JP2005064822A - Radio communication apparatus and radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable data transmission with low power consumption and simple communication setting by using a system as a RFID system and a radio LAN system which use a 2.4HGz band together. <P>SOLUTION: When a radio LAN device is used as a RFID reader, an antenna switch is replaced with a circulator and a function of transmitting a non-modulated carrier and an ASK modulated wave is added in order to simultaneously perform data transmission operation and data reception operation. In order to use a radio LAN device as a RFID tag, one antenna is always made open and the other antenna is constituted so as to be switched to opening and closing, thus a back scatter system is attained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radio communication apparatus and radio communication system using a radio wave communication method using a microwave of a specific frequency band, and more particularly to an RFID system using a microwave of 2.4 GHz band, IEEE802.11b, IEEE802.11g, etc. The present invention relates to a wireless communication apparatus and a wireless communication system including a wireless LAN using the 2.4 GHz band.

  More particularly, the present invention relates to a wireless communication apparatus and a wireless communication system that also use a plurality of radio wave communication methods, and in particular, to use both the RFID system and the wireless LAN system that use the same 2.4 GHz band, thereby reducing power consumption. The present invention relates to a wireless communication apparatus and a wireless communication system that realize data transmission and simple communication settings.

  As an example of wireless communication means that can be applied only locally, RFID can be cited. The RFID is a system composed of a tag and a reader, and is a system that reads information stored in the tag in a contactless manner with a reader. Other names include "ID system, data carrier system", etc., but this RFID system is common worldwide. For short, it may be called RFID. Translated into Japanese, it becomes “a recognition system using high frequency (wireless)”. Examples of the communication method between the tag and the reader / writer include an electromagnetic coupling method, an electromagnetic induction method, and a radio wave communication method (for example, see Non-Patent Document 1). Of these, the present invention relates to a radio wave communication system using a microwave such as a 2.4 GHz band (described later).

  An RFID tag is a device including unique identification information, has an operating characteristic of oscillating a radio wave of a modulation frequency corresponding to the identification information in response to reception of a radio wave of a specific frequency, and the RFID tag on the reader side Based on the oscillation frequency, it is possible to specify what it is. Therefore, in a system using RFID, it is possible to perform identification of an article, identification of an owner, and the like using a unique ID written in an RFID tag. Currently, RFID systems are used in many systems, including entry / exit management systems, goods identification systems in logistics, fee clearing systems in canteens, and unauthorized removal prevention systems at stores such as CDs and software. ing.

  For example, an IC chip having transmission / reception and memory functions, a driving source of the chip, and an antenna can be packaged to manufacture a wireless identification device in a small size (see, for example, Patent Document 1). According to this wireless identification device, various data relating to articles and the like are transmitted to the receiving means of the IC chip via the antenna, the output is stored in the memory, and the data in the memory is read as necessary, It can be supplied to the outside wirelessly through an antenna. Accordingly, it is possible to quickly and easily confirm or track the presence or position of an article or the like.

  FIG. 7 shows a configuration example of a conventional RFID system. Reference numeral 101 corresponds to the tag side of the RFID, and includes a tag chip 102 and an antenna 103. As the antenna 103, a half-wave dipole antenna or the like is used. The tag chip 102 includes a modulation unit 110, a rectification / demodulation unit 112, and a memory unit 113.

The radio wave f _o transmitted from the tag reader 100 is received by the antenna 103 and input to the rectifying / demodulating unit 110. Here, the received radio wave f _o is rectified, and at the same time is converted into a DC power source, the demodulation function by the DC power supply starts operating, that for the tag 101 is a read signal is recognized. The power generated by receiving the radio wave f _o is also supplied to the memory unit 113 and the modulation unit 110.

  The memory unit 113 reads ID information stored therein in advance and sends it to the modulation unit 110 as transmission data. The modulation unit 110 includes a diode switch 111, and repeats the on / off operation of the diode switch 111 according to the bit image of the transmission data. That is, when the data is 1, the switch is turned on, and the antenna is terminated with an antenna impedance (for example, 50Ω). At this time, radio waves from the tag reader 100 are absorbed. When the data is 0, the switch is turned off, the diode switch 111 is opened, and at the same time, the end of the antenna is opened. At this time, the radio wave from the tag reader 100 is reflected and returns to the transmission source. Such a communication method is called a “back scatter method”. In this way, the tag 101 can send internal information to the reader side with no power supply.

  One tag reader 100 includes a host device 106 such as a portable information terminal, a tag reader module 104, and an antenna 105 connected to the tag reader module 104.

The host device 106 notifies the communication control unit 120 of a read instruction for the tag 101 via the host interface unit 121. Upon receiving the tag read command from the communication control unit 120, the baseband processing unit 119 performs a predetermined editing process on the transmission data, performs further filtering, and then sends the filtered data to the ASK modulation unit 117 as a baseband signal. send. ASK modulating unit 117, ASK with frequency f _o of the frequency synthesizer 116: performing (Amplitude Shift Keying amplitude shift keying) modulation.

  The frequency setting of the frequency synthesizer 116 is performed by the communication control unit 120. In general, the transmission frequency to the tag is used by hopping in order to reduce the standing wave of the signal from the RF tag and multipath. This hopping instruction is also given by the communication control unit 120. The transmission signal subjected to ASK modulation is radiated from the antenna 105 toward the tag 101 via the circulator 114.

