KR100272764B1 - Method for tracing phone location of a mobile communication cdma - Google Patents

Abstract

The present invention relates to a method for tracking the location of a terminal in a mobile communication system, and more particularly, to a method for tracking the location of a terminal in a code division multiple access (CDMA) mobile communication system. The present invention relates to a pilot-pien-of pilot signals of neighbor base stations (active, candidata and neighbor set) by a base station through a short message service to a terminal in a code division multiple access (CDMA) mobile communication system. Send a command to report pace. After receiving the above command and searching for a predetermined time, the terminal can accurately determine the location of the current terminal by transmitting a pilot-piene phase of pilot signals of neighboring base stations to the base station through a short service.

Description

Code Division Multiple Access Method Terminal Location Tracking Method of Mobile Communication System

The present invention relates to a method for tracking the location of a terminal in a mobile communication system, and more particularly, to a method for tracking the location of a terminal in a code division multiple access (CDMA) mobile communication system.

In recent years, as mobile communication spreads around the world, it has become legal to provide a service for tracking the location of a terminal. In the United States, the Federal Communications Commission (FCC) provides a location information service that guarantees a certain degree of accuracy, which is expected to be legislated in Korea soon.

As a method of tracking the location of a terminal in a mobile communication system, a global positioning system (GPS) receiver is embedded in a terminal to determine a location using information received from a satellite. However, this method has a problem that a separate receiver must be built in the terminal.

In addition, in an analog cellular mobile phone service (AMPS), a time difference (TDOA; time difference) between signals received by a plurality of base stations is monitored by monitoring a signal (reverse channel) transmitted from a terminal to neighboring base stations. The method of calculating the position of the terminal by collecting information of Of Arrival or Angle of Arrival (AOA) is adopted. In this method, at least three base stations for receiving a signal of a terminal are required in a method using a reception time difference, and at least two base stations are required in a method using the reception angle. However, in the code division multiple access mobile communication system, since the power control of the reverse channel is performed, the base station for receiving the signal of the terminal can be one when the handoff area is not used. Therefore, the terminal location using the reverse channel of the analog cellular system is used. There are many problems in employing the tracking method.

The present invention provides a method for tracking the location of a terminal in a code division multiple access method using a message transmitted from a mobile station to a candidate base station and a candidate base station in a code division multiple access method. The purpose is to provide.

1 is a diagram illustrating a PN offset peculiar to a base station.

2 is a diagram illustrating a P & N offset in a state in which a terminal is separated from a base station.

3 is a diagram illustrating a P & N offset in a state in which a terminal is close to a base station,

4 is a diagram showing a pilot PN PHASE for explaining the present invention.

5 is a reference diagram for calculating a position of a terminal.

* Explanation of symbols for main parts of the drawings

BS1: Operation base station BS2, BS3: Peripheral base station

MS: Terminal

Terminal location tracking method of the code division multiple access method mobile communication system according to the present invention for achieving the above object, a pilot strength measurement message (PSMM: Pilot Strength Measurement Message) transmitted from the terminal to the operating base station and the candidate base station; Includes pilot phase information of active sets and candidate sets in the base station and transmits them to the base station, and transmits each base station in the pilot phase information included in the pilot strength measurement message. The distance between each base station and the terminal is calculated by obtaining the difference in arrival delay time for the pilot signals to reach the terminal. In this case, when the pilot strength measurement message is used as it is, the pilot phase information of three or more base stations is always required to measure the position of the terminal, but many cases may not be met in the handoff mode of the terminal. The problem arises even when the handoff area is not.

Of course, the base station may instruct the terminal to lower the handoff reference value by using a control message so that at least three pilots necessary for position calculation are included in the operating base station and the candidate base station. Another problem arises.

Accordingly, in the present invention, the terminal searches for a pilot signal of a neighbor base station in addition to the operating base station and the candidate base station to calculate a pilot phase telegram of the neighbor base station and a signal, The pilot phase information of one or more pilots is transmitted to the base station so that the location of the terminal can be tracked at all times.

