KR20050063522A - A method for estimating position of the ue used rtt value - Google Patents

Abstract

The present invention relates to a UE location prediction method using an RTT value. In particular, when the UE is in soft handover, it is possible to predict a more accurate location of the UE by using each RTT value between the associated base station and the UE and the distance between the base station. It relates to a UE location prediction method using the RTT value.

The constituent means of the UE location prediction method using the proposed RTT value according to the present invention includes the steps of: requesting a CN (Core Network) from a SRNC (Serving RNC) to identify a location of a user equipment (UE); The SRNC receiving the location request determines a cell ID of the UE, and determines whether the UE is in soft handover; Requesting a round trip time (RTT) measurement value from one base station if not in soft handover, and requesting a RTT measurement value from all base stations involved in soft handover; Measuring, by the base stations receiving the request, an RTT value and delivering the same to the SRNC; SRNC using the received RTT value and a specific data value to predict the location of the UE and characterized in that it comprises the step of transmitting to the CN.

Description

A METHOD FOR ESTIMATING POSITION OF THE UE USED RTT VALUE}

The present invention relates to a method for predicting a UE location using an RTT value, and more particularly, when the UE is in a soft handover, using the respective RTT value between the base station and the UE and the distance between the base station to more accurately predict the location of the UE. The present invention relates to a UE location prediction method using an RTT value.

There are three main methods for predicting a location of a standard user equipment (UE) provided by a conventional universal terrestrial radio access network (UTRAN).

First, based on the cell ID, a method of requesting a location service (LCS) request (LCS) from a Core Network (hereinafter referred to as "CN") (where CN is located). When a command is issued to know, SRNC (Serving RNC, hereinafter referred to as "SRNC") (which is smaller than CN but covers base station) finds the cell ID to which the UE belongs, which is the basic data of UE location prediction. Once the cell ID is found, the area where the UE is located may be located by using a round trip time (RTT) measurement.

The RTT measurement value converts the time (RTT measurement value) taken from the base station back to the base station through the area where the user or the terminal (UE) is located by the distance, and divides the converted distance value by half, and the terminal from the base station You can find the distance to (UE).

Second, the Observed Time Difference Of Arrival (OTDOA) location prediction method is a method that can accurately display the location of a UE based on longitude and latitude, and predicts the location based on "SFN-SFN observed time difference." These difference values are then used to predict the location of the UE in parallel with the known geographic location and the Real Time Defference (RTD) of the actual downlink signals. The OTDOA measurements between the UE and one base station are hyperbolic, and the area predicted by the UE location is the intersection of the OTDOA measurements between each base station and the UE. In order to increase the accuracy of UE location prediction, the RTT or RX Timing Deviation value may be referred to.

Third, as a network-assisted GPS location prediction method, when a location prediction request comes down from the CN, SRNC, an intermediate medium between the UE location entity in the UTRAN and the CN, considers the UE location prediction possibility. In consideration of UE location predictability, the network sends GPS assistance information such as GPS reference time, satellite lds, and Doppler frequency to the UE. These network-assisted GPS location prediction methods include the UE-assisted method and the UE-based method. In the UE-assisted method, the LNC (location measurement medium) update and one-way propagation before the SRNC sends an assistance message to the UE. RTT measurements may be required for delay compensation. When the UE receives a GPS measurement request (GPS assistance data), the UE reports the GPS satellite pseudorange or other information (SFN-SFN Observed Time Difference measurement, Rx-Tx time difference) to the SRNC and the UE position prediction is calculated on the network. . In the UE-based method, the UE predicts the location value and reports it to the SRNC. Finally, the SRNC delivers the location prediction value to the CN.

There are advantages and disadvantages to the three location prediction methods as described above. In brief, the UE location prediction method according to the second and third methods can predict a more accurate location than the location prediction method based on the cell ID, which is the first method. However, the position estimation by the second method has a burden that the UE can directly measure the "SFN-SFN observed time difference", and the position estimation by the third method requires additional GPS receivers (receivers) in the UTRAN and the UE. There is a burden.

Therefore, the first method, the position prediction method based on the cell ID, does not need an additional device and can predict the location of the UE using only the RTT measurement value.

FIG. 1 is a procedure diagram of a UE location prediction method based on a cell ID, which is the first of the three UE location prediction methods, and a conventional cell ID based UE location prediction method will be described in detail with reference to this.

First, the CN requests the SRNC to confirm the location of the UE to determine the location of the UE or the user (S1). Then, the SRNC receiving the location request determines what happens to the current cell ID of the UE that requested the location (S2). As described above, since the cell ID should be determined first, and the approximate location of the UE can be identified, the cell ID determination must be preceded when the UE location request is required.