A signal having the same frequency as the transmission signal from the tag reader 100 is returned from the tag 101 by reflection by the back scatter method (described above). This signal is received by the antenna 105 of the tag reader 100 and input to the mixer 115. Since the mixer 115 the same local frequency f _o and the transmission is inputted, so that the signal subjected to modulation by the tag 101 appears at the output of the mixer 115. The demodulator 118 demodulates data consisting of 1 and 0 bit sequences from this signal and sends the data to the communication controller 119. The communication control unit 119 decodes the data, extracts the data (ID) stored in the memory 113 in the tag 101, and transfers the data (ID) from the host interface unit 120 to the host device 106.

  The tag reader 100 can read information in the tag 101 by the mechanism as described above. In general, the tag reader can also be used as a tag writer, and can write specified data on the host device 106 side in the memory 113 in the tag 101.

  By the way, a wireless LAN has attracted attention as a system for releasing users from wired LAN connection. According to the wireless LAN, most of the wired cables can be omitted in a work space such as an office, so that a communication terminal such as a personal computer (PC) can be moved relatively easily. In recent years, the demand for wireless LAN systems has increased remarkably with the increase in speed and cost. In particular, recently, in order to establish a small-scale wireless network between a plurality of electronic devices existing around a person and perform information communication, introduction of a personal area network (PAN) has been studied. For example, different radio communication apparatuses and radio communication systems are defined using frequency bands that do not require a license from a supervisory agency, such as 2.4 GHz band and 5 GHz band.

  In recent years, the prevalence of wireless LANs has increased, and in addition to information devices such as PCs and PDAs, they are also used in portable devices such as mobile phones and digital cameras. Examples of the application include uploading image data taken with a camera-equipped mobile phone or a digital camera to a PC via a wireless LAN.

  One standard for wireless networks is a standard such as 802.11 standardized by IEEE (The Institute of Electrical and Electronics Engineers) (see Non-Patent Document 2, for example), HiperLAN / 2, IEEE 302.15.3, Bluetooth communication, and the like. As for the IEEE802.11 standard, there are various wireless communication systems such as the IEEE802.11a standard, the IEEE802.11b standard, etc., depending on the wireless communication system and the frequency band to be used.

  The present invention pays particular attention to IEEE 802.11b as a wireless LAN system. IEEE 802.11b uses a 2.4 GHz band, uses DS-SS (Direct Sequence Spectrum Spread) as a modulation method, and is a wireless LAN standard with a maximum transmission rate of 11 Mbps. As an access control method, CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) is used.

  FIG. 8 shows a configuration example of the wireless LAN system. The wireless LAN terminal 200 is used with a wireless LAN module 201 added to a host device 202 such as a portable information terminal. The host device 202 and the wireless LAN module 201 are connected to each other by, for example, a compact flash interface.

  The wireless LAN terminal 200 can be connected to a wide area network such as the Internet 206 via the wireless LAN base station 203. The wireless LAN base station 200 is equipped with two antennas 204 and 205 in order to obtain a diversity effect, for example. The wireless LAN module 201 may also perform diversity. Here, the configuration of the wireless LAN module 201 will be described below.

  The wireless LAN module 201 mainly includes two antennas 210 and 211 for diversity, two antenna switches 212 and 213, a reception unit 214, a transmission unit 217, a frequency synthesizer unit 218, and a baseband unit 219. Consists of.

  The receiving unit 214 includes a quadrature detector 215 and an AGC (Auto Gain Control) amplifier 216. The baseband unit 219 includes a PHY (Physical) unit 220 that performs modulation / demodulation and radio control, and a CPU (Central Processing Unit) 222. The MAC unit 221 that performs 802.11 MAC (Media Access Control) control and a host An interface unit 223 is included.

  The antenna switch 212 is controlled to be switched between the antenna 210 and the antenna 211 by the CNT 201 via the PHY unit 220 in accordance with an instruction from the CPU 222 of the MAC unit 221 according to the communication quality. The antenna switch 213 is used for switching between transmission and reception under the control of the CNT 202.

  At the time of reception, the receiving unit 215 is activated by the control signal CNT 203 from the PHY unit 220. The 2.4 GHz band IEEE 802.11b modulated wave is input to the receiving unit 214 via either one of the two antennas 210 or 211 and the two antenna switches 212 and 213. A carrier having the same frequency as the received wave is supplied from the frequency synthesizer unit 218 to the quadrature detector 214 as a local frequency. The frequency setting of the frequency synthesizer 218 is also performed by the PHY unit 220. The modulated wave input to the quadrature detector 214 is directly converted, converted into I-axis and Q-axis baseband signals, and then sent to the AGC amplifier 216 at the subsequent stage. The AGC amplifier 216 is controlled by a control signal CNT203 from the PHY unit 220 so that its output becomes a constant level.

  The AGC-controlled I-axis and Q-axis baseband signals are input to the PHY unit 220 and demodulated from the DS-SS signal to digital data. The MAC unit 221 decomposes packet data according to the MAC layer protocol defined by IEEE 802.11b, and obtains target payload data. The series of processes of the baseband unit 219 is executed according to instructions from the CPU 222.

  The host interface unit 223 outputs the received data to the host device side. If the host device is a PDA or the like, the host interface unit 223 is composed of a compact flash card, and becomes Ethernet (registered trademark) when connected to a network like a base station.

