Patent Publication Number: US-2012044057-A1

Title: Pairing method of device using milimeter wave band and device for performing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of Korean Patent Application No. 10-2010-0079378 filed on Aug. 17, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to pairing of a wireless communication device and, more particularly, to a pairing method of a device using a millimeter wave band that can be applicable to a device using a millimeter wave band, and a device for performing the same. 
     2. Description of the Related Art 
     As a millimeter wave (57 to 66 GHz) band was allocated as an unlicensed or ISM (industrial, scientific and medical) band and used as a solution to the shortage of frequency resources worldwide, standardizations are being actively ongoing, such as ETSI/BRAN in Europe, IEEE 802 in North America, as well as ISO 21216, WiHD consortium, Ecma International, and the like, elsewhere. 
     A 60 GHz frequency band has advantages in that it has a higher data transfer rate than Bluetooth™ or UWB (Ultra-Wide Band) by using an ultra-wide band, has strong straightness to resist ambient interference, has high security, and allows for the re-use of a frequency. In addition, because the 60 GHz frequency band has a short wavelength, it allows for a reduction in size and weight of various elements, as such the 60 GHz frequency band can be easily applied for a mobile device. 
     However, the 60 GHz frequency band has shortcomings in that it has a short propagation distance due to absorption by oxygen molecules, an attenuation phenomenon in the case of rain and the necessity of securing a line of sight due to the characteristics of straightness, so currently, the 60 GHz frequency band is largely applied for high resolution AV streaming in devices having a proximity within a maximum 10 meters, a wireless docking station, a short range communication device (e.g., a short range sync &amp; go.) 
     For communication between devices using the 60 GHz frequency band, it is first required to determine whether or not there is a device, available for communication, within a short distance (or nearby) such as Bluetooth™ or WLAN and then a pairing process is required to establish security. 
     However, when the pairing process is performed by using the 60 GHz band, it consumes a great deal of power as compared with a system that performs pairing by using a 2.4 GHz band, a usage time of a mobile device that uses a battery as a power source is reduced. In detail, when a certain communication device using the 60 GHz band receives a request for pairing from a user, the communication device first searches for adjacent devices, displays found devices, and performs a pairing with a particular device selected from among the displayed devices searched for by the user. In this case, the devices around the certain communication device must periodically wake up a 60 GHz band communication module in order to respond to the pairing request from the certain communication device, causing power consumption, resulting in a reduction of overall usage time of the devices using a battery as a power source. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention provides a pairing method of a device using a millimeter wave band capable of minimizing power consumption of the device using a millimeter wave band and easily performing pairing. 
     An aspect of the present invention provides a device using a millimeter wave band performing the pairing method. 
     According to an aspect of the present invention, there is provided a pairing method of first and second devices each having a communication function using a millimeter wave band, including: determining, by the first device, whether or not the a security code of the second device has been registered; when the first device determines that the security code of the second device has been registered, transmitting, by the first device, an activation command instructing the second device to perform millimeter wave band communication, a device ID, and the security code of the second device to the second device through RFID communication; and when the first device receives a message indicating that the second device is ready for millimeter wave band communication from the second device, activating, by the first device, an element for performing communication using the millimeter wave band. 
     The method may further include, before determining, by the first device, whether or not the a security code of the second device has been registered: generating a list of registered devices which are available for communication using the millimeter wave band, including the second device among one or more ambient devices included within an RFID communication distance; and displaying the generated list of the registered devices. 
     The generating of the list of the registered devices may include: requesting, by the first device, device IDs of the respective ambient devices and communication mode information indicating whether or not each of the devices is available for millimeter wave band communication from the one or more ambient devices included within the RFID communication distance through RFID communication; determining, by the first device, whether or not there is a device available for millimeter wave band communication on the basis of the device IDs and the communication mode information transmitted from the one or more ambient devices included within the RFID communication distance through RFID communication; and when there is at least one device available for millimeter wave band communication, updating, by the first device, the list of the registered devices. 
