JP2001514476A - Positioning system for digital mobile phones - Google Patents

Abstract

(57) Abstract: A digital cellular communication network, such as a GSM or CDMA network, comprising a plurality of mobile stations and a number of reference stations (BSs), each capable of communicating with some of the mobile stations. And has a fixed geographical location known in the network and location determining means for determining the geographical location of the mobile station in the network. The location determining means comprises at least one reference mobile station having a known geographical location in the network and capable of receiving signals broadcast from the reference station, wherein the received signal is a subscriber mobile station in the network. Used to determine the geographical location of the The mobile station (a) identifies and measures the arrival time of the earliest arriving copy of the signal broadcast by the reference station and received as a composite of the plurality of copies, wherein the arrival time is based on an internal time reference of the mobile station. (B) determine the relative timing of the broadcast signal by several reference stations. The relative timing of the signals is used to determine the geographic location of the mobile station in the network. This signal can be broadcast on the BCCH of each reference station, and the BCCH signal carries mobile station information regarding the broadcast reference station and the digital cellular radio communication network.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a digital cellular radio communication network such as a GSM (Global System for Mobile Communication) or CDMA (Code Division Multiple Access) network, and in particular to the geographical location of mobile stations within the service area of this network. . The invention may also be used in the tracking of motor vehicles, each having a mobile station, and / or in a motor vehicle navigation system.
A position location system including a digital cellular radio communication network.

[0002]

[Background Art]

The principles of measuring time-of-flight differences between radio signals from several transmitters to determine the location of a mobile radio receiver are well known, and numerous systems have been proposed and implemented. Many of the known systems rely on accurate time synchronization of the transmitter so that time-of-flight differences can be calculated directly. By knowing the geographic location of the transmitters, the particular value of these time differences identifies the hyperbolic surface where the radio receiver must be located in the space between each set of monitored transmitters. Given three such hyperbolic surfaces, i.e., three hyperbolic surfaces obtained from three transmitters in a set, the mobile radio receiver should be at the intersection of the surfaces.

[0003] Positioning systems that use time-synchronous transmitters, such as DECCA, OMEGA, and LORAN-C, have been widely used since the 1940's. It is only necessary to know the actual time offset between transmitters (referred to here as 'real time difference', or 'RTD'), excluding any time of flight to the receiver, and the transmitter must actually know the zero time difference. Note that it is not necessary to send in. Error in position determination is reduced by using more than three transmitters.

A related position determination system in which the transmitter RTD does not need to be known a priori is proposed and described in our European patent EP-B-0 303 371. The system comprises a mobile station 1 (hereinafter referred to as a "reference mobile station") having a fixed geographic location known in the system and capable of monitoring signals broadcast from three transmitters 2-4. The use of the same system can be found in FIG. 1 of the accompanying drawings, which schematically illustrates our earlier system in block diagram form. These transmitters are used as a basis to determine the geographic location of the mobile station.

As shown in FIG. 1, the target mobile station 5 can monitor the same broadcast signal as the reference mobile station 1. At some point, the target mobile station 5 makes a short record of each signal broadcast by the three transmitters 2-4. The three records created by the target transfer station must be precisely separated in time.

The reference mobile station 1 makes a similar set of recordings almost simultaneously with the recordings made by the target mobile station 5. The three records are reference mobile station 1,
It is important that this is done at exactly the same interval at the target mobile station 5.
By precisely synchronizing the recording start times, by reducing the length of the records that have to be made at the reference mobile station 1, by calculating the geographical location of the target mobile station 5, and ,
It reduces the amount of storage required for the reference mobile station 1 and the target mobile station 5, but does not affect the accuracy of the determined geographic location and is therefore not critical. The representations of the three records are communicated from the target mobile station 5 to the reference mobile station 1, where correlation techniques are used to determine the time offset between the signals received at the target mobile station 5 and the reference mobile station 1. .

[0007] The recording is long enough to ensure that the worst case time offset between the reference and target recordings still performs a substantial overlap of the recordings. Since the geographical positions of the three transmitters 2 to 4 and the reference mobile station 1 are known, the observed time-of-flight differences can be determined by solving the equations given in EP-B-0 303 371, for the target mobile station 5. It is used to determine the position and the synchronization offset between the reference mobile station 1 and the target mobile station 5.

From the above description, it can be seen that the system of FIG. 1 of the accompanying drawings compares two records of 'raw' signals broadcast by transmitters 2-4. The transmitters 2 to 4 are, for example, GS
Reference stations (BSs) in digital cellular radio communication networks such as M or CDMA. It should be noted that the exact time difference when the recording is started can be omitted in subsequent position calculations.

[0009]

[Problems to be solved by the invention]

The system in FIG. 1 of the accompanying drawings has several disadvantages. That is, a reference mobile station is needed to capture a reference copy of the broadcast signal at a known location. Significant computational power is required to perform the necessary correlation to determine the time offset between the signal seen at the reference mobile station and the signal seen at the target mobile station.

[0010] If it is necessary to determine the position with a very short time delay, each time it becomes necessary to determine the geographical position of the target mobile station, a record created at the target mobile station is transferred to the reference mobile station. A real-time communication link is required. The bandwidth required for the communication link is substantial, increasing the cost of the communication.