Hereinafter, a method for tracking a terminal location of a code division multiple access method mobile communication system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the code division multiple access mobile communication system, each base station has its own Pseudo Noise Offset, which is composed of 2 ¹⁵ bits. The 1-bit time interval is defined as chip (chip = 1 sec / 1.2288 × 10 ⁶ = 833 ns). In addition, since the PN offsets 2 ⁶ 64 bits of each base station are configured to have a phase difference, 2 ⁹ 512 PN offsets can be allocated to each base station as a result.

1 shows a peen offset inherent to a base station, and will be described based on the peen offset of a base station (operating base station) currently communicating with a terminal.

As shown in the figure, each base station has its own peen offset, which each has a 64-bit phase difference. In the present embodiment, for convenience of description, the PEN offset values of the operating base station BS1 are 0, and the PEN offset values of the peripheral base stations BS2 and BS3 are 64 and 128, respectively.

In this case, assuming that the distance between the three base stations and the terminal is the same (here, the arrival delay time from the base station to the terminal is not taken into account), the pilot signal reception time of the base stations arriving at the terminal is the same. Further, when the pilot signal transmission time of the operation base station is used as a reference, the PEN offset values of the pilot signals of the BS2 and BS3 base stations are the same as the 64 and 128 values. However, as shown in FIG. 2, when the distance between the BS2 and BS3 base stations is further away from the terminal, the corresponding PEN offset values of the BS2 and BS3 base stations received at the terminal are τ1 and τ2 than the 64 and 128 values, respectively. As small as.

Meanwhile, FIG. 4 is a diagram illustrating a pilot-PN-PHASE for explaining a terminal location tracking method according to the present invention, wherein the pilot-PIEN phase is expressed as follows. It is expressed in units of (Chip).

In the above equation, PILOT-PN is an offset index of the corresponding pilot, and PILOT-ARRIVAL is a time reference of the terminal, that is, the arrival time of the pilot signal first received at the terminal. It means that the arrival time of the received signal is calculated in units of chips. And the above equation is expressed to correspond to the 2 ¹⁵ PN offset domain.

As shown in FIG. 4, when the terminal transmits a pilot signal from a serving BS (BS1), which is held as a reference, the pilot signal arrives at the terminal after the arrival delay time of τ1. Takes this as their time base. When a pilot signal having a different offset is transmitted from a corresponding BS or BS2, the terminal arrives after the arrival delay time of τ2.

Accordingly, the terminal calculates PILOT-ARRIVAL (τ2-τ1) through an internal counter to indicate the PILOT-PN-PHASE to correspond to the 2 ¹⁵ PN offset domain. In the current code division multiple access scheme, the active base station transmits not only its own PIN offset value but also the PIN offset values of neighboring base stations to the terminal, so that the terminal knows the PIN offset of the neighboring base station in advance. Based on the Pien offset value of the base station's pilot, the energy is calculated at each position and the position is stored in the register while searching in the predetermined search window size (approximately 20 to 24 chips) in units of 1/8 chips. By first finding the first arrival component (where the first arrival component is determined to be the first of the components with energy above a certain criterion, where the predetermined reference value is chosen as an appropriate value to minimize false alarms). The arrival time of the pilot signal can be known.

The terminal calculates the PILOT-PN-PHASE from the value stored in the register and sends it to the base station of operation. Since the pilot signals of adjacent base stations received by the terminal are at least three in most cases, the terminal position can be calculated.

In addition, in the embodiment of the present invention, when the operation base station transmits a command to the corresponding terminal to report the PILOT-PN-PHASE of the base stations through a short message service (SMS), the terminal transmits a paging channel. The PILOT-PN-PHASE of the active set, candidate set and neighbor set is searched by the above method and reported through an access channel as a short service. Of course, the operating base station may send a command to report for a predetermined period of time.

