filter. That is, the device 30 According to one exemplary embodiment of the present invention, it can have a low-pass filter for filtering received signal paths stored in the measurement packets GMP _n (n = 1,..., N) of a trail.

Another additional or alternative pre-processing stage, which can be used if necessary, examines whether adjacent measurement packages GMP _n , GMP _{n + 1} are identical within a trail. This is due to the fact that different mobile devices, such. B. WLAN clients, perform new measurements at different time intervals. If, for example, a measurement interval specified by a software is smaller than a measurement interval that is possible by the terminal, then the driver often returns a measurement that was determined last. Terminals differ here in their possibilities, which may result in an integration of data sets of two different terminals, which differ just in this point, ie, a device updates a measurement z. For example, only once every 5 seconds and another one that creates 5 measurements per second, which could lead to errors. For example, an unwanted equal weighting of redundant data sets would occur with the same software-based measurement interval. Thus, a removal of redundant data sets may be useful in advance.

After an optional preprocessing by low-pass filtering and removal of redundant measurement packets, subgroups of measurement packets are formed by a splitting device of the plurality of measurement packets (for example of a trail) GMP _n (n = 1,..., N) according to a similarity criterion. In this case, according to an exemplary embodiment of the present invention, the similarity criterion may be a similar spatial orientation of the measurement packages GMP _n (n = 1,..., N). In other words, each measurement package is assigned a spatial orientation of a used mobile terminal at the geographic measurement position corresponding to the measurement package, and the segmentation facility is designed to match the group of measurement packages GMP _n (n = 1,..., N) according to their assigned Divide spatial orientations into subgroups, so that the spatial orientations of the subgroups are within a predefined tolerance range around a default value. In this case, the spatial orientations according to the cardinal directions (north, south, east, west) could be arranged so that, for example, only measurement packets corresponding to the same compass direction are selected by the distribution device. On the other hand, the orientation could also in an angular extent, such. As the radian measure or degree, be specified, so that a certain orientation corresponds to an angle that can vary by a tolerance of, for example, 45 ° by a predetermined value. This relationship is schematic in 4a represented where the measurement packages GMP _n (n = 1, ..., N) of a total covered measuring path (Trail) in different orientation-dependent sub-trails (Trail 1, Trail 2, etc.) are divided. This ensures that no data sets with different orientations are processed together in a later cluster and / or integration process.

The measurement packages GMP _n (n = 1,..., N) of a trail or orientation-dependent partial trail are typically recorded chronologically successively at different measurement positions (x _n , y _n , z _n ) along a measurement path. Accordingly, the device is 32 for selecting additionally designed to select the group of measurement packages GMP _i (i = 1,..., M _GMP ) according to their measurement times T _i , so that the measurement instants of the selected measurement packets GMP _i (i = 1,..., M _GMP ) lie in a predefined tolerance range or time window. In other words, this means that the measurement times T _{i of} the selected measurement packets differ from each other only within a predetermined time window. The size of this time window depends, for example, on how high a positional accuracy of the later resulting reference measurement packet RRP should be and / or on which speed the individual measurement packets GMP _n (n = 1,..., N) were recorded. For example, time lanes in a range of 10 s are suitable for paths or trails in which the measurement packages GMP _n (n = 1,..., N) of the trail or orientation-dependent partial trail were recorded at walking speed.

The selection of the group of measurement packages GMP _i (i = 1,..., M _GMP ) according to their measurement times (so-called time clustering) is schematically shown in FIG 4b shown. The criterion for time clustering is therefore a certain time interval in seconds between individual selected measurement packages GMP _i (i = 1,..., M _GMP ). Since the measurement packages GMP _n (n = 1,..., N) are already arranged in a time sequence within a trail or orientation-dependent sub-trail, a corresponding selection or clustering can be implemented relatively efficiently since the reference packet RRP only the measurement objects must be examined in the immediate vicinity of a desired cluster center. In principle, only the geographical distance of the individual points or measurement packets GMP _i (i = 1,..., M _GMP ) may be used as a similarity criterion for generating reference data. However, since the positions change continuously with time within a trail or orientation-dependent partial trail, the temporal relation can also be utilized here.

