KR20000007804A - Tracking method of terminal position for mobile communication system of code division multiple access method - Google Patents

Abstract

PURPOSE: A tracking method of a terminal position is provided to exactly gasp the position of the current terminal by transmitting the pilot-PN phase of the pilot signals of the neighbor base station to the base station through the short message service. CONSTITUTION: The tracking method of a terminal position for mobile communication system comprises the steps of: receiving the PN offset information of the active and the neighbor base station transmitted from the active base station; setting the arrival time of the pilot signal as a reference; searching the pilot signal of the neighbor base station; and setting the arrival time of the pilot signal of the neighbor base station.

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 by a terminal to neighboring base stations. A method of calculating the position of a terminal by collecting information of Of Arrival or Angle of Arrival (AOA) is employed. 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 that receives the signal of the terminal may be one in a non-handoff area, so that the terminal using the reverse channel of the analog cellular system is used. There are many problems in employing the location tracking method.

The present invention provides a terminal location tracking method of a code division multiple access method mobile communication system that can accurately determine the location of the terminal using a message transmitted by the terminal to the operating base station and the candidate base station in the code division multiple access method mobile communication system. Its purpose is to.

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.

* Description of the symbols for the 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) transmitted from the terminal to the operating base station and the candidate base station (PSMM) Includes pilot phase information of the active base station and the candidate base station to the base station and transmits it 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 a 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 for the measurement of the location of the terminal, which often occurs 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 the operating base station and the candidate base station include three or more pilots necessary for position calculation, but if so, Another problem arises.

Therefore, in the present invention, the terminal searches for the pilot signal of the neighbor base station (neighbor set) in addition to the operation base station and the candidate base station, and also calculates the pilot phase information of the pilot signal of the neighbor base station, and then needs three positions for calculation The pilot phase information of the above 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 a chip (chip = 1 sec / 1.2288 x 10 ⁶ = 833 ns). In addition, since the PN offset of each base station is configured to have a phase difference of 2 ⁶ 64 bits, as a result, 2 ⁹ 512 PN offsets may be allocated to each base station.

FIG. 1 shows a peen offset inherent to a base station, and will be described based on a 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 operation BS BS1 are 0, and the PEN offset values of the neighbor BSs BS2 and BS3 are 64 and 128, respectively.

In this case, assuming that the distance between the three base stations and the terminal are the same (here, the arrival delay time from the base station to the terminal is not taken into account), the pilot signal reception points of the base stations arriving at the terminal are the same. . In addition, when the pilot signal of the operation base station is transmitted, 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 becomes further from the terminal, the corresponding PEN offset values of the BS2 and BS3 base stations received by the terminal are τ1 and τ2 rather than 64 and 128 values, respectively. It becomes big. On the contrary, when the distance of the base station is closer to the terminal, as shown in FIG. 3, the corresponding PEN offset value becomes smaller by τ1 and τ2 than 64 and 128, respectively.

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).

PILOT-PN-PHASE = {PILOT-ARRIVAL + (64 X PILOT-PN)} mod 2 ¹⁵

= {Δτ + (64 × PILOT-PN)} mod 2 ¹⁵

= {τ2-τ1 + (64 × PILOT-PN)} mod 2 ¹⁵

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 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 base station (serving BS, BS1) held as a reference, the pilot signal arrives at the terminal after the arrival delay time of τ1. Take this as your 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 that the PILOT-PN-PHASE corresponds 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 UE, so that the UE knows the PIN offset of the neighboring BS in advance. The energy calculated at each position and its position are stored in a register while searching in units of 1/8 chips within a predetermined search window size (approximately 20 to 24 chips) based on the pien offset value of the base station pilot. 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 threshold, where the constant reference value is chosen as the 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, according to an embodiment of the present invention, when the operation base station transmits a command to report the PILOT-PN-PHASE of the base stations to the corresponding terminal through a short message service, the terminal. Searches for the PILOT-PN-PHASE of the active base station, the candidate base station and the neighbor base station by the above-described method, and reports the short-term service through an access channel. 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 through 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 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 a 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.

√ (X ₁ -X ₀ ) ² + (Y ₁ -Y ₀ ) ² -√ (X ₂ -X ₀ ) ² + (Y ₂ -Y ₀ ) ² = mt _c c

√ (X ₂ -X ₀ ) ² + (Y ₂ -Y ₀ ) ² -√ (X ₃ -X ₀ ) ² + (Y ₃ -Y ₀ ) ² = (n-m) t _c c

√ (X ₃ -X ₀ ) ² + (Y ₃ -Y ₀ ) ² -√ (X ₁ -X ₀ ) ² + (Y ₁ -Y ₀ ) ² = -nt _c c

Where

X ₁ Y ₁ , X ₂ Y ₂ and X ₃ Y ₃ = corresponding Base Station Coordinates,

t _c = chip time (833 ns),

c = propagation speed,

X ₀ , Y ₀ = Mobile Coordinates to be estimated.

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 illustrated 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 the operating base station and neighboring base stations transmitted from the operating base station; b) setting the arrival time of the 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 the pilot signals of the neighbor base stations arrive; e) comparing the reference time with the time at which the pilot signals of the neighboring base stations arrive, and calculating a pilot pien phase by calculating a time difference; f) transmitting the pilot pien phase to the operating base station; And g) calculating a location of the terminal by comparing the pilot PN phase transmitted to the operation base station with a known location of the corresponding base station, and calculating the location of the terminal. The method of claim 1, Receiving the PEN offset information of step a), the terminal location tracking method of a code division multiple access method mobile communication system characterized in that for receiving at least three or more PN offset information. The method of claim 1, In the pilot signal search of step c), the terminal location of the code division multiple access type mobile communication system is configured to store the signal size and the location of the corresponding location while searching in a predetermined time unit within a predetermined search window size. Tracking method. The pilot signal arrival time setting in step d) is a terminal of a code division multiple access type mobile communication system, wherein the pilot signal arrival time is set to a time that is first reached and has a predetermined size or more among pilot signals of neighboring base stations. Location tracking method. a) transmitting a command to report a pilot PN phase from the operating base station to the corresponding terminal; b) receiving the P & N offset of the 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 signals of the neighboring base stations arrive and calculating a time difference to calculate a pilot pien phase; g) reporting the pilot pien phase to the operating base station; And h) Computing the location of the terminal by comparing the pilot PN phase reported to the operating base station and the location of the known base station, the terminal location tracking method of a code division multiple access method mobile communication system. The method of claim 5, The pilot PIEN phase report of step a) is a terminal location tracking method of a code division multiple access type mobile communication system, characterized in that for reporting a certain period of time. 7. The method of claim 6, wherein the pilot PN face report is transmitted using an access channel. The method of claim 5, And receiving the P & N offset in step b) comprises receiving at least three or more P & N offsets. The method of claim 5, In the pilot signal search of step d), the terminal location of the code division multiple access method mobile communication system is configured to store the signal size and the location of the corresponding location while searching in a predetermined time unit within a predetermined search window size. Tracking method. The method of claim 5, The pilot signal arrival time setting in step e) is a terminal of a code division multiple access type mobile communication system, wherein the pilot signal arrival time is set to a time which is first reached and has a predetermined size or more among pilot signals of neighboring base stations. Location tracking method. The method of claim 5, The pilot PN phase report of step g) is transmitted using a paging channel, wherein the terminal location tracking method of a code division multiple access method mobile communication system.