The reference mobile station of the system of FIG. 1 must perform recording and correlation for all target mobile stations wishing to determine its geographic location at any one time, thereby further referencing. Increase the computing power required of the station. Further, if in fact there is a need for location information at the target mobile station rather than at a certain central location, a separate decision is made to transmit the results of the position determination back to the target mobile station in a timely manner. Near real-time communication link is required.

In the following application (WO-A-97-11384) we show how this system is applied to GSM and other digital cellular networks. There is disclosed a method for improving the effect of multipath propagation on the accuracy of position determination. In fact, the expected cross-correlation function between the signals received by reference MS1 and MS5
function) is estimated from the autocorrelation of the signals received at the two MSs, and this is consistent with the observed cross-correlation. The effect of this is to take into account the spectrum of the delayed signal in a way that gives a better estimate of the faithful time difference.

In yet another patent application (WO-A-97-30360), it is shown how the location of a mobile station in a GSM network can be obtained. However, the largest source of position error actually calculated appears to be due to multipath propagation between the transmitter and the receiver. In this application, the output from the equalizer in the GSM handset is used to determine the time offset. This output is optimized to give the minimum bit error to the signal received from the mobile station,
And does not mitigate the effects of multiple paths on the received signal for timing purposes.

[0014] In yet another patent application (WO-A-97-23785), a standard equalizer included in all digital mobile telephones uses a channel impulse response estimation for multiple paths. As distinguished, the method adapted thereby is disclosed.

It is an object of the present invention to provide a digital cellular radio communication network such as a GSM or CDMA network that alleviates some of the above problems of the known system of FIG. 1 of the accompanying drawings. This means that TDMA broadcast channels, or CDMA pilots, use signal structures designed to have good autocorrelation properties while transmitting system information from each reference station (BS) in the network, and such Signaling is accomplished by providing a system that is predictable / repeatable at predetermined time intervals, distinguishable from other information in the broadcast signal, such as by frame numbering. The method outlined above highlights the benefits of easily identified signal structures designed to have good autocorrelation properties, such as extended training sequences in GSM, to distinguish against multipath propagation. Combining is the purpose of another aspect of the invention. It is another object of the present invention to provide a localization system including the digital cellular radio communication network of the present invention for use in tracking a motor vehicle with a mobile station and / or for a vehicle navigation system.

[0016]

[Means for Solving the Problems]

According to a first aspect of the present invention, a plurality of subscriber mobile stations, each of which is capable of communicating with a plurality of mobile stations, and a plurality of reference stations having a known fixed geographic location in the network, and a mobile station in the network A digital cellular radio communication network is provided having position determining means for determining the geographical position of a station, said position determining means having a known geographical position in the network and capable of receiving signals broadcast by said reference station The received signal is used to determine the geographical location of a subscriber mobile station in the network, the mobile station identifying the time of arrival of the signal broadcast from the reference station. And means for measuring Wherein each broadcast signal received at the mobile station is a composite signal comprising one or more copies of the signal transmitted from the respective reference station, wherein the copy is passed by each copy between the respective reference station and the mobile station. The time of arrival relative to each other according to the relative length of the route taken, the time of arrival being measured as the time of arrival of the earliest arriving copy forming the composite signal with respect to the internal time reference of the mobile station, Means are arranged for determining the relative timing of signals broadcast from a number of reference stations, wherein the relative timing of the signals is used for determining the geographical location of the mobile station in a network. A wireless telecommunications network is provided. The arrival time of the composite signal and the identification and measurement of the earliest arriving copy can be performed as described below. Signals transmitted on a digital cellular telephone network are transmitted at known intervals and include portions that are easily identifiable and known in advance.

The arrival time of the signal received from the reference station with respect to the internal time reference, autocorrelating the measured part of the signal, autocorrelating part of the expected part of the signal, and part of the measuring part of the signal Constructing a template that includes an autocorrelation portion of; cross-correlating the expected portion of the received signal with the measurement portion of the received signal; and At the right time or by measuring the equivalent transformed interval (in time or equivalent tra
Preferably, it is identified and measured in an nsformed space). The present invention also includes a mobile station having means for performing the above method.

This process can be equivalently performed, for example, in the Fourier transform domain, where the autocorrelation function becomes the power spectrum and the cross-correlation function becomes the cross-power spectrum. For example, in the case of a GSM system, the signal portion that is easily identifiable and known in advance may be an extended training sequence. For a CDMA system, the signal portion may be a pilot extension code.

The signal may be broadcast on a broadcast control channel (BCCH) of each of the reference stations, and the BCCH signal transmitted at the reference station is transmitted to a mobile station with which the reference station is enabled to communicate, a reference station and a reference station. Transmitting information about the digital cellular radio communication network, and the handset,
Using, for example, frame numbering and other identifying features of the BCCH signal, the relative timing of signals broadcast from multiple reference stations can be determined.

[0020] The network may be either a GSM or a CDMA network, and the relative timing of the signals broadcast from multiple reference stations may be TDM for GSM.
The training sequence in A and, in the case of CDMA, the pilot extension code can be determined.