In the event that at the entrance of the institution 32 Pending measurement packets GMP _n (n = 1, ..., N) are not arranged in chronological order, the device 32 be configured for selecting to the group of measurement packages GMP _i (i = 1, ..., M _GMP ) according to their associated measuring positions (x _i , y _i , z _i ) so that the measurement positions of the selected measurement packets GMP _i (i = 1,..., M _GMP ) lie in a predefined tolerance range, for example by the intended reference measurement position. In this case, the tolerance range or a radius around the reference position is dependent on a desired position accuracy of the reference measurement position to be generated. This type of grouping or clustering is referred to in the context of the present invention as so-called. Geo-clustering, which will be discussed in more detail later.

Depending on the selection criteria used, the output of the device is located 32 the selected measurement packages GMP _i (i = 1,..., M _GMP ) or of the selected measurement packages included individual measurements GM _i (i = 1,..., M _GM ).

The blocks 34 . 36 and 38 which also acts as an integration unit 39 can now be called, then process the individual measurements (corresponding to individual radio transmitter) of the selected measurement packets GMP _i (i = 1, ..., M _GMP ) to obtain the reference packet or reference measurement packet RRP. This relationship is schematic in 4c shown. The integration unit 39 requires as inputs a set of individual measurements GM _i (i = 1, ..., M _GM ), as well as certain additional information regarding the selected measurement packages GMP _i (i = 1, ..., M _GMP ). The individual measurements GM _i can be generated from the selected measurement packages GMP _i (i = 1,..., M _GMP ), since the selected measurement packages GMP _i (i = 1,..., M _GMP ) are merely a summary of individual measurements GM are with the same time stamp, as in the above already on the basis of 1a , b has been explained. The timestamp "Timestamp" of the generated reference packet or RRP object is, in one embodiment, the timestamp of the most recent GM object used to generate it.

The device 34 In order to determine the coordinates (RRP.x, RRP.y, RRP.z) of the geographical reference position, according to one exemplary embodiment, the coordinates of the geographical measurement positions assigned to the selected measurement packages GMP _i (i = 1,..., M _GMP ) are transmitted based thereon to determine the coordinates of the geographical reference position. This is done, according to an exemplary embodiment, based on an averaging of the corresponding coordinates of the geographical measurement positions assigned to the selected measurement packages. In detail is the decor 34 designed to determine the reference geographic reference position based on the following rules:

Where M _{GMP is} the number of devices 32 selected measurement packages or measurement objects GMP _i (i = 1,..., M _GMP ) and M _GM designates a number of radio transmitters or individual measurements listed in the selected measurement packages. In Eq. (1) M _{GM (GMPi)} denotes the individual measurements GM relating to different radio transmitters contained in the selected measurement package GMP _i . The units for the coordinates (x, y, z) can be, for example, meters. The unit of orientation may, for example, be radians in the range of 0 to 2π. Eq. (5) is by definition only valid if all involved orientation values GM.Orientation _i differ by a maximum of π / 2. Furthermore, a fixed offset of π / 2 is added to all the orientation values GM.orientation _i involved, if an involved orientation value is smaller than π / 2. This offset, after completed averaging according to Eq. (5) subtracted from the resulting RRP.Orientation result. The device 36 for determining the electromagnetic reference signal property RRP.RSSI _{MACj of} the radio signal of the at least one radio transmitter MAC _j is designed in accordance with an embodiment of the present invention to determine the electromagnetic reference signal _property based on an averaging of the radio transmitter corresponding electromagnetic signal properties of the selected measurement packets. According to one embodiment, the calculation rule may be as follows: 0 <j <M _diffMACs (6)

In this case, M _diffMACs designates a number of different radio transmitter identifiers occurring in the selected measurement packets GMP _i (i = 1,..., M _GMP ), such as eg. B. MAC addresses. M _MACj denotes a number of individual _measurements GM assigned to the radio transmitter MAC _j . In other words, M _{MACj means} a number of selected measurement packets with the reference end detection MAC _j . M _GMP again designates the number of selected measurement objects GMP _i . Finally, RRP.RSSI MACj _denotes the electromagnetic signal characteristic of the generated reference measurement _packet for the radio end _detection MAC _j . The same indexing applies to optionally calculated PGS values according to Eq. (9), wherein a PGS value assigned to the radio transmitter MAC _j results from a ratio of M _MACj to M _GMP .

