KR20080071397A - Radio frequency identification/ ubiquitous sensor network system - Google Patents

Abstract

An RFID(Radio Frequency IDentification)/USN(Ubiquitous Sensor Network) system is provided to determine entry of a tag without any monitoring system and network by using characteristics of an RFID or USN communication environment, use computing resources and power efficiently depending on the entry of the tag, and perform a building management function such as worker location tracking, intruder monitoring, and theft prevention. An RF sensor device(120) includes a signal coupler(124) coupling a signal received from an RF reception end, a signal detector(125) generating a first detection signal by detecting change of the coupled signal when an object is moved in an electromagnetic field, and a controller(129) generating a second detection signal by operating an RF transmission end when the change of the coupled signal is determined based on the first detection signal. A sensor management device generates location information of the object when the second detection signal is received, and generates tracking information of the object by using the second detection signal. The controller determines whether the coupled signal is changed by calculating a reflection coefficient based on the first detection signal.

Description

RDF / WSN system {Radio Frequency IDentification / Ubiquitous Sensor Network system}

1 is a diagram illustrating an installation form of a general RFID system.

2 is a view illustrating a form in which an RF sensor device and a sensor management device are connected among RFID / USN systems according to an embodiment of the present invention.

Figure 3 is a block diagram schematically showing the components of the RF sensor device of the RFID / USN system according to an embodiment of the present invention.

4 is a data table illustrating an RF transmission detector table provided in the control unit of the RF sensor device according to an embodiment of the present invention.

FIG. 5 is a block diagram schematically illustrating components of a sensor management apparatus of an RFID / USN system according to an embodiment of the present invention. FIG.

<Explanation of symbols for main parts of drawing>

100: RFID / USN system 120: RF sensor device

121, 122: first antenna and second antenna 123: LNA

124: signal coupling unit 125: signal detection unit

126 and 133: first filter and second filter 127: signal converter

128: demodulation unit 129: control unit

130: first connection unit 131: power supply unit

132: modulator 134: PAM

135: phase synchronization circuit (PLL) 140: sensor management device

141: second connection unit 142: location information generation unit

143: tracking information management unit 144: data analysis unit

145: alarm device 146: database

The present invention relates to an RFID / USN 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.

Examples of such ubiquitous network technology include RFID or USN technology, and among them, RFID technology introduced in commerce is representative.

Ubiquitous Sensor Network (USN) refers to a network system configured to wirelessly collect information collected from various sensors. For example, by installing hundreds of sensor network nodes in inaccessible vulnerable areas, It can play the same role as monitoring.

In general, a commerce RFID system consists of a reader attached to a product, a tag embedded with detailed information, and a tag reader that reads information of the tag using RF communication, and the logistics / distribution such as distribution, assembly, price change, and sale of the product. It provides a foundation for management to be handled efficiently.

1 is a diagram illustrating an installation form of a general RFID system.

The reader 10 of the RFID system periodically transmits an information request signal to set an RFID communication channel with a tag 20 that has entered the propagation region of the antenna 12 and collects tag information.

At this time, since the reader 10 collects information for the unspecified number of tags 20, the reader 10 always transmits an information request signal at a high power, and this communication method reduces the efficiency of hardware resources and causes a high power waste. This can be called.

For example, the reader 10 needs to constantly transmit the information request signal regardless of whether the tag 20 has entered the communication area and is unnecessary because the main operation circuit operates in the full mode and maintains the standby state. This increases the burden on the circuit and consumes a lot of power.

In order to improve such an inefficient communication method, a method of introducing a separate sensing device 30 as shown in FIG. 1 has been proposed, and a plurality of sensing devices 30 such as an optical (infrared) sensor and a vibration (ultrasound) sensor are proposed. ) Monitors the communication area of the reader 10, and transmits an operation signal to the reader 10 when an object is detected.

The reader 10, which has been in a sleep mode, activates circuits and computational resources as the object is detected and operates in full mode to communicate with the tags.

However, due to the addition of a plurality of sensing equipment 30, the installation cost is increased, the network configuration is complicated, there is a problem that a separate software and hardware resources are required to process the signal transmitted from the sensing equipment (30). .

On the other hand, building facilities such as research institutes, corporations, and hotels have important aspects of management such as access control, worker flow, and asset theft prevention. Access is controlled only at the main entrance or entrance of the building where the site is located.

Conventionally, a solution for identifying a person's location by using an image photographing device (video camera), an image processing system, a mobile communication terminal, a recognition card, etc. has been provided. However, it is cumbersome to use and difficult to install. Due to the limitation, it is difficult to control the whole building, and the installation location is exposed to the outside, so that the accessor may artificially leave the control area.

