KR20070061077A - Method for the power control of rfid chip in active rfid system and rfid chip therefor - Google Patents

Abstract

A method for controlling power of an RFID chip in an active RFID system and an RFID chip thereof are provided to enable the RFID chip to transmit a signal to an RFID reader by measuring an attenuation level of a pilot tone signal received from the RFID reader and adjusting a transmission power level according to the measured attenuation level. A measurer measures the attenuation level of the pilot tone signal received from the RFID reader(10). A memory(24) stores the power level of a transmission signal corresponding to the measured attenuation level of the pilot tone signal. A power level checker checks the power level of the transmission signal corresponding to the measured attenuation level of the pilot tone signal from the table stored in the storing part. A signal transmitter transmits the transmission signal to the RFID reader at the checked power level.

Description

Method for the power control of RFID chip in active RFID system and RFID chip therefor}

1 is a configuration diagram of an embodiment of an RFID system network to which the present invention is applied;

2 is a configuration diagram of an embodiment of an RFID reader and an RFID chip according to the present invention;

3 is a flowchart illustrating an embodiment of a power control method of an RFID chip according to the present invention;

* Explanation of symbols on the main parts of the drawing

10: RFID Reader 11: RF Reader

12: reader control unit 20: RFID chip

21: chip RF unit 22: chip control unit

23: battery 24: storage

The present invention relates to a power control method of an RFID chip in an active RFID system and an RFID chip for the same. More particularly, a pilot tone signal transmitted from the RFID reader after being driven by receiving a wake-up signal from an RFID reader The RFID chip in the active RFID system for measuring the attenuation of the signal, and checking the power strength of the signal transmitted to the RFID reader corresponding to the attenuation degree of the measured pilot tone signal and transmitting the signal of the power strength identified by the RFID reader To provide a power control method and an RFID chip for the same.

An active radio frequency identification (RFID) system is composed of an active RFID chip and an RFID reader. The active RFID chip has a battery and a transmission device built therein so that it can transmit by itself. In this case, the general active RFID chip operates only when a wake-up signal is received from the RFID reader, and maintains a sleep state when the wake-up signal is not received.

In addition, one RFID reader may manage a plurality of RFID chips and mutually transmit / receive with an RFID chip using a half duplex (HDX) method.

On the other hand, the representative frequency band used by the active RFID system is the Ultra High Frequency (UHF; Ultra High Frequency) band of 433MHz, the active RFID system is applied to the pallet of the airport, port, container management, factory parts management.

In the conventional active RFID system, since the battery is installed in the RFID chip, the battery needs to be replaced every one to two years. As a result, in order to maintain a conventional active RFID system, human, material loss, and time loss due to replacement of a battery occur.

In the active RFID system as described above, the RFID chip transmits a signal of a constant power strength to the RFID reader regardless of the distance from the RFID reader. As a result, in the conventional active RFID system, even if the RFID chip is located close to the RFID reader, there is a problem that the battery is quickly consumed because the signal is transmitted with a greater power than necessary.

In addition, as the information exchange between the RFID reader and the RFID chip increases in the conventional active RFID system, the battery consumption of the RFID chip also increases. Accordingly, the need for power control of a battery installed in an RFID chip is increasing in a conventional active RFID system.

The present invention has been proposed to solve the above problems, and after the RFID chip is driven by receiving a wake-up signal from the RFID reader, the attenuation degree of the pilot tone signal transmitted from the RFID reader is measured, and the measured pilot tone signal is measured. The present invention provides a power control method of an RFID chip and an RFID chip for the same in an active RFID system that transmits a signal of the power strength identified by an RFID reader by checking the power strength of a signal transmitted to an RFID reader corresponding to the attenuation degree of the present invention. There is a purpose.

In addition, other objects and advantages of the present invention can be understood by the following description, will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In the present invention for achieving the above object, in the active RFID system in the active RFID system that is driven by the wake-up signal received from the RFID reader to transmit the chip transmission signal containing the chip identification information to the RFID reader, A first step of receiving and driving the wake-up signal and receiving a pilot tone signal for confirming the power strength of the chip transmission signal from the RFID reader and measuring the attenuation degree of the pilot tone signal; A second step of checking a power intensity of the chip transmission signal corresponding to the attenuation degree according to the attenuation degree measurement result of the pilot tone signal; And a third step of transmitting the chip transmission signal to the identified power strength when the power intensity of the chip transmission signal is confirmed.