[0021] A network evaluates the relative timing of the signal to determine a geographical location of the mobile station in the network, and transmits the relative timing from the mobile station to the evaluation means. It has transmission means. The mobile station has means adapted to receive data relating to its geographic location in the network from said evaluating means and to be able to store said data.

The mobile station (MS) whose geographic location is to be determined receives the relative timing from at least one external source and information about the geographic location of the reference station, and It may have means capable of storing information.

A mobile station (MS) using the relative timing in combination with reference station timing and geographical location information to determine a geographical location of the mobile station in the network; Having.

[0024] The mobile station used to determine the relative timing may be a reference mobile station, and the reference mobile station determines the difference in bit and frame timing between transmissions from different reference stations. Computing means, which can be calculated with information about the geographical location of the reference mobile station and the geographical location of the reference station, wherein the calculated data comprises RTDs (real time differences) of the reference station, and thereby The geographic location of the subscriber mobile station may be used to determine.

The reference mobile station may have means for determining the rate of change of the timing difference between the reference stations and being predictable. The reference mobile station has transmission means for transmitting the calculated relative timing and rate of change to an external system for use in determining a geographic location. The transmitting means can transmit the position information of the reference station to the external system.

The reference mobile station has a fixed geographic location known in the network. Alternatively, the geographical location of the reference mobile station in the network may change, but can be determined at any instant in time, for example using the signals of the global positioning system GPS.

[0027] At least some of the reference stations may each have a reference mobile station integral therewith. The present invention also has a position determination system that includes a digital cellular radio communication network, as outlined above. The position determination system has a control center for controlling the operation of the system.

The position determination system is capable of determining a geographical position of any one of the mobile stations (MSs) in the network, wherein a reference station (BSs) used to determine the geographical position is provided. The relative timing of the reference station changes at a rate approaching the rate of change of the outgoing frame rate of the signal transmitted by the reference station, wherein the system determines the position of the reference station used to determine the geographic location. A mobile station whose location is to be determined (hereinafter referred to as a 'target mobile station') is assigned a set of reference stations by the control center and includes a reference mobile station for each set. Is the assigned set of reference stations The relative timing of the signals transmitted from the at least one said target associated with said assigned set of reference stations, at a frequency given by the frame number conditions at the agreed upon reference station. A mobile station is capable of measuring the relative timing of the signals transmitted by the assigned set of reference stations, wherein the target mobile station and the reference mobile station transmit the measured timing to the control center. Transmission enabled, wherein the control center is capable of comparing the time information from the target mobile station and the reference mobile station to determine a time difference, and wherein the control center is capable of comparing the time difference information, A target mobile station geographic location can be calculated using information known to the control center with respect to the assigned set of reference stations and the geographic location of the reference mobile station, wherein the calculation is a conventional This is performed using a hyperbolic geometric equation. Since the mobile station operates within the service area of the digital cellular radio communication network, the control center is able to change the set of reference stations assigned to the mobile station. The control center is adapted to adjust information regarding timing measurements from at least some of the reference mobile stations. Each of the position determination systems is capable of tracking a vehicle including a mobile station (MS).

The present invention also includes a vehicle navigation system adapted to cause a vehicle to determine its geographic location, wherein the navigation system includes a positioning system as outlined above, and wherein each vehicle is mobile. Station (target moving station).

The system includes a reference mobile station for each set of reference stations used to determine the geographic location, wherein the rate of change of relative timing between reference stations is such that the relative timing According to a model shared between the reference and the target mobile station, it is sufficiently stable over a relatively long period of time that the relative timing is accurately predicted, so that the control center A rate of relative timing information and change information measured by each of the reference mobile stations for a set, wherein the control center is capable of collecting the measurement information collected from the reference mobile stations into the digital cellular radio communication network; Services Distributable to said target mobile stations operating in an area, said information distribution being relative timing of a reference station with which each target mobile station can communicate at any given geographical location of said network. The target mobile station measures the relative timing of signals transmitted by a set of reference stations at its current location, and is distributed by the control center. The measured value, together with the information and the geographical location of the set of reference stations, can be used to determine its geographical location. A control center is capable of providing information regarding the geographic location of the set of reference stations to the target mobile station. The target mobile station includes a database in which the information regarding the geographic location of the set of reference stations is stored.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

The following description of the invention, which is presented by way of example only, relates in particular to the geographic location of mobile stations in a GSM digital cellular radio communication network. However, those skilled in the art will readily appreciate that the present invention can be used with other digital cellular radio communication networks, such as, for example, CDMA digital cellular radio communication networks.

From FIG. 2 of the accompanying drawings, which shows diagrammatically in the form of a block diagram, a digital cellular radio communication network of the GSM type, the reference mobile station, the target mobile station and the reference station correspond to the corresponding equipment of FIG. 1 of the accompanying drawings. It can be seen that the same reference numbers have been given.

In this example of a GSM digital cellular radio communication network according to the present invention, each reference station (BS) of the network has a digital cellular mobile station (BSs) within its service area on a broadcast control channel (BCCH). Broadcast signals that carry information about the system and the broadcast reference station.

