KR102155910B1 - System and method for time synchronization of time at time difference of arrival - Google Patents

Abstract

The present invention is a TDOA time synchronization system capable of achieving time synchronization of the system and all APs included in the system by combining a sync signal and a clock signal and delivering it to a wireless access point (AP) and unifying the clock in the system through the sync signal. And a method.

Description

TDOA time synchronization system and method {SYSTEM AND METHOD FOR TIME SYNCHRONIZATION OF TIME AT TIME DIFFERENCE OF ARRIVAL}

The present invention relates to a TDOA time synchronization system and method, in which a sync signal and a clock signal are combined and transmitted to an AP (Wireless Access Point), and the clock in the system is periodically synchronized through a sync signal. It relates to a TDOA time synchronization system and method capable of achieving time synchronization between APs.

As the number of personal wireless devices and services using location information increase, the need for a technology for accurately measuring the location of a device is increasing. To this end, various methods of positioning technology such as positioning using GPS or positioning using wireless signals are used.

In addition, as a positioning method using a radio signal, a Time Difference Of Arrival (TDOA) method using a difference in reception time of a radio signal is widely used. In the TDOA method, a device (TAG) transmits a signal, and a plurality of receivers (APs) receive it and perform a multi-directional survey to estimate the position. A specific base station transmits a signal to the terminal (TAG), and the base station An OTDOA method for estimating the location of the terminal based on the delay time until the signal arrives at the terminal is used.

Meanwhile, in a method of estimating the position of a tag by receiving a signal from a tag (TAG), the plurality of receivers must have the same frequency and time offset of a clock used to generate time stamp information. In particular, synchronization of the used clock is very important for high-precision positioning. To this end, a reference clock supply line for clock synchronization of each receiver and a data communication line for receiving time stamp information have been separately configured. Here, even if the reference clock is transmitted through the reference clock supply line, the signal is distorted or the reference clock is delayed in the signal transmission process depending on the environment of each receiving device and the length, characteristics and development path of each receiving device. There is this.

Korean Patent Registration No. 10-1575885

The present invention is derived to solve the above-described problem, by combining a sync signal and a clock signal and transmitting it to the AP and periodically synchronizing the clock in the system through the sync signal, the clock delay that may occur in the wired clock supply line and It is intended to deliver a TDOA time synchronization system and method capable of solving the offset change and achieving time synchronization between the system and all APs included in the system, and thereby more accurately estimating the position of the tag (TAG).

The TDOA time synchronization system according to an embodiment of the present invention generates a signal generator for generating a sync signal and a clock signal, and a combined signal by combining the sync signal and a clock signal received from the signal generator, and It may include a signal combiner for transmitting the combined signal to the AP (Wireless Access Point) to use the same clock as the clock.

In an embodiment, an AP may further include an AP receiving the combined signal and using the same clock as that of the clock signal included in the combined signal.

In an embodiment, it may further include a POE switch that supplies power to the AP and transmits information on a tag (TAG) generated by the AP to a server.

In an embodiment, when the number of APs is plural, the signal generator may periodically unify the clocks used by each of the plurality of APs through a sync signal received from each of the plurality of APs.

In one embodiment, the signal combiner generates the combined signal including power provided from the POE switch together with the sync signal and the clock signal, and transmits the combined signal to the AP to supply power to the AP. I can.

The TDOA time synchronization method according to another embodiment of the present invention comprises the steps of generating a sync signal and a clock signal through a signal generator and a combined signal combining the sync signal and a clock signal received from the signal generator through a signal combining unit. And transmitting the combined signal to an AP that will use the same clock as that of the clock signal.

In an embodiment, the method may further include receiving the combined signal through the AP and using the same clock as that of the clock signal included in the combined signal.

In an embodiment, it may further include the step of supplying power to the AP through a POE switch, and transmitting information on a tag generated in the AP to a server.

In one embodiment, the step of generating a sync signal and a clock signal through the signal generator comprises: when the number of APs is plural, each of the plurality of APs is used through a sync signal received from each of the plurality of APs. It may include the step of periodically unifying the clock.

In one embodiment, generating a combined signal by combining the sync signal and a clock signal received from the signal generation unit through the signal combining unit, and transmitting the combined signal to an AP that will use the same clock as the clock signal. The step may include generating the combined signal including power provided from the POE switch together with the sync signal and the clock signal, and transmitting the combined signal to the AP to supply power to the AP. .

The TDOA time synchronization system and method according to an embodiment of the present invention combines a sync signal and a clock signal, transmits it to the AP, and periodically synchronizes the clock in the system through the sync signal, thereby causing a clock delay that may occur in the wired clock supply line And it is possible to solve the change of the offset, and achieve time synchronization between the system and all APs included in the system, it has the advantage of being able to more accurately estimate the position of the tag (TAG) through this.

