KR20070014805A - Apparatus for controlling the gain of a transmission signal in a mobile radio frequency identification interrogator and method thereof - Google Patents

Abstract

An apparatus and a method for controlling a transmission signal gain of a wireless terminal having an RFID function are provided to transmit a signal with a gin lower than a gain corresponding to the maximum output distance because the distance between an RFID reader and a tag is shorter than the maximum output distance which is traditionally set, thereby reducing power consumption as much as that. A power control apparatus comprises the followings: an antenna(120); an RFID(Radio Frequency IDentification) RF unit(130) which processes signals, which will be transmitted to or is received from a tag through the antenna(120), at an RF band; and an RFID baseband modem(140) which processes a transmission signal, which will be processed by the RF unit(130), and a receiving signal processed by the RF unit(130) in a baseband. The baseband modem(140) automatically controls a gain of a signal which will be transmitted through the RF unit(130).

Description

Apparatus and method for controlling the transmission signal gain of a wireless terminal having a wireless recognition function

1 is a view showing the configuration of a wireless terminal having a wireless recognition function to which the present invention is applied.

2 is a diagram illustrating a connection configuration between an RFID RF unit and a baseband modem shown in FIG. 1 for controlling a gain of a transmission signal according to an exemplary embodiment of the present invention.

3 is a diagram illustrating a processing flow of an operation of controlling a gain of a transmission signal according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable wireless terminal having a radio frequency identification (hereinafter referred to as "RFID") function, and more particularly, to an apparatus and a method for controlling an output gain of a transmission signal.

RFID is a technology that attaches a tag to an object and collects, stores, processes, and tracks information from the tag through radio waves to enable positioning, remote processing, management, and information exchange. The RFID system (or smart tag system) is composed of a reader, an antenna, a tag, a server, a network interface module, and the like. The tag is a component for storing information, the reader is a component that enables reading / writing of information to / from the tag, and the antenna is a predefined frequency (eg 125 KHz, 134 KHz, 13.56 MHz). It may be included in the reader as a component for transmitting and receiving information with the tag by communicating with the tag in the protocol of.

Such RFID technology can be widely used in traffic systems, anti-theft systems, access control systems, logistics and data management systems, such as toll collection, vehicle location tracking, such as bus cards. In particular, such RFID technology is also being implemented in portable wireless terminals. In other words, due to the development of technology, the wireless terminal requires and implements more functions in addition to the voice communication function. For example, as a function of an RFID reader or interrogator is implemented in the wireless terminal, various tags may be read without a separate reader so that the information is output using a screen or a speaker of the wireless terminal.

On the other hand, since the magnitude of the output of the high frequency (RF) signal, which is a signal transmitted from the wireless terminal, affects the communication distance, the gain of the RF output in the wireless terminal implemented with the function of the RFID reader is It is fixedly set to output the maximum distance that can be communicated. The reader with the fixed output gain thus shoots a radio wave toward the tag with the same output and reads the signal back from the tag.

Since the RFID reader in the wireless terminal corresponds to a reader carried directly by a person, the distance between the tag and the RFID reader of the wireless terminal is different each time it is used. Since the RFID reader is generally used directly in front of the tag, the distance between the reader and the tag when using the RFID reader is generally shorter than the fixed maximum set output distance. Thus, even if the output gain of the RFID reader is lowered, it can communicate sufficiently with a close range tag. If the output gain can be lowered in this way, the operating current can be lowered, resulting in reduced battery consumption of the wireless terminal.

Accordingly, an object of the present invention is to provide an apparatus and method for controlling a gain of a transmission signal to reduce battery consumption by lowering a use current in a wireless terminal having an RFID function.

Another object of the present invention is to provide an apparatus and method capable of variably controlling the output gain of an RFID reader according to a distance in a wireless terminal having an RFID function.

According to an embodiment of the present invention for achieving the above objects, an apparatus for controlling the power of a signal transmitted from a wireless terminal having an RFID function for exchanging and recognizing information stored in a tag, through an antenna and the antenna An RFID RF unit which processes a signal to be transmitted to the tag and a signal received from the tag in a radio frequency band, and a baseband to process the transmission signal to be processed by the RF unit and the received signal processed by the RF unit in a baseband And an RFID baseband modem, wherein the baseband modem automatically controls the gain of a signal to be transmitted through the RF unit.

Preferably, the RF unit includes a first gain control unit controlling the gain of the signal to be transmitted according to the analog signal level provided. The baseband modem outputs a first digital first gain value at the beginning of the connection with the tag and does not receive information from the tag until a predetermined time elapses after the first gain value is output. A second gain controller configured to increase a preset gain value to the first gain value and output the increased gain value as a second gain value; and a digital gain value output from the second gain controller to an analog signal level. And a digital-to-analog converter for converting the output signal to the first gain controller.

Preferably, the second gain control unit increases the set gain value when the information from the tag is not received until the set time elapses after outputting the second gain value, and performs the increase operation. Repeatedly until information is received from the tag. The gain value increasing operation by the second gain controller is performed until the preset threshold gain value is reached. When the gain value increased by the second gain controller is the threshold gain value, an error message is output for recognition of the user.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that those skilled in the art may better understand the following detailed description of the invention.

