KR20080067538A - Control system of radio frequency identification reader - Google Patents

Abstract

An RFID(Radio Frequency Identification) reader control system is provided to improve a recognition rate, reception sensitivity, and a recognition distance of a signal even though plural readers are installed in a limited area, and to exclude interference between channels used by the readers, thereby more freely arranging the readers. A reader control device(120) generates control information for each reader by comprising as follows. A switch control module(122) generates synchronization information of frequency hopping by using frequency hopping start information, and generates switching control information according to the synchronization information to deliver the generated information to the readers. A hopping control module(124) generates coding information of a hopping period to deliver the generated information to the readers. The readers process the frequency hopping on different hopping start channels by receiving the control information for each reader.

Description

RFC reader control system {Control system of Radio Frequency IDentification reader}

1 is a diagram illustrating a hopping channel in a frequency band when a typical RFID reader is operated in a frequency hopping manner.

2 is a diagram illustrating a form in which an RFID reader control system according to an embodiment of the present invention is installed in a building.

3 is a block diagram schematically illustrating components of a reader control apparatus of an RFID reader control system according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a form in which readers of an RFID reader control system according to an embodiment of the present invention hop by switch control information.

5 is a block diagram schematically illustrating components of a reader in an RFID reader control system according to an exemplary embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

100: RFID reader control system 120: reader control device

121: memory 122: switching control module

123: control module 124: hopping control module

125: connection module 140: reader

141a, 141b: receive / transmit antenna 142: LNA

143 and 151: first filter and second filter 144: mixer section

145: demodulation unit 146: control unit

147: phase synchronization circuit portion 148: connection portion

149: modulator 150: PAM

The present invention relates to an RFID reader control system.

Currently, ubiquitous network technology has attracted the attention of many people, ubiquitous network technology means a technology that allows to naturally connect to various networks regardless of time and place.

Such ubiquitous network technology includes RFID technology, and among them, RFID technology introduced in commerce is representative.

In general, a commercial RFID system consists of an RFID tag attached to a product and embedded with details, an RFID reader that reads information of the RFID tag using RF communication, and the RFID tag attached to the product is located at which the RFID reader is located. Since information is transmitted through RF communication through the region, it provides a foundation for efficiently managing logistics / distribution such as distribution, assembly, price change, and sales of goods.

Meanwhile, a conventional RFID reader is generally implemented through envelope detection using an amplitude shift keying (ASK) modulation scheme. According to the conventional design scheme, a bit error rate is lowered, thereby lowering a data recognition rate.

In addition, since the RFID reader targets a tag moving at a high speed, the radio wave environment is severely changed, and a change in the reception signal is greatly caused by an external environment change. It has a big impact.

RFID frequencies vary from low frequency (LF) such as 125 KHz and 135 KHz, high frequency (HF) such as 13.56 MHz, ultra high frequency (UHF) of 433 MHz and 900 MHz bands, and microwave of 2.45 GHz band. The advantages of low cost, small size, long recognition distance, and the ability to distinguish multiple tags are expected to make wide use of the frequency in the 900 MHz band.

However, the frequency in the 900 MHz band is largely affected by interference because of the narrow frequency band and the small number of carriers, and especially when a large number of readers are installed, the radio wave interference between the readers and the tags makes the tag information stable. It is recognized as a big obstacle in processing.

In order to minimize the influence of the frequency interference phenomenon, a frequency hopping method is generally used. A typical frequency hopping method is Frequency-Hopping Spread Spectrum (FHSS), which uses 15 independent channels and the entire channel. It handles frequency hopping and sends and receives data.

1 is a diagram illustrating a hopping channel in a frequency band when a typical RFID reader is operated in a frequency hopping manner.

Referring to FIG. 1, a general RFID reader processes frequency hopping using an independent channel. When one channel 1FA is used and then jumps to the next channel 2FA, a tag is interposed between reader signals carried on each channel. The signal a3 is buried.