  At the time of transmission, the transmission unit 217 is activated by the control signal CNT202 from the PHY unit 220. The host interface unit 223 passes the transmission data transferred from the host device to the MAC unit 221. The MAC unit 221 packetizes transmission data according to the MAC layer protocol defined by IEEE 802.11b, and transfers the packet to the PHY unit 220. The PHY unit 222 performs modulation processing based on the PHY layer protocol defined in IEEE 802.11b, generates I-axis and Q-axis baseband signals, and passes them to the orthogonal modulator of the transmission unit 217. The transmission unit 217 performs quadrature modulation using the carrier of the frequency synthesizer 218, and obtains a target modulated wave in the 2.4 GHz band. This modulated wave is transmitted from one of the antennas 210 or 211 via the antenna switch 213 and the antenna switch 212.

  In recent years, both RFID systems and wireless LAN systems such as IEEE802.11b have become widespread, and small devices such as PCs and PDAs are often equipped with any one of these radio communication systems. An application that uses both of these two radio communication systems at the same time is also conceivable. For example, data read from a tag at a close distance using an RFID system can be sent to the Internet using a wireless LAN, or related data downloaded from the Internet can be written to a device at a close distance via the RFID system.

  However, in such a case, each communication module is required for a single device. However, it is complicated to use two communication modules by replacing them, resulting in an increase in cost.

  In addition, when a wireless LAN is mounted on a portable device such as a mobile phone or a digital camera, the power consumption becomes a problem. Most of the commercially available IEEE802.11b wireless LAN cards consume power of 800 mW or more during transmission and 600 mW or more during reception. This power consumption is a heavy burden for portable devices that are predicated on battery drive. Moreover, even if the transmission power is reduced only for a short distance, the power consumption can be reduced only by about 80%.

  In order to connect a wireless LAN device to a base station, initial settings such as an encryption key and other communication parameter setting processes are required first. However, a portable device such as a digital camera with few input means has a problem that the data input operation at the time of initial setting becomes complicated.

JP-A-6-123773 Klaus Finkenzeller (Translated by Software Engineering Laboratory) "RFID Handbook Principles and Applications of Contactless IC Cards" (Nikkan Kogyo Shimbun) International Standard ISO / IEC 8802-11: 1999 (E) ANSI / IEEE Std 802.11, 1999 Edition, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layers (PH)

  An object of the present invention is to provide an excellent wireless communication apparatus and wireless communication system that also use a plurality of radio wave communication systems.

  A further object of the present invention is to provide an excellent wireless communication apparatus and wireless communication that can realize low power consumption data transmission and simple communication setting by using both the RFID system and the wireless LAN system using the same 2.4 GHz band. It is to provide a communication system.

The present invention has been made in consideration of the above problems, and a first aspect of the present invention is a reader / writer function for reading and writing data of a radio frequency identification (RFID) tag, a wireless communication function, and a connected host device. A wireless communication device having a common host interface unit and a direct conversion method transmitter and receiver shared by the two functions,
A reader / writer function mode for controlling and controlling the transmitting unit and the receiving unit to be turned on at the same time so that the transmitting unit can transmit a modulated or unmodulated carrier;
A wireless communication function mode for controlling the transmission unit and the reception unit to be exclusively turned on;
A wireless communication apparatus comprising:

  Therefore, according to the present invention, a small shared module can be realized at low cost by combining the RFID tag reader function and the wireless LAN communication function with a common RF block.

  Here, the wireless communication apparatus according to the present invention modulates and transmits a control signal to an external device in the reader / writer function mode.

  The wireless communication apparatus according to the present invention further includes an antenna connection means including an antenna that transmits and receives radio waves, and a circulator that can connect the antenna to either the transmission unit or the reception or simultaneously. Yes. A circulator has a property that a signal is transmitted only to ports adjacent to each other in a certain direction, and is used for separation of a transmission wave and a reception wave for an RFID reader.

  In addition, the wireless communication apparatus according to the present invention controls the on / off of the antenna switch that terminates or opens the antenna, and backs up data by absorbing or reflecting external radio waves according to the data bit string. -You may further provide the RFID tag function mode which transmits by a scatter method.

A second aspect of the present invention is a wireless communication system including a wireless base station and a wireless terminal,
The radio base station and the radio terminal are both equipped with an RFID system based on a radio wave communication method using microwaves,
The wireless terminal transmits a predetermined wireless communication setting data request by absorbing or reflecting an external radio wave based on antenna termination control using a carrier received from a wireless base station,
In response to the wireless communication setting data request, the wireless base station transmits wireless communication setting data by a reflected wave based on antenna termination control using a carrier received from the wireless terminal.
This is a wireless communication system.

  However, “system” here refers to a logical collection of a plurality of devices (or functional modules that realize specific functions), and each device or functional module is in a single housing. It does not matter whether or not (the same applies hereinafter).

  The wireless communication setting data mentioned here includes, for example, initial setting values such as a channel number, an ESSID (Extended Service Set Identifier), and a WEP (Wired Equivalent Privacy) key.

  Since the WEP key is an encryption key, the user must actually set it. It is cumbersome to perform such a setting operation on a portable device with a poor user interface. Although it is cumbersome to perform such setting work on a portable device with a poor user interface, according to the present invention, the user input operation can be replaced by reading a tag using an RFID system. Can do.

  Although security is important in the process of setting the encryption key, the reflected wave used for data transmission in the RFID system is very small power, and its communicable range is limited to within 1 m. Security can be ensured by adding the mutual devices to the initial setting mode manually at the beginning of the setting.

