KR100873384B1 - Control method for multiful rfid reader - Google Patents

Abstract

A method for controlling a multiple RF ID is presented to minimize collision and interference between tag acknowledge signals, under multiple RFID reader environment. According to a method for controlling a multiple RFID reader, the RFID readers are grouped into a plurality of groups including a constant number of RFID readers(S1000). One RFID reader is set as a master reader and the other RFID readers are set as slave readers(S2000). The master reader transmits a frequency hopping announcement signal to the master reader and the slave readers(S3000). Each group performs frequency hopping with an equal frequency, and frequency hopping is performed with a difference frequency between groups(S4000).

Description

CONTROL METHOD FOR MULTIFUL RFID READER}

The present invention relates to a control method of a multiple RFID reader, and more particularly, to minimize collision and interference problems between tag recognition signals transmitted from each RFID reader in a multiple RFID reader environment in which a plurality of RFID readers recognize RFID tags. The present invention relates to a control method of a multiple RFID reader.

With the development of communication technology, radio frequency identifier (RFID) technology has been applied in various fields of port, medical and defense agriculture, fisheries and fisheries.

The RFID technology is one of wireless communication technologies that attaches an IC chip called an RFID tag to an object and reads a unique value recorded in the RFID tag using an RFID reader to distinguish the object to which the RFID tag is attached. to be.

In addition, the RFID technology is in the spotlight because it does not require a specific display compared to the magnetic or barcode, and solves the problem that the recognition rate decreases with time.

In general, RFID technology is classified into an active method and a passive method according to the type of RFID tag. The active method is a method in which an RFID tag actively transmits a tag signal because power is included in the RFID tag. The passive method is a method of passively transmitting a tag signal by obtaining an energy source by a tag recognition signal transmitted from an RFID reader within a radio wave range of the RFID reader.

In addition, various frequencies such as 125Khz, 135Khz, 13.56Mhz, 900Mhz and 2.45Ghz are currently allocated to the RFID technology. Of these, the 900Mhz and UHF band frequencies are used for the passive RFID technology and can recognize up to 10m. It is expected to be widely used in logistics and distribution worldwide.

On the other hand, in the RFID technology using the UHF band, there is a problem that the collision between the operating frequencies often fall into an incompatibility state or a crosstalk state, and these problems are largely caused when one RFID reader recognizes multiple RFID tags. The collision and interference between the tags, and the collision and interference between readers that occur when multiple RFID readers recognize one RFID tag are caused.

Collision means that the communication at the same frequency caused the incommunication state with each other, and interference means that the operation at the adjacent frequencies cause communication crosstalk with each other.

In order to solve these problems, ISO 18006-C, a standard of RFID technology that has been widely accepted and widely used in recent years, uses a method called slot aloha to solve the collision problem between tags.

The slot allo is a method for resolving collisions between tag signals transmitted from each tag by transmitting a tag signal by an RFID tag that is in an incapable of communication or a confusion state after a certain time after the collision problem occurs. .

In addition, unlike the Aloha method of transmitting a tag signal whenever there is a transmission request for a slot allo, it operates by dividing a transmission time into a plurality of time slots, and each tag arbitrarily selects and transmits a slot.

Similarly, there is a time division multiple access (TDMA) method in mobile communication technology. This time division multiple access method is a technology that allows multiple users to simultaneously transmit and receive data to one repeater. By dividing the same frequency into smaller times, the user monopolizes the frequency at the time given to him.

That is, the slot aloha method and the time division multiple access method may be referred to as a method for solving a collision problem with one RFID reader or repeater with multiple RFID tags or user mobile phones, respectively.

However, studies to solve the conflict problem between multiple RFID readers and RFID tags are still insufficient.

In particular, the tag recognition signal transmitted by the RFID reader has a much larger propagation distance than the tag signal transmitted by the RFID tag, and thus may collide with each other even between readers apart from each other. The possibility is even more serious.

The present invention was devised to solve the above problems, and an object of the present invention is to provide a control method of a multiple RFID reader for reducing a collision or interference between the multiple RFID reader and the RFID tag.