Therefore, the tag signal a3 does not affect the reader signals a1 and a2 as interference signals or is stably restored by the reader signals a1 and a2.

In addition, when a plurality of readers are operated, when one reader uses the first channel 1FA and the other reader uses the second channel 2FA, some regions of the reader signals a1 and a2 overlap. And thus interfere with each other. Therefore, in the FHSS scheme, if the hopped channel is used by another reader, it is difficult to completely eliminate the inter-reader interference because a frequency collision occurs.

For this reason, there is an urgent need to develop a reader control technique and a channel coding technique capable of improving the recognition rate of a tag by excluding the influence of radio wave interference.

The present invention can stably restore a tag signal when a plurality of readers are operated in a limited area, and provide an RFID reader control system that controls interference of each reader so that interference does not occur between frequency channels.

In addition, the present invention provides an RFID reader control system for controlling a plurality of readers and efficiently processing tag information through a minimum circuit configuration and network configuration.

The RFID reader control system according to the present invention comprises: a switch control module for generating frequency hopping synchronization information using frequency hopping start information, and generating switching control information according to the synchronization information and transmitting the same to the reader; A reader control device for generating control information for each reader, including a hopping control module for generating coding information of a hopping period and transferring the coding information to the reader; And a plurality of readers receiving the control information for each leader and processing frequency hopping in different hopping start channels.

Hereinafter, an RFID reader control system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating a form in which the RFID reader control system 100 according to an embodiment of the present invention is installed inside a building.

2, the RFID reader control system 100 according to the embodiment of the present invention is largely composed of a reader control device 120 and a reader 140, the reader 140 is a predetermined area (in FIG. Exemplary) is installed in plurality, and performs RFID communication with the tag 300.

The tag 300 is attached to an article, a human body, and the like, and transmits tag information such as article information or personal information, and the reader 140 is installed in a moving area of the article and sends an information request signal (Command data) to the tag 300. Transmits the tag information from the tag 300 and processes it.

In the embodiment of the present invention, the reader 140 and the tag 300 are assumed to use a UHF signal in the 900 MHz band as a carrier signal.

In addition, the reader 140 performs frequency hopping in a FHSS scheme to communicate with the tag 300. The FHSS scheme uses a phase shift keying (PSK) phase modulation technique with an SNR of 12 dB. Unlike Direct Sequence Spread Spectrum (DSSS) method, which operates and uses overlapping channels, 15 independent channels are used and channels are leaped and transmitted and received by "Random Hopping Sequence" method over the entire channel.

However, even if the reader 140 is operated in the FHSS scheme, if the leap channel is used by another reader (for example, in the case of the reader installed in the upper and lower layers), it is difficult to exclude the interference between the readers because a frequency collision occurs.

In addition, even when jumping on an independent channel, when jumping to the next channel, the tag signal existing between the channels is buried in the reader signal on each channel, so that it is difficult to stably restore the tag signal.

Accordingly, the plurality of readers 140 start frequency hopping on different channels, respectively, and process hopping operations by avoiding adjacent channels among the 15 channels, and the operation of the reader 140 is performed by the reader controller 120. It is possible by control of.

The reader controller 120 and the plurality of readers 140 may be connected through a short-range wired / wireless network. When using a short-range wireless network, Wi-Fi (Wireless LAN), UWB (Ultra Wide Band), and Bluetooth (Bluetooth) may be connected. ), World Interoperability for Microwave Access (WiMax), Zigbee, Dedicated Short Range Communication (DSRC), etc., and UART (Universal Asynchronous Receiver / Transmitter), Internet (TCP / IP) , Switch hubs, serial / parallel cables, etc. may be used.

In the embodiment of the present invention, the reader control device 120 and the reader 140 are connected using a UART connection device.

First, the configuration and operation of the reader control device 120 will be described in detail.

