WO2002065801A1 - Method for determining the location of a mobile communication terminal in a non-time synchronous mobile radio system - Google Patents

Abstract

The invention relates to a method for determining the location of a mobile communication terminal in a non-time synchronous mobile radio system. Non-time synchronous bursts and the respective locations thereof are periodically broadcast together from individual base stations, said bursts are received by base stations and the transit times thereof are compared. Transit time information thus determined is transmitted to the communication terminal where the location of the communication terminal is determined by means of said information, the bursts which are likewise received by the communication terminal, and the received locations of the base stations.

Description

 description

Method for determining the location of a mobile communication terminal in a non-time-synchronous mobile radio system.

The invention relates to a method for determining the location of a mobile communication terminal in a non-time-synchronous mobile radio system with a plurality of base stations.

A large number of methods for determining the location of mobile communication terminals are known in the case of mobile radio systems.

For example, location determination in a non-time-synchronous mobile radio network is known using the so-called timing advance. Data is exchanged between the base stations and a mobile communication terminal via specially constructed traffic channels and with the help of which the respective distance between the base stations and the communication terminal is determined and thus its location is determined.

In another method, the position of the communication terminal in a time-synchronous mobile radio network is determined with the aid of time-synchronous signals from the base stations and by means of a global positioning system (GPS) (US Pat. No. 5,815,538).

Signals of the base stations are transmitted in a time-synchronized manner using GPS and the respective locations of the base stations are determined using GPS. The transit time differences measured there between the time-synchronous signals are evaluated on the communication terminal and converted into distances. The position of the communication terminal can then be calculated using the data of the locations of the base stations. In all known methods in which data are exchanged between the communication terminal and the base station, the capacity of the mobile radio network is additionally burdened by occupied traffic channels. This results in large expenditure on hardware, hardware-specific software and increased computing capacity.

When using the timing advance, the accuracy of the location determination is typically in the range of approx. 500 m. When using the position determination as part of an emergency call function, the greatest possible accuracy is of crucial importance.

When using GPS to determine the location, GPS receivers must be provided at each base station location, which leads to considerable additional costs.

A GPS receiver integrated in the communication terminal for determining the location cannot be considered due to the associated high costs, the additional weight and the relatively high power consumption of the GPS receiver.

The invention is therefore based on the object of determining the location of a communication terminal in a non-time-synchronous mobile radio network with simple means and without additional load on the mobile radio network with sufficient accuracy. The location should also be possible in the event of reception interference on the communication terminal.

The object of the invention is solved by the features of claims 1 and 2, respectively. Advantageous developments of the invention are specified in the subclaims. Due to the exclusive broadcasting of the signals of the base stations and the location calculation on the communication terminal itself, the capacity of the mobile radio network is not unnecessarily burdened, traffic channels for mutual data exchange are not required.

By using already existing bursts of the individual base stations and by taking into account the non-time-synchronized position of these bursts with one another, the use of further aids such as GPS can be completely dispensed with.

For an internal time stability of a base station, accuracies of 0.05 ppm are typically required. The respective time differences should therefore be measured with comparable accuracy - both at the base stations and at the communication terminal itself. Advantageously, a highly accurate counter is used for this purpose, the counting frequency of which is derived from the frequency of the respective transmission oscillator.

With a preferred use of bursts with a typical length of 471 μs and due to the highly precise counter, location accuracies of 85 m can typically be achieved. When using signals from more than 3 base stations for location determination, this accuracy can be further increased.

In a first preferred embodiment The individual locations of the base stations, which are a- to a first _B sisstation adjacent transmitted together with the location of the first base station by means of its broadcast control channel (BCCH) to the communication terminal. As a result the location terminal of the other base stations is tracked by the communication terminal.

In a second preferred embodiment, the individual locations of the base stations are above the respective

Broadcast control channel (BCCH) received directly individually at the communication terminal, whereby the scarce capacity of the broadcast control channel (BCCH) is less burdened.

According to the invention, suitable other channels could also be used to transmit the locations instead of the broadcast control channel (BCCH).

In order to be able to determine the signal delay differences between the bursts, an additional device is advantageously arranged at each base station. With the help of this additional device, the network quality can also be monitored with the aid of the channels transmitting with constant, maximum power.

The signal propagation time differences between the bursts determined at the first base station and thus also the determined respective transmission times of these bursts will hardly change. The transmission times can therefore be transmitted relatively rarely.

