KR20040008971A - Apparatus and method for measuring information to support location service in universal mobile telecommunication system - Google Patents

Abstract

PURPOSE: A device of measuring information for supplying a position service in an asynchronous mobile communication system and a method therefor are provided to measure an AT(Absolute Time) by using information on a system frame number and time information transmitted from worldwide GPS receivers, and to transmit the measured AT to a base station main board, thereby exactly measuring the information for supplying the position service. CONSTITUTION: An EPLD(Erasable Programmable Logic Device)(303) generates a frame of a system frame number by using a clock received from a clock generation board(203), finds out delivery time of a common pilot channel having the system frame number, and measures an AT by using time information received from a worldwide GPS receiver(305). A processor(307) transmits the measured AT to a base station main board(209). An alarm unit(309) alarms that a device of measuring information for supplying a position service has a failure.

Description

Apparatus and method for measuring information for providing location service in asynchronous mobile communication system {APPARATUS AND METHOD FOR MEASURING INFORMATION TO SUPPORT LOCATION SERVICE IN UNIVERSAL MOBILE TELECOMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for measuring information for providing a location service of a mobile terminal in an asynchronous mobile communication system, and in particular, to implement an apparatus and method for providing a location service using a network-based system.

In general, the method used to detect the position of a mobile terminal in a mobile communication system includes a cell-id (CELL-ID) method, an angle of arrival (AOA) method, a time of arrival (TOA), and an arrival delay. It can be classified into four methods: a time difference of arrival (TDOA) method and a global positioning system (GPS) satellite method.

First, the cell-ID method is a method of determining the location of a mobile terminal existing in the cell with the location information of the base station while having accurate location information of the base station in charge of each cell.

Next, the arrival angle (AOA) method is a method of knowing the position of the mobile terminal when the angle of the base station and the mobile terminal is known using an intelligent antenna such as a smart antenna.

The arrival time (TOA) method is a method of detecting the position of a mobile terminal with a difference between the time that a signal is transmitted from the base station and the arrival time of the signal, and the arrival delay time (TDOA) method is at least three base stations Is a method of detecting the position of the mobile terminal using the same method as the triangular positioning method transmitted to the mobile terminal.

Finally, the method of using GPS satellite signals is a method of identifying the location of a mobile terminal using the signals received from GPS satellites.

Currently, the mobile communication system measures the position of the mobile terminal by selecting a combination of the four position measuring methods or one of the four methods. In particular, the method of using the GPS satellite signal is increasing in use because it provides an accurate absolute position for the mobile terminal using the signal provided from the GPS satellite.

However, the method of using the GPS satellite signal has a problem that the position of the mobile terminal cannot be measured because the satellite signal does not reach a shaded area such as an underpass. In addition, the cell-ID method has a problem that the location of the mobile terminal is incorrect because the location of the mobile terminal is determined in units of base station cells. In addition, the arrival angle method has a problem that it is impossible to accurately determine the location of the mobile terminal if the transmission angle cannot be determined. In addition, the arrival time and arrival delay time method has a problem that it is not possible to determine the exact position of the mobile terminal due to the position error factors such as the deflection and diffraction of the signal in an environment in which obstacles such as high-rise buildings are concentrated. In addition, since the synchronous mobile communication system synchronizes the base station using a GPS satellite receiver, a position measuring device is not required in hardware, but an asynchronous mobile communication system is required.

Accordingly, an object of the present invention is to provide an apparatus and method for measuring information required for providing a location service of a mobile terminal using a network base in an asynchronous mobile communication system.

Another object of the present invention is to provide an apparatus and method for increasing the accuracy of measured information by measuring a transmission time of a common pilot channel using GPS timing.

The apparatus of the present invention for achieving the above object; In an asynchronous communication system having a base station having a clock generation board and a base station main board, an apparatus for measuring information for providing location services, the system frame number frame is generated by using the clock received from the clock generation board A clock comparator for determining the transmission time of the common pilot channel having the system frame number and using the time information received from the global position system receivers, and transmitting the measured absolute time to the base station mainboard; And an alarm unit for notifying a problem occurring in the device measuring the information for providing the location service.

The method of the present invention for achieving the above object; A method of measuring information for providing location service in an asynchronous communication system having base stations having a clock generation board and a base station main board, the method comprising: generating a system frame number frame using a clock received from the clock generation board; Determining the transmission time of the common pilot channel having the system frame number and measuring the absolute time using the time information received from the global position system receivers, and transmitting the measured absolute time to the base station mainboard. Characterized by including the process.