  In addition, by adding a detector for radio waves in the use frequency band (for example, 2.4 GHz band) to the reception side, it is possible to transmit an unmodulated carrier at an arbitrary frequency in the use frequency band on the transmission side. This makes it even more difficult to intercept the exchange of wireless communication setting data such as an encryption key from the outside.

  It is also possible to encrypt and transmit uncentered communication setting data such as initial setting items. Also, nobody may be able to easily obtain an encryption key for wireless LAN communication by an initial setting operation.

  As a specific method, an RFID tag is used for initial setting, and a common key of a common key cryptosystem is stored in advance in some way. Examples of the common key cryptosystem include DES (Data Encryption Standard) and FEAL (Fast data Encryption Algorithm).

  For example, the wireless base station stores the common key in the RFID beforehand using the RFID writer function. Alternatively, the wireless base station and the RFID may store the common key by some method at the time of sale.

A third aspect of the present invention is a wireless communication system for transmitting data by radio waves,
Transmits an unmodulated carrier or modulated control signal from the data providing destination device, and the data supply source device transmits data by absorbing or reflecting external radio waves based on antenna termination control.
This is a wireless communication system.

  Using such a wireless communication system, data is transmitted from a source device that supplies image data such as a digital camera or a camera-equipped mobile phone to a sink device such as a display device such as a PC or a television. be able to. In this data transmission, the source device uses a reflected wave based on the back scatter method, while the control signal from the sink device uses an ASK-modulated transmission signal.

  Since the reflected wave is basically generated only by the on / off operation of the antenna switch, the power consumed by battery-powered digital cameras and camera-equipped mobile phones is on the order of microwatts, and images with extremely low power consumption Transmission can be realized. Further, as the transmitted image data, a JPEG (Joint Photographic Experts Group) format is used. Since reflected waves are also used for this data transmission, the communication distance is limited to about 1 m.

  When streaming data is transferred, an operation sequence can be configured by one-way transmission. In this case, an operation for transmitting an ASK-modulated control signal from the sink device side becomes unnecessary, and the reception operation becomes unnecessary on the source device side, so that further power consumption can be saved.

  According to the present invention, by sharing the RFID tag reader function and the wireless LAN communication function with a common RF block, a small shared module can be realized at low cost.

  Advantageous Effects of Invention According to the present invention, an excellent wireless communication apparatus and wireless communication that can be used as both an RFID system using the same 2.4 GHz band and a wireless LAN system, and can realize low power consumption data transmission and simple communication settings. A system can be provided.

  Further, according to the present invention, it is possible to realize initial setting of a wireless LAN without inputting data by using an ID reading procedure from an RFID tag, and convenience is improved.

  In addition, according to the present invention, by using a data upload system using reflected waves in the RFID system, power consumption can be reduced to 1/10 to 20 or less compared to data transmission using a wireless LAN. can do.

  Other objects, features, and advantages of the present invention will become apparent from more detailed description based on embodiments of the present invention described later and the accompanying drawings.

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

  The present invention provides a wireless system that integrates an RFID system and a wireless LAN system to realize the following matters.

(1) Providing a wireless module that can be used as both an RFID reader and a wireless LAN (2) Providing a simple initial setting system with an RFID tag function in the wireless LAN (3) Providing a wireless data upload system with ultra-low power consumption

Providing a wireless module that can be used as both an RFID reader and a wireless LAN:
In the present invention, a small shared module is realized at low cost by combining the RFID tag reader function and the wireless LAN communication function with a common RF block. Basically, the RFID system is realized by making some changes to the configuration of the conventional wireless LAN device shown in FIG.

(1) When used as an RFID reader, a data transmission operation and a data reception operation are performed simultaneously. Accordingly, the antenna switch 213 in FIG. 8 is replaced with a circulator 305 in order to control transmission and reception to be turned on simultaneously.

(2) The RFID tag expresses transmission data by a back scatter method in which the antenna is terminated with an antenna impedance or the antenna is opened to reflect a transmission radio wave from the reader side. In other words, in order to add the RFID tag function to the wireless LAN, it is necessary to switch between opening and termination of one antenna. For this reason, the antenna switch 212 in FIG. 8 is composed of two antenna switches 303 and 304. When the RFID tag function is realized, one antenna is always open, and the other antenna can be switched between open and terminated.

(3) A function for transmitting an unmodulated carrier and an ASK modulated wave is added to the PHY unit 220 in FIG. 8 for use as an RFID reader.

  FIG. 1 shows a configuration of a wireless communication apparatus for both RFID and wireless LAN according to an embodiment of the present invention. As shown in the figure, the wireless communication apparatus 300 that combines the RFID function and the wireless LAN function mainly includes two antennas 301 and 302 for diversity, two antenna switches 303 and 304, a circulator 305, and a receiving unit 306. A transmission unit 309, a frequency synthesizer unit 310, and a baseband unit 311.

  The receiving unit 306 includes a quadrature detector 307 and an AGC amplifier 308. The baseband unit 311 includes a PHY unit 312 that performs modulation / demodulation and radio control, a MAC unit 313 that includes a CPU 314 and performs IEEE802.11 MAC control, and a host interface unit 315.

  The antenna switches 303 and 304 are switched and controlled by the control signals CNT301 and CNT302 via the PHY unit 312 according to an instruction from the CPU 314 in the MAC unit 314 according to the communication quality. CNT 301 and CNT 302 are signals inverted from each other. That is, when one antenna switch is on, the other antenna switch is off.

