CN1852591B - A method for locating a mobile terminal - Google Patents

Abstract

When mobile terminal in non-soft switch area, RNC determines current location of mobile terminal based on multiple distance values from mobile terminal to base stations in each neighboring cell as well as ToA distance value between mobile terminal to base station in current cell. The invention raises accuracy for positioning mobile terminal

Description

A method for locating a mobile terminal

technical field

The present invention relates to a positioning technology in a mobile communication system, in particular to a method for positioning a mobile terminal.

Background technique

The research on wireless positioning technology began with the automatic vehicle positioning system in the 1960s, and then the technology was widely used in public transportation, taxi dispatching, and security tracking. Later, as people's demand for location-based information services increased, wireless positioning technology received more attention from researchers. improvement.

In the wideband code division multiple access (WCDMA) system, three positioning technologies are defined, namely cell identification (Cell-ID), observed time difference of arrival (OTDOA) and assisted GPS (A-GPS), among them, OTDOA and A-GPS Both put forward higher requirements for WCDMA system or mobile terminal in WCDMA system. The former increases the network cost of WCDMA system, and the latter increases the cost of mobile terminal. Moreover, A-GPS is also restricted by the environment where the mobile terminal is located. Cell-ID is the simplest to implement, but the accuracy is also the worst.

Therefore, an enhanced Cell-ID positioning technology is proposed, that is, a cell identification combined with a round-trip time (CIRTT) positioning method. -Tx Time Difference) measurement request, and according to the identification of the mobile terminal, determine the cell (one or more) that the mobile terminal currently belongs to, and send a signal round-trip time (RTT) measurement request to the base station of the cell to which the mobile terminal currently belongs; secondly, the mobile The base station of the cell to which the terminal currently belongs tests the signal round-trip time (RTT) between the mobile terminal and the mobile terminal that receives the measurement request tests its own Rx-Tx Time Difference; again, the base station of the cell to which the mobile terminal currently belongs will measure the RTT Send it to the RNC, and the mobile terminal also sends the measured Rx-Tx Time Difference value to the RNC; finally, the RNC obtains the time of arrival (ToA) according to the formula (RTT-Rx-Tx Time Difference)/2, and then according to the formula (RTT -Rx-Tx Time Difference)×speed of light/2 to get the ToA distance value to determine the current location of the mobile terminal.

Using the CIRTT positioning method, for a mobile terminal in a non-soft handover area, since the RNC can only obtain the RTT between the base station and the mobile terminal in a cell to which the mobile terminal currently belongs, the ToA distance value is obtained by combining the Rx-Tx Time Difference of the mobile terminal , so the range of locating the mobile terminal is a circle for the omni-directional cell, and an arc ring for the sector cell. As shown in FIG. 1 , FIG. 1 is a schematic diagram of using the CIRTT positioning method to locate a mobile terminal in a non-soft handover area in the prior art.

Using the CIRTT positioning method, for a mobile terminal in a soft handover area, since the RNC can obtain multiple RTTs between the base station and the mobile terminal in multiple cells to which the mobile terminal currently belongs, combined with the Rx-Tx Time Difference of the mobile terminal, multiple ToA distance value, so that multiple circular rings can be obtained for omnidirectional cells, and multiple arc rings can be obtained for sectoral cells, and the specific position of the mobile terminal can be located through the intersection points between these multiple circular (arc) rings. As shown in FIG. 2 , FIG. 2 is a schematic diagram of positioning a mobile terminal in a soft handover area by using the CIRTT positioning method in the prior art.

There are disadvantages in using the CIRTT positioning method to locate the mobile terminal. First, for the positioning of the mobile terminal in the non-soft handover area, since the RNC can only obtain the RTT between the base station and the mobile terminal of the cell to which the mobile terminal currently belongs, it can locate The range of the mobile terminal will only be a circle (arc) ring, the position is uncertain and the range is relatively large; second, for the positioning of the mobile terminal in the soft handover area, although the RNC can obtain multiple RRTs to determine the specific location of the mobile terminal location, but in the WCDMA system, the soft handover of the mobile terminal only accounts for a small proportion, that is, the probability that the mobile terminal is in the soft handover area is small, and in most cases the mobile terminal is in the non-soft handover area. Therefore, in In most cases, the positioning of mobile terminals still has the problem of uncertain location and large range.