As an alternative to sending the respective transmission times of the bursts, the transmission delay differences determined at the base station and the subsequent determination of the transmission times of the bursts can also be carried out on the communication terminal.

If environmental disturbances or shadows occur, the location of the communication end devices can nevertheless be calculated using the previously determined received data using statistical methods. According to the invention, the received data are stored in a list in the communication terminal. This calculation option is of great advantage, particularly in the case of difficult topography.

Application examples of the invention can be found in determining the location of a communication terminal in a non-time-synchronized mobile radio network.

An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. According to the invention:

1 shows a mobile radio system with a plurality of base stations and a communication terminal,

2 shows the signal propagation time differences determined at a first base station between the bursts of the base stations from FIG. 1, FIG. 3 shows the determination of the propagation time differences on the communication terminal that are used for determining the location. FIG. 4 shows a representation for determining the location of a communication terminal.

1 shows three base stations BTS1, BTS2, BTS3 within a mobile radio system, each broadcasting their known locations ZI, Z2, Z3, and their Burstl, Burst2 and Burst3, which are not time-synchronized with one another, as signals periodically. Likewise, at a first base station BTS1, for example, the transmission times of burst2 and burst3 determined there, based in each case on their own burstl, are periodically broadcast by this first base station BTSl. The ascertained transmission times of the bursts are described in FIG. 3 and are not shown here. The signals described are received at the communication terminal MS and with their help the location Zm of the communication terminal MS is calculated independently and without communication with the network.

2 shows the signal transit time differences .DELTA.tx2 and .DELTA.tx3 determined at a first base station BTS1, the burst2 and the burst3 being received by two adjacent base stations BTS2 and BTS3 at the first base station and being compared with one's own burst1.

The rising edge of the Burstsl is used for example as a reference and compared with the rising edges of Burst2 or Burst3. The signal transit time differences .DELTA.tx2 and .DELTA. The signal delay differences .DELTA.tx2 and .DELTA.tx3 each consist of the time offsets of the non-time-synchronized bursts among one another and of the transit times of the bursts Burst2 and Burst3, respectively, which are caused by the distance of the base station BTS1 to the base station BTS2 or the base station BTS1 to the base station BTS3. With the help of the known at the first base station sites ZI, Z2, Z3 of the base stations BTSl, BTS2, BTS3, the respective distance between the base stations BTSl and B _TS may be 2 or calculated between BTSl and BTS3 and the respective _A ussendezeitpunkt Δ _{BTSI / BT} S2 of burst2 or Δ _{BTS1 BTS3} of burst3 can be determined as the respective relative time zero. The transmission _times Δ _{BTSI / BTS2} and Δ _{BTS1 BTS3} are shown in FIG. 3 below. With the help of the broadcast control channel BCCH of the first base station BTS1, these are broadcast and thus reach the communication terminal MS. Instead of the BCCH, another suitable channel could be used.

The time analysis described here for the first base station BTS1 and the subsequent broadcasting apply in the same way to all other base stations with the signals received there in each case.

3 shows the burst delay time differences .DELTA.t'2 and .DELTA.t'3 determined on the communication terminal, wherein the burst I of the base station BTS1 received there is compared with the received burst 2 or burst 3 of the neighboring base stations BTS2 and BTS3 and also here, for example, the rising edge of the burst I as Serves reference.

As described in FIG 2, and the measurements from the first base station _BTS ι Aussendezeitpunkte Δ _/ Δ _BTS2 and _BT SI _{/ B} T _S3 ls ^a relative time access nodes to the communication terminal MS. With the aid of the burst delay differences Δt'2 and Δt'3 determined on the communication terminal MS, it is now possible to determine related delay differences Δt2 and Δt3 which are used to determine the location Zm of the communication terminal.

4 shows the location Zm of the communication terminal MS and three locations ZI, Z2, Z3 of the base stations BTS1, BTS2, BTS3. With the help of the distances k, k + c-Δt ₂ and k + c-Δt _{3 of} the communication terminal MS to the three base stations BTS1, BTS2 and BTS3 and their locations Z1, Z2, Z3, the location z _{m of} the communication terminal MS can be determined using a implemented be determined algorithm on the communication terminal MS can be determined.

From the equation system: | z _m - zι | = k

| z _m - z ₂ | = k + Δt ₂ -c | z _m - z ₃ | = k + Δt ₃ -c with zi as the known location of the first base station BTS1, z ₂ as the known location of the second base station BTS2, z ₃ as the known location of the third base station BTS3, k as the distance of the communication terminal MS to be determined from the first base station BTSl,

Δt ₂ and Δt ₃ as determined transit time differences and with the speed of light c the location z _m can be determined.