After the SRNC determines the cell ID of the UE, the SRNC requests an RTT value from the base station in the cell where the UE is located in order to predict a more accurate location (S3). The RTT value refers to the time taken from the specific base station to return to the base station through the UE. When this value is measured, the distance from the specific base station to the UE can be known by converting the RTT value into a distance and dividing it by half.

The SRNC, which has received the RTT value of the UE by the base station, converts the distance with the RTT measurement value and transmits information to the CN where the specific UE is located (S4).

FIG. 2 illustrates the range of areas that can be predicted by the location of the UE when the location of the UE is predicted using the RTT value as described above. As shown in the figure, the hatched BCDE area can be predicted as the location of the UE. It is a range.

That is, in the conventional UE location estimation method based on the cell ID based location prediction method, only the information that the UE is in one sector area can be obtained, which makes it difficult to know a more accurate location.

The present invention was devised to solve the problems occurring in the UE location prediction method based on the cell ID among the conventional UE location prediction methods, and is applicable when the UE requiring the location prediction is in soft handover. In the case of soft handover, the UE requests a RTT measurement value from a related base station, and estimates UE location using the RTT value, which allows a more accurate UE location to be estimated based on a distance between known base stations. The purpose is to provide.

In order to solve the above technical problem, the constituent means of the UE location prediction method using the present invention, the RTT value,

Requesting a CN (Core Network) from a Serving RNC (SRNC) to locate a user equipment (UE);

The SRNC receiving the location request determines a cell ID of the UE, and determines whether the UE is in soft handover;

Requesting a round trip time (RTT) measurement value from one base station if not in soft handover, and requesting a RTT measurement value from all base stations involved in soft handover;

Measuring, by the base stations receiving the request, an RTT value and delivering the same to the SRNC;

Characterized in that the SRNC has a step of estimating the location of the UE and transmitting to the CN with the received RTT value and a specific data value,

When the SRNC determines the cell ID of the UE, when the SRNC does not know the cell ID for the UE, the SRNC can find out the cell ID by a paging procedure by the CN.

In the case of the soft handover, the SRNC predicting the position of the UE includes using a second cosine law, in which the triangular triangular distance between the RTT values received from each base station and the distance between the known base stations is defined by the triangle. In the case of the soft handover, the location of the UE is more accurate.

Hereinafter, with reference to the accompanying drawings will be described in detail the operation and preferred embodiment of the UE location prediction method using the present invention RTT consisting of the above configuration means. 3 is a flowchart illustrating a method for predicting a UE location according to the present invention, and FIG. 4 is a diagram illustrating a UE location prediction range according to the present invention.

First, in order to identify the position of a UE located at a specific sector within a specific base station cell, a CN (Core Network: referred to as "CN") is sent to the SRNC (Serving RNC, referred to as "SRNC"). A request is made to confirm the current position of Equipment (hereinafter referred to as "UE") (S10) The SRNC is a system that manages a base station (RNC) (hereinafter referred to as "RNC"), which is required for call processing. RNC connected to CN, which is necessary for call processing.

The SRNC, which has been requested to confirm the location, must first determine the ID of the cell in which the UE is located as a prerequisite for predicting the location of the UE. When the cell ID is determined, the SRNC should determine whether the current UE is in soft handover. (S20, S30). The SRNC, which has been requested to confirm the UE location, may determine a known cell ID when the cell ID of the UE is known, and determine the cell ID by a paging procedure by the CN when the cell ID is not known. When the cell ID is determined as such, the approximate location of the UE is determined. Therefore, the following procedure should be performed to predict the more accurate location.

If it is determined that the UE is in soft handover and is not in soft handover, the RTT measurement value is requested to one specific base station, and in the case of soft handover, the RTT value is requested to all related base stations (S40 and S50). . The RTT (Round Trip Time, hereinafter referred to as "RTT") means a time taken from the base station to return to the base station through the UE. In the case of the non-soft handover, since there is only one base station in the cell including the UE to be predicted for location, the RTT measurement value is requested to one base station. If the UE is in soft handover, the UE belongs to the soft handover. Since there may be several base stations in charge of the cell, all the related base stations request the RTT measurement value. In the case of handover, a feature of the present invention is to predict a more accurate UE location using a plurality of RTT values.

The base stations received the RTT measurement from the SRNC measures the RTT value and transmits the measured RTT value to the SRNC. In this case, if the UE is not in soft handover, it will receive an RTT measurement value from one base station, and in soft handover, it will receive an RTT value from several related base stations (S60).