The information required for locating a mobile terminal by means of a reference packet RRP are the vectors MAC [], RSSI [], the reference positions and optionally PGS [] and the reference orientation. By weighted averaging, these quantities for the reference packet RRP result from one through the device 32 suitably assembled set of measurement packages GMP _i (i = 1, ..., M _GMP ) or derived therefrom single measurements GM According to the same principle, even more information, such. As quality indicators, etc., are processed.

The weighting factor "Weight" in the individual data formats is a pure control variable, which can be assigned differently for different processing steps. If the weight is to be disregarded, then this quantity can be set to the same value "1" for all data involved in the processing, for example. In this case, a linear averaging of the respective data is performed.

In the foregoing, therefore, a concept for generating a reference measurement packet RRP generated from a plurality of previously recorded "raw measurement packets" GMP _n (n = 1, ..., N) corresponding to a traversed path has been described. However, the concept according to the invention is not limited to the previously described generation of reference packages from raw measured values. Likewise, the present invention can be used to also perform updating measures on an existing database, consisting of reference packets RRP, by means of newly added reference measurement packets.

As it is in 5a can be shown according to the present invention, the device 32 For selection, reference measurement packets RRP are also passed in order to select a plurality of reference measurement packets according to a similarity criterion. To guarantee that no records with different orientations will be processed together in a later cluster and integration process In order to be able to obtain a location-based method with less effort, in which the data are assigned to specific areas, it makes sense to divide the data (reference measurement packets RRP). Orientations can again be differentiated according to the cardinal directions (north, west, south, east). "Areas" are z. B. neighborhoods, which can be used as a spatial criterion. Other model objects are, for example, buildings which, for other reasons, also require separate treatment of the data (reference measurement packages or measurement packages). Here would be z. B. a smaller target distance of the reference points to call (indoor 3-8 m, outdoor 8-20 m). Another distribution criterion which is also required elsewhere is, as already described above, the orientation of the individual data records or measurement packages. The further processing of the individual subsets then takes place sequentially.

As previously mentioned, the facility is 32 for selecting the measurement packets or reference packets according to an embodiment designed to select the group according to their measurement or reference positions, so that the positions of the selected measurement or reference paces are in a predefined tolerance range by a predetermined position value. This selection of measurement packages according to their assigned geographic locations is called geo-clustering ( 5b ). The criteria for geo-clustering are distances in meters, in the respective x-, y- or z-coordinates. Location-dependent clustering strategies have the property that the cluster size "distance" is multidimensional (x, y, z). Distance values for each point to all others must be calculated in order to be able to decide which measurement or reference points P ₁ , P _{2 have} a required proximity as a criterion of similarity to one another. D _xy = √ (P₁.x - P₂.x) ² + (P₁.y - P₂.y) ² (10) D _z = √ (P₁.z - P₂.z) ² (11)

In Eq. (10) D _xy denotes a distance of the two measuring or reference points P ₁ , P ₂ in the xy plane. A distance D _z (Eq. 11) with respect to the height, ie distance in the z-direction, is separately evaluated as a criterion according to one embodiment to ensure that, for example, positions within multi-level buildings from two different levels are not treated together, although a distance condition such. B. D <8 m, would be fulfilled.

Based on 6 Here is an explanation of the basic functionality of a possible Geo-Cluster algorithm in a small set of five geographic positions:
In the different subfigures of the 6 Three sets of points are shown, which are managed by the cluster algorithm in the appropriate form to finally terminate. Represented white, ie, unfilled, points represent a set of points not yet used by the clustering algorithm. Hatched points represent a set of points already used by the clustering algorithm. The with reference numerals 54 denoted points mean a set of finished RRP or RP objects, ie, reference packets, which are supplied by the integration unit 39 generated and then not further processed by the cluster algorithm.