  The circulator 305 has a property that signals are transmitted only to ports adjacent to each other in the direction of the arrow in the figure. For example, the transmission wave from the transmitter to the antenna, the antenna to the receiver, etc. Used to separate received waves. The circulator 305 can function in the same manner as an antenna switch even in a wireless LAN in which transmission and reception timings are different.

  At the time of reception, the receiving unit 306 is activated by the control signal CNT303 from the PHY unit 312. The IEEE 802.11b modulated wave using the 2.4 GHz band is input to the receiving unit 306 via either one of the two antennas 301 or 302 and the circulator 305.

  A carrier having the same frequency as the received wave is supplied from the frequency synthesizer unit 310 to the quadrature detector 307 as a local frequency. The frequency setting of the frequency synthesizer 310 is also performed by the PHY unit 312.

  The modulated wave input to the quadrature detector 307 is directly converted, converted into I-axis and Q-axis baseband signals, and then sent to the AGC amplifier 308 at the subsequent stage. The AGC amplifier 308 is controlled by a control signal CNT303 from the PHY unit 313 so that its output becomes a constant level.

  The AGC-controlled I-axis and Q-axis baseband signals are input to the PHY unit 313 and demodulated into digital data using the DS-SS signal. The MAC unit 313 decomposes the packet data according to the MAC layer protocol defined by IEEE802.11b, and obtains target payload data. The host interface unit 315 outputs the received data to the host device side (not shown). The host interface unit 315 is configured by a compact flash card, for example, if the host device is a PDA, and becomes Ethernet (registered trademark) when connected to a network like a base station. A series of these processes in the baseband unit 311 is executed according to an instruction from the CPU 314.

  On the other hand, at the time of transmission, the transmission unit 309 is activated by the control signal CNT304 from the PHY unit 312. The host interface unit 315 passes the transmission data transferred from the host device to the MAC unit 313. The MAC unit 313 packetizes transmission data according to the MAC layer protocol defined by IEEE 802.11b, and transfers the packetized data to the PHY unit 312.

  The PHY unit 312 performs modulation in accordance with the IEEE 802.11b PHY layer protocol, generates I-axis and Q-axis baseband signals, and passes them to the orthogonal modulator of the transmission unit 309. The transmission unit 309 performs quadrature modulation using the carrier supplied from the frequency synthesizer 310, and obtains a target modulated wave in the 2.4 GHz band. This modulated wave is transmitted from the antenna 301 or 302 via the circulator 305 and the antenna switch 303 or 304, respectively.

  Next, a case where the wireless communication apparatus shown in FIG. 1 operates as an RFID reader will be described.

The host device first notifies the MAC unit 314 of a tag read instruction via the host interface unit 316. When receiving a tag read command from the MAC unit 314 in response to an instruction from the CPU 315, the PHY unit 119 edits transmission data. As a result, when the data is 1, _a baseband signal is obtained with the DC voltage Va on the I-axis side and 0V on the Q-axis side, and when the data is 0, the I-axis and Q-axis are both 0V. Such a transmission signal is subjected to ASK modulation using the carrier from the frequency synthesizer 310 by the quadrature modulator of the transmission unit 309.

  The frequency setting of the frequency synthesizer 310 is performed by the PHY unit 312. In general, the transmission frequency to the tag is used by hopping in order to reduce the standing wave of the signal from the RF tag and multipath. This hopping instruction is also given by the PHY unit 312.

  In the case where the wireless communication device 300 operates as an RFID reader, the antenna 301 is used here. Therefore, the CNT 301 and the CNT 302 are controlled so that the antenna switch 303 is turned on and the antenna switch 304 is turned off. The transmission signal subjected to ASK modulation is transmitted from the antenna 301 via the antenna switch 303.

  The reflected signal returned from the RFID tag by the back scatter method has the same frequency as the signal transmitted from the tag reader (described above). This reflected signal is received by the antenna 301 and input to the receiving unit 306 via the antenna switch 303 and the circulator 305.

  Since the same local frequency as the transmission is input to the quadrature detector 307, a signal modulated on the tag side appears at the output of the quadrature detector 307. However, since the received signal has a phase different from that of the local signal, a tag-side modulation signal corresponding to the phase difference appears in each of the I-axis and Q-axis signals.

  The AGC amplifier unit 308 is controlled to have the maximum gain by the control signal CNT303 from the PHY unit 312 and its output signal is passed to the PHY unit 312. The PHY unit 312 demodulates the I-axis and Q-axis signals into digital data and outputs the digital data to the MAC unit 313. The MAC unit 313 decodes the data, extracts the data stored in the memory in the tag, and transfers the data from the host interface unit 315 to the host device.

  In this way, the RFID reader and the wireless LAN can be combined with one wireless device.

  FIG. 2 shows an operation sequence with the RF tag when the dual-purpose device is used.

  In the illustrated example, the tag reader and the wireless LAN terminal device 400 use the tag reader / wireless LAN module 401 to read the data stored in the RFID tag 402 in the RFID reader mode, and then enter the wireless LAN mode. The Internet is accessed via the wireless LAN base station 403. Assume that the RFID tag 402 stores, for example, a URL (Uniform Resource Locator) of a home page in the server 408 constructed on the Internet 407 where detailed information of a certain object is browsed. According to the illustrated procedure, the tag reader / wireless LAN terminal device 400 can read this URL and access the homepage to obtain detailed information.

  First, the transmitter / receiver of the tag reader / wireless LAN terminal 400 is simultaneously turned on to enter the tag reader mode (S1).