[0034] The BCCH emitted by the reference station (BS) may be transmitted when the mobile station first powers up, or when the mobile station re-enters the service area of the signaling reference station after a temporary loss of signal. Help mobile stations (MSs) within their service area to acquire synchronization to the signaling reference station. The BCCH signal contains features designed to gain and maintain bit synchronization with the reference station associated with the mobile station, which features are transmitted at precise and regular intervals in the TDMA structure of the GSM network. , And can be easily identified.

It will be readily apparent to those skilled in the art that the BCCH signal, when received at the mobile station, can be used to establish the bit and frame timing of any particular reference station with high accuracy. Under normal signal conditions
The accuracy of the bit and frame timing information established in the BCCH signal is typically only a small part of the bit period.

If the mobile station cannot see the reference station, the received signal is very often a composite signal consisting of one or more copies of the signal transmitted from the reference station, where each copy of the signal is Displaced in time with respect to each other by the relative length of the path between the receiving mobile station and the transmitting reference station
(displaced in time).

The earliest arriving copy of the signal is the copy that takes the shortest path between the reference station and the mobile station. The shortest path need not necessarily be a direct path between the reference station and the mobile station. Path error in the shortest receive path will be the largest source of signal error in most of the position measurements performed using the digital cellular radio communication network of the present invention.

Measuring the earliest arrival time of such a copy of the multiplexed signal relative to the mobile station's internal time reference minimizes this error. This example of the invention uses an easily identifiable signal structure designed to have good autocorrelation properties, such as an extended training sequence in the GSM digital cellular system illustrated in FIGS. 3A to 3D.

The automatic correlation of extended training sequences in a GSM digital cellular system (shown in FIG. 3A) is well known. This left side (corresponding to the negative time axis)
The estimated cross-correlation function of the received signal and the expected extended training sequence (Figure 3C
As shown on the left).

The right side of the autocorrelation function of the measured extended training sequence (shown in FIG. 3B,
And corresponding to the positive time axis) are used as the right side of the estimated cross-correlation function. The received signal is cross-correlated with the resulting measured cross-correlation function (shown in FIG. 3D), which is compared with the extended training sequence and the estimated cross-correlation function (shown in FIG. 3C) to find the timing offset.

FIG. 4 is a schematic diagram of a mobile station including a conventional digital cellular radio handset operable in accordance with the present invention. The handset 5 has an antenna 51 for providing a signal to a receiver 52, from which the received signal is passed to a digital signal processor (DSP) 53.

The digital signal processor 53 has an associated RAM 54 and ROM 55 containing software used by the DSP 53, or the like. A conventional microprocessor 56 receives the signals processed by the DSP and has an associated RAM 57 and ROM or similar 58 containing operating software.

Other conventional components of a cellular telephone handset, such as a battery, keypad, LCD screen, etc., are not shown as they are not closely related to the present invention. A DSP that operates under the control of a correction program stored in ROM 55 when used in accordance with the present invention.
53 and associated RAM 54 operate to perform the required signal measurements, and microprocessor 56 and associated RAM 57 operate to measure the timing offset under the control of a correction program stored in ROM 58. I do.

To achieve the minimum bit error rate in the demodulated signal, the mobile station determines which copy of the composite signal resulting from the signal transmitted from the reference station is to be selected and uses, for example, the channel Another method would use the fact that the GSM mobile station (MS) includes an equalizer-like mechanism with a sounder.

A modified MS mobile station is used that includes equalizer means (including a channel sounder) that can identify the signal transmitted from the reference station and measure its time of arrival. In practice, the signal identified and measured by the equalizer mechanism will be the earliest arriving copy of the composite signal transmitted from the reference station.

An equalizer operating in this mode does not need to demodulate the signal, but only needs to establish its timing, and thus has a lower received signal level than is normally required by the equalizer for reliable demodulation of the signal. Can work. Such a mobile station is a reference mobile station (MS) and / or a target mobile station (MS), i.e. the mobile station whose geographic location within the service area of the network is to be determined.

In a CDMA network such as IS 95, the time of arrival of the signal can be identified by means of an equalizer in the form of a CDMA searcher element in the mobile station. From FIG. 2, the reference mobile station 1 and the target mobile station 5 of the GSM network are capable of communicating with the reference stations (BSs) 2 to 4 of the network, respectively.
Can be seen to be able to communicate with each other by the GSM network.

The reference mobile station 1 and the target mobile station 5 each include means such as, for example, an equalizer mechanism as outlined in the previous section. Furthermore, the reference mobile station 1 has a known geographical location within the service area of the network. In fact, the reference mobile station 1 usually has a known fixed geographic location in the network,
It may have a geographic location that changes but can be determined at any instant in time, for example by GPS.

Alternatively, at least some of the reference stations of the network may each have a reference mobile station integral therewith, ie formed as a component of the reference station, thereby eliminating the need for a separate unit. good.
In fact, each reference station in the network has a reference mobile station integrally formed thereon, and network operators and / or central control when any one or more integrated reference mobile stations are needed. Being driven by the unit is useful and cost-saving.