The control method of a multi-RFID reader according to an embodiment of the present invention is a multi-RFID reader for reducing an operating frequency collision and interference problem between the respective RFID readers in a multi-RFID reader environment in which a plurality of RFID readers recognize RFID tags. In a control method, the first step of setting the RFID readers into a plurality of groups including a predetermined number of RFID readers, the RFID reader of any one of the entire RFID readers included in the groups as a master reader And a second step of setting the remaining RFID readers as slave readers, a third step of the master reader transmitting a frequency hopping notification signal to the master reader and the slave readers, and each of the readers simultaneously frequency hopping at a constant operating frequency. (Hopping), but performing frequency hopping at the same frequency for each group, Each group includes a fourth step of performing frequency hopping at different frequencies.

In a preferred embodiment, after the fourth step, the master reader and the slave reader further comprises a fifth step of transmitting a tag recognition signal to the RFID tag to recognize the RFID tag, wherein the steps are repeated Recognize the RFID tag.

In a preferred embodiment, the fifth step allows the tag recognition signals between the readers in each group to be transmitted at different times so that the tag recognition signals in the respective groups do not collide with each other.

In a preferred embodiment, the readers in each group transmits the tag recognition signal sequentially in a predetermined order for a time divided by the time interval of the repeated frequency hopping notification signal by the number of readers included in each group, The tag recognition signals are transmitted at different times.

In a preferred embodiment, the readers in each group sequentially transmits the tag recognition signals in a random order for the time interval of the repeated frequency hopping notification signal divided by the number of readers included in each group, The tag recognition signals may be transmitted at different times.

In a preferred embodiment, the number m of groups in the first step is set to satisfy the following equation, and the operating frequencies of the respective groups are hopped according to a constant frequency permutation so as not to cross each other within an allowable frequency bandwidth. However, the width between the hopping operating frequencies is hopped larger than the set interference prevention frequency spacing width.

Equation

Where c is a minimum integer that is multiplied by the bandwidth between operating frequencies such that the operating frequency bandwidth can be greater than the interference avoidance frequency spacing.

In a preferred embodiment, the frequency hopping notification signal is transmitted using any frequency within the allowable frequency bandwidth.

As described above, according to the present invention, a plurality of RFID readers are divided into predetermined groups, and any one of the RFID readers included in the entire groups is set as a master reader, and frequency hopping transmitted by the master reader. All the RFID readers in each group are hopped by the notification signal at the same time, but each group is hopped with a different frequency permutation, thereby minimizing collision and interference between groups.

In addition, according to the present invention, the leaders in each group transmit the tag recognition signals sequentially in a predetermined order or in a random order, thereby minimizing collision and interference between the leaders in the group.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a multiple RFID reader environment to which a control method of a multiple RFID reader according to an embodiment of the present invention is applied, and FIG. 2 is a flowchart of a control method of a multiple RFID reader according to an embodiment of the present invention.

Referring to the drawings, a control method of a multiple RFID reader according to an embodiment of the present invention is applied in a multiple RFID reader environment 10 in which a plurality of RFID readers 110 to 160, 210 to 260 recognize RFID tags 300 and 300a. do.

That is, the present invention is not intended to solve the problem of collision or interference between the tag signals transmitted from the RFID tags 300 and 300a, but the tag recognition signals 110a to the RFID readers 110 to 160, 210 to 260. It is to solve the collision and interference problem between 160a, 210a ~ 260a).

A control method of a multi-RFID reader according to an embodiment of the present invention, first, the RFID readers 110 to 160, 210 to 260 include a predetermined number of different RFID readers 110 to 160 and 210 to 260, respectively. A plurality of groups 100 and 200 are set (S1000).

That is, the RFID readers 110 to 160, 210 to 260 are grouped into a certain number of groups 200 to be included in only one group.

In an embodiment of the present invention, the RFID readers 110 to 160, 210 to 260 are set to two groups of the first group 100 and the second group 200 by way of example.