     The updating of the list of the registered devices may include: determining, by the first device, whether or not each of one or more devices available for millimeter wave band communication has been registered based on a device ID of each of one or more devices available for millimeter wave band communication; and storing a device, which has not been registered, among the one or more devices available for millimeter wave band communication, in the list of the registered devices. 
     The transmitting of an activation command instructing the second device to perform millimeter wave band communication, a device ID, and the security code of the second device by the first device to the second device through RFID communication when the first device determines that the security code of the second device has been registered may include: when the first device determines that the security code of the second device has not been registered, displaying, by the first device, a user interface for receiving the security code from a user. 
     The method may further include, after transmitting, by the first device, an activation command instructing the second device to perform millimeter wave band communication, a device ID, and the security code of the second device to the second device through RFID communication: comparing, by the second device, the security code transmitted from the first device and a stored security code to determine whether or not both security codes are identical; and when the security code transmitted from the first device and the stored security code are not identical, requesting, by the second device, a retransmission of the security code from the first device through RFID communication. 
     The requesting, by the second device, of a retransmission of the security code from the first device through RFID communication, when the security code transmitted from the first device and the stored security code are not identical, may include: when the security code transmitted from the first device and the stored security code are identical, activating, by the second device, an element for performing communication using a milliliter wave band; and transmitting, by the second device, a message indicating that the second device is ready for millimeter wave band communication to the first device. 
     According to another aspect of the present invention, there is provided a device using a millimeter wave band, including: a millimeter wave communication unit activated according to an activation control signal and performing data transmission and reception by using a millimeter wave band; an RFID communication unit performing pairing with a particular device selected according to a pairing control signal; and a controller providing the pairing control signal to the RFID communication unit and providing the activation control signal to the millimeter wave communication unit after the pairing with the particular device is completed in order to thus provide control to perform data transmission and reception by using the millimeter wave band with the particular device. 
     The RFID communication unit may include: an RFID reader activated under the control of the controller to generate a list of registered devices and provide a pairing request signal to the selected particular device; and an RFID tag transmitting a device ID and communication mode information indicating whether or not millimeter wave band communication is available according to a request for information of a certain device. 
     The RFID reader may be activated under the control of the controller to request a device ID of each of ambient devices and communication mode information from one or more ambient devices included within RFID communication distance, and generate a list of the registered devices which are available for millimeter wave band communication based on the device IDs and communication mode information provided from one or more ambient devices included within the RFID communication distance. 
     The device may further include: a storage unit storing the list of the registered devices; an input/output unit displaying the list of the registered devices under the control of the controller, and providing information regarding a device selected by a user from the displayed list of the registered devices to the controller. 
     When a pairing control signal indicating pairing with the selected particular device is provided from the controller, the RFID reader may determine whether or not a security code of the selected particular device has been registered, and when the security code of the selected particular device has been registered, the RFID reader may transmit an activation command instructing an activation of the millimeter wave communication unit of the selected particular device, the device ID, and the security code of the selected particular device. 
     When it is determined that the security code of the selected particular device has not been registered, the RFID reader may provide an event signal for receiving the security code of the selected particular device from the user to the controller, and the controller may provide control to display a user interface to receive the security code of the selected particular device according to the event signal. 
     When the security code is received from the certain device and the received security code is identical to a previously stored security code, the RFID tag may provide a signal indicating an activation of the millimeter wave communication unit to the controller, and the controller may activate the millimeter wave communication unit according to the signal indicating the activation of the millimeter wave communication unit provided from the RFID tag. 
     When a message indicating that the certain device is ready for millimeter wave band communication, the RFID tag may provide a signal indicating an activation of the millimeter wave communication unit to the controller, and the controller may activate the millimeter wave communication unit according to the signal indicating the activation of the millimeter wave communication unit provided from the RFID tag. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a conceptual view for explaining a pairing of devices using a millimeter wave band according to an exemplary embodiment of the present invention; 
         FIG. 2  is a schematic block diagram of a device using the millimeter wave band according to an exemplary embodiment of the present invention; 
         FIG. 3  is a schematic block diagram of a device using a millimeter wave band according to another exemplary embodiment of the present invention; 
         FIG. 4  is a flow chart illustrating the process of creating a list of ambient devices of a device using a millimeter wave band according to another exemplary embodiment of the present invention; and 
         FIG. 5  is a flow chart illustrating a pairing process of the device using the millimeter wave band according to another exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention may be modified variably and may have various embodiments, particular examples of which will be illustrated in drawings and described in detail. 