In operation, the reference mobile station 1 receives signal transmissions from three reference stations (BSs) 2 to 4, for example: the known geographical location of the reference stations 2 to 4 in the network; Calculate RTDs (real time differences) between reference station signal transmissions using information about the known geographic location of the reference mobile station 1 and the measured time difference between the arrival times of the signal transmissions at the reference mobile station 1 It is possible.

According to the invention, the reference mobile station 1 can determine the rate of change of the RTD. The target mobile station 5 can receive the same set of signal transmissions from the reference stations 2 to 4 as the reference mobile station 1 and determine OTDs (observation time differences) between the sets of signal transmissions. The OTDs and RTDs are then combined with information about the geographic location of the reference stations (BSs) 2-4 to determine the geographic location of the target mobile station 5 in the network using conventional hyperbolic geometric calculations. Used.

As shown diagrammatically in FIG. 2 of the drawings, the RTDs are transmitted from the reference mobile station 1 to the target mobile station 5 together with the rate of change information, if available, or the OTDs are transmitted from the target mobile station 5. Transmitted to the reference mobile station 1 and then the two sets of time differences are used to calculate the position of the target mobile station using conventional hyperbolic geometric equations to determine the geographical location of the reference stations (BSs) 2-4. Combined with knowledge.

In other words, to determine the geographic location of the target mobile station 1, the RTDs alone or in combination with the rate-of-change information, the OTDs and the three reference stations 2
4 to the target mobile station 5 for use in combination with the information on the geographical location of. Alternatively, to determine the geographic location of the target mobile station, the OTDs may be used in combination with RTDs, alone or in combination with rate of change information, and information on the geographic location of the three reference stations 2-4,
It is transmitted to the target mobile station 1.

From the foregoing description of the invention, rather than finding the time difference between the flight times from a reference station (transmitter) to two mobile stations, as in our previous system, the invention provides a standard DECCA- It can be seen that the RTDs between the reference station transmissions are determined such that the hyperbolic calculation, or LORAN-C type, can be used.

The use of a reference mobile station at a precisely known geographic location to determine the relative bit and frame timing of a set of reference stations is the basis for all implementations of the invention. If these relative timings do not change, the reference mobile station does not need to be permanently present, i.e. the relative timing can be determined once and for all in the first search.

However, if these relative timings change for some reason (
In the normal case) a reference mobile station is present to monitor the relative timing, and needs to update information about such timing at an appropriate rate. This rate depends in particular on the frequency of network reconfiguration and the stability of the relative frequency of reference stations. The frequency with which the updates need to be transmitted is reduced by monitoring the rate of change of the relative timing at a defined start time and transmitting this information along with the timing.

Thus, the reference mobile station 1 of the digital cellular radio communication network according to the invention first establishes the time difference for the three reference stations 2 to 4,
Then, the relative timing can be updated at a predetermined time interval or later when a change in the time difference information is detected, whichever is earlier. In this case, the reference mobile station 1 includes monitoring means capable of monitoring the rate of change of the relative timing and transmitting the information on the rate of change of the relative timing together with the relative timing information at regular time intervals.

From the previous description of the invention, the equalizer used in the mobile station is:
It can be seen that it has another mode of operation that identifies the earliest arriving copy of the composite signal transmitted from the reference station and measures the time of arrival of that copy with respect to a suitable internal time base.

As described above, the equalizer operating in this mode does not need to demodulate a signal, but only needs to establish its timing. Therefore, in order to perform reliable signal demodulation, a request from an ordinary equalizer is required. Operating at lower received signal levels than is possible.

Thus, the mobile station of the present invention uses another equalizer mode, taking into account frame numbering and other signal identifying features, especially the training sequence of TDMA frames (in the case of GSM). And has the ability to determine the relative timing of the signals from several reference stations BCCHs to an appropriate / appropriate accuracy. The moving object may have transmission means for transmitting the three relative timings to another point on either the opposite station side or the own station side for evaluation.

The target mobile stations of the digital cellular radio communication network of the present invention, ie, those described in the preceding section, have one or both of the following generally provided as part of the normal communication functions of the mobile station: It is just obvious to those skilled in the art to include

Means for receiving the result of the calculated position from an external source; and relative timing from one or more external sources, either on the opposite side or on the local side, and the reference station. Means for receiving information relating to geographic location The means for the target mobile station to use the timing of the reference station, together with the relative timing measured at the local station, and position information to calculate its own position.

It will be apparent to those skilled in the art that the reference mobile stations of the digital cellular radio communication network of the present invention, ie, those described in the preceding section, include the following.

Observations that are exactly synchronized using the relative timing measured between transmissions from different reference stations, together with the knowledge of the geographical position of the reference station and its own geographical position Means to calculate the actual difference in bit and frame timing between transmissions from different reference stations, as observed by the actual reference station, determining the difference in the rate of change of timing between the reference stations, and Means of prediction-means of transmitting the calculated relative timing and rate of change to an external system, either remote or local, for use in determining the geographic location of the target mobile station. A means of transmitting reference station position information to an external system for use in position determination.

A basic application of the digital cellular radio communication network of the present invention is a position determination system capable of determining the geographical position of any one of a number of mobile stations in the network. However, the position determination system of the present invention can also be used in some applications, such as tracking / monitoring a motor vehicle, each of which includes a mobile station (target mobile station).