The locations of Zl, Z2, Z3 can be transmitted, for example, in the coordinates of the UTM coordinate system, the Cartesian coordinate system or any other coordinate system. When transmitting in Cartesian (x, y) coordinates, the location z _{m of} the communication terminal MS is calculated using: z _m = Xm + j-ym as the location of the communication terminal MS, zi = xi + j-yials location of a first base station BTS1, z ₂ = x ₂ + jy ₂ as the location of a second base station BTS2, z ₃ = x ₃ + jy ₃ as the location of a third base station BT _S 3,

wherein further received locations zi from other base stations with the coordinates (x, y, z) the accuracy of the stand ortberechnung of the communication terminal MS further increased or the individual z-coordinates of these locations for _A as _A usdruck for the height of the location z _m of the communication terminal MS can still be included. The data of the individual locations Z1, Z2, Z3 are communicated to the respective base stations, for example, via an operating & maintenance center (OMC) or via an assigned administration device, or these are programmed in at the base stations via a local maintenance terminal (LMT) and are therefore available there.

In the exemplary embodiment, the runtime differences required for determining the location are determined using Burstl, Burst2 and Burst3, but the evaluation of other signals periodically broadcast by the respective base stations is also possible, provided they are suitable for determining the location with sufficient accuracy.

Likewise, the use of appropriately suitable other channels for broadcasting the described signals from the base stations instead of the broadcast control channel (BCCH) is possible.