1 is a diagram illustrating a basic concept of a position measuring device in a network-based method according to an embodiment of the present invention.

2 is a block diagram showing a base station according to an embodiment of the present invention.

3 is a block diagram showing a position measuring device according to an embodiment of the present invention.

4 is a diagram illustrating SFN frame generation in a position measuring apparatus according to an embodiment of the present invention.

5 is a diagram illustrating a timing relationship between an absolute GPS timing time and a CPICH frame according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

Information required for providing location services in an asynchronous mobile communication system is absolute time (AT) and relative time difference (RTD), and the position of the mobile terminal is calculated based on the information. The difference between the absolute time and the relative time is calculated based on the transmission time of the common pilot channel frame (hereinafter referred to as "CPICH"). In the present invention, the position measuring device is a device for reading the transmission time of the CPICH frame as an absolute time using a GPS receiver.

1 is a diagram illustrating a basic concept of a position measuring device in a network-based method. Referring to FIG. 1, an Observed Time Difference of Arrival (OTDOA) method observed in an asynchronous mobile communication system may receive at least three base station signals by a mobile terminal for receiving location service. It should be possible. The reason why the mobile station must receive at least three base station signals is that the mobile station performs position measurement on the basis of triangulation using relative time difference information. Since the OTDOA method, which is a network-based location service, uses a base station frequency, a location can be continuously obtained in a communication area of a mobile terminal.

The synchronous mobile communication system does not need to measure the information of the relative time difference 104 because the synchronization between the base stations is consistent with the GPS, but the asynchronous mobile communication system is a subordinate synchronization that synchronizes the synchronization from the network. Do not. Therefore, in order to obtain the relative time difference 104, it is necessary to know the times of the other base stations 105 and 107 based on one base station 103. In this case, the reference time is the CPICH frame transmission time of the base station 103 and the CPICH frame transmission time of the other base stations 105 and 107, and the relative time difference 104 is known through the CPICH frame transmission time.

In the asynchronous mobile communication system, the clock of the base station operates as a base station frame number (BFN) counter having a 10 ms period and a 4096 chip range, and has a difference of chip offset (T_cell) for each sector. . The difference between the chip offsets is called a system frame number ("SFN") counter. In addition, the SFN has the same period and range as the BFN.

Therefore, the present invention measures the absolute time (GPS timing measurement) 102 using the GPS timing 101 as the transmission time of the CPICH frame having the SFN of 10 ms period in each sector. Here, it is assumed that the position measuring device 211 is a transmission time of a CPICH frame for each SFN frame.

2 is a diagram illustrating a base station according to an embodiment of the present invention. Referring to FIG. 2, in the asynchronous system, the network synchronizer uses a slave clock distributed from the core network. In the core network, synchronization between the base station controller (RNC) uses STM-1, and the clock is adjusted using the E1 / T1 interface between the base station controller 201 and the base station 213. The base station 213 distributes the clock to the board that is matched to the base station through the clock generation board 203, the dependent clock obtained from the E1 / T1 interface.

The modem 205 transmits a CPICH frame having an SFN of 10 ms period to the radio section by using the divided clock. At this time, it is necessary to find out the transmission time of the CPICH frame.

The clock generation board 203 distributes the clock to all boards matched to the base station 213 such as the modem 205 and the position measuring device 211. The clocks distributed to the modem 205 and the position measuring device 211 should be synchronized. However, due to factors such as line length or processor delay, accurate synchronization cannot be achieved. However, if the factors are known in advance, synchronization can be achieved. In addition, in the position measuring device 211 of the present invention, even if synchronization is not correct, it does not matter much.

Since the position measuring apparatus 211 uses the relative time difference of the OTDOA method, if the other base station also has a time delay environment due to the above factors, it may eliminate the delay time. That is, if the time measured by one base station is T1 + α1 and the time measured by the other base station is T2 + α2, and α1 and α2 are errors of the line length or processor delay time common to each base station, T1 + Since T2 + (α1-α2), the common error portion will be almost eliminated.

The position measuring device 211 receives chip offset (T_cell) information from a Node B Application (NBAP) protocol when setting an initial position measuring device, and transmits the measured information to the base station main board 209 equipped with the NBAP protocol. To pass. The base station main board 209 encodes the information received from the position measuring device 211 into a message and transmits the information to a higher location service server. Here, the measured information of the position measuring device 211 is information required for calculating the position of the mobile terminal in the OTDOA method, and means an absolute time.