3 is a block diagram schematically illustrating the components of the reader control device 120 of the RFID reader control system 100 according to an embodiment of the present invention.

According to FIG. 3, the reader control device 120 includes a switching control module 122, a hopping control module 124, a control module 123, a memory 121, and a connection module 125. In the 121, reader installation information, reader identification information, hopping start information for each reader, hopping channel information, hopping period information, and the like are stored.

The reader installation information refers to the location information (for example, to differentiate the installation area of the leader by floor) of the leader 140 installed inside the building, and the leader identification information refers to leader-specific control information to the corresponding reader 140. Identification information required for delivery.

The hopping start information for each reader is information for setting a start channel so that the readers 140 start hopping from different channels according to the installed region, and the hopping channel information is used in the RFID reader control system 100 according to the present invention. Information that defines a hopping method and channel information according to a signal standard and a hopping method.

The hopping period information is information set for each reader 140 as to whether or not to hop to how many channels.

The control module 123 operates by controlling the switching control module 122 and the hopping control module 124, extracts necessary information from the information stored in the memory 121, and controls the switching control module 122 and the hopping control module. Forward to 124.

The switching control module 122 generates the synchronization information of the frequency hopping by using the hopping start information, and configures the switch control information according to the synchronization information and transmits it to the readers 140.

Accordingly, the readers 140 receiving the switch control information start frequency hopping differently in the initial operation, and eventually have a result of starting hopping on different channels when synchronized.

This time separation and hopping in different channels is based on a time-frequency hopping spread spectrum (T-FHSS) channel coding scheme.

In addition, the hopping control module 124 sets the order of the frequency band to be hopping to generate coding information of the hopping period. From the hopping start channel differentiated for each reader 140, the hopping control module 124 forms a cyclic structure with a constant hopping period. By generating the coding information of the hopping period.

The coding information is transmitted by configuring leader-specific control information together with the switching control information, and the channel hopping operation of the reader 140 is processed by the leader-specific control information.

4 is a diagram illustrating a form in which the readers 140 of the RFID reader control system 100 are hopped by switch control information according to an exemplary embodiment of the present invention.

Referring to (a) of FIG. 4, a form in which the reader 140 installed on the first floor of the building processes frequency hopping is shown. The first channel is used as a start channel and two channels are taken as leap periods. Channel, 5 channels... Hopping is performed by cycling through 13 channels and 15 channels.

Therefore, since the area of the tag signal b3 existing between the reception signals b1 and b2 carried on the hopping channel is clearly separated, the tag signal b3 does not cause a problem that it cannot act as an interference signal or is buried in the reception signal and thus cannot be restored.

Referring to (b) of FIG. 4, a form in which the reader 140 installed on the second floor of the building processes frequency hopping is shown. The 11th channel is used as the start channel and the two channels are leap cycles. Channel, 15 channels, 1 channel... Hopping is performed by cycling through 7 channels, 9 channels, and so on.

Referring to (c) of FIG. 4, a form in which the reader 140 installed on the third floor of a building processes frequency hopping is shown. The sixth channel is used as a start channel and two channels are taken as leap periods. Channel, 10 channels... Hopping is performed by cycling through 14 channels, 2 channels, and 4 channels.

As such, the hopping start channels of the reader 140 installed on the first and third floors are spaced at a considerable interval compared to the reader 140 installed on the second floor, so that interference between channels is hardly generated.

Meanwhile, the connection module 125 forms a UART network together with the connection part 148 (see FIG. 5) of the reader 140. The connection module 125 is a kind of UART connection device, and the switching control module 122 And switching control information and coding information from the hopping control module 124 are configured as control information for each reader and transferred to the connection unit 148 of the reader 140.

The UART connection device may be implemented as a microchip equipped with a program for controlling an interface with a serial device connected to the main computing device, and provides an RS-232C DTE interface to the switching control module 122 and the hopping control module 124. This allows data transmission and reception with serial devices.