Therefore, a method for controlling the location of the occupants, preventing theft, and grasping work efficiency using ubiquitous technology is required.

The present invention can determine the entry into the communication area of the object (tag) by using the characteristics of the RFID or USN communication environment without having to provide a separate monitoring system and network, and the operator and power depending on the entry of the object It can be used efficiently and provides RFID / USN system that performs building management functions such as worker location, intruder identification and theft prevention.

RFID / USN system according to the present invention comprises a signal coupling unit for coupling a signal present in the RF receiver; A signal detector configured to detect a change in the coupled signal and generate a first detection signal as the object moves in the electromagnetic field; And a controller configured to operate the RF transmitter and generate a second sensed signal when it is determined that there is a change in the coupled signal by the first sensed signal. And

And a sensor management device generating position information of the object and generating position tracking information of the object by using the position information when the second detection signal is transmitted.

Hereinafter, an RFID / USN 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 an RF sensor device 120 and a sensor management device 140 are connected among the RFID / USN system 100 according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the RFID / USN system 100 according to the embodiment of the present invention includes an RF sensor device 120 and a sensor management device 140. In the embodiment of the present invention, the RF sensor device ( 120 is assumed to be a reader that communicates with the tag. Of course, the RF sensor device 120 may be implemented as a leader of the USN system.

In addition, the sensor management device 140 is connected to the RF sensor device 120 through a wired / wireless network and collects and manages movement information, tag information, etc. of an object detected by the RF sensor device 120, for example. It can be implemented in the form of a computer located in the central center of the building.

Referring to FIG. 2, the RF sensor device 120 is located in various places within a building to detect movement of an object, and receives tag information when the object is tagged.

The detection signal and tag information generated by the RF sensor device 120 are transmitted to the sensor management device 140 through a wired / wireless network. The RF sensor device 120 and the sensor management device 140 may be, for example, wireless networks. When connected via Wi-Fi (Wireless LAN), UWB (Ultra Wide Band), Bluetooth (Bluetooth), World interoperability for Microwave access (WiMax), Zigbee, Dedicated Short Range Communication (DSRC) Can be.

In the embodiment of the present invention, it is assumed that the RF sensor device 120 and the sensor management device 140 are connected through a WLAN.

The sensor management device 140 generates location information of the object based on the transmitted detection signal and tag information, generates location tracking information of the object using the location information, object recognition, intruder determination, staff management, and the like. Perform administrative functions.

Hereinafter, the RF sensor device 120 and the sensor management device 140 will be described in detail with reference to the accompanying drawings.

3 is a block diagram schematically showing the components of the RF sensor device 120 of the RFID / USN system 100 according to an embodiment of the present invention.

Referring to FIG. 3, the RF sensor device 120 includes a first antenna 121, a low noise amplifier (LNA) 123, a signal combiner 124, a signal detector 125, and a first filter 126. , Signal converter 127, demodulator 128, controller 129, first connector 130, power supply 131, modulator 132, second filter 133, PAM 134, phase A synchronization circuit (PLL; phase locked loop) 135 and the second antenna 122 is included.

The control unit 129 controls the power supply unit 131 to maintain the power supply to the receiving path stage consisting of the LNA 123 to the demodulation unit 128, and thus is constant for the entire circuit constituting the receiving path stage. Impedance is generated.

In addition, the first antenna 121 is an antenna for receiving a tag signal. When power supply is maintained at the receiving path end, an electromagnetic field is formed around the first antenna 121, and a conductive object such as a metallic material or a human body is formed in the electromagnetic field. If it moves from, the impedance value of the receiving path end (change of impedance matching) occurs.

This is a phenomenon based on Lorentz's law, in which a physical force (moving force of an object) affects an electromagnetic field, so that a current is generated in a conductive object in which an electromagnetic field is formed. Will flow.

The generated current may be understood as a concept of reflection amount (coefficient) generated by an impedance difference on a connection end (eg, a connection end based on the first antenna 121), and thus the current may have a predetermined reflection coefficient. It can be regarded as a kind of reflection wave signal having (Γ, gamma, Reflection Coefficient) (hereinafter, the current generated at the receiving path end by the movement of an object is called a "reflection wave signal").

The reflection coefficient can be calculated by the following equation.

In Equation 1,

"V +" means the input voltage (voltage of power maintained at the receiving path end),

"V-" means the reflected voltage (the amount of change in voltage due to the reflected wave signal).