1 is a diagram showing an embodiment of a conventional TDOA position estimation system 1.
2 is a diagram showing the configuration of a TODA time synchronization system 100 according to an embodiment of the present invention.
3 is a diagram showing an embodiment of a TDOA time synchronization system 100 according to an embodiment of the present invention.
4 is a flowchart illustrating a time synchronization process through the TDOA time synchronization system 100 according to an embodiment of the present invention.

The present invention will be described in detail with reference to the accompanying drawings as follows. Here, repeated descriptions, well-known functions that may unnecessarily obscure the subject matter of the present invention, and detailed descriptions of configurations are omitted. Embodiments of the present invention are provided to more completely explain the present invention to those with average knowledge in the art. Accordingly, the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

In addition, the term "... unit" described in the specification means a unit that processes one or more functions or operations, which may be implemented by hardware or software, or a combination of hardware and software.

1 is a diagram showing an embodiment of a conventional TDOA position estimation system 1.

Location estimation using TDOA (Time difference of arrival) can be configured including AP (Wireless Access Point) (1a) and tag (TAG) (1b), from AP (1a) to tag (1b) or tag (1b) This is a method of finding the location of the tag 1b based on the difference in arrival time of the signal transmitted from the AP 1a to the AP 1a. Since the speed of the radio wave area used is determined, the time difference becomes the distance difference, and the position of the tag 1b is estimated through calculation using the distance difference according to the time difference between each AP(1a) and the tag 1b used for location estimation. can do.

Since the position estimation method of the TDOA method is based on time difference, it can be said that time synchronization in the TDOA position estimation system (1) is essential. When high-precision estimation of the position of the tag (1b) is required, its importance is greatly increased. do.

On the other hand, time synchronization of devices included in the TDOA location estimation system 1 can be achieved through a reference clock used for each device, and the state of each AP 1a and the device used in the TDOA location estimation system 1 Alternatively, there is a problem that the reference clock signal is delayed or distorted due to the characteristic of the line supplying the reference clock to each AP 1a.

2 is a diagram showing the configuration of a TODA time synchronization system 100 according to an embodiment of the present invention, and FIG. 3 is a diagram showing an embodiment of a TDOA time synchronization system 100 according to an embodiment of the present invention .

Referring to FIGS. 2 and 3, the TDOA time synchronization system 100 according to an embodiment of the present invention may largely include a signal generator 101 and a signal combiner 102. In addition, it may be configured to further include an AP 103 and a POE switch 104.

The TDOA time synchronization system 100 shown in FIGS. 2 and 3 is according to an embodiment, and its components are not limited to the embodiment shown in FIGS. 2 and 3, and some components are It can be added, changed or deleted.

First, the signal generator 101 may generate a sync signal and a clock signal.

Here, when there are a plurality of APs 103 as in the exemplary embodiment of FIG. 3, the signal generator 101 may generate a clock used by each of the plurality of APs 103 through a sync signal received from each of the plurality of APs. It can be unified periodically.

Here, the unification of the clocks may mean equalizing the operating speed of the clocks used by each of the plurality of APs 103 or eliminating an operation difference due to a delay of the clocks.

In addition, the embodiment shown in FIG. 3 is an embodiment of the present invention, and may be more or less than the number of APs 103 of the embodiment shown in FIG. 3 in actual operation.

Next, the signal combining unit 102 generates a combined signal that combines the sync signal and the clock signal received from the signal generation unit 101, and transmits the combined signal to the AP 103 that will use the same clock as the clock signal. can do.

In addition, the signal combining unit 102 generates a combined signal including power provided from the POE switch 104 to be described later together with a sync signal and a clock signal, and transmits the combined signal to the AP 103 to the AP 103 Can supply power to

In addition, the signal combining unit 102 may transmit the above-described combined signal through a POE (Power Over Ethernet) connector included in the AP 103.

In addition, the signal combining unit 102 may transmit the combined signal through the RJ45 connector instead of the POE connector.

Here, the POE connector included in the AP 103 may receive a combined signal through a Mode A method. The Mode A method described above is one of the modes determined according to a method of using a pin included in the POE connector to receive a signal, and a total of 7 pins are used. In addition, the pin configuration according to each mode of the POE connector is shown in Table 1 below.

[Table 1]

In addition, a clock signal and a sync signal included in the combined signal may be transmitted to the AP 103 in the form of a differential input signal in order to respond to noise that may occur during signal transmission.

Here, referring to Table 1, the clock signal and the sync signal may be transmitted through 4 pins of Pins 1 to 7 connected to the POE connector for signal transmission in the form of a differential signal described above, and the clock signal And each of the sync signals may be transmitted through two of the four pins described above.

In addition, the signal combination unit 102 may transmit information received from the AP 103 to the POE switch 104 through the signal combination unit 102 and the POE connector included in the POE switch 104.

Next, the AP 103 may receive the combined signal and use the same clock as that of the clock signal included in the combined signal.