In the following, further features and advantages of the invention will be described which form the subject of the claims of the invention. Those skilled in the art should recognize that the concepts and specific embodiments disclosed in the present invention may be readily used as a basis for changing or designing other structures in order to achieve the same objects of the present invention. Those skilled in the art should also recognize that structures equivalent to the invention do not depart from the spirit and scope of the broadest form of the invention.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be noted that reference numerals and like elements among the drawings are denoted by the same reference numerals and symbols as much as possible even though they are shown in different drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

First, the inventors of the present application considered a method in which a user arbitrarily sets and changes an output gain of a signal transmitted from a wireless terminal as a method of variably controlling a gain of a transmission signal according to a distance. When the tag is located at a short distance, the output gain of the transmission signal is set low, and when the tag is located at a long distance, the output gain of the transmission signal is set high. However, this setting is cumbersome in itself, and it is very inconvenient to recognize the distance and determine what gain to set accordingly.

Therefore, the inventor of the present application causes a signal of low output gain to be sent out when the RFID reader is operated for the first time to read a tag, and when the information of the tag is received from it (when read), the received tag information is processed according to a conventional procedure. do. On the other hand, if the information of the tag is not received (not read), the output gain is increased a little more so that the signal of increased gain is sent out. As such, the operation of receiving the tag information by increasing the output gain may be repeatedly performed a predetermined number of times. In an embodiment of the present invention, the iterative operation is performed until the increased gain value is smaller than the preset threshold.

1 is a view showing the configuration of a wireless terminal having an RFID function to which the present invention is applied.

Referring to FIG. 1, the wireless terminal includes components such as an antenna 101, an RF unit 102, a modem 103, an audio processing unit 104, a microphone 105, a speaker 106, a keypad 107, a memory 108, a display unit 113, and a controller 109. These components make up a typical wireless terminal that enables voice calls, such as mobile phones. The camera 110, the signal processor 111, the image processor 112, and the display 113 are components that enable transmission and reception of image information. As such components that enable transmission and reception of voice calls and video information are well known to those skilled in the art at the time of filing the present invention, detailed description thereof will be omitted.

In addition, the wireless terminal further includes an antenna 120, an RFID RF unit 130, and an RFID baseband modem 140, which are elements constituting an RFID reader or interrogator directly related to the present invention. These components have a function of wirelessly exchanging and recognizing information stored in a tag (not shown). The RFID RF unit 130 processes a signal to be transmitted to a tag through the antenna 120 and a signal received from the tag in a radio frequency (RF) band. The RFID baseband modem 140 processes the transmission signal to be processed by the RF unit 130 and the received signal to be processed by the RF unit 130 at the baseband. The RFID baseband modem 140 automatically controls a gain of a signal to be transmitted through the RF unit 140. Detailed description thereof will be described later.

FIG. 2 is a diagram illustrating a connection configuration between an RFID RF unit 130 and a baseband modem 140 shown in FIG. 1 for controlling a gain of a transmission signal according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the RF unit 130 includes a first gain controller 132 that controls a gain of a signal to be transmitted according to an analog signal level provided from the baseband modem 140. Such a gain control unit is a component included in the inside of the wireless terminal according to the prior art, but there is an obvious difference in the operation of the gain control. The gain control unit according to the prior art controls the output of the transmission signal with a fixedly set gain. On the other hand, the gain control unit according to the embodiment of the present invention automatically controls the output of the transmission signal with the gain determined by the baseband modem 140.

The baseband modem 140 outputs a first digital gain value which is preset in the initial connection with the tag. The determination of the initial connection with the tag and the output operation of the first gain value are performed by the processor 142 in response to the start signal being input from the controller 109 shown in FIG. 1. The processor (or core) 142 controls the second gain control unit 144 to control the second gain control unit 144 when it is determined that the information from the tag is not received until a predetermined time interval elapses after the first gain value is output. The gain value set in advance to the first gain value is increased and the increased gain value is output as the second gain value. The digital / analog converter 146 converts the gain value of the digital output from the second gain controller 144 into an analog signal level and outputs it to the first gain controller 132. The second gain control unit 144 may be separately configured as a separate element from the processor 142, or may be included and included therein as shown in the drawing.

The second gain control unit 144 outputs the second gain value under the control of the processor 142 and increases the set gain value when information from the tag is not received until the set time interval elapses. The increment operation is performed repeatedly until information is received from the tag. This repetitive operation may be performed until reaching a preset threshold gain value. When it is determined that the gain value increased by the second gain controller 144 corresponds to the threshold gain value during the repetitive operation, the processor 142 communicates with the controller 109 of FIG. 1 to display an error message. Users can recognize it by outputting it through. That is, the error message may be a visual message output through the display 113 or an audio message output through the speaker 106.

3 is a diagram illustrating a processing flow of an operation of controlling a gain of a transmission signal according to an exemplary embodiment of the present invention. This processing flow may be performed under the control of the processor 142 of the RFID baseband modem 140 of FIG. 2 described above.