In addition, although not described in detail in the present embodiment, it will be apparent that the present invention may be implemented by other methods for transmitting and receiving information between the base station and the terminal in addition to the short service.

The short service transmitted from the terminal is received by the base station and then sent to a computing center via a short message service center (SMSC). The calculation center calculates the position of the terminal from the PILOT-PN-PHASE information. Since the GPS information (latitude, longitude, etc.) of the base stations is already known, when the relative arrival delay time of the corresponding pilots with respect to the pilot of the operating base station is converted from the PILOT-PN-PHASE information into the distance, The difference between the distance and the distance between the base station having the corresponding pilot and the terminal can be known.

Referring to FIG. 5, the equation for calculating the terminal position from the PILOT-PN-PHASE information is as follows.

Therefore, since the coordinates of the base station are already known, the position of the terminal can be obtained.

As described above, according to the present invention, many problems of the conventional terminal tracking method can be eliminated, and the position of the terminal can be accurately determined in the code division multiple access method.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the above-described embodiments, and the general knowledge in the field to which the present invention pertains without departing from the gist of the present invention as claimed in the following claims. Anyone with a variety of changes will be possible.

Claims (11)

a) receiving PN offset information of an operating base station and neighboring base stations transmitted from the operating base station; b) setting an arrival time of a pilot signal transmitted from the operating base station as a reference time; c) searching for a pilot signal of the neighbor base stations for a predetermined time based on the P & N offset of the neighbor base stations; d) setting a time at which a pilot signal of the neighbor base stations arrives; e) comparing the reference time with the time when the pilot hanho of the neighboring base stations arrives, calculating a time difference, and calculating a pilot pien phase; f) sending said pilot pien phase to said operating base station; and g) calculating a location of the terminal by comparing the pilot PN phase transmitted to the operating base station with a known location of the corresponding base station. The method of claim 1, wherein the reception of the PEN offset information in step a) comprises receiving at least three PEN offset information. 2. The code division multiple access method mobile communication of claim 1, wherein the pilot signal search of step c) stores a signal size and a location of a corresponding location while searching for a predetermined time unit within a predetermined search window size. Terminal location tracking method of system. The code division multiple access according to claim 1, wherein the pilot signal arrival time set in step d) is set to a time which is first reached and has a predetermined size or more among pilot signals of neighboring base stations. Terminal location tracking method in a mobile communication system. a) transmitting a command to report a pilot PN phase from the operating base station to the corresponding terminal; b) receiving a P & N offset of an operating base station and neighboring base stations transmitted from the operating base station; c) setting an arrival time of a pilot signal transmitted from the operating base station as a reference time; d) searching for a pilot signal of the neighbor base stations for a predetermined time based on the P & N offset of the neighbor base stations; e) setting a time at which the pilot signals of the neighbor base stations arrive; f) comparing the reference time with the time when the pilot signal of the neighboring base stations arrived, calculating a time difference, and calculating a pilot pien phase: g) reporting the pilot pien phase to the operating base station And h) calculating a position of the terminal by comparing the pilot pien phase reported to the operating base station with a known position of the base station. [6] The method of claim 5, wherein the pilot PN phase report of step a) is reported for a predetermined time at a predetermined period. 7. The method of claim 6, wherein the pilot PN face report is transmitted using an access channel. [6] The method of claim 5, wherein the reception of the P & N offset in step b) includes receiving at least three or more P & N offsets. 6. The code division multiple access method of claim 5, wherein the pilot signal search of step d) stores a signal size and a location of a corresponding location while searching for a predetermined time unit within a predetermined search window size. Terminal location tracking method of mobile communication system. 6. The code division multiple access of claim 5, wherein the pilot signal arrival time setting in step e) is set to a time that is first reached and has a magnitude greater than or equal to a pilot signal among the discovered neighbor BSs. Terminal location tracking method in a mobile communication system. [6] The method of claim 5, wherein the pilot PN phase report of step g) is transmitted using a paging channel.