Claims

claims 1.) Method for determining the location of a mobile communication terminal (MS) in a non-time-synchronous mobile radio system with several base stations (BTS1, BTS2, BTS3, ...), where each base station (BTSl, BTS2, BTS3, ...) signals its burst (Burstl, Burst2, Burst3, ...), its location data (ZI, Z2, Z3, ...) and determined times of transmission ( Δ _{BTSI BT} S, Δ _BTS IB _T S3) of the bursts broadcast periodically, in which the communication terminal (MS) receives the signals from neighboring base stations (BTS1, BTS2, BTS3, ...) and uses it to calculate its location (z _m ) independently and without communication with the network. 2.) Method for determining the location of a mobile communication terminal (MS) in a non-time-synchronous mobile radio system with several base stations (BTS1, BTS2, BTS3, ...), where each base station (BTS1, BTS2, BTS3, ...) signals as their burst (Burstl, Burst2, Burst3, ...), their location data (Zl, Z2, Z3, ...) and determined signal delay differences between periodically broadcasts the bursts of neighboring base stations, in which the communication terminal (MS) receives the signals from neighboring base stations (BTS1, BTS2, BTS3, ...) and uses it to calculate its location (z _m ) independently and without communication with the network. 3.) Method according to claim 1, in which with the aid of an additional device at a first base station (BTSl) their burst (Burstl) related signal delay differences (Δtxl = 0, Δtx2, Δtx3, ...) between the burst (Burstl) of the first base station (BTSl) and the bursts (Burst2, Burst3, ...) of neighboring base stations (BTS2, BTS3 , ...) and the respective transmission times of the bursts (Δ _{BTS1 / BTS2} , Δ _{BTΞI / BTS3 /} ...) with the aid of the distances from the first base station (BTS1) to the neighboring base stations (BTS2, BTS3, ...) known from the location data and the transmission _times (Δ _{BTS1 BTS} , Δ _{BTS1 BTS3} ) are each transmitted as relative time zero points to the communication terminal (MS). 4.) Method according to claim 2, in which with the aid of an additional device at a first base station (BTSl) the signal propagation time differences related to their burst (Burstl) (Δtxl = 0, Δtx2, Δtx3, ...) between the burst (Burstl) of the first base station (BTSl) and the bursts (Burst2, Burst3, ...) of neighboring base stations (BTS2, BTS3, ...) determined and are transmitted to the communication _terminal (MS) and there the respective time of transmission of the bursts (Δ _BTS ι _{/ BTS2} , Δ _{BTS1 BTS3} ) as a relative time zero with the aid of the distances of the first base station (BTS1) to the neighboring ones known from the location data to the communication terminal (MS) Base stations (BTS2, BTS3, ...) is calculated. 5.) Method according to claim 3 or 4, in which on the communication terminal (MS) the burst delay differences (Δt '1 = 0, Δt ^' 2, Δt'3, ... based on the burst (Burstl) of the first base station (BTSl) ... ) between the burst (Burstl) the ERS th base station and the burst (BURST2, Burst3, ...) of adjacent base stations (BTS2, BTS3, ... determined) and elp _H with the respective relative time zero (Δ _BT sι _/ Bτs2 _' Δ _BTS ι / _BTS 3) based on the burst (Burstl) of the first base station (BTSl) related transit time differences (Δt2, Δt3, ...) are calculated, which are used to determine the location (z _m ) of the Communication terminal (MS) can be used. 6.) Method according to one of the preceding claims, in which the data of the respective location (ZI, Z2, Z3, ...) of each individual base station via the respective broadcast control channel (BCCH) or via its own channel to the Communication terminal (MS) arrive. 7.) Method according to one of claims 1 to 5, in which the data of the locations (Z2, Z3, ...) of neighboring base stations (BTS2, BTS3, ...) of a first base station (BTS1) together with the Data of your own location (ZI) via the Broadcast control channel (BCCH) of the first base station or via a separate channel of the first base station (BTS1) reach the communication terminal (MS). 8.) Method according to one of the preceding claims, in which the first base station (BTS1) determines the one determined by it _{Transmission times of} the bursts (Δ _{BTS1 / BTS2} , Δ _{BTS1 BTS3} ) or the signal propagation time differences determined with them (Δtxl = 0, Δtx2, Δtx3, ...) broadcast via their broadcast control channel (BCCH) or via their own channel and broadcast them get to the communication terminal (MS). 9.) Method according to one of the preceding claims, in which, with the aid of an implemented algorithm on the communication terminal (MS), its location (z _m ) on the basis of the respectively determined transit time differences (Δt2, Δt3, ...) of the bursts (Burstl, Burst2 , Burst3, ...) and the transmitted data of the Locations (ZI, Z2, Z3, ...) of neighboring base stations (BTS1, BTS2, BTS3, ...) is calculated. 10.) Method according to one of the preceding claims, in which the location to be determined z _{m of} the communication terminal (MS) is determined using the signals from at least three base stations (BTS1, BTS2, BTS3) using the system of equations | z _m - zι | = k | z _m - z ₂ | = k + Δt ₂ -c | z _m - z ₃ | = k + Δt ₃ -c calculated with zi as the location of a first base station (BTS1), z ₂ as the location of a second base station (BTS2), z ₃ as the location of a third base station (BTS3), k as the distance to be determined of the communication terminal ( MS) from the first base station (BTSl), Δt ₂ as the determined transit time difference between the bursts of the second and the first base station, Δt ₃ as the determined transit time difference between the bursts of the third and the first base station and with c, the speed of light. 11.) Method according to one of the preceding claims, in which the locations of the base stations (ZI, Z2, Z3, ...) are transmitted in the coordinates of the UTM coordinate system or the Cartesian coordinate system or any other coordinate system. 12.) Method according to claim 10, in which locations zi of the base stations are transmitted in Cartesian coordinates and the location z _{m of} a communication terminal (MS) is calculated in Cartesian (x, y) coordinates with: z _ra = u + j- ym as the location of the communication terminal (MS), zi = xi + j -yi as the location of a first base station (BTS1), z ₂ = * 2 + jy ₂ as the location of a second base station (BTS2), z ₃ = x ₃ + jy ₃ as the location of a third base station (BTS3), whereby optionally the additional location Zi received with the coordinates (x, y, z) increases the accuracy of the location calculation of the communication terminal (MS) and / or the individual z coordinates of the locations Zi of the base stations as an expression of the height of the location of the communication - end devices (MS) can be included. 13.) Method according to the preceding claims, in which the respective burst delay time difference (Δt '1 = 0, Δt' 2, Δt '3, ...) or signal delay time difference (Δtxl = 0, Δtx2, Δtx3, ...) at Communication terminal and / or at the respective base station is determined with the aid of a high-precision counter with a counting frequency derived from the frequency of the transmission oscillator. 14.) Method according to the preceding claims, in which the communication terminal extrapolates its location (z _m ) from older and current received data or only from older received data using statistical methods, said received data being stored in a list in the communication terminal (MS) , 15) The process according to the preceding claims, wherein each base station (BTSl, BTS2, BTS3, ...) the data of the jeweili _¬ gen locations (ZI, Z2, Z3, ...) via a Operating & Maintenance Center (OMC ⁾ or via an assigned administrative facility or during the establishment via a local maintenance terminal (LMT) at each base station be programmed in and are therefore available there.