In field A is a point with reference numerals 62 from which distances to all other points shown are checked in order to those in sub-picture B by line 63 Identify identified amount of points that meet the similarity criterion with respect to distance. These selected points become the integration unit 39 pass, which the in sub-picture C with reference numerals 64 provided reference point provided. Furthermore, from this previously mentioned amount 63 converts all white or transparent points into the set of hatched points already used by the algorithm. A next point to select 62 , from which again distances to all other points are checked, is an arbitrary point from the set of white dots (partial picture D). In the partial images E to F, the same steps are shown, which have already been described with reference to the partial images B and C. The cluster algorithm terminates when all points are converted to the set of hatched points, or the amount of white / transparent points is empty (see drawing G).

verwendet werden. In Gl. (12) bedeutet acc die Distanz zwischen einem Messpaket und einem Referenzpaket und N_eq eine Anzahl von in beiden Paketen vorkommenden Funksendern. Differenzen von RSSI-Werten von identischen Funksendern werden als ΔRSSI_n (n = 1, ..., N_eq) bezeichnet. Anstatt der Gl. (12) können auch andere Distanzformeln, die zusätzlich unterschiedliche Funksender in Messpaketen berücksichtigen, verwendet werden.If information is compiled exclusively according to geographic criteria, there is the danger that in a geo-cluster individual measurement packages GMP or RRP are present which have incorrect location information. If this is the case, it must be ensured that WLAN information (eg RSSI values) of partly correct points or measurement packets GMP or RRP are not offset with those of the faulty ones. One way to identify bad location information is to create clusters based on appropriate WLAN information. For this purpose, all measurement packages GMP or RRP of the previously formed geo-cluster on their similarity with respect to the included WLAN information, such. B. RSSI values, compared and valued accordingly. This process can be implemented, for example, using methods of WLAN localization by means of fingerprinting, with received radio transmitters being compared with their respectively associated reception field strength (measurement packet) with reference packets in a calibration phase. Reference packages with a small distance to a measurement package, ie many common radio transmitters and little different RSSI values, fit well with the measurement package. In the adjustment phase, for example, the distance formula

be used. In Eq. (12) acc denotes the distance between a measurement packet and a reference packet, and N _eq a number of radio transmitters occurring in both packets. Differences of RSSI values from identical radio transmitters are referred to as ΔRSSI _n (n = 1, ..., N _eq ). Instead of Eqs. (12) also other distance formulas, which additionally consider different radio transmitters in measurement packages, can be used.

The comparison algorithms of the WLAN fingerprinting calculate for each candidate to be compared a size acc, which indicates the similarity to a specific candidate or reference packet. Similar to the geo-cluster method described above, clusters can also be formed here, except that a similarity measure acc regarding the WLAN information is used instead of the geographical distance in meters as an exclusion criterion. The device 32 for selecting the measurement packets GMP _i ; RRP _i is therefore configured according to an embodiment to the measurement packets GMP _i ; Selecting RRP _i according to their listed radio transmitters associated electromagnetic signal properties (eg RSSI values), so that the electromagnetic signal characteristics (RSSI values) of the radio transmitter of the selected measurement packets GMP _i ; RRP _i lie in a predefined tolerance range to one another. Ie. the distance acc between two Kanditen-Messpaketen should be as small as possible. If more than one cluster is created by this method, then the cluster containing the most units or measurement packages must be selected. The remaining measurement packages or reference measurement packages are to be excluded from the integration process described below.

Hereinafter, an embodiment of the integration unit 39 described which from a previously by the institution 32 determined selection of RRP objects generates a new or updated RRP object.

As it is schematic in 5c is shown requires the integration unit 39 a set of GM objects (individual measurements) as input parameters, as well as certain additional information regarding the original reference packets RRP. GM objects can be generated from reference packages RRP, since reference objects RRP are a summary of GM objects with the same time stamp. The timestamp of the generated new or updated reference packet RRP is always the timestamp of the "youngest" GM object.

In comparison to the embodiment of the integration unit described above 39 , result in the embodiment described here, the integration unit 39 slight changes in the calculation of the size "Weightsum" because GM objects are not generated from raw measurement packages GMP, but from reference packages RRP.