Alternatively, the position determination system may comprise a vehicle having a mobile station (target mobile station) located therein to determine its own position while operating within the service area of the digital cellular radio communication network. And may form part of a car navigation system.

A position determination system for tracking / monitoring motor vehicles may determine the position of any one of a number of vehicles, such as taxi vehicles, when operating within a digital cellular radio communication network service area. , The central side, or the control center wants to know.

With this application of the positioning system of the present invention, by way of example, the relative timing of the reference stations (BSs) used for the geographical positioning of the vehicle is determined by the transmission frame of the signal transmitted from the reference station. It is conceivable that the rate of change changes at a rate approaching the rate of change of the rate. This means that it is necessary to provide a reference mobile station for each set of reference stations used to determine the geographic location.

The vehicle (target mobile station) whose geographical position is to be determined in operation in this way is assigned, for example, a set of reference stations (BSs) by the control center, the mobile mobile station being outlined above. In this way, the relative timing of the assigned set of reference stations can be measured at a given time with respect to the frame number at the reference station that has been periodically or aggressively requested.

The reference mobile station associated with the assigned set of reference stations is capable of measuring the relevant timing of signals transmitted from the same set of reference stations as the target mobile station (vehicle) in the manner outlined above. You. The measured timing information is transmitted from the reference mobile station and the target mobile station to the control center. The control center can determine the time difference by comparing the timing information from the target mobile station with the timing information from the reference mobile station, i.e. from the same set of reference stations with the same frame number as received at the reference mobile station It has become.

The control center then uses the time difference information and the information known to the control center regarding the geographic location of the assigned set of reference and reference mobile stations, and the geographic location of the vehicle (target mobile station). Is calculated. The calculations are made using conventional hyperbolic geometric calculations.

With the position determination system of the present invention in which the reference mobile station is coordinated by the control center, the signals broadcast from at least two reference stations to determine the geographical position of the target mobile station are measured by the reference mobile station. It only needs to be done.

In practice, the set of reference stations assigned to a vehicle is a subset of those reference stations from which the vehicle mobile station can measure its transmitted signal. The control center is capable of changing the set of reference stations assigned to the vehicle (target mobile station) when the vehicle is operating within the coverage area of the digital cellular radio communication network. In other words, the set of reference stations used to fix the position of the vehicle is typically updated from the control center while the vehicle is operating.

A set of reference stations to which no given reference mobile station can measure its signal transmission is generally a superset of those reference stations for which a particular target mobile (vehicle) can measure its signal transmission. (superset). Thus, the control center needs to be able to coordinate measurements from some or all reference mobile stations.

From the previous description of the vehicle positioning system, it is not necessary to transmit any indication of the received signal for correlation, as compared to our previous system, the time difference is measured directly at the target mobile station, And it can be seen that only this information is sent to the control center, thereby greatly reducing the required bandwidth.

A vehicle navigation system in which each vehicle includes a mobile station (target mobile station) therein to determine its geographic location is a more rigid application than the positioning system of the present invention. With this system, by way of example only, the rate of change of the relative timing between the reference stations (BSs) is such that the relative timing determines the reference mobile station and the target mobile station, ie its geographic location. It is expected to be sufficiently stable to be accurately predictable over a relatively long period of time, according to a shared model located in the desired vehicle.

With this system including a reference mobile station for each set of reference stations used to determine the geographic location, the control center can:-determine the relative measured by each said mobile station relative to the respective set of reference stations; Collecting timing information and rate-of-change information; and distributing the measurement information collected from the reference mobile station to target mobile stations operating within the coverage area of the digital cellular radio communication network.

The distributed information is sufficiently accurate information regarding the relative timing of the reference stations (BSs) with which each of the target mobile stations (vehicles) can communicate at any given geographic location of the network. It has something.

When the vehicle wants to determine its geographic location, the target mobile station of the vehicle will not match the reference station in its current location (generally does not match the set of reference stations it uses for communication) ) And measure the relative timing of the signals transmitted from one set, and calculate the relative timing measurements, along with the rate of change information distributed by the control center and information on the geographic location of the set of reference stations (BSs). Use to determine its geographic location.

The control center of the vehicle navigation system may be able to provide the target mobile station with information on the geographic location of said set of reference stations (BSs), or the target mobile station may be a reference station (BSs) May include a database that stores information relating to the geographic location of the set.

From the foregoing description of particular embodiments of the present invention, the position determination system according to the present invention has the following features and / or advantages over known systems for the geolocation of mobile devices. The reference mobile station needs to capture a reference copy of the signal broadcast from the set of reference stations at known locations. However, this can be very close to the target mobile station and usually only needs to update the timing information infrequently, and is therefore low cost.

-The correlation between the two raw signal records previously proposed for our system is no longer necessary to determine the time-of-flight difference, thus reducing the required computing power of the system. The amount of data required to be transferred between the reference mobile station and the target mobile station is relatively small, and in one mode of operation of the present invention, transfer from the reference mobile station to the target mobile station is rare; The operation cost of the position determination system of the present invention is reduced.