However, the number of groups 100 and 200 may be set by Equation 1 to be described below. A detailed description will be made in the description of Equation 1 below.

In addition, the groups 100 and 200 perform frequency hopping at the same operating frequency with respect to the groups 100 and 200 at the same time, but perform frequency hopping at different operating frequencies between the groups 100 and 200. Group.

In other words, all the RFID readers 110a to 160a in the first group 100 hop at the same operating frequency, but are different from the RFID readers 210 to 260 of the second group 200. Hop to In addition, the RFID readers 210 to 260 of the second group 200 all hop at the same operating frequency, but are different from the RFID readers 110a to 160a in the first group 100. Hop to frequency.

On the other hand, frequency hopping (FH) refers to a method of minimizing collision and interference occurring in a communication channel as a method of communicating while changing a frequency over time without fixing a frequency at a transmitting side.

In addition, the number of the groups (100, 200) is set to a predetermined number according to the allowed frequency bandwidth allowed in the multi-RFID reader environment and the interference prevention frequency spacing to minimize the interference between each RFID reader.

In more detail, the number m of the groups 100 and 200 is determined to satisfy Equation 1 below.

Here, c is a minimum integer that can be multiplied by the bandwidth between operating frequencies so that the bandwidth between operating frequencies can be larger than the interference prevention frequency separation width, and can be expressed by Equation 2 below.

For example, when the allowable frequency bandwidth of the multi-RFID reader environment is about 5Mhz and the bandwidth between each operating frequency is 500Khz, if the interference prevention frequency separation is set to 800Khz, the integer c becomes 2 and the group Number m may be {m = 1,2,3,4}.

That is, each of the groups 100 and 200 may be hopped at an operating frequency greater than or equal to the interference prevention frequency spacing, and the collision and interference problems between the groups may be minimized in creating a frequency permutation between groups.

Next, one of the RFID readers included in the groups 100 and 200 as a whole is set as the master reader 160, and the remaining RFID readers 120 to 150 and 210 to 260 are slave readers, respectively. Set (S2000).

In other words, the master reader 160 is configured as one RFID reader 160 among the RFID readers of the multiple RFID reader environment 10 regardless of whether the group 100 or 200 is set.

Next, the master reader 160 transmits a frequency hopping notification signal 160b to itself and the slave readers (S3000).

That is, the master reader 160 is a reader for transmitting the frequency hopping notification signals 110b and 210b to itself and all slave readers.

In addition, the master reader 160 may be provided with a separate omni-directional antenna for transmitting the frequency hopping notification signal (160b).

In addition, the frequency hopping notification signal 160b is a signal for the master leader 160 and the slave leader to simultaneously hop to a constant operating frequency.

Next, the RFID readers in the groups 100 and 200 hop at the same frequency at the same time, but are hopped at different frequencies between the groups 100 and 200 (S4000).

That is, the groups 100 and 200 are hopped according to different frequency permutations.

For example, when the first group is hopped in the order of the first operating frequency-> second operating frequency-> third operating frequency, the second group is the second at the same time as the hopping time of the first group. The operating frequency-> third operating frequency-> first operating frequency is hopped to allow the RFID readers to operate at different operating frequencies for each group (100,200).

That is, since the RFID readers operate at different operating frequencies for each of the groups 100 and 200, collisions and interferences between the groups can be prevented.

In addition, the groups 100 and 200 are hopped according to different constant frequency permutations within an allowable frequency bandwidth allowed for the multi-RFID reader environment, and the number of groups to be set is set by Equation 1, thereby hopping. The width between the frequencies may be hopped larger than the anti-interference frequency spacing, which may minimize interference between each RFID reader.

Next, the readers of the groups 100 and 200 transmit the tag recognition signals 110a to 160a and 210a to 260a to the RFID tags 300 and 300a to recognize the RFID tags 300 and 300a (S5000).

That is, the master reader 160 transmits the frequency hopping notification signal 160b to the slave readers so that the slave readers including the receiver can perform frequency hopping, while in the region of the tag reader signal ( The RFID tag 300a is recognized by transmitting 160a.