Therefore, using the CIRTT positioning method to locate a mobile terminal generally has relatively low positioning accuracy.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for locating a mobile terminal, which can improve the positioning accuracy of locating the mobile terminal when the mobile terminal is in a non-soft handover area.

According to above-mentioned purpose, technical scheme of the present invention is achieved like this:

A method for locating a mobile terminal, the radio network controller RNC stores the signal propagation model of each cell, the method includes: A, when the RNC receives the round-trip time RTT from the base station of the cell to which the mobile terminal currently belongs and the transmission and reception received from the mobile terminal The time difference Rx-Tx TimeDifference is calculated, and when only the time of arrival ToA distance value between the mobile terminal and the base station of a current cell is obtained, the adjacent cell measurement control signal is sent to the mobile terminal;

B. The mobile terminal reports to the RNC the downlink path loss value of each neighboring cell or the signal strength of the signal received from each neighboring cell;

C, RNC will report the downlink path loss value of each neighboring cell corresponding to the signal propagation model of each neighboring cell saved by RNC, and obtain multiple distance values between the mobile terminal and the base stations of each neighboring cell; or according to the reported value from each neighboring cell After the signal strength of the signal received by the cell and the signal strength of the transmitted signal of each adjacent cell are calculated to obtain the downlink path loss value from the mobile terminal to each adjacent cell, corresponding to the signal propagation model of each adjacent cell saved by the RNC in advance, the mobile terminal to each adjacent cell is obtained. Multiple distance values between base stations of each neighboring cell;

D. The RNC determines the current location of the mobile terminal according to multiple distance values between the mobile terminal and the base stations of each neighboring cell and the ToA distance value between the mobile terminal and the base station of the cell it currently belongs to.

The Rx-Tx Time Difference described in step A is obtained by testing the mobile terminal.

Before step A, the method also includes:

A1. The RNC sends a Rx-Tx Time difference measurement request to the mobile terminal, and sends an RTT measurement request to the base station of the cell to which the mobile terminal currently belongs;

A2. The base station of the cell where the mobile terminal currently belongs to the RTT measurement request performs RTT measurement, and the mobile terminal that receives the Rx-Tx Time difference measurement request performs Rx-Tx Time difference measurement;

A3. The base station of the cell to which the mobile terminal currently belongs sends the measured RTT to the RNC; the mobile terminal sends the measured Rx-Tx Time difference to the RNC;

A4. The RNC uses the formula (RTT-Rx-Tx Time Difference) × speed of light/2 to calculate the ToA distance value between the mobile terminal and the base station of the cell to which the mobile terminal currently belongs;

A5, RNC judges whether more than one ToA distance value is calculated, if yes, execute step A6; otherwise, execute step A;

A6. According to more than one ToA distance value, the RNC obtains a plurality of rings or circular arcs in which the mobile terminal currently belongs to respectively locate the mobile terminal, and uses the intersection points between these rings or circular arcs as the current location of the mobile terminal.

When the mobile terminal described in step B reports the downlink path loss value of each neighboring cell, the neighboring cell is a same-frequency neighboring cell or a different-frequency neighboring cell;

When the mobile terminal in step B reports the signal strength of the received signal, the adjacent cell is an intra-frequency adjacent cell, an inter-frequency adjacent cell or an inter-system adjacent cell.

The process of obtaining the downlink path loss value described in step B is:

The mobile terminal receives signals from each neighboring cell and detects the signal strength of the received signal, and obtains the signal strength of the transmitted signal of each neighboring cell through the system message broadcast by each neighboring cell, and then calculates the signal strength of the transmitted signal of each neighboring cell and the signal strength of the received signal to obtain the downlink path loss value of each neighboring cell.

The signal strength of the transmitted signal of each neighboring cell described in step C is pre-stored by the RNC;

The calculated downlink path loss value from the mobile terminal to each neighboring cell as described in step C is the difference between the signal strength of the transmitted signal and the signal strength of the received signal of each neighboring cell.