     However, it should be understood that the following exemplifying description of the invention is not intended to restrict the invention to specific forms of the present invention but rather the present invention is meant to cover all modifications, similarities and alternatives which are included in the spirit and scope of the present invention. 
     While terms such as “first” and “second,” etc., may be used to describe various components, such components must not be understood as being limited to the above terms. The above terms are used only to distinguish one component from another. For example, a first component may be referred to as a second component without departing from the scope of rights of the present invention, and likewise a second component may be referred to as a first component. The term “and/or” encompasses both combinations of the plurality of related items disclosed and any item from among the plurality of related items disclosed. 
     When a component is mentioned as being “connected” to or “accessing” another component, this may mean that it is directly connected to or accessing the other component, but it is to be understood that another component may exist therebetween. On the other hand, when a component is mentioned as being “directly connected” to or “directly accessing” another component, it is to be understood that there are no other components in-between. 
     The terms used in the present application are merely used to describe particular embodiments, and are not intended to limit the present invention. An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context in which it is used. In the present application, it is to be understood that the terms such as “including” or “having,” etc., are intended to indicate the existence of the features, numbers, operations, actions, components, parts, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, numbers, operations, actions, components, parts, or combinations thereof may exist or may be added. 
     Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those with ordinary knowledge in the field of art to which the present invention belongs. Such terms as those defined in a generally used dictionary are to be interpreted as having meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted as having ideal or excessively formal meanings unless clearly defined as having such in the present application. 
     Embodiments of the present invention will be described below in detail with reference to the accompanying drawings, where those components are rendered using the same reference number that are the same or are in correspondence, regardless of the figure number, and redundant explanations are omitted. 
       FIG. 1  is a conceptual view for explaining a pairing of devices using a millimeter wave band according to an exemplary embodiment of the present invention, illustrating a case in which devices at home perform pairing therebetween and transmit and receive data by using a 60 GHz band. 
     With reference to  FIG. 1 , communication using the 60 GHz band is available for ultra-high wireless transmission, allowing a display device  10 , a mobile terminal  20 , a camcorder  30 , and a large capacity storage device  40  located at home to be wirelessly connected and transmit or receive HD image data, high quality audio or large capacity data therebetween. 
     For example, the camcorder  30  may transmit HD image data stored therein to the display device  10  through radio communication using the 60 GHz band, whereby a recorded image can be reproduced conveniently without having to connect the two devices  10  and  30  through a data cable. Also, the mobile terminal  20  and the large capacity storage device  40  may transmit and receive large capacity data through radio communication using the 60 GHz band. 
     In order to perform radio communication between the devices, the display device  10 , the mobile terminal  20 , the camcorder  30 , and the large capacity storage device  40  include a 60 GHz communication unit for performing communication by using the 60 GHz band and an RFID communication unit acquiring information regarding whether or not there is an ambient device and communication mode information indicating whether or not 60 GHz communication is available, and performing pairing with the corresponding device, respectively. 
     For example, the pairing process between the mobile terminal  20  and the large capacity storage device  40 , among the devices illustrated in  FIG. 1 , will now be described. When an event indicating pairing is provided from a user, the mobile terminal  20  reads RFID tags from devices present around the mobile terminal  20  (e.g., within 10 meters) to determine whether or not there are ambient devices, whether or not the ambient devices are available for communication using 60 GHz band, security information, and the like, and registers the same. 
     Thereafter, when the user instructs communication using the 60 GHz band with the large capacity storage device  40  among the devices registered through the mobile terminal  20 , the mobile terminal  20  transmits a wakeup command, a unique device ID, and a security code to an RFID tag of the large capacity storage device  40 . Then, the large capacity storage device  40  compares the received security code and its security code, and when the two security codes are identical, the large capacity storage device  40  wakes up the 60 GHz communication unit and transmits and receives data to and from the mobile terminal  20  by using the 60 GHz band. 