-The reference mobile station will have to perform a set of timing and rate-of-change measurements common to all target mobile stations, thus further reducing the computational power required for the reference mobile station. . -If the need for location knowledge actually exists at the target mobile station, rather than at some central location, the target mobile station can make a position determination based on infrequent updates of reference station timing information. It can be conveniently implemented by itself.

[Brief description of the drawings]

FIG. 1 shows, in the form of a block diagram, a known system for determining the geographical location of a mobile receiving device.

FIG. 2 shows a digital cellular radio communication network according to the invention in the form of a block diagram.

FIG. 3A-D shows the auto- or cross-correlation function of the estimated or measured signal in the system described below.

FIG. 4 schematically illustrates a mobile handset for a digital cellular radio network embodying the present invention.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GE, GH, GM, HR, HU, ID, IL, IS, JP, KE, KG, KP , KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZW (72) Inventor Fog Andrew UK Esg 19 3 Adie Bedfordshire Sandy Great Grangesden Middle Street 13 F term (reference) 5J062 AA06 BB01 BB05 CC12 CC16 5K067 BB04 BB36 CC04 CC06 CC10 DD42 DD43 EE23 JJ51 JJ56 KK13 KK15 LL11 [Continuation of abstract] This signal can be broadcast on the BCCH of each reference station, and the BCCH signal carries mobile station information about the broadcast reference station and the digital cellular radio communication network.

Claims (32)