In addition, "Z _L " means an impedance (hereinafter, referred to as "initial impedance") formed when power is maintained at the reception path end.

"Z _O " means impedance formed by the reflected wave signal.

By this principle, the RF sensor device 120 according to the embodiment of the present invention can detect the reflected wave signal, and when the reflected wave signal is detected, it is interpreted that an object enters the vicinity.

When the reflected wave signal is detected (if the movement of the object is confirmed), the controller 129 considers to perform RFID communication (a tag is approached) and operates in a full mode, and the reflected wave signal is not detected. If not, it operates in the low power mode. Functions of the controller 129 related to the full mode and the low power mode will be described later.

On the other hand, the LNA 123 suppresses and amplifies noise components when the power of the signal received through the first antenna 121 is lowered due to the effects of attenuation and noise.

The signal combiner 124 is connected between the LNA 123 and the first filter 126 and performs a function of coupling a signal component present at the receiving path end to the signal detector 125, for example. It can be implemented using a coupling capacitor or a directional coupler.

The first filter 126 may be provided as a saw filter, and filters only the received signal of the corresponding RFID band among the signals received through the first antenna 121.

The signal converter 127 mixes the received signal transmitted from the first filter 126 with the oscillation frequency signal and converts the signal into an intermediate frequency signal. The I-in-phase signal is provided through two mixers 127a and 127b. And a quadrature-phase (Q) signal.

In this case, the phase synchronization circuit part 135 generates an oscillation frequency signal of, for example, a 900 MHz band, and transmits the generated oscillation frequency signal to the signal converter 127 and the modulator 132, respectively.

The demodulator 128 processes the analog signal as a digital signal and transmits it to the controller 129.

The signal detection unit 124 converts the coupled signal into a digital signal of a predetermined level (hereinafter referred to as a "first detection signal") and transmits it to the control unit 129, and the control unit 129 transmits the converted signal. The analysis is performed to determine whether a reflected wave signal is present.

The signal detector 124 may be provided in the form of a combiner, for example, a log amplifier, capable of detecting electric field and impedance values of the coupled signal.

The log amplifier may include an amplifier, a sensing circuit, a compensation circuit, and a bias circuit. The log amplifier outputs a coupling signal in an analog state as a DC voltage signal to detect a level, and the coupling signal is directly decibeled. By outputting a proportional DC voltage signal, it is possible to extend the signal sensitivity range of the power level that can be received.

The controller 129 includes a communication protocol to control wireless communication with the tag, analyze a code of a signal transmitted from the demodulator 128, and process data conversion, filtering for information extraction, and the like.

In addition, when the first detection signal is transmitted, the control unit 129 applies a control signal to the power supply unit 131 to supply power to the transmission path stages from the modulation unit 132 to the PAM 134. Before the detection signal is transmitted, the power of the transmission path end is disconnected.

That is, in the standby state where the movement of the object is not detected, only the reception path end maintains operation (low power mode), and when the movement of the object is detected by the reflected wave signal, the transmission path end also starts operation (full mode) to perform RFID communication. Will be performed. Therefore, the RF sensor device 120 can prevent the waste of power in the state that the object is not detected and can efficiently use the computational resources.

The power supply unit 131 may be implemented as, for example, a power management integrated circuit (PMIC) device.

4 is a data table illustrating an RF transmission detector table included in the control unit 129 of the RF sensor device 120 according to an embodiment of the present invention.

Referring to FIG. 4, VSWR (Voltage Standing Wave Ratio; a value representing a reflection coefficient or S11, S22, etc., and means a height ratio of standing waves generated by reflection) and reflection loss ( RL; Return Loss; converted from reflection coefficient to log scale (dB) of power) and reflection coefficient (Γ; Reflection Coefficient). Can be calculated.

The controller 129 needs to correct (initialize) the initial impedance or the electric field value to determine whether the change in the initial impedance of the receiving path stage is caused by the reflected wave signal, and the correction operation is performed by the RF transmission wave detector. Can be processed based on the table.

In addition, the controller 129 may determine whether the first detection signal is a reflected wave signal by calculating Equation 1 or Equation 2 using the impedance and the electric field as variables, and comparing the result value with the table value. .

When the first detection signal is transmitted from the signal detection unit 125, the controller 129 generates a second detection signal and transmits the second detection signal to the first connection unit 130 along with the tag information.

The first connection unit 130 configures the second detection signal and tag information into packet data in accordance with the WLAN communication standard and transmits the packet data to the sensor management apparatus 140 in accordance with the transmission standard.