The process of determining the current location of the mobile terminal according to the multiple distance values between the mobile terminal to the base stations of each neighboring cell and the ToA distance value between the mobile terminal and the base station of the cell to which it currently belongs is as described in step D:

According to the multiple distance values between the mobile terminal and the base stations of each neighboring cell, the RNC obtains multiple rings or circular arcs for positioning the mobile terminal in each neighboring cell, and obtains according to the ToA distance value between the mobile terminal and the base station of the current cell. The cell to which the mobile terminal currently belongs locates the rings or arcs of the mobile terminal, and uses the intersection of these rings or arcs as the current location of the mobile terminal.

The process of determining the current location of the mobile terminal according to the multiple distance values between the mobile terminal to the base stations of each neighboring cell and the ToA distance value between the mobile terminal and the base station of the cell to which it currently belongs is as described in step D:

According to the ToA distance value between the mobile terminal and the base station of the current cell and the measurement error stipulated by the 3GPP protocol, determine the location area range of the mobile terminal and divide it into blocks. According to multiple distance values between the mobile terminal and the base stations of each neighboring cell, Then calculate the sum of the squares of the difference between the distance between each block center and the distance between the antennas of each neighboring cell and the distance between the mobile terminal and the base station of each neighboring cell, and finally obtain the block center with the smallest cumulative sum, and use the The central position of the block is used as the current position of the mobile terminal.

The process of obtaining the distance from the center of each block to each neighboring cell antenna is as follows:

The RNC pre-stores the antenna positions of each neighboring cell, and calculates the distance between each block center and each neighboring cell antenna according to the position of the block center and the antenna positions of each neighboring cell pre-stored by the RNC.

The RNC stores the sector information of each cell, and the determination of the location area range of the mobile terminal is also based on the sector information of the cell to which the mobile terminal belongs stored by the RNC.

The method of dividing into blocks is a method of dividing into blocks with equal intervals or a method of dividing into blocks with equal arc lengths. As can be seen from the above scheme, when the mobile terminal is in a non-soft handover area, the RNC of the present invention can obtain the distance from the mobile terminal to the current cell according to the multiple distance values between the mobile terminal and the base stations of each adjacent cell and the current cell distance obtained by using the prior art. The specific location of the terminal is determined by the ToA distance value between the base stations, instead of determining the specific location of the mobile terminal only according to the ToA distance value between the mobile terminal and the base station of the current cell as in the prior art, thereby improving the positioning of the mobile terminal. positioning accuracy.

Description of drawings

FIG. 1 is a schematic diagram of positioning a mobile terminal in a non-soft handover area by using the CIRTT positioning method in the prior art.

Fig. 2 is a schematic diagram of positioning a mobile terminal in a soft handover area by using the CIRTT positioning method in the prior art.

FIG. 3 is a flowchart of a method for locating a mobile terminal according to the present invention.

FIG. 4 is a flowchart of a second method for locating a mobile terminal according to the present invention.

Fig. 5 is a schematic diagram of location areas and blocks of mobile terminals determined in the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail by giving specific embodiments and referring to the accompanying drawings.

In order to improve the positioning accuracy of positioning the mobile terminal, the present invention adopts the following methods.

When the mobile terminal is in the soft handover area, the method provided by the prior art is used to locate the mobile terminal.

The present invention pre-stores the signal propagation models of each cell in the RNC. When the mobile terminal is in a non-soft handover area, first, the RNC sends the adjacent cell measurement control signal to the mobile terminal; secondly, the mobile terminal that receives the adjacent cell measurement control signal sends The RNC reports the downlink path loss value of each adjacent cell detected by itself, and the adjacent cell can be the same frequency adjacent cell or a different frequency adjacent cell; finally, the RNC corresponds the obtained downlink path loss value of each adjacent cell to each pre-stored adjacent cell Based on the signal propagation model of the district, the multiple distance values between the mobile terminal and the base stations of each neighboring district are obtained. The ToA distance value between the base stations of the cell currently belonging to determines the specific location of the mobile terminal.

The signal propagation model of each cell pre-saved in RNC respectively defines the signal propagation loss characteristics of the corresponding cell, and the present invention can determine according to the signal propagation model of each adjacent cell and the downlink path loss value of each adjacent cell reported by the mobile terminal The distance between the base station of each neighboring cell and the mobile terminal.