Where M _{RRP is} the number of devices 32 selected reference measurement packets RRP _i (i = 1, ..., M _RRP ). In Eq. (13) M _{GM (RRPi} ) denotes the _{individual measurements} GM relating to different radio transmitters contained in the selected reference _{measurement packet} RRP _i . The units for the coordinates (x, y, z) can be, for example, meters. The unit of orientation may, for example, be radians in the range of 0 to 2π. Eq. (17) is by definition only valid if all involved orientation values GM.Orientation _i differ by a maximum of π / 2. Furthermore, a fixed offset of π / 2 is added to all the orientation values GM.orientation _i involved, if an involved orientation value is smaller than π / 2. This offset, after completed averaging according to Eq. (17) subtracted from the resulting result RRP.Orientation again. The device 36 for determining the electromagnetic reference signal property RRP.RSSI _{MACj of} the radio signal of the at least one radio transmitter MAC _j is designed in accordance with an embodiment of the present invention to determine the electromagnetic reference signal _property based on an averaging of the radio transmitter corresponding electromagnetic signal properties of the selected reference measurement packets. According to one embodiment, the calculation rule may be as follows: 0 <j <M _diffMACs (17)

In this case, M _diffMACs designates a number of different radio transmitter identifiers occurring in the selected reference _{measurement packets} RRP _i (i = 1,..., M _RRP ), such as eg. B. MAC addresses. M _MACj denotes a number of individual _measurements GM assigned to the radio transmitter MAC _j . In other words, M _{MACj means} a number of selected measurement packets with the reference end detection MAC _j . M _RRP again denotes the number of selected reference measurement packets RRP _i . Finally, RRP.RSSI MACj _designates the electromagnetic signal _{property of} the generated new reference measurement _packet MAC _j . The auxiliary variable RRP.MaxNmbM _MACj denotes a maximum number of potential knife sequences for the radio transmitter MAC _j . In comparison to the embodiment of the integration unit described above 39 In the present case, changes result in the calculation of the size RRP.PGS _MACj .

In the simplest case, the GM.Weight values for all the individual measurements GM in question are also set to 1 here, with the result that a linear averaging of the respective data is carried out. GM.Weight can accept a different value for each relevant size. For example, the calculation of the PGS value requires a different procedure than the calculation of the RSSI value or the coordinates x, y, z. A possible dependence of this value is z. For example, to the age of the records, records of different ages should be offset against each other. That is, GM.Weight = f (GM.Timestamp).

Starting from the in 2 shown raw measured values or raw measuring packages are in the 7a , Results of the inventive concept shown, wherein a target for a distance D of the generated reference packets was 8 m. Compared to 7a shows 7b a result which excludes that measuring packages with different orientations (process directions of the sections) have been integrated. This is important, for example, in the case of WLAN localization, since signals have a directional dependence due to an antenna characteristic and due to an attenuation of the human body in the near field of the antenna.

Although some aspects of the present invention have been described in the context of a device, it is to be understood that these aspects also constitute a description of the appropriate method such that a block or device of the device 30 is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also provide a description of a corresponding block or detail or feature of a corresponding device 30 represents.

As with certain implementation requirements, embodiments of the present invention may be implemented in hardware or in software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-Ray disk, a CD, a ROM, a PROM, an EPROM, an EEPROM or flash memory, a hard disk or other magnetic or optical memory, are stored on the electronically readable control signals that can cooperate with a programmable computer system or cooperate such that the respective method is performed. Therefore, the digital storage medium can be computer readable. Thus, some embodiments according to the invention include a data carrier having electronically readable control signals capable of interacting with a programmable computer system to perform one of the methods described herein.

In general, embodiments of the present invention may be implemented as a computer program product having a program code, wherein the program code is operative to perform inventive methods for generating a reference packet that executes computer program product on a computer or microcontroller. The program code can also be stored, for example, on a machine-readable carrier.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• IEEE 802.11 [0002]
• IEEE 802.11 [0003]

Claims (18)