  Next, the tag reader / wireless LAN terminal 400 transmits the tag read command after ASK modulation (S2). In response to this, the tag 402 receives this command and prepares to transmit the stored data.

  Next, the tag reader / wireless LAN terminal 400 transmits an unmodulated carrier (S3).

  Next, the tag 402 transmits the stored data as a reflected wave by the back scatter method (S4). The tag reader / wireless LAN terminal 400 reads this data.

  Next, the tag reader / wireless LAN terminal 400 turns off the transmission unit reception unit and ends the tag reader mode (S5).

  Thereafter, the tag reader / wireless LAN terminal 400 switches to the wireless LAN mode, and performs mutual communication with the wireless LAN base station via the wireless LAN (S6). At this time, the transmission / reception unit is controlled according to CSMA / CA according to the IEEE 802.11 MAC layer protocol. The tag reader mode and the wireless LAN mode are not turned on at the same time.

Provision of a simple initial setting system in which an RFID tag function is provided in a wireless LAN:
Next, an example of an initial setting operation between wireless LAN devices using an RFID system will be described.

  Generally, in order to connect a wireless LAN terminal (wireless LAN card) to a wireless LAN base station (access point), initial setting is required first. As initial setting items of the wireless LAN, three items of a channel number, an ESSID (Extended Service Set Identifier), and a WEP (Wired Equivalent Privacy) key are required. The channel number is a channel number defined by IEEE802.11b, which means which channel is used. The ESSID is one of network identifiers in an IEEE 802.11 wireless LAN, and is a network name given to avoid interference, and can be arbitrarily set up to 32 alphanumeric characters. The WEP key is an encryption key in IEEE802.11 wireless LAN communication. By encrypting the transmitted packet so that the contents are not known to the eavesdropper, it is possible to ensure the same safety as that of wired communication. A secret key cryptosystem based on the RC4 algorithm has been standardized by IEEE and adopted as a security system of IEEE 802.11b. The old method using 40-bit data for the secret key and the new method using 128-bit data are mixed.

  Of these three settings, many channel numbers do not need to be set because the conventional wireless LAN terminal has a function of automatic search. Further, since the ESSID is also included in the beacon signal from the wireless LAN base station, it can be recognized immediately. On the other hand, since the WEP key is an encryption key, the user must actually set it. It is cumbersome to perform such a setting operation on a portable device with a poor user interface.

  FIG. 3 shows an operation sequence for performing initial setting between wireless LAN devices. As a wireless LAN terminal, for example, a portable device such as a digital camera with a poor user interface is assumed. However, it is assumed that the wireless LAN terminal 500 and the wireless LAN base station 501 each incorporate the RFID / wireless LAN combined apparatus 300 shown in FIG.

  The wireless LAN base station 501 is manually set to the initial setting mode (S11). Similarly, the wireless LAN terminal 500 is also manually set to the initial setting mode (S12).

  Next, the wireless LAN base station 501 transmits an unmodulated carrier (S13). On the other hand, the wireless LAN terminal 500 that has received the non-modulated carrier makes an initial setting data request using the reflected wave by the back scatter method (S14).

  After confirming that transmission of the unmodulated carrier from the wireless LAN base station 501 is completed, the wireless LAN terminal 500 transmits an unmodulated carrier from its own station (S15).

  The wireless LAN base station 501 transmits the channel number, ESSID, and WEP key currently set in the local station as a reflected wave by the back scatter method (S16). The wireless LAN terminal 500 sets initial setting values such as the received channel number, ESSID, and WEP key in the apparatus.

  When the wireless LAN terminal 500 confirms that the transmission of the non-modulated carrier from the wireless LAN base station 501 is completed (S17), it notifies the reception completion by the reflected wave (S18).

  Since the initial setting for communication between the wireless LAN terminal 500 and the wireless LAN base station 501 has been completed (S19, S20), communication using a normal wireless LAN is started using the initially set parameters (S21).

  Here, the reflected wave transmitted from the wireless LAN terminal 500 and the wireless LAN base station 501 controls on / off of the antenna switch 303 of the RFID / wireless LAN combined apparatus 300 shown in FIG. 1 based on the back scatter method. Please fully understand that it is produced by. In addition, although it is complicated to perform such setting work on a portable device with a poor user interface, according to the present embodiment, user input operations can be performed by reading tags using an RFID system. Can be substituted.

  Security is important in the process of setting the encryption key. In the embodiment shown in FIG. 3, the reflected wave is very small power, and its communicable range is limited to within 1 m, so that the mutual devices are manually set to the initial setting mode at the beginning of the initial setting. In addition, security is ensured.

  Further, by adding a detector of radio waves within the used frequency band (for example, 2.4 GHz band) to the receiving side (for example, by taking out from the input of the quadrature detector 307 in FIG. 1), the unmodulated carrier is Transmission can be performed at any frequency within the used frequency band. This makes it even more difficult to intercept this initial setting exchange from the outside.

  FIG. 4 shows an example of an operation sequence in which security is further enhanced with respect to the initial setting operation sequence shown in FIG.

  In the illustrated example, the initial setting items are encrypted and transmitted. Also, nobody can easily obtain an encryption key for wireless LAN communication by an initial setting operation. As a specific method, the RFID tag 800 is used for the initial setting, and the common key of the common key cryptosystem previously stored therein is stored in this method. Examples of the common key cryptosystem include DES (Data Encryption Standard) and FEAL (Fast data Encryption Algorithm). In the example illustrated in FIG. 4, the wireless LAN base station 501 stores a common key (here, “common key A”) in the RFID 800 in advance using the RFID writer function. Alternatively, the wireless LAN base station 501 and the RFID 800 may store the common key A by some method at the time of sale.