[Claims] A plurality of subscriber mobile stations (5), each of which is capable of communicating with a plurality of mobile stations, and a plurality of reference stations (2, 3) having a known fixed geographical location in the network; A digital cellular radio communication network having position determining means for determining the geographical position of the mobile station at said position determining means having a known geographical position in the network and being broadcast by said reference station (2,3). At least one reference mobile station (1) enabled to receive the received signal, said received signal being used to determine the geographical location of a subscriber mobile station (5) in the network; ) Indicates the arrival of the signal broadcast from the reference station (2, 3). Means for identifying and measuring time, wherein each broadcast signal received at the mobile station is a composite signal consisting of one or more copies of the signal transmitted from a respective reference station, wherein the copy is a respective signal. Time-shifted with respect to each other according to the relative length of the path traversed by each copy between the reference station and the mobile station, the arrival times arriving earliest to form the composite signal with respect to the mobile station's internal time reference. Measured as the time of arrival of the copy, said means is arranged to determine the relative timing of signals broadcast from a number of reference stations, wherein said relative timing of said signals is determined using conventional hyperbolic geometry Used for the determination of the geographical location of said mobile station in the network Digital cellular radio communication network, characterized in that. 2. The network of claim 1, wherein the identified and measured transmission signal is transmitted at known intervals and has a portion that is easily identified and known in advance. 3. The means for identifying and measuring the time of arrival of a signal received from a reference station with respect to the internal time reference, at the right time or at an equivalent transformed interval, comprises: Means for auto-correlating, means for constructing a template including an auto-correlation part of an expected part of the signal, and a part of an auto-correlation part of the measuring part of the signal, a measuring part of the received signal 3. The apparatus of claim 2, further comprising: means for cross-correlating with the signal, and means for measuring the offset at which the template best matches the cross-correlation as the arrival time of the signal broadcast from the reference station with respect to the internal time reference. Network. 4. The network according to claim 2, wherein the network is a GSM network, and the part of the signal has an extended training sequence. 5. The network according to claim 2, wherein the network is a CDMA network, and the portion of the signal has a pilot extension code. 6. The means for constructing the template includes: converting an autocorrelation portion of an expected portion of the signal corresponding to an offset time before the autocorrelation of the central peak of the signal to an offset time after the autocorrelation of the central peak. 6. The network according to claim 2, comprising means for combining with a part of the autocorrelation part of the corresponding measurement part of the signal. 7. The network according to claim 1, wherein said means for identifying and measuring the time of arrival of a signal broadcast from a reference station (2, 3) comprises an equalizer adapted thereto. 8. The signal is transmitted to a broadcast control channel of each of the reference stations.
A BCCH signal broadcast on a BCCH and transmitted by a reference station, the reference station transmitting information about the reference station and the digital cellular radio communication network to a mobile station communicable therewith, the equalizer means Is adapted to be able to determine the relative timing of signals broadcast from several reference stations using frame numbering and other identification features of the BCCH signal. A network according to any of the above. 9. The network further comprising: evaluation means for evaluating the relative timing of the signal to determine a geographical location of the mobile station in the network; and evaluating the relative timing from the mobile station. A network according to any preceding claim, comprising transmitting means for transmitting to the means. 10. The mobile station of claim 9, wherein the mobile station receives data from the evaluator regarding geographical location in a network, and includes means enabled to store the data. network. 11. The mobile station whose geographic location is determined is capable of receiving information about the relative timing and geographic location of the reference station from at least one external source and storing the data. A network according to any of the preceding claims, comprising means. 12. The mobile station determines the geographic location of the mobile station in the network using the relative timing determined by the mobile station's equalizer means in combination with reference station timing and geographic location information. 12. A network as claimed in any one of claims 1 or 7 to 11 when dependent, characterized in that it comprises a location determining means enabled. 13. The mobile station used to determine the relative timing is a reference mobile station, wherein the reference mobile station is a geographic location of the reference mobile station and a geographic location of the reference station. Calculating means for calculating the difference in bit and frame timing between transmissions from different reference stations using the relative timing in combination with the reference station's RTDs ( Network according to any of the preceding claims, used to determine the real time difference) and thereby the geographical location of the subscriber mobile station. 14. The network of claim 13, wherein the reference mobile station has means for determining and predicting the rate of change of the time difference between reference stations. 15. The reference mobile station according to claim 14, wherein the reference mobile station has transmitting means for transmitting the calculated relative timing and rate of change to an external system for use in geographic location determination. Network. 16. The network according to claim 15, wherein said transmission means is capable of transmitting reference station position information to said external system. 17. The network according to claim 1, wherein the reference mobile station has a known fixed geographic location in the network. 18. The network according to claim 1, wherein the geographical position of the reference mobile station in the network is variable and can be determined at any time. 19. The network according to claim 18, wherein the geographic location of the reference mobile station in the network is determined by GPS. 20. A network according to claim 1, wherein at least some of the reference stations each have a reference mobile station integrated therewith. 21. A positioning system comprising a digital cellular radio communication network as claimed in any of the preceding claims. 22. The position determination system according to claim 21, wherein the system has a control center for controlling the operation of the system. 23. A positioning system adapted to determine a geographical position of any one of said mobile stations (MSs) in said network, wherein said reference station is used to determine said geographical position. The relative timing of the BSs) changes at a rate approaching the rate of change of the outgoing frame rate of the signal transmitted by the reference station, and the system uses the reference station used to determine the geographic location. The mobile station whose location is to be determined (hereinafter referred to as the "target mobile station") is assigned by the control center a set of reference stations, the target mobile station comprising: Transmitted from the assigned set of stations The relative timing of the signals can be measured at a frequency given by the terms of the frame number at the agreed reference station, wherein at least one of the target mobile stations associated with the assigned set of reference stations comprises: The relative timing of the signals transmitted by the assigned set of reference stations can be measured; the target mobile station and the reference mobile station can transmit the measured timing to the control center; The control center is capable of comparing the time information from the target mobile station and the reference mobile station to determine a time difference, wherein the control center is configured to control the assigned set of reference stations and the reference mobile station. The time difference information known to the control center with respect to the geographic location of the station can be used to calculate a target mobile station geographic location, wherein the calculation is performed using conventional hyperbolic geometric equations 23. The position determination system according to claim 22, wherein: 24. The control center, wherein when a mobile station operates within a service area of a digital cellular radio communication network, a set of reference stations assigned to the mobile station can be changed. 21. The position determination system according to claim 20, wherein 25. The position determination system according to claim 23, wherein the control center is capable of adjusting information relating to timing measurements from at least some of the reference mobile stations. 26. The position determination system according to claim 23, wherein the system is capable of tracking motor vehicles including mobile stations (MS). 27. A vehicle navigation system adapted to cause a vehicle to determine its geographic location, said navigation system comprising a position determination system as claimed in claim 22, wherein said vehicle Each of which includes a target travel station. 28. A system comprising: a reference mobile station for each set of reference stations used to determine the geographic location; and a rate of change of relative timing between reference stations, wherein the relative timing comprises According to a model shared between the target mobile stations, for a relatively long period of time, the relative timing is sufficiently stable so that the relative timing is accurately predicted; The ratio of relative timing information and change information measured by each reference mobile station can be collected, and the control center can store the measurement information collected from the reference mobile station in a service area of the digital cellular radio communication network. Operating the target moving train Stations, the information distribution being such that each target mobile station has sufficiently accurate information regarding the relative timing of the reference station with which it can communicate at any given geographical location of the network. The target mobile station measures the relative timing of signals transmitted by the set of reference stations at its current location, and relates to the information distributed by the control center and the geographic location of the set of reference stations. 28. The vehicle navigation system according to claim 27, wherein the geographic location can be determined using the measurements together with information. 29. The vehicle navigation system of claim 28, wherein the control center is capable of providing the target mobile station with information regarding the geographic location of the set of reference stations. 30. The vehicle navigation system according to claim 28, wherein the target mobile station has a database in which the information regarding the geographic location of the set of reference stations is stored. 31. Means for identifying and measuring the time of arrival of signals broadcast from reference stations (2, 3), wherein each broadcast signal received at said mobile station is transmitted from a respective reference station. A composite signal comprising one or more copies, wherein the copies are temporally displaced with respect to each other according to a relative length of a path traversed by each copy between a respective reference station and a mobile station; Measured as the arrival time of the earliest arriving copy forming the composite signal with respect to the mobile station's internal time reference, the means being arranged to determine the relative timing of the signals broadcast from the multiple reference stations Network or location determination according to any of the preceding claims Mobile navigation cellular radio communication networks the terminal to be used for the stem. 32. A terminal according to claim 31, having any of the features of a mobile station of a digital cellular radio communication network as defined in any of the preceding claims.