5 is a block diagram schematically illustrating the components of the reader 140 of the RFID reader control system 100 according to an embodiment of the present invention.

Referring to FIG. 5, the reader includes a receiving antenna 141a, a low noise amplifier (LNA) 142, a first filter 143, a mixer unit 144, a demodulator 145, a controller 146, and phase synchronization. It includes a circuit unit 147, a connection unit 148, a modulator 149, a power amplifier module (PAM) 150, a second filter 151, and a transmission antenna 141b.

The receiving antenna 141a receives a signal from a tag, and the LNA 142 suppresses and amplifies the noise component of the tag signal.

The first filter 143 filters the noise component mixed during the low noise amplification, and the mixer unit 144 converts the oscillation frequency signal supplied from the phase synchronization circuit unit 147 into a baseband signal by mixing it with a tag signal.

The demodulator 145 converts the baseband signal into a digital signal and transmits it to the control unit 146. The control unit 146 has a communication protocol to control wireless communication with the tag, interprets the digital signal, and stores tag information in memory. Store in and manage.

The modulator 149 synthesizes the digital signal (Command data) transmitted from the control unit 146 with the oscillation frequency signal of the phase synchronization circuit unit 147 and modulates it into an analog signal, and the PAM 150 transmits the modulated signal. Amplify to the size possible.

The second filter 151 filters the amplified transmission signal to remove the signal of the unwanted component, and the transmission antenna 141b transmits the filtered signal to the tag.

In this case, the mixer 144, the demodulator 145, and the modulator 149 are operated in the FHSS method, and process signals using 15 frequency channels in the 900 MHz band as described above.

The controller 146 controls the phase synchronization circuit 147 to selectively supply the oscillation frequency signals corresponding to 15 channels. Thus, the mixer 144 or the modulator 149 leaps 15 channels. Signals can be processed.

As described above, the control unit 146 receives the control signal for each reader through the connection unit 148, sets a hopping start channel, and tabulates a hopping period to thereby table the oscillation frequency signal. It can be controlled to supply selectively.

Although the present invention has been described above with reference to the embodiments, these are only examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains may have an abnormality within the scope not departing from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not illustrated. For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

According to the RFID reader control system according to the present invention, even if a plurality of readers are installed in a limited area, the recognition distance, reception sensitivity, and recognition rate of the signal can be improved, and the inter-channel interference phenomenon used by the readers can be eliminated. The degree of freedom of placement is secured.

In addition, according to the present invention, there is an effect that it is not necessary to have a complicated control system to control a plurality of leaders.

Claims (6)

A switch control module for generating frequency hopping synchronization information by using the frequency hopping start information, and generating switching control information according to the synchronization information and transmitting the same to the reader; A reader control device for generating control information for each reader, including a hopping control module for generating coding information of a hopping period and transferring the coding information to the reader; And And a plurality of readers receiving the control information for each reader and processing frequency hopping in different hopping start channels. The method of claim 1, wherein the reader control device and the reader RFID reader control system connected through short-distance wired / wireless network. The method of claim 1, wherein the reader control device A memory unit for storing at least one of reader installation information, reader identification information, hopping start information for each reader, hopping channel information, and hopping period information; And And a control module for controlling and operating the switching control module and the hopping control module, and extracting necessary information from the information stored in the memory unit and transferring the necessary information to the switching control module and the hopping control module. The method of claim 1, wherein the reader control device RFID reader control system for generating the coding information by a Time-Frequency Hopping Spread Spectrum (T-FHSS) channel coding scheme. The method of claim 1, wherein the leader Communication unit for processing the RFID communication; And And a controller configured to control the frequency hopping processing operation of the communication unit by receiving the synchronization information and the coding information. The method of claim 1, wherein the reader control device An RFID reader control system for generating coding information of a hopping period by arranging channels to form a cyclic structure with a constant hopping period from a hopping start channel differentiated for each reader.

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