  First, the wireless LAN base station 501 stores the common key A in the RFID 800 using the RFID writer function (S31). The RFID 800 is stored by the user.

  Here, when trying to connect to the wireless LAN base station 501, the wireless LAN terminal 500 reads the common key A with the RFID reader function (S32).

  The wireless LAN base station 501 is manually set to the initial setting mode (S33). Similarly, the wireless LAN terminal 500 is also manually set to the initial setting mode (S34).

  The wireless LAN base station 501 transmits an unmodulated carrier (S35). On the other hand, the wireless LAN terminal 500 that has received the non-modulated carrier makes an initial setting data request using a reflected wave based on the back scatter method (S36).

  After confirming that transmission of the unmodulated carrier from the wireless LAN base station 501 is completed, the wireless LAN terminal 500 transmits an unmodulated carrier from its own station (S37).

  The wireless LAN base station 501 encrypts the channel number, ESSID, and WEP key using the common key A by the common key encryption method (S38). Then, the wireless LAN base station 501 transmits the encrypted channel number, ESSID, and WEP key as a reflected wave based on the back scatter method (S39).

  The wireless LAN terminal 500 can obtain a channel number, ESSID, and WEP key as initial setting items by performing decryption from the received reflected wave using the common key A by the common key encryption method ( S40). The wireless LAN terminal 500 sets these initial setting items in its own device.

  When the wireless LAN terminal 500 confirms that the transmission of the non-modulated carrier from the wireless LAN base station 501 is completed (S41), it notifies the reception completion by the reflected wave (S42).

  Since the initial setting for communication with the wireless LAN base station 501 of the wireless LAN terminal 500 has been completed (S43, S44), communication via a normal wireless LAN is started (S45).

  As described above, when the user securely stores the RFID 800 in which the common key A is stored, it is extremely difficult for a third party to easily approach the wireless LAN base station 501 and perform the initial setting illegally. . When the user purchases a new wireless LAN terminal, the procedure starts with reading the common key A in FIG.

  FIG. 5 shows another operation sequence example regarding the initial setting using the RFID 800.

  In the example shown in the figure, first, the wireless LAN base station 501 directly writes initial setting data to the RFID 800 (S51).

  The wireless LAN terminal 500 can obtain initial setting data including a channel number, ESSID, and WEP key by performing read access to the RFID 800 (S52).

  After securely acquiring the initial setting items in this way, the wireless LAN terminal 500 sets the initial setting items in its own device. Then, normal wireless LAN communication is performed (S53).

  In the embodiment shown in FIG. 5, the security level is lower than in the example shown in FIG. 4, but it becomes difficult for a third party to perform the initial setting operation by storing the RFID 800 safely by the user. Become.

Providing ultra-low power wireless data upload system:
Next, an ultra-low power consumption wireless data upload system using a wireless LAN device also serving as an RFID system will be described.

  According to the device configuration shown in FIG. 1, wireless transmission with ultra-low consumption can be realized by the functions of the RFID tag and the RFID reader. The transmission speed in this transmission system depends on the on / off speed of the antenna switch and the reception bandwidth of the RFID reader. For example, considering that an antenna switch using an element made of gallium arsenide is combined with an RF of an IEEE802.11b wireless LAN, a transmission speed of about 8 Mbps can be achieved.

  In FIG. 6, as a wireless LAN terminal, the RFID / wireless LAN combined apparatus 300 is externally provided as an adapter, for example, from the digital camera 600 or the camera-equipped mobile phone 602 incorporating the RFID / wireless LAN combined apparatus 300 shown in FIG. An operation sequence for uploading an image to a connected PC 606 or television 608 is shown.

  First, on the wireless LAN terminal 600 or 601 side, the data transmission mode is set by manual operation (S61). Similarly, on the display device 606 or 608 side, the data reception waiting mode is manually set (S62).

  The display device 606 or 608 transmits an unmodulated carrier (S63). On the other hand, the wireless LAN terminal 600 or 601 that has received the non-modulated carrier makes a data transmission request using a reflected wave based on the back scatter method (S64).

  The display device 606 or 608 that has received the data transmission request transmits transmission permission by ASK modulation (S65).

  The display device 606 or 608 transmits an unmodulated carrier (S66). Then, the wireless LAN terminal 600 or 601 that has received the unmodulated carrier transmits packetized data using a reflected wave based on the back scatter method (S67).

  If the received packet data is correct, the display device 606 or 608 sends an acknowledgment ACK (Acknowledgement) by ASK modulation. If the received data is incorrect, a negative acknowledgment NAK (Negative Acknowledgment) is transmitted by ASK modulation (S68). Whether the data is correct or not can be determined by a CRC (Cyclic Redundancy Check) code added to the data packet.

  Thereafter, the sequence of S66 to S67 is repeatedly executed until the end of data transmission.

  The transmission from the digital camera 600 or the camera-equipped mobile phone 602 uses a reflected wave based on the back scatter method, while the control signal from the PC 606 or the television 608 uses an ASK-modulated transmission signal. Since the reflected wave is basically generated only by the on / off operation of the antenna switch (described above), the power consumed by the battery-powered digital camera 600 or the camera-equipped mobile phone 602 is on the order of microwatts, Image transmission with low power consumption can be realized. In addition, JPEG (Joint Photographic Experts Group) format is used as image data to be transmitted. Since reflected waves are also used for this data transmission, the communication distance is limited to about 1 m.