     As described above, in the pairing method of the device using the millimeter band according to an exemplary embodiment of the present invention, pairing between the respective devices is performed by using RFID communication, and an element (namely, the 60 GHz communication unit) performing communication by using the 60 GHz band is activated (or wakes up) only when it performs data communication, and when the 60 GHz communication unit does not perform communication, it is in a sleep state. Thus, power consumption can be remarkably reduced when compared with the related art devices which are periodically activated in response to a pairing request. 
       FIG. 2  is a schematic block diagram of a device using the millimeter wave band according to an exemplary embodiment of the present invention. 
     With reference to  FIG. 2 , a device using a millimeter wave band (referred to as a ‘millimeter wave band using device’, hereinafter) according to an exemplary embodiment of the present invention includes a controller  210 , an RFID communication unit  220 , a 60 GHz communication unit  230 , a storage unit  240 , and an input/output unit  250 . 
     The controller  210  controls the RFID communication unit  220  and the 60 GHz communication unit  230  to register an ambient device and perform pairing in order to perform communication using a 60 GHz band. 
     In detail, the controller  210  may activate the RFID reader  221  according to an ambient device registration request from the user and determine whether or not there is an ambient device based on the ambient device information provided from the RFID reader  221 , the controller  210  displays that there is no ambient device available for communication through the input/output unit  250 . 
     Also, when a pairing request is provided from the user through the input/output unit  250 , the controller  210  controls the RFID reader  221  to receive a list of registered devices from the RFID reader  221  and displays the received list of registered devices through the input/output unit  250 . When the user selects a particular device from the displayed list of registered devices, the controller  210  controls the RFID communication unit  220  to perform pairing with the particular device. 
     Also, when an event signal requesting a security code is provided from the RFID reader in the process of performing pairing with the particular device, the controller  210  displays a user interface for receiving a security code from the user through the input/output unit  250 , and provides a security code input by the user through the input/output unit  250  to the RFID reader  221 . 
     When the pairing with the particular device through the RFID communication unit  220  is completed, the controller  210  activates the 60 GHz communication unit  230  to perform data communication using the 60 GHz band with the particular device. 
     In detail, when a signal indicating an activation of the 60 GHz communication unit  230  is provided from the RFID tag  223 , the controller  210  activates the 60 GHz communication unit  230 , connects a different element included in the millimeter wave band using device to the 60 GHz communication unit  230  and provides control to perform communication. At the time that the signal indicating the activation of the 60 GHz communication unit  230  is provided, the controller  210  may also activate the 60 GHz communication unit  230 , receive data from a different element included in the millimeter wave band using device, deliver the received data to the 60 GHz communication unit  230  or deliver it to a corresponding element included in the millimeter wave band using device, thus performing communication using the 60 GHz band with the different device. 
     The RFID communication unit  220  may include an RFID reader  221  and an RFID tag  223 . The RFID reader  221  and the RFID tag  223  may be activated or deactivated under the control of the controller  210 . For example, the RFID reader  221  and the RFID tag  223  may be activated under the control of the controller  210  only when pairing is performed with a different device available for communication by using the 60 GHz band. 
     The RFID reader  221  is activated under the control of the controller  210  to read an RFID tag installed in an ambient device and provide the read ambient device information to the controller  210 . 
     Or, the RFID reader  221  may be periodically activated at pre-set time intervals to read the RFID tags of ambient devices and store a list of registered devices based on the read content in the storage unit  240 . If reading the RFID tags of the ambient devices, an ambient device having no reaction is excluded from the stored list of registered devices and an ambient device corresponding to the newly read RFID tag is stored in the list of the registered devices, thus periodically updating the list of the registered devices. 
     Also, the RFID reader  221  requests a device ID and communication mode information from each ambient device and deletes an ambient device not available for communication using the 60 GHz band from the list of the registered devices on the basis of the communication mode information transmitted from the RFID tag of each ambient device. When an ambient device is available for communication using the 60 GHz band, the RFID reader  221  determines whether or not a security code of the ambient device has been registered based on the device ID transmitted from the corresponding device. Here, when the security code of the ambient device has been registered, it can communicate using the 60 GHz band according to a communication request from the user without performing a security code input procedure. The communication mode information refers to whether or not communication using the 60 GHz band is available. The user of each device may set the communication mode, and although a device supports communication using the 60 GHz band, if the user has set a device to not use communication using 60 GHz band, communication using the 60 GHz band cannot be performed. 