The process for the mobile terminal to detect the downlink path loss value of each neighboring cell is as follows: firstly, the mobile terminal receives signals from each neighboring cell and detects the signal strength of the received signal; secondly, the mobile terminal acquires The signal strength of the transmitted signal of each neighboring cell; finally, the mobile terminal calculates the difference between the signal strength of the transmitted signal of each neighboring cell and the signal strength of the received signal to obtain the downlink path loss value of each neighboring cell.

When the mobile terminal does not support the function of reporting the downlink path loss value of each adjacent cell, the present invention can also enable the mobile terminal to report the signal strength of the signal received from each adjacent cell to the RNC, and the RNC then reports the signal strength from each adjacent cell to the RNC. The downlink path loss value of each adjacent cell is obtained by calculating the signal strength of the signal received by the cell and the signal strength of the transmitted signal of each adjacent cell. The signal strength of the transmitted signal of each neighboring cell is pre-stored by the RNC.

When the adjacent cell of the mobile terminal is a different system adjacent cell, the present invention also adopts the mobile terminal to report the signal strength of the received signal from the adjacent cell to the RNC, and the RNC uses the reported signal strength of the received signal and the The downlink path loss value of the adjacent cell is obtained by calculating the signal strength of the transmitted signal of the adjacent cell, and the signal strength of the transmitted signal of the adjacent cell is pre-stored by the RNC.

There are two ways for the RNC to determine the specific location of the mobile terminal according to the multiple distance values between the mobile terminal and the base stations of each neighboring cell and the ToA distance value between the mobile terminal and the base station of the current cell obtained by using the prior art. These two methods will be described separately.

In the first method, the RNC obtains a plurality of circular (arc) rings for positioning the mobile terminal in each neighboring cell according to multiple distance values between the mobile terminal and the base stations of each neighboring cell, and obtains a plurality of circular (arc) rings according to the mobile terminal obtained by using the prior art to the current The ToA distance value between the base stations of the cell to which the mobile terminal belongs is obtained from the circular (arc) ring in which the mobile terminal currently belongs to the cell to locate the mobile terminal, and the intersection point between these circular rings or circular arcs is the specific location of the mobile terminal.

Fig. 3 is the flow chart of the method 1 of positioning mobile terminal of the present invention, and its concrete steps are:

Step 300, RNC sends Rx-Tx Time difference measurement request to mobile terminal, and RNC determines the cell (one or more) that mobile terminal currently belongs to according to the identification of mobile terminal, sends RTT measurement request to the base station of mobile terminal current cell.

The RNC of the present invention initiates a location-related test for a mobile terminal in a dedicated channel connection state. If the mobile terminal is currently in a non-dedicated channel connection state, the RNC transfers the mobile terminal to a dedicated channel connection state by paging or other means before initiating a positioning correlation test. test.

Step 301, the base station of the cell (one or more) to which the mobile terminal currently belongs to which receives the RTT measurement request performs RTT measurement, and the mobile terminal which receives the Rx-Tx Time difference measurement request performs Rx-Tx Time difference measurement.

Step 302, the base station of the cell (one or more) to which the mobile terminal currently belongs sends the measured RTT to the RNC; the mobile terminal sends the measured Rx-Tx Time difference to the RNC.

Step 303, the RNC uses the formula ToA distance value=(RTT-Rx-Tx Time Difference)*speed of light/2 to calculate the ToA distance value between the mobile terminal and the base station of the cell (one or more) to which the mobile terminal currently belongs.

Step 304 , the RNC judges whether more than one ToA distance value has been calculated, and if yes, executes step 305 ; otherwise, executes step 306 .

Step 305, the RNC obtains a plurality of circular (arc) rings in which the mobile terminal currently belongs to respectively locate the mobile terminal according to more than one ToA distance value, and uses the intersection point between these circular (arc) rings as the current location of the mobile terminal.

Step 306, the RNC sends a neighboring cell measurement control signal to the mobile terminal.

Step 307, the mobile terminal having received the neighboring cell measurement control signal measures the neighboring cells, and reports the detected downlink path loss values of each neighboring cell to the RNC.

The mobile terminal of the present invention can also report the signal strength of the signal received from each neighboring cell to the RNC.

Step 308, the RNC judges whether the measurement result is received within the set time, if yes, executes step 310; otherwise, executes step 309.

Step 309, the RNC obtains the circle (arc) ring where the mobile terminal currently belongs to locate the mobile terminal according to the ToA distance value calculated in step 303, and uses the circle (arc) ring as the current location of the mobile terminal.

Step 310, RNC corresponds the obtained downlink path loss value of each adjacent cell to the signal propagation model of each adjacent cell stored in advance, obtains multiple distance values between the mobile terminal and the base stations of each adjacent cell, and obtains the respective distance values of each adjacent cell Locate a plurality of circular (arc) rings of the mobile terminal, and adopt step 309 to obtain the circular (arc) rings of the cell to which the mobile terminal currently belongs to locate the mobile terminal, and use the intersection points between these circular (arc) rings as the current location of the mobile terminal ,Finish.

When the mobile terminal reports the signal strength of the signal received from each neighboring cell, the RNC obtains each Step 310 is performed after the downlink path loss value of the neighboring cell is obtained.

Using the method described in Figure 3, although the positioning accuracy of positioning the mobile terminal can be improved when the mobile terminal is in a non-soft handover area, since the attenuation characteristics of the signals of each neighboring cell of the mobile terminal during propagation are greatly affected by the environment, Moreover, the signal itself also has certain fluctuations, so the signal propagation model of each cell pre-stored by the RNC is also difficult to accurately reflect each actual situation. If step 310 is simply used to determine the current location of the mobile terminal, the robustness of the algorithm is not good enough, and at the same time, there may be a large deviation in the specific location of the mobile terminal. Therefore, the present invention proposes a second method.

The second method, considering the measurement error and the distance deviation caused by non-line-of-sight (NLOS) propagation, this method first determines the location area range of the mobile terminal according to the ToA distance value between the mobile terminal and the base station of the current cell. The range is divided into blocks, and then the distance between each block center and each neighboring cell antenna is calculated according to the position of the block center and the antenna position of each cell pre-saved by RNC, and then the distance between each block center and each neighboring cell is calculated The sum of squares of the difference between the distance between the antennas and the distance between the mobile terminal and the base stations of each neighboring cell, and finally obtain the block center with the smallest cumulative sum, and use the block center position as the current location of the mobile terminal .

Wherein, the distance from the mobile terminal to each neighboring cell may adopt some steps described in FIG. 3 .

Fig. 4 is the second flow chart of the method for positioning mobile terminal of the present invention, and its specific steps are:

Steps 400-409 adopt the process described in steps 300-309.

Step 410 , the RNC obtains the cell where the mobile terminal currently belongs to locate the location area of the mobile terminal according to the ToA distance value calculated in step 303 , the pre-saved sector information, the NLOS introduced bias and the measurement error.

According to the 3GPP agreement, the RTT measurement accuracy is +-0.5chips, the quantization accuracy is 1/16chips, and the quantization error is +-1/32chips; the Rx-Tx Time Difference Type 1 measurement accuracy is +-1.5chips, the quantization accuracy is 1chips, and the quantization error is +-0.5 chips; Rx-Tx Time Difference Type 2 measurement accuracy +-1chips, quantization accuracy 1/16chips, quantization error +-1/32chips. NLOS introduces a deviation RNLOS is related to the environment, and generally can be in the range of 0 to 200m. From this, the upper and lower limits of the ToA distance value can be obtained:

When measuring with Type 1:

Lower limit of ToA distance value 1=ToA distance value+(-0.5chips-1/32chips-1.5chips-0.5chips)×light speed/2=ToA distance value-98m

Upper limit of ToA distance value 1=ToA distance value+(0.5chips+1/32chips+1.5chips+0.5chips)×light speed/2+RNLOS=ToA distance value+98m+RNLOS

When measuring with Type 2:

ToA distance value lower limit 2 = ToA distance value + (-0.5chips-1/32chips-1chips-1/32chips) x light speed / 2 = ToA distance value -59m

Upper limit of ToA distance value 2 = ToA distance value + (0.5chips + 1/32chips + 1chips + 1/32chips) × speed of light / 2 + RNLOS = ToA distance value + 59m + RNLOS

The RNC of the present invention can determine the location area of the mobile terminal according to the upper limit of the ToA distance value and the lower limit of the ToA distance value. The lower limit of the ToA distance value and the sector information are determined. Fig. 5 is a schematic diagram of location areas and blocks of mobile terminals determined in the present invention.