Referring to FIG. 3, an operation according to an embodiment of the present invention is performed when the processor 142 determines that a start signal is received from the controller 109 of FIG. 1, which is the main processor of the wireless terminal, in step 301. Here, the start signal is a signal provided from the control unit 109 to instruct the RFID reader to read the tag. When the start signal is received, the processor 142 controls the gain controller 144 to control the RF unit 130.

In step 302, the gain controller 144 sets the input value of the D / A converter 146 to a preset gain value. In this case, the gain value may be set to a minimum gain value. After setting the input value of the D / A converter 146 to the minimum gain value, the processor 142 reads a tag in step 303. If it is determined in step 304 that information of the tag is not received or that cannot be interpreted until a predetermined time elapses, the processor 142 controls the gain control unit 144 to control the gain control unit 144 in step 306. The preset gain is increased, the increased gain is output as the input value of the D / A converter 146, and the tag is read again.

The operations of steps 303, 304, and 306, that is, reading the tag information by increasing the gain value by a predetermined value until the information of the tag is received, is input by the D / A converter 146 in step 305. Until the value is determined to be a preset threshold.

When it is determined in step 305 that the input value of the D / A converter 146 is the threshold value, the processor 142 transmits an error message to the controller 109 to notify the user of this fact. Then, the controller 109 notifies the fact visually or audibly through the display unit 113 or the speaker 106. When it is determined in step 304 that the tag information is received, the processor 142 transmits the received tag information to the controller 109. Transmission and reception between the processor 142 and the controller 109 may be performed by inter-processor communication (IPC). If step 307 or step 308 is performed, the operation is terminated.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

As described above, the present invention can automatically adjust the output gain of a signal transmitted for RFID in a wireless terminal equipped with an RFID reader. This invention has the following effects.

First, since the distance between the RFID reader and the tag is generally closer than the maximum output distance set in the related art, power consumption can be reduced by transmitting a signal with a gain lower than the gain according to the maximum output distance.

Second, when security is a problem, it is advantageous for security because if you read near the tag, it reads with less output. In general, if you have multiple tags, you will want to read only the tags closest to the wireless terminal. And when the tag is read in a situation where security is a problem, the signal output will be sent small when brought closer, thus preventing a security accident caused by the large output. Therefore, at the very beginning, the radio wave is transmitted with a small output, and if only the unread, the step is taken to increase the output gain of the radio wave in turn so that only the desired tag can be read and the security can be prepared.

Third, the trouble of manually adjusting the output of the RF signal can be avoided.

Claims (9)

An apparatus for controlling the power of a signal transmitted from a wireless terminal having a radio recognition (RFID) function for exchanging and recognizing information stored in a tag wirelessly, With antenna, An RFID radio frequency (RF) unit for processing a signal to be transmitted to the tag and a signal received from the tag through the antenna in a radio frequency band; An RFID baseband modem for processing a transmission signal to be processed by the RF unit and a received signal processed by the RF unit at a baseband, And the baseband modem automatically controls a gain of a signal to be transmitted through the RF unit. The method of claim 1, The RF unit includes a first gain control unit for controlling the gain of the signal to be transmitted according to the analog signal level provided, The baseband modem outputs a first digital first gain value at the beginning of the connection with the tag and does not receive information from the tag until a predetermined time elapses after the first gain value is output. A second gain control unit which increases a predetermined gain value to the first gain value and outputs the increased gain value as a second gain value, and a digital gain value output from the second gain control unit. And a digital-to-analog converter for converting the signal to the first gain controller. The method of claim 2, wherein the second gain control unit increases the set gain value when the information from the tag is not received until the set time elapses after outputting the second gain value. And repeatedly performing an operation until information is received from the tag. The power control apparatus of claim 3, wherein the gain value increasing operation by the second gain controller is performed until a preset threshold gain value is reached. The power control device of claim 4, wherein an error message is output for recognition of a user when the gain value increased by the second gain controller is the threshold gain value. RFID radio frequency (RFID) function for wirelessly exchanging information stored in a tag and recognizing it, and processing an antenna, a signal to be transmitted to the tag through the antenna and a signal received from the tag in a radio frequency band A wireless terminal comprising a (RF) unit and an RFID baseband modem for processing in a baseband a transmission signal to be processed by the RF unit and a received signal to be processed by the RF unit. In the method, Outputting a first digital gain value preset in the initial connection with the tag; If the information from the tag is not received until a preset time elapses after the first gain value is output, increase the preset gain value to the first gain value and convert the increased gain value into a digital second. Outputting the gain value, And controlling the gain of a signal to be transmitted through the wireless unit by converting the first gain value or the second gain value to an analog signal level. The method of claim 6, wherein the set gain value is increased when the information is not received from the tag until the set time elapses after outputting the second gain value. And repeatedly performing the process until it is received. 8. The method of claim 7, wherein the iterative process is performed until a predetermined threshold gain value is reached. The method of claim 8, further comprising outputting an error message for recognition of a user when the increased gain value is the threshold gain value.

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