Contraption ( 30 ) for generating a geographic reference position associated reference measurement packet (RRP), the reference geographical reference position (MAC _j ) assigns at least one radio transmitter and an electromagnetic reference signal property of the at least one radio transmitter, at least in the vicinity of the geographical reference position from a mobile terminal to a Measuring point can be received from a plurality of measuring packets (GMP _n , RRP _n ), each of the measuring packets having a transmitter identification and an electromagnetic signal characteristic of a radio transmitter receivable at a geographical position at a measuring time, comprising: 32 ) for selecting measurement packages from the plurality of measurement packages (GMP _n ; RRP _n ) according to a similarity criterion to obtain selected measurement packages (GMP _i ; RRP _i ); a facility ( 34 ) for determining coordinates (RRP.x; RRP.y; RRP.z) of the geographical reference position based on coordinates of the geographic positions associated with the selected measurement packages (GMP _i ; RRP _i ); a facility ( 36 ) for determining the electromagnetic reference signal _property (RRP.RSSI _MACj ) associated with the at least one reference end identifier (MAC _j ) based on the reference end _detection (MAC _j ) of the selected measurement packets (GMP _i ; RRP _i ); and a facility ( 38 ) for generating the reference measurement packet (RRP) from the determined coordinates (RRP.x; RRP.y; RRP.z) of the geographical reference position and the electromagnetic reference signal property (RRP.RSSI) associated with the at least one reference end identifier (MAC _j ). The apparatus of claim 1, wherein the reference electromagnetic signal characteristic and the associated electromagnetic signal characteristics of the selected measurement packets are signal properties of radio signals related to a reception field strength. The apparatus of claim 2, wherein the electromagnetic reference signal property and the associated electromagnetic signal characteristics of the selected measurement packets are each an RSSI value, a received power spectrum, or a signal-to-noise power ratio. The apparatus of claim 1, wherein each of the plurality of measurement packets is assigned a spatial orientation of a mobile terminal at the geographic location corresponding to the measurement packet, and wherein the set of measurement package selection means is configured to group the measurement packets according to their associated one Select spatial orientations, so that the spatial orientations lie in a predefined tolerance range by a predetermined orientation. Apparatus according to claim 4, wherein the spatial orientation of the mobile terminal is defined by a spatial orientation of the main lobe of an antenna directivity of the mobile terminal. Apparatus according to any one of the preceding claims, wherein the plurality of measurement packets (GMP _n ; RRP _n ) have been recorded in temporal succession at positions along a path to receive radio signals from fixedly positioned radio transmitters along the path, and wherein 32 ) for selecting the measurement packets (GMP _i , RRP _i ) is designed to select the measurement packets (GMP _i , RRP _i ) according to their measurement times so that the measurement times of the selected measurement packets (GMP _i , RRP _i ) are within a predefined tolerance range , Device according to one of the preceding claims, wherein the device ( 32 for selecting the measurement packages (GMP _i , RRP _i ) to select the measurement packages (GMP _i , RRP _i ) according to their associated geographical positions, such that the geographical positions of the selected measurement packages (GMP _i , RRP _i ) are predefined Tolerance range to each other. Device according to one of the preceding claims, wherein the device ( 32 for selecting the measurement packets (GMP _i , RRP _i ) to select the measurement packets (GMP _i , RRP _i ) according to their associated radio transmitters associated electromagnetic signal properties, so that the electromagnetic signal characteristics of the radio transmitter of the selected measurement packets (GMP _i ; RRP _i ) lie in a predefined tolerance range to one another. Device according to one of the preceding claims, wherein the device ( 34 ) for determining the coordinates (RRP.x; RRP.y; RRP.z) of the geographical reference position is formed around each of Coordinates (RRP.x; RRP.y; RRP.z) of the reference position based on an averaging of the corresponding coordinates (x _i ; y _i ; z _i ) of the geographic positions associated with the selected measurement packages. Apparatus according to claim 9, wherein the means for determining the coordinates (RRP.x; RRP.y; RRP.z) of the reference geographical position is adapted to reference each of the coordinates of the reference position

where RRP.x is a Cartesian coordinate of the geographical reference position, M _{GM is} a number of radio transmitters listed in the selected measurement packets (GMP _i ; RRP _i ), GM.Weight _{i means} a weighting factor of an ith selected measurement packet, GM .x _{i means} a Cartesian coordinate corresponding to the reference coordinate of the geographical position of the ith selected measurement packet, and WeightSum correspondingly