Step 411, the RNC divides the location area of the mobile terminal into N blocks in a preset manner, and the center of each block is denoted as (Xn, Yn, Zn), n=0, ..., N-1 .

The pre-set manner may be equal distance or equal arc length, and other similar manners.

Step 412 , the RNC calculates the distances from the center of each block to the antennas of each neighboring cell according to the block result of the location area and the pre-stored antenna positions of each neighboring cell.

The antenna positions of each neighboring cell are denoted as (X'm, Y'm, Z'm), m=0, . Then the distance between each block center and each neighboring antenna is obtained as Rnm=[(Xn-X'm) ² +(Yn-Y'm) ² +(Zn-Z'm) ² ] ^1/2 , (n=0, . . . , N-1, m=0, . . . , M-1).

(n＝0，...，N-1)。Step 413, RNC corresponds the obtained downlink path loss value of each adjacent cell to the signal propagation model of each adjacent cell stored in advance, and obtains multiple distance values between the mobile terminal and the base stations of each adjacent cell, denoted as R'm , m=0,..., M-1; Calculate the sum of the squares of the distance Rnm and R'm difference between the center of each block and the antennas of each neighboring area, that is

(n=0, . . . , N-1).

When the mobile terminal reports the signal strength of the signal received from each neighboring cell, the RNC obtains each Step 413 is executed after the downlink path loss value of the neighboring cell is obtained.

Step 414, RNC takes the block center position (Xn, Yn, Zn) corresponding to the smallest Rn ² as the current location of the mobile terminal according to the calculated Rn ² , n=0, ..., N-1.

When the mobile terminal is in a non-soft handover area, the RNC of the present invention is based on the multiple distance values between the mobile terminal and the base stations of each neighboring cell and the ToA distance between the mobile terminal and the base station of the current cell obtained by using the prior art The value determines the specific location of the terminal, instead of determining the specific location of the terminal only by the ToA distance value between the mobile terminal and the base station of the cell as in the prior art, thereby improving the positioning accuracy of locating the mobile terminal.

Furthermore, in order to make the positioning accuracy of the mobile terminal higher, the present invention determines the location area of the mobile terminal based on the ToA distance value and the measurement error between the mobile terminal and the base station of the current cell, and divides the mobile terminal into blocks. A plurality of distance values between the base stations of each adjacent cell and the distance between each block center and each adjacent cell are calculated to obtain the most suitable block center, and the block center position is used as the current position of the mobile terminal, The robustness of the algorithm for locating the position of the mobile terminal is ensured.

The method provided by the invention can complete the precise positioning of the mobile terminal without increasing the network cost and mobile terminal cost of the WCDMA system.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention. within the scope of protection.

Claims (11)

1. A method for locating a mobile terminal, characterized in that the radio network controller RNC preserves the signal propagation model of each sub-district, the method comprising: A, when RNC receives the round-trip time RTT and From the calculation of the sending and receiving time difference Rx-TxTime Difference received by the mobile terminal, when only the time of arrival ToA distance value between the mobile terminal and the base station of a current cell is obtained, the adjacent cell measurement control signal is sent to the mobile terminal; B. The mobile terminal reports to the RNC the downlink path loss value of each neighboring cell or the signal strength of the signal received from each neighboring cell; C, RNC will report the downlink path loss value of each neighboring cell corresponding to the signal propagation model of each neighboring cell saved by RNC, and obtain multiple distance values between the mobile terminal and the base stations of each neighboring cell; or according to the reported value from each neighboring cell After the signal strength of the signal received by the cell and the signal strength of the transmitted signal of each adjacent cell are calculated to obtain the downlink path loss value from the mobile terminal to each adjacent cell, corresponding to the signal propagation model of each adjacent cell saved by the RNC in advance, the mobile terminal to each adjacent cell is obtained. Multiple distance values between base stations of each neighboring cell; D. The RNC determines the current location of the mobile terminal according to multiple distance values between the mobile terminal and the base stations of each neighboring cell and the ToA distance value between the mobile terminal and the base station of the cell it currently belongs to. 2. The method according to claim 1, characterized in that, the Rx-Tx TimeDifference described in step A is obtained by mobile terminal testing. 3. The method according to claim 1, characterized in that, before step A, the method further comprises: A1. The RNC sends a Rx-Tx Time difference measurement request to the mobile terminal, and sends an RTT measurement request to the base station of the cell to which the mobile terminal currently belongs; A2. The base station of the cell where the mobile terminal currently belongs to the RTT measurement request performs RTT measurement, and the mobile terminal that receives the Rx-Tx Time difference measurement request performs Rx-Tx Time difference measurement; A3. The base station of the cell to which the mobile terminal currently belongs sends the measured RTT to the RNC; the mobile terminal sends the measured Rx-Tx Time difference to the RNC; A4. The RNC uses the formula (RTT-Rx-Tx Time Difference) × speed of light/2 to calculate the ToA distance value between the mobile terminal and the base station of the cell to which the mobile terminal currently belongs; A5, RNC judges whether more than one ToA distance value is calculated, if yes, execute step A6; otherwise, execute step A; A6. According to more than one ToA distance value, the RNC obtains a plurality of rings or circular arcs in which the mobile terminal currently belongs to respectively locate the mobile terminal, and uses the intersection points between these rings or circular arcs as the current location of the mobile terminal. 4. The method according to claim 1, wherein when the mobile terminal described in step B reports the downlink path loss value of each adjacent cell, the adjacent cell is a same-frequency adjacent cell or a different-frequency adjacent cell; When the mobile terminal in step B reports the signal strength of the received signal, the adjacent cell is an intra-frequency adjacent cell, an inter-frequency adjacent cell or an inter-system adjacent cell. 5. The method according to claim 1, wherein the obtaining process of the downlink path loss value described in step B is: The mobile terminal receives signals from each neighboring cell and detects the signal strength of the received signal, and obtains the signal strength of the transmitted signal of each neighboring cell through the system message broadcast by each neighboring cell, and then calculates the signal strength of the transmitted signal of each neighboring cell and the signal strength of the received signal to obtain the downlink path loss value of each neighboring cell. 6. The method according to claim 1, characterized in that, the signal strength of the transmitted signal of each neighboring cell described in step C is pre-stored by RNC; The calculated downlink path loss value from the mobile terminal to each neighboring cell as described in step C is the difference between the signal strength of the transmitted signal and the signal strength of the received signal of each neighboring cell. 7. The method according to claim 1, characterized in that, according to the multiple distance values between the mobile terminal and the base stations of each neighboring cell and the ToA distance between the mobile terminal and the base station of the cell currently belonging to the mobile terminal described in step D The process of determining the current location of the mobile terminal is as follows: According to the multiple distance values between the mobile terminal and the base stations of each neighboring cell, the RNC obtains multiple rings or circular arcs for positioning the mobile terminal in each neighboring cell, and obtains according to the ToA distance value between the mobile terminal and the base station of the current cell. The cell to which the mobile terminal currently belongs locates the rings or arcs of the mobile terminal, and uses the intersection of these rings or arcs as the current location of the mobile terminal. 8. The method as claimed in claim 1, characterized in that, according to the multiple distance values between the mobile terminal and the base stations of each neighboring cell and the ToA distance between the mobile terminal and the base station of the current cell according to the step D The process of determining the current location of the mobile terminal is as follows: According to the ToA distance value between the mobile terminal and the base station of the current cell and the measurement error stipulated by the 3GPP protocol, determine the location area range of the mobile terminal and divide it into blocks. According to multiple distance values between the mobile terminal and the base stations of each neighboring cell, Then calculate the sum of the squares of the difference between the distance between each block center and the distance between the antennas of each neighboring cell and the distance between the mobile terminal and the base station of each neighboring cell, and finally obtain the block center with the smallest cumulative sum, and use the The central position of the block is used as the current position of the mobile terminal. 9. The method according to claim 8, characterized in that, the obtaining process of the distance between the center of each block and each adjacent cell antenna is: The RNC pre-stores the antenna positions of each neighboring cell, and calculates the distance between each block center and each neighboring cell antenna according to the position of the block center and the antenna positions of each neighboring cell pre-stored by the RNC. 10. The method according to claim 8, wherein the RNC stores sector information of each cell, and the determination of the location area range of the mobile terminal is also based on the sector information of the cell to which the mobile terminal belongs stored by the RNC. 11. The method according to claim 8, characterized in that, the block method is an equidistant block method or an equal arc length block method.

Images