Meanwhile, the modulator 132 modulates the digital signal transmitted from the controller 129 into an analog signal of a high frequency band, and uses the oscillation frequency signal transmitted from the phase synchronization circuit 135 when modulating.

In addition, the second filter 133 (the first filter 126 and the second filter 133 may be provided as a saw filter) filters the signals of the undesired components mixed during modulation.

The PAM 134 amplifies the filtered signal and transmits the amplified signal to the second antenna 122, and the leader information (Command data) is transferred to the tag through the second antenna 122.

FIG. 5 is a block diagram schematically illustrating components of the sensor management apparatus 140 of the RFID / USN system 100 according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the sensor management device 140 includes a second connection unit 141, a location information generation unit 142, a tracking information management unit 143, a data analysis unit 144, an alarm device 145, and a database D. / B) 146, wherein the second connection unit 141 performs wireless LAN communication with the first connection unit 130 to receive the second detection signal and tag information.

The second connection unit 141 analyzes / extracts the second detection signal and tag information according to the signal standard, converts the second detection signal and the tag information into digital data that can be processed by the program, and transmits the converted information to the location information generation unit 142.

The location information generation unit 142 generates the location information of the detected object as the second detection signal is transmitted, and recognizes the object by tag information and matches it with the location information when the tag is attached to the corresponding object.

For example, the partition area of the building is coordinated, and the RF sensor device 120 may be displayed as coordinate information according to the installation area. Therefore, it is possible to determine the position information of the detected object by determining which RF sensor device has transmitted the second detection signal.

In addition, when the object moves, the second sensing signal is continuously received from the RF sensor devices 120, and the tracking information manager 143 generates the location tracking information by managing the location information as group data.

The data analysis unit 144 performs information processing such as object recognition, intruder determination, employee management, and work efficiency using the location information, location tracking information, tag information, and the like. If not, the data analysis unit 144 interprets the location information of the intruder and operates the alarm device 145.

On the other hand, if there is tag information corresponding to the location information, the data analysis unit 144, for example, can determine what work at which place and time workers work, according to the D / B (146) data according to the statistical information By doing so, you can manage your staff and understand your work efficiency.

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 / USN system according to the present invention, there is an effect that it is possible to monitor the radio wave area using the reflected wave signal without using a separate sensing system, and to efficiently use power and circuit resources according to the monitoring result.

In addition, according to the present invention, it is possible to accurately determine whether or not the object is moved by introducing the concept of reflected wave, it is possible to easily configure the building management system through a simple circuit configuration and software processing, intruder determination, work flow grasp, assets It is effective to efficiently carry out building management tasks such as theft prevention.

Claims (10)

An RF device comprising an RF transmitter and an RF receiver, comprising: a signal coupling unit for coupling a signal present in the RF receiver; A signal detector configured to detect a change in the coupled signal and generate a first detection signal as the object moves in the electromagnetic field; And a controller configured to operate the RF transmitter and generate a second sensed signal when it is determined that there is a change in the coupled signal by the first sensed signal. And And a sensor management device to generate location information of the object and generate location tracking information of the object using the location information when the second detection signal is transmitted. The method of claim 1, wherein the signal detection unit RFID / USN system for generating the detection signal by detecting a change in one or more of the basic impedance value and the basic electric field value of the coupled signal. The method of claim 1, wherein the control unit RFID / USN system to turn off the operation of the RF transmitter if it is determined that there is no change in the coupled signal. The method of claim 1, wherein the control unit RFID / USN system to control the power supply unit so that power is supplied or not supplied to the RF transmitter. The method of claim 1, wherein the signal detection unit RFID / USN system including a log amplifier. The method of claim 1, wherein the control unit RFID / USN system for determining whether the coupled signal changes by calculating the reflection coefficient according to the detection signal. The method of claim 1, When the power is supplied to the RF receiver includes an antenna which is formed an electromagnetic field of a predetermined area, The control unit is an RFID / USN system for maintaining the RF receiver in the operation mode irrespective of the detection signal. The method of claim 2, wherein the control unit Equipped with an RF carrier detector table, RFID / USN system for correcting the initial value of the basic impedance value and the basic electric field value by the table value. The method of claim 1, wherein the RF sensor device RFID / USN system that is the leader of a Radio Frequency IDentification (RFID) system or a Ubiquitous Sensor Network (USN) system. The method of claim 1, The RF sensor device communicates with a tag attached to the object as the RF transmitter is operated, generates tag information, and transmits the tag information to the sensor management device. The sensor management device is RFID / USN system for performing at least one information processing of object recognition, intruder determination, staff management based on the tag information.

Images