The SRNC, which has received the RTT value from the base station, predicts the location of the UE using specific data already known in advance and transmits the result to the CN (S70). The specific data known in advance may be various, but in particular, when the UE is in soft handover, the distance between each base station is required to predict a more accurate position, and the distance between the base stations is a previously known value. And it can be used to reduce the error of the area of the location of the UE.

The method of estimating the location of a UE using the received RTT measurement value is, first, when the UE is not a soft handover and receives the RTT measurement value from one base station, converts the received RTT value into a distance value. By dividing this in half, the distance from the base station to the corresponding UE can be obtained. In such a case, it may be said to be the same method as the position prediction method based on the cell ID using the conventional RTT measurement value.

When the UE receives an RTT value from several base stations in soft handover, the SRNC converts all received RTT measurements into distance values and then divides them by half. Then, the distances from the respective base stations to the UEs in the soft handover are respectively obtained.

After obtaining all the distances between the base station and the UE, the SRNC calculates the line segment connecting the base station and the UE between the base stations using the cosine second law using the previously known distance between the base station and the calculated distance between the base station and the UE as variables. Find the angle between the connecting segments. Then, it can be predicted that the position of the UE exists at a corresponding position (of course, at a position corresponding to the distance between the base station and the UE) by the obtained angle in the line segment between the base stations.

In FIG. 4, when the UE is in soft handover, when the location of the UE is predicted by receiving RTT measurements from several base stations, the range of the UE location prediction region is shown.

4 (a) shows the range of the UE location prediction area when the UE is in soft handover between two base stations. From the two RTT measurements, the SRNC is the distance from the first base station to the UE (segment AB). Or calculate the line segment AD) and the distance from the second base station to the UE (line segment CB or line segment CD) and use the second cosine law with the distance between the two known base stations (line segment AC). Obtain

That is, a triangle is formed by a line segment connecting a base station and a line segment connecting a UE and each base station, and a line segment connecting a base station and a base station and a UE are connected by using a cosine second law that knows three line segments and calculates their angles. Engraving Between Line Segments The position of the UE can be estimated according to the hatched portions of the two regions as shown in (a) of FIG. 4.

On the other hand, Figure 4 (b) shows the range of the location prediction area of the UE when the UE is a soft handover in the three base stations, the distance from the UE to the base station from each of the three RTT measurement values Next, the position of the UE can be predicted in the same manner as the method described above (when soft handover occurs in the two base stations) by using three known segments of the distance between each known base station and the calculated distance between the base station and the UE. . In this case, unlike the case where the handover occurs in the two base stations, since the distance between the UE and the three base stations is known, position prediction is possible by the shaded portion of one region as shown in FIG.

As shown above, the UE is in soft handover, and the more related base stations that are in charge of the cell where the UE is located, the more accurate the position of the UE can be predicted.

According to the UE location prediction method using the RTT of the present invention having the above configuration means and preferred embodiments, the location prediction method is divided according to whether the UE requiring the location prediction is in the handover, In this case, all base stations in the active SET may request the UE to make an RTT measurement, thereby reducing the area error of the UE location predicted by the simple RTT measurement, thereby providing more improved information on the UE location prediction method. .

1 is a flowchart of a conventional UE location prediction method.

2 is an understanding diagram showing a UE location prediction range by a conventional method.

3 is a flowchart illustrating a UE location prediction method according to the present invention.

4 is an understanding diagram showing a UE location prediction range according to the present invention.

Claims (4)

Requesting a CN (Core Network) from a Serving RNC (SRNC) to locate a user equipment (UE); The SRNC receiving the location request determines a cell ID of the UE, and determines whether the UE is in soft handover; Requesting all associated base stations for RTT measurements when in soft handover as a result of the determination; Measuring, by the base stations receiving the request, an RTT value and delivering the same to the SRNC; The SRNC predicting the location of the UE with the received RTT value and a specific data value and transmitting to the CN, UE location prediction method using the RTT value. The method according to claim 1, When the SRNC determines the cell ID of the UE, when the SRNC does not know the cell ID for the UE, the UE may predict the cell ID by a paging procedure by the CN. . The method of claim 1, wherein in the case of the soft handover, The step of estimating the position of the UE by the SRNC, the position of the UE is estimated by using the second cosine law of the triangular triangle between the RTT values received from each base station and the known distance between the base stations RTT, characterized in that UE location prediction method using values. The method according to claim 1, In the case of the soft handover, the UE location prediction method using the RTT value, characterized in that the more the base stations are more accurate can predict the location of the UE.