In addition, the steps are repeated so that the readers of each of the groups 100 and 200 repeatedly recognize the RFID tags 300 and 300a.

Here, the tag recognition signals 110a to 160a and 210a to 260a transmitted by the readers in the groups 100 and 200 may be transmitted at different times, respectively, of the repeated frequency hopping notification signals 110b and 210b. The tag recognition signals 110a to 160a and 210a to 260a are sequentially transmitted in a predetermined order or a random order during the time interval divided by the number of leaders in each group 100 and 200.

In other words, tag recognition signals transmitted by leaders in each group do not collide with each other.

That is, by dividing a plurality of RFID readers into groups 100 and 200, frequency hopping is performed with different frequency permutations between the groups 100 and 200, thereby minimizing collision and interference (a) between groups, By transmitting the tag recognition signals 110a to 160a and 210a to 260a sequentially in a predetermined order or random order, collisions and interferences b between the readers in the groups 100 and 200 can be minimized.

In the above, the configuration and operation of the present invention has been shown in accordance with the above description and drawings, but this is merely described, for example, and various changes and modifications are possible without departing from the spirit and scope of the present invention. .

1 is a view showing a multi-RFID reader environment to which a control method of a multi-RFID reader according to an embodiment of the present invention is applied.

2 is a flowchart illustrating a control method of a multiple RFID reader according to an embodiment of the present invention.

In the drawings according to the present invention, the same reference numerals are used for components having substantially the same configuration and function.

<Description of the symbols for the main parts of the drawings>

100: first group 160: master leader

110 ~ 150,210 ~ 260: Slave Reader 200: Second Group

300,300a: RFID tag

Claims (7)

In a control method of a multiple RFID reader to reduce the operating frequency collision and interference problems between each RFID reader in a multiple RFID reader environment in which a plurality of RFID readers recognize RFID tags, A first step of setting the RFID readers into a plurality of groups including a predetermined number of RFID readers; A second step of setting any one of all RFID readers included in the groups as a master reader and setting the remaining RFID readers as slave readers; Transmitting, by the master leader, a frequency hopping notification signal to the master leader and the slave readers; And A fourth step in which each of the readers simultaneously performs frequency hopping at a predetermined operating frequency, performing frequency hopping at the same frequency for each group, and performing frequency hopping at different frequencies between the respective groups; Control method of multiple RFID reader, characterized in that. The method of claim 1, After the fourth step, the master reader and the slave reader further comprises a fifth step of transmitting the tag recognition signal to the RFID tag to recognize the RFID tag, And repeating the above steps and recognizing the RFID tag. The method of claim 2, In the fifth step, the tag recognition signals of the readers in the groups are transmitted at different times so that the tag recognition signals in the groups do not collide with each other. The method of claim 3, wherein The readers in each group transmit the tag recognition signals sequentially in a predetermined order for a time divided by the time interval of repeated frequency hopping notification signals by the number of readers included in each group, so that the tag recognition signals are different from each other. The control method of the multiple RFID reader, characterized in that to be transmitted in time. The method of claim 3, wherein The readers in each group transmit the tag recognition signals sequentially in a random order for a time divided by the time interval of the repeated frequency hopping notification signal by the number of readers included in each group, so that the tag recognition signals The control method of the multiple RFID reader, characterized in that to be transmitted at different times. The method according to any one of claims 1 to 5, The number m of groups in the first step is set to satisfy the following equation, The operating frequencies of the groups are hopped according to a constant frequency permutation so as not to cross each other within the allowable frequency bandwidth. The control method of the multiple RFID reader, characterized in that the width between the hopping operating frequency is larger than the set interference prevention frequency spacing width. Equation

Where c is a minimum integer that is multiplied by the bandwidth between operating frequencies such that the operating frequency bandwidth can be greater than the interference avoidance frequency spacing. The method of claim 6, And the frequency hopping notification signal is transmitted using an arbitrary frequency within an allowable frequency bandwidth.

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