In addition, the present invention is a RFID chip which is driven by a wake-up signal received from the RFID reader to transmit a chip transmission signal containing the chip identification information to the RFID reader,

Measuring means for receiving a pilot tone signal for confirming the power strength of a chip transmitting signal from the RFID reader to the RFID reader and measuring attenuation of the pilot tone signal; A memory for storing a table of power intensities of corresponding chip transmission signals according to attenuation degree of the pilot tone signal; Power intensity checking means for checking the power intensity of the chip sending signal corresponding to the attenuation degree of the pilot tone signal measured by the measuring means through a table stored in the memory; And signal transmission means for transmitting a chip transmission signal at the power strength identified by the power strength checking means.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of an embodiment of an RFID system network to which the present invention is applied. Here, the RFID system network will be described with an active RFID chip (hereinafter referred to as an "RFID chip") and an RFID reader installed for container management for convenience of description.

As shown in FIG. 1, the RFID system network to which the present invention is applied includes one RFID reader 10 and an RFID chip 1 (1), an RFID chip 2 (2), and an RFID chip 3 (attached to each container). 3) RFID chip 4 (4) (collectively referred to as " RFID chip 20 "). In this case, the RFID reader 10 and the RFID chip 20 are separated at different distances. In addition, the RFID chip 20 stores data for identifying itself and detailed data of a container (hereinafter referred to as "chip identification information").

Although not shown in FIG. 1, the RFID reader 10 is connected to a server or a network that provides chip identification information of the RFID chip 20 so that a user may check the information.

2 is a block diagram of an embodiment of an RFID reader 10 and an RFID chip 20 according to the present invention.

As shown in FIG. 2, the RFID reader 10 according to the present invention includes a reader RF unit 11 and a reader controller 12. In addition, the RFID chip 20 according to the present invention includes a chip RF unit 21, a chip control unit 22, a battery 23, and a storage unit 24.

Hereinafter, the reader RF unit 11 and the reader controller 12 of the RFID reader 10 will be described.

The reader RF unit 11 transmits a wake-up signal to the RFID reader 10 for converting a sleep state into a driving state, and a signal including chip identification information in the RFID chip 20 (hereinafter referred to as “chip transmission”). Signal "). In particular, the reader RF unit 11 transmits a pilot tone signal to control the power strength required for the RFID chip 20 to transmit the chip transmission signal.

In addition, the reader RF unit 11 communicates with the RFID chip 20 in a half duplex (HDX) manner using a 433 MHz frequency band. Here, the reader RF unit 11 communicates with the RFID chip 20 by using a frequency shifting keying (FSK).

The reader controller 12 controls the reader RF unit 11 and communicates with the RFID chip 20 through the reader RF unit 11. That is, the reader controller 12 receives a wake-up signal for a predetermined time (for example, 2.5 seconds) or more to check the position and movement information of the RFID chip 20. The RFID chip 20 in a sleep state is driven by transmitting to the apparatus. In particular, the reader controller 12 transmits the wake-up signal, that is, drives the RFID chip 20 and then transmits a pilot-tone signal to the RFID chip 20.

In this case, the reader control unit 12 transmits a pilot tone signal at a constant intensity (that is, a reference amplitude or a reference phase) instead of a command signal after the RFID chip 20 transmits the wake-up signal. When the chip 20 receives the pilot tone signal, the distance between the RFID reader 10 and the RFID chip 20 and attenuated by the surrounding environment can be measured to determine how much power strength of the chip transmission signal is to be achieved. Make sure

On the other hand, the reader control unit 12 receives the signal from the RFID chip 20, checks the chip identification information, and then switches the RFID chip 20 to the sleep state, if you want more information of the specific RFID chip 20 More detailed information may be requested by communicating with the specific RFID chip 20 (eg, a point-to-point method).