  In the embodiment shown in FIG. 6, since image transfer is performed, bi-directional communication is performed for data delivery confirmation. However, when streaming data is transferred from a video camera or the like, one-way communication is performed. An operation sequence may be configured by transmission. In this case, the operation of transmitting the ASK-modulated control signal from the display device 606 or 608 becomes unnecessary, and the reception operation becomes unnecessary on the wireless LAN terminal side, so that further power consumption can be reduced.

[Supplement]
The present invention has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiment without departing from the gist of the present invention. That is, the present invention has been disclosed in the form of exemplification, and the contents described in the present specification should not be interpreted in a limited manner. In order to determine the gist of the present invention, the claims section described at the beginning should be considered.

FIG. 1 is a diagram showing a configuration of a wireless communication apparatus for both RFID and wireless LAN according to an embodiment of the present invention. FIG. 2 is a diagram showing an operation sequence between the RFID reader and the RF tag when the wireless LAN combined device is used. FIG. 3 is a diagram showing an operation sequence for initial setting between wireless LAN devices. FIG. 4 is a diagram showing an example of an operation sequence in which security is further strengthened with respect to the initial setting operation sequence shown in FIG. FIG. 5 is a diagram illustrating another example of an operation sequence for the initial setting using the RFID 800. FIG. 6 is an operation sequence diagram showing a data transmission procedure in the ultra-low power consumption wireless data upload system configured by the RFID / wireless LAN combined device shown in FIG. FIG. 7 is a diagram illustrating a configuration example of a conventional RFID system. FIG. 8 is a diagram illustrating a configuration example of a conventional wireless LAN system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 300 ... Wireless communication apparatus 301, 302 ... Antenna 303, 304 ... Antenna switch 305 ... Circulator 306 ... Receiving part 307 ... Quadrature detector 308 ... AGC amplifier 309 ... Transmission part 310 ... Frequency synthesizer part 311 ... Baseband part 312 ... PHY Unit 313 ... MAC unit 314 ... CPU
315 ... Interface section

Claims (12)

A reader / writer function for reading and writing data of an RFID (Radio Frequency Identification) tag, a wireless communication function, and a host interface unit common to a host device to be connected are provided. A wireless communication device shared by two functions,
A reader / writer function mode for controlling and controlling the transmitting unit and the receiving unit to be turned on at the same time so that the transmitting unit can transmit a modulated or unmodulated carrier;
A wireless communication function mode for controlling the transmission unit and the reception unit to be exclusively turned on;
A wireless communication apparatus comprising: Under the reader / writer function mode, a control signal for an external device is modulated and transmitted.
The wireless communication apparatus according to claim 1. An antenna for transmitting and receiving radio waves, and an antenna connection means for connecting the antenna to either the transmission unit or the reception or simultaneously,
The wireless communication apparatus according to claim 1. An RFID tag function mode for transmitting data by a back scatter method by controlling on / off of an antenna switch for terminating or opening the antenna, and absorbing or reflecting an external radio wave according to a data bit string. In addition,
The wireless communication apparatus according to claim 3. Wireless communication setting data storage means for storing wireless communication setting data used under the wireless communication function mode;
In response to the communication partner approaching an extremely short distance or manual setting, the antenna switch for terminating or opening the antenna is turned on / off under the RFID tag function mode to control the wireless communication setting data. By absorbing or reflecting external radio waves according to the bit string, the wireless communication setting data is transmitted by a back scatter method.
The wireless communication apparatus according to claim 4. The wireless communication setting data includes initial setting values such as a channel number, ESSID (Extended Service Set Identifier), and WEP (Wired Equivalent Privacy) key.
The wireless communication apparatus according to claim 5. Wireless communication setting data storage means for storing transmission data;
A bit string of the transmission data by controlling on / off of an antenna switch that terminates or opens the antenna under an RFID tag function mode in response to a data reception device approaching an extremely short distance or in response to a manual setting. The transmission data is transmitted by a back scatter method by absorbing or reflecting external radio waves according to
The wireless communication apparatus according to claim 4. The wireless communication device further includes data acquisition means for acquiring or generating transmission data,
The data receiving device has a function of reproducing data;
The wireless communication apparatus according to claim 7. A wireless communication system comprising a wireless base station and a wireless terminal,
The radio base station and the radio terminal are both equipped with an RFID system based on a radio wave communication method using microwaves,
The wireless terminal transmits a predetermined wireless communication setting data request by absorbing or reflecting external radio waves based on antenna termination control using a carrier received from a wireless base station,
In response to the wireless communication setting data request, the wireless base station absorbs or reflects radio waves from outside based on antenna termination control using a carrier received from the wireless terminal. Send,
A wireless communication system. The wireless communication setting data includes initial setting values such as a channel number, ESSID (Extended Service Set Identifier), and WEP (Wired Equivalent Privacy) key.
The wireless communication system according to claim 9. The receiving side is equipped with a detector that detects radio waves in the frequency band used, and the transmitting side transmits carriers at any frequency within the frequency band used.
The wireless communication system according to claim 9. An RFID for storing a predetermined key for performing encrypted communication with the wireless base station is interposed,
The wireless terminal obtains the key from the RFID;
The wireless base station transmits wireless communication setting data encrypted using the key, and the wireless terminal decrypts the received wireless communication setting data using the key.
The wireless communication system according to claim 9.

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