3 is a block diagram showing a position measuring apparatus according to an embodiment of the present invention. Referring to FIG. 3, the position measuring device 211 includes a clock receiver 301, a clock comparator 303, a controller 307, an interface 311, an alarm 309, a GPS receiver 305, The alarm unit 309 is configured. In particular, the GPS receiver 305 is a module that receives only GPS timing to measure absolute time. The clock receiver 301 receives the clock of the base station and transfers it to the clock comparator 303. The clock comparator 303 generates an SFN frame by using the clock of the base station received from the clock receiver 301 and recognizes the SFN frame start point using time information (GPS timing) output from the GPS receiver 305. Serve A method of generating an SFN frame, a relationship between an SFN frame start point and a transmission time of a CPICH frame, and a detailed method of displaying GPS timing in absolute time will be described later. The controller 307 is responsible for control and management functions, and transmits the measured information received from the clock comparator 303 to the base station main board 209 through the interface unit 311. When a problem occurs in the position measuring device 211, the alarm unit 309 transmits a signal indicating that a problem has occurred to the display unit 322.

4 is a diagram illustrating SFN frame generation in a position measuring apparatus according to an embodiment of the present invention. A process of generating the SFN frame by the clock comparing unit 303 of the position measuring device 211 will be described with reference to FIG. 4.

The position measuring device 211 generates a 10ms BFN frame by inputting a system dependent clock and generates an SFN frame using chip offset (T_cell) information. Here, the position measuring device 211 knows the chip offset (T_cell) information in advance for each sector. The position measuring device 211 generates a BFN frame by inputting a system dependent clock having a 10 ms dependent clock and a T nsec. If T nsec is eight (T_bit), one chip is T_chip, 256 chips are regarded as one symbol T_symbol, and ten symbols are one slot T_slot. That is, one slot is composed of 2560 chips. Therefore, the BFN consists of 15 slots, and can generate an SFN frame having a difference of the chip offset T_cell. The SFN frame of the position measuring device 211 and the SFN frame generated by the modem 205 are synchronized with each other.

5 is a diagram illustrating a timing relationship between a GPS timing absolute time and a CPICH frame according to an embodiment of the present invention. A process of converting GPS timing into absolute time will be described with reference to FIG. 5.

The clock comparator 303 which uses the frequency received from the GPS module 305 as a clock input counts a pulse and converts the pulse into an absolute time. The GPS timing is reset at 1PPS at the GPS Time of Week on Sunday 00:00:00 seconds. That is, the GPS TOW has 604800 seconds. In order to increase the measurement accuracy of the position measuring device 211, the frequency received from the GPS module 305 is designed to have a resolution N times higher than the chip ratio (3.84 Mcps) of the system.

The GPS module 305 generates a clock having T_g nsec obtained by subdividing GPS timing, and the clock comparator 303 counts T_g and converts it to absolute time. The transmission time of the CPICH frame transmitted every 10ms is known as the counted absolute time of GPS timing. That is, the absolute time is measured using time information (GPS timing) based on the transmission time of the CPICH frame. The measured information is transferred to the base station controller 201 and delivered to the processor managing the location service resource. The processor may determine a relative time difference by comparing the measured information (absolute time) received from one base station location measuring apparatus with the measured information (absolute time) received from a location measuring apparatus of other base stations.

In order to provide a location service in an asynchronous mobile communication system, a Serving Mobile Location Center (SMLC) calculates the location of a mobile terminal using the absolute time and the relative time difference.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, while the position of the mobile terminal cannot be measured in the shaded region where the satellite signal is disconnected in the method using the GPS satellite, in the present invention, the information for providing the location service is measured by using the position measuring apparatus. The advantage is that you can. In addition, by measuring information using GPS timing, there is an advantage that the accuracy of the measured information can be improved.

Claims (2)

An apparatus for measuring information for providing a location service in an asynchronous mobile communication system having base stations having a clock generation board and a base station main board, A system frame number frame is generated by using the clock received from the clock generation board, the transmission time of the common pilot channel having the system frame number is determined, and the absolute time is measured using the time information received from the global position system receiver. With clock comparison to do, A control unit for transmitting the measured absolute time to the base station main board; Apparatus for measuring the information for providing location services in the asynchronous mobile communication system, characterized in that it comprises an alarm unit to notify if a problem occurs in the device for measuring the information for providing the location service. A method of measuring information for providing location service in an asynchronous mobile communication system having base stations having a clock generation board and a base station main board, Generating a system frame number frame using the clock received from the clock generation board; Finding out the transmission time of the common pilot channel having the system frame number and measuring the absolute time using the time information received from the global position system receivers; And transmitting the measured absolute time to a base station main board.