where _{GMM (GMPi) means} a number of transmitter identifications contained in the i-th selected measurement packet and GM.Weight _{j means} a weighting factor of a jth radio transmitter of the ith selected measurement packet. Device according to one of the preceding claims, wherein the device ( 36 ) for determining the electromagnetic reference signal _property (RRP.RSSI _MACj ) associated with the at least one reference end _detection (MAC _j ), based on an averaging of corresponding electromagnetic signal characteristics associated with the reference end _detection (MAC _j ), the reference signal _property (RRP.RSSI _MACj ) (GM _MACj .RSSI) of the selected measurement packets (GMP _i ; RRP _i ). Apparatus according to claim 11, wherein the device ( 36 ) for determining the electromagnetic reference signal _property (RRP.RSSI _MACj ) associated with the at least one reference end identifier (MAC _j ) in order to obtain the reference signal _property (RRP.RSSI _MACj ) in accordance with

where M _{MACj means} a number of selected measurement packets with the at least one reference end identifier (MAC _j ), GM _MACj-i .Weight means a weighting factor of an ith selected measurement packet with the reference end detection (MAC _j ), the corresponding one with the receive field strength means related quantity of the i th selected measurement packet with the reference end detection (MAC _j ), and wherein WeightSum _MACj accordingly

is calculated. Apparatus according to any one of the preceding claims, comprising means for determining a spatial orientation associated with the reference measurement packet (RRP), which is arranged to provide the spatial orientation associated with the reference measurement packet (RRP) based on averaging of the selected measurement packets (GMP _i ; RRP _i ) to determine assigned spatial orientations. Device according to one of the preceding claims, wherein a device for determining the spatial orientation associated with the reference measurement packet (RRP) is formed in accordance with the spatial orientation assigned to the reference measurement packet (RRP)

where _{GM is} a number of radio transmitters listed in the selected measurement packets (GMP _i ; RRP _i ), GM.Weight _{i means} a weighting factor of an i th selected measurement packet, and GM.Orientation _{i is} a spatial orientation of the ith means selected measurement packages. Device according to one of the preceding claims, comprising _means for determining a PGS value (RRP.PGS _MACj ) associated with the at least one reference end identifier (MAC _j ) of the reference measurement _packet (RRP), the means for determining the PGS value (RRP. PGS _MACj ) is designed to select it correspondingly (M _MACj / M _GMP ) x 100, where M _{MACj comprises} a number of selected measurement packets with the at least one reference end identifier (MAC _j ) and M _GM a number of times in the selected measurement packets (GMP _i ; RRP _i ) listed radio transmitter means. Device according to one of the preceding claims, comprising _means for determining a PGS value (RRP.PGS _MACj ) associated with the at least one reference end identifier (MAC _j ) of the reference measurement _packet (RRP), the means for determining the PGS value (RRP. PGS _MACj ) is designed according to this

where M _{MACj means} a number of selected measurement packets with the at least one reference end identifier (MAC _j ), where

means a maximum number with which the reference end _detection (MAC _j ) could have been registered, and where RRP.PGS _{MACj_i means} a PGS value of the ith selected measurement packet with the at least one reference end identifier (MAC _j ). A method for generating a geographic reference position associated reference measurement packet (RRP), the reference geographical reference position (MAC _j ) assigns at least one radio transmitter and an electromagnetic reference signal property of the at least one radio transmitter, at least in the vicinity of the geographical reference position from a mobile terminal to a Measuring point can be received from a plurality of measurement packets (GMP _n ; RRP _n ), each of the measurement packets having a transmitter identification and an electromagnetic signal property of a transmitter receivable at a geographic location at a time of measurement, comprising the steps of: selecting measurement packages the plurality of measurement packets (GMP _n ; RRP _n ) according to a similarity criterion to obtain selected measurement packets (GMP _i ; RRP _i ); Determining coordinates (RRP.x; RRP.y; RRP.z) of the geographical reference position based on coordinates of the geographic locations associated with the selected measurement packages (GMP _i ; RRP _i ); and determining the electromagnetic reference signal _property (RRP.RSSI _MACj ) associated with the at least one reference end identifier (MAC _j ) based on the reference end _detection (MAC _j ) of the selected measurement packets (GMP _i ; RRP _i ) associated with that electromagnetic signal characteristics; and generating the reference measurement packet (RRP) from the determined coordinates (RRP.x; RRP.y; RRP.z) of the geographical reference position and the electromagnetic reference signal property (RRP.RSSI) associated with the at least one reference end identifier (MAC _j ). Computer program for carrying out the method according to claim 17, when the computer program runs on a computer or microcontroller.

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