In addition, the AP 103 receives information on the tag 10 through wireless communication with the tag 10, and transmits the received information to the signal combining unit 102 through a signal transmission line connected to the POE connector described above. I can.

Here, the wireless communication used may include ultra wide band communication.

In addition, the information on the tag 10, when one or more tags 10 exist, tag identification information that can identify which tag 10 among the one or more tags 10, and the AP 103 and the tag (10) It may include a time stamp indicating the signal reception time of the AP 103 according to the communication distance between.

Next, the POE (Power Over Ethernet) switch 104 may supply power to the AP 103 and transmit information on the tag 10 generated in the AP to the server 20.

Here, the POE switch 104 may supply power to the AP 103 through a combined signal generated by the signal combining unit 102.

In addition, when there are more than one AP 103 as in the embodiment illustrated in FIG. 3, the POE switch 104 may supply power to the one or more APs 103 through the signal combining unit 102 described above.

In addition, the POE switch 104 transmits the information on the tag 10 transmitted from the AP 103 through the signal combining unit 102 to the signal generation unit 101, and the signal generation unit 101 receives The information may be processed as information that can be transmitted to the server 20, and the processed information may be received again and transmitted to the server 20.

Here, the POE switch 104 transmits information on the tag 10 to the signal generation unit 101 through the RJ45 connector included in the signal generation unit 101, and the information processed by the signal generation unit 101 May be received again and transmitted to the server 20.

Next, a time synchronization process through the TDOA time synchronization system 100 will be described with reference to FIG. 4.

4 is a flowchart illustrating a time synchronization process through the TDOA time synchronization system 100 according to an embodiment of the present invention.

Referring to FIG. 4, first, a signal generator generates a sync signal and a clock signal (S401).

Next, the sync signal and the clock signal generated by the signal generation unit are received by the signal combining unit (S402).

Next, the received sync signal and the clock signal are combined with the power provided from the POE switch to generate a combined signal (S403), and a combined signal is transmitted to each of the one or more APs connected to the signal combining unit to each AP Is received (S404).

Next, the AP receiving the combined signal generated by the signal combining unit operates by receiving power based on the combined signal, uses the clock of the clock signal, and periodically corrects the offset of the clock through the reception of the sync signal. The time synchronization of is maintained (S405).

The above-described TDOA time synchronization method has been described with reference to the flowchart shown in the drawings. For simplicity, the method has been illustrated and described as a series of blocks, but the present invention is not limited to the order of the blocks, and some blocks may occur in a different order or concurrently with other blocks than those shown and described herein. Alternatively, various other branches, flow paths, and orders of blocks may be implemented that achieve the same or similar result. Also, not all illustrated blocks may be required for implementation of the method described herein.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. You will understand that you can do it.

1: TDOA position estimation system
1a: AP
1b: tag
10: tag
100: TDOA time synchronization system
101: signal generation unit
102: signal combining unit
103: AP
104: POE switch

Claims (10)

A signal generator that generates a sync signal and a clock signal;
A signal combiner for generating a combined signal by combining the sync signal and a clock signal received from the signal generator, and transmitting the combined signal to a wireless access point (AP) that will use the same clock as the clock signal of the clock signal;
An AP receiving the combined signal by wire and using the same clock as that of the clock signal included in the combined signal; And
Includes; a POE switch that supplies power to the AP and transmits information on a tag (TAG) generated in the AP to a server,
The signal generator,
When the number of APs is plural, the clocks used by each of the plurality of APs are periodically unified through a sync signal received from each of the plurality of APs,
The signal combining unit,
Generating the combined signal including power provided from the POE switch together with the sync signal and the clock signal, and transmitting the combined signal to the AP to supply power to the AP,
The signal combining unit,
The sync signal and the clock signal are transmitted to the AP in the form of a differential input signal ,
TDOA time synchronization system.
delete delete delete delete Generating a sync signal and a clock signal through a signal generator;
Generating a combined signal by combining the sync signal and a clock signal received from the signal generation unit through a signal combining unit, and transmitting the combined signal to an AP that will use the same clock as the clock signal;
Receiving the combined signal via a wire through an AP and using a clock equal to the clock of the clock signal included in the combined signal; And
Including; supplying power to the AP through a POE switch, and transmitting information on a tag generated by the AP to a server; Including,
Generating the sync signal and the clock signal,
When the number of APs is plural, periodically unifying a clock used by each of the plurality of APs through a sync signal received from each of the plurality of APs; and
Transmitting the combined signal to an AP that will use the same clock as that of the clock signal,
Generating the combined signal including power supplied from the POE switch together with the sync signal and the clock signal, and transmitting the combined signal to the AP to supply power to the AP; and
Transmitting the combined signal to an AP that will use the same clock as that of the clock signal,
Transmitting the sync signal and the clock signal to the AP in the form of a differential input signal; Characterized in that it comprises a,
TDOA time synchronization method. delete delete delete delete

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