Hereinafter, the chip RF unit 21, the chip control unit 22, the battery 23, and the storage unit 24 of the RFID chip 20 will be described.

The chip RF unit 21 receives the wakeup signal and the pilot tone signal from the RFID reader 10 and transmits the chip transmission signal to the RFID reader 10.

In addition, the chip RF unit 21 communicates with the RFID reader 10 in a half-duplex manner using the 433 MHz frequency band. Here, the chip RF unit 11 communicates with the RFID reader 10 using Frequency Shifting Keying (FSK).

The battery 23 supplies power that the RFID chip 20 can drive. In particular, the battery 23 supplies power so that the RFID chip 20 can transmit the chip transmission signal, so that the RFID chip 20 transmits the chip transmission signal by its own power. There is this.

The storage unit 24 stores chip identification data of the RFID chip 20. In particular, the storage unit 24 divides the attenuation degree of the pilot tone signal transmitted by the RFID reader 10 step by step and stores the power strength of the chip transmission signal corresponding to the step as a table.

The chip controller 22 controls the chip RF unit 21, the battery 23, and the storage unit 24.

In addition, the chip controller 22 receives and drives the wake-up signal from the RFID reader 10. Here, the chip controller 22 waits in a sleep state capable of receiving a wake-up signal using the minimum power from the RFID reader 10, and is driven by receiving the wake-up signal from the RFID reader 10. Control not to consume power.

In addition, the chip controller 22 receives the wake-up signal and the pilot tone signal from the RFID reader 10. At this time, the chip control unit 22 measures the attenuation degree of the received pilot tone signal when driven by the wake-up signal. Here, the technique of measuring the attenuation degree of the pilot tone signal in the chip control unit 22 can be easily understood by those skilled in the art, so a detailed description thereof will be omitted.

In particular, the chip control unit 22 measures the attenuation degree of the pilot tone signal received from the RFID reader 10 to determine how much power strength of the chip transmission signal is to be set. That is, the chip control unit 22 inquires and confirms the power strength of the chip transmission signal corresponding to the step corresponding to the attenuation degree of the pilot tone signal measured using the table stored in the storage unit 24.

In addition, the chip controller 22 receives a signal in which the strength of the pilot tone signal is attenuated according to the distance between the RFID reader 10 and the RFID chip 20 and peripheral obstacles. For example, the strength of the pilot tone signal may be proportional to one fourth of the power of the distance between the RFID reader 10 and the RFID chip 20 as shown in Equation 1.

)의

제곱승 분의 1에 비례할 수 있다. 여기서, 상기

은 경로감쇄지수(path loss exponent)로서, 자유공간(free space)에서 "2"의 값을 갖는다.The strength of the pilot tone signal is the distance between the RFID reader 10 and the RFID chip 20 as

)of

It can be proportional to one-squared power. Where

Is a path loss exponent and has a value of "2" in free space.

Hereinafter, an example will be described with reference to Table 1 and FIG. 1. Table 1 shows a table stored in the storage unit 24.

Step corresponding to the attenuation of the measured pilot tone signal Power Strength of Chip Transmission Signal One P10 2 P9 3 P8 4 P7 5 P6 6 P5 7 P4 8 P3 9 P2 10 P1

In the present invention, the strength of the pilot tone signal is divided into 10 stages (minimum 1 stage to maximum 10 stages), and the power intensity of the chip sending signal is divided into 10 stages (minimum stage 1 to maximum 10 stages) corresponding to the pilot tone signal. do.

As shown in Table 1, it can be seen that the step corresponding to the attenuation degree of the measured pilot tone signal is inversely proportional to the power strength of the chip transmission signal. That is, if the step corresponding to the attenuation degree of the pilot tone signal measured in Table 1 is the minimum "step 1", the RFID chip 20 checks the power intensity of the chip transmission signal as the maximum "P10".

For example, in FIG. 1, after the RFID chip 1 (1), the RFID chip 2 (2), the RFID chip 3 (3), and the RFID chip 4 (4) receive a wake-up signal from the RFID reader 10, a pilot tone is generated. Upon receiving the signal, the chip control unit 22 of each RFID chip 20 measures the attenuation degree of the pilot tone signal and checks the corresponding step. Here, the RFID chip 1 (1) is "step 1", the RFID chip 2 (2) is "step 2", the RFID chip 3 (3) is "step 3", and the RFID chip 4 (4) is "step 4" Let's do it.

Then, the chip control unit 22 checks the power intensity of the chip transmission signal corresponding to each step by using the table stored in the storage unit 24. That is, the chip transmission signal of "P10" of the RFID chip 1 (1), "P9" of the RFID chip 2 (2), "P8" of the RFID chip 3 (3), and "P7" of the RFID chip 4 (4). Each transmits at power strength of.

Through this, the user may roughly grasp the distance of the RFID chip 20 away from the RFID reader 10 through a server or a network connected to the RFID reader 10.

3 is a flowchart illustrating a power control method of the RFID chip 20 according to the present invention.

As shown in FIG. 3, the RFID chip 20 normally waits to receive a wake-up signal in a sleep state (S100).

Thereafter, when the RFID chip 20 receives the wake-up signal from the RFID reader 10 (S101), the RFID chip 20 is driven by the power of the battery 23 provided therein (S102). At this time, when the RFID chip 20 receives the pilot tone signal from the RFID reader 10 (S103), the degree of attenuation of the pilot tone signal is measured (S104), and the table stored in the storage unit 24 is used. Check the level corresponding to the attenuation of the prestored pilot tone signal.

At this time, the RFID chip 20 checks the power strength of the chip transmission signal corresponding to the step corresponding to the attenuation degree of the identified pilot tone signal using the table stored in the storage unit 24 (S105).

On the other hand, the RFID chip 20, when the power strength of the chip sending signal is confirmed, prepares to transmit the chip sending signal (S106).

Then, the RFID chip 20 transmits a chip transmission signal to the RFID reader 10 according to the identified power strength (S107), and the RFID reader 10 waiting for the chip transmission signal from the RFID chip 20. Receives the chip sending signal (S108).

On the other hand, the RFID reader 10 checks the chip identification information included in the received chip transmission signal and provides it to the server or network (S109).

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention as described above, by controlling the power of the battery in the active RFID chip has an effect that can effectively utilize the RFID system by extending the replacement cycle of the battery.

In addition, the present invention has the effect of reducing the loss of human, physical and time due to the replacement of the battery of the active RFID chip.

Claims (3)

In the active RFID system of the active RFID system that is driven by the wake-up signal received from the RFID reader to transmit the chip transmission signal containing the chip identification information to the RFID reader, A first step of receiving and driving the wake-up signal and receiving a pilot tone signal for confirming the power strength of the chip transmission signal from the RFID reader and measuring attenuation of the pilot tone signal; A second step of checking a power intensity of the chip transmission signal corresponding to the attenuation degree according to the attenuation degree measurement result of the pilot tone signal; And A third step of transmitting a chip transmission signal at the identified power strength when the power strength of the chip transmission signal is confirmed; Power control method of the RFID chip in the active RFID system comprising a. The method of claim 1, In the second step, the power intensity of the chip transmission signal corresponding to the attenuation degree of the pilot tone signal is stored as a table, and the power intensity of the chip transmission signal according to the attenuation degree measurement result of the pilot tone signal measured in the first step. The power control method of the RFID chip in the active RFID system, characterized in that to check the query in the table. An RFID chip which is driven by a wake-up signal received from an RFID reader and transmits a chip transmission signal including chip identification information to the RFID reader, Measuring means for receiving a pilot tone signal for confirming the power strength of a chip transmission signal from the RFID reader to the RFID reader and measuring attenuation of the pilot tone signal; A memory for storing a table of power intensities of corresponding chip transmission signals according to attenuation degree of the pilot tone signal; Power intensity checking means for checking the power intensity of the chip sending signal corresponding to the attenuation degree of the pilot tone signal measured by the measuring means through a table stored in the memory; And Signal transmitting means for transmitting a chip transmitting signal at the power strength identified by the power measuring means; RFID chip for power control in an active RFID system comprising a.

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