     Also, the RFID reader  221  provides the stored list of registered devices to the controller  210  under the control of the controller  210 , and when a request for pairing with a particular device is provided from the controller  210 , the RFID reader  221  checks whether or not the security code of the particular device has been registered. When the security code of the particular device has been registered, the RFID reader  221  transmits an activation command, a device ID, and the security code to the RFID tag of the particular device. In the case that the security code has not been registered, the RFID reader  221  provides an event signal for acquiring the security code from the user to the controller  210 . Then, the controller  210  displays a user interface for receiving a security code on the input/output unit  250  according to the event signal provided from the RFID reader  221 , acquires a security code provided through the input/output unit  250  by the user, and provides the acquired security code to the RFID reader  221 . 
     When the RFID tag  223  receives an information request transmitted from an RFID reader of an ambient device, it transmits a device ID and communication mode information to the RFID reader of the ambient device. 
     Also, when a security code is transmitted from an RFID reader of a different device, the RFID tag  223  receives it and compares the received security code with its security code stored in the storage unit  240 . When the two security codes are identical, the RFID tag  223  provides a signal for activating the 60 GHz communication unit  230  to the controller  210 . When the two security codes are not identical, the RFID tag  223  provides an event signal indicating a re-transmission of the security code to the RFID reader  221  or the controller  210 . When the security code re-transmitted from the different device is still not identical, the RFID tag  223  provides an event signal for acquiring a security code from the user to the controller  210 . 
     When a communication preparation completion message using the 60 GHz band is received from a particular device performing pairing, the RFID tag  223  provides an activation signal indicating an activation of the 60 GHz communication unit  230  to the controller  210 . 
     The 60 GHz communication unit  230  is activated (wakes up) or deactivated (sleeps) under the control of the controller  210 , and performs high speed data communication by using the 60 GHZ frequency band. Here, after completing pairing with a communication counterpart device, the 60 GHz communication unit  230  is activated under the control of the controller  210  only when it substantially performs communication by using the 60 GHz band, and deactivated when it does not perform communication, thereby preventing unnecessary power consumption. 
     The storage unit  240  may be configured as a non-volatile memory storing a device ID, a communication mode, a security code. Also, the storage unit  240  stores the list of registered devices provided by the RFID reader  221 . 
     The input/output unit  250  may include an input unit  251  having a plurality of keypads and an output unit  253  configured as a liquid crystal display (LCD) or an organic light emitting diode (OLED). The input unit  251  and the output unit  253  may be implemented in the form of a single touch screen or a touch pad. 
     The input/output unit  250  displays a user interface for receiving the list of the registered devices or the security code under the control of the controller  210 , and provides a key event signal corresponding to a key manipulated by the user to the controller  210 . 
     The millimeter wave band using device illustrated in  FIG. 2  may be installed in the device having various forms as shown in  FIG. 1 , and in this case, various other elements than those illustrated in  FIG. 1  may be further included. For example, when the millimeter wave band using device illustrated in  FIG. 2  is installed in the display device  10  illustrated in  FIG. 1 , elements such as a tuner, an image processing unit, a large display element, and the like, for performing a unique function of the display device  10  may be further included in addition to the elements illustrated in  FIG. 2 . 
       FIG. 3  is a schematic block diagram of a device using a millimeter wave band according to another exemplary embodiment of the present invention. 
     The device using a millimeter wave band according to another exemplary embodiment of the present invention is configured not to include the input/output unit and the RFID reader of the millimeter wave band using device illustrated in  FIG. 2 . 
     Namely, the device using a millimeter wave band according to an exemplary embodiment of the present invention illustrated in  FIG. 2  may request pairing from a different ambient device or respond to a request for pairing from the different device, but the device using a millimeter wave band according to another exemplary embodiment of the present invention illustrated in  FIG. 3  cannot perform a request for pairing from a different device and can only respond to a request for pairing from a different device. 
     With reference to  FIG. 3 , the device using a millimeter wave band according to another exemplary embodiment of the present invention includes a controller  210   a , an RFID communication unit  220   a , a 60 GHz communication unit  230   a , and a storage unit  240   a.    
     In order to perform communication using the 60 GHz band, the controller  210   a  controls the RFID communication unit  220   a  and the 60 GHz communication unit  230   a.    
     In detail, when a signal indicating an activation of the 60 GHz communication unit  230   a  is provided from the RFID tag  223   a , the controller  210   a  activates the 60 GHz communication unit  230   a , connects a different element included in the millimeter wave band using device to the 60 GHz communication unit  230   a  and provides control to perform communication. Or, when the signal indicating the activation of the 60 GHz communication unit  230   a  is provided, the controller  210   a  may activate the 60 GHz communication unit  230   a , receive data from a different element included in the millimeter wave band using device, deliver the received data to the 60 GHz communication unit  230   a  or deliver it to a corresponding element included in the millimeter wave band using device, thus performing communication using the 60 GHz band with the different device. 
     The RFID communication unit  220   a  may include an RFID tag  223   a . When an information request transmitted from an RFID reader of an ambient device is received, the RFID tag  223   a  transmits a device ID and communication mode information to the RFID reader of the ambient device. Here, the communication mode refers to whether or not communication using the 60 GHz band is available. The user of each device may set the communication mode, and although a device supports communication using the 60 GHz band, if the user has set a device to not use communication using the 60 GHz band, communication using the 60 GHz band cannot be performed. 
     Also, when a security code is transmitted from an RFID reader of a different device, the RFID tag  223   a  receives it and compares the received security code with its security code stored in the storage unit  240   a . When the two security codes are identical, the RFID tag  223   a  provides a signal for activating the 60 GHz communication unit  230   a  to the controller  210   a . When the two security codes are not identical, the RFID tag  223   a  transmits an event signal indicating a re-transmission of the security code to the RFID reader of the different device. When a communication preparation completion message using the 60 GHz band is received from a particular device performing pairing, the RFID tag  223   a  provides an activation signal indicating an activation of the 60 GHz communication unit  230   a  to the controller  210   a.    
     The 60 GHz communication unit  230   a  is activated (wakes up) or deactivated (sleeps) under the control of the controller  210   a , and performs high speed data communication by using the 60 GHZ frequency band. Here, after completing pairing with a communication counterpart device, the 60 GHz communication unit  230   a  is activated under the control of the controller  210   a  only when it substantially performs communication by using the 60 GHz band, and deactivated when it does not perform communication, thereby preventing unnecessary power consumption. 
     The storage unit  240   a  may be configured as a non-volatile memory storing a device ID, a communication mode, a security code. 
     The millimeter wave band using device illustrated in  FIG. 3  may be implemented in the form of a device that does not require an input/output unit such as the large capacity storage device  40  illustrated in  FIG. 1 . 
       FIG. 4  is a flow chart illustrating the process of creating a list of ambient devices of a device using a millimeter wave band according to another exemplary embodiment of the present invention, specifically, illustrating the process of creating a list of ambient devices performed by a millimeter wave band using device including an RFID reader and an RFID tag. 
     With reference to  FIG. 4 , first, the millimeter wave band using device applies power to the RFID reader to activate the RFID reader, and the activated RFID reader reads an RFID tag included in each of devices located nearby to search for ambient devices (step  401 ). 
     Next, the millimeter wave band using device determines whether or not there is an ambient device based on the results of reading the RFID tags (step S 403 ). When the millimeter wave band using device determines that there is no ambient device, it outputs a message indicating that there is no ambient device available for communication (step  405 ) and terminates the ambient device list creating process. 
     Meanwhile, when the millimeter wave band using device determines that there is at least one ambient device in step  403 , the RFID reader of the millimeter wave band using device requests a device ID and communication mode information from the RFID tag of each of the detected devices (step  407 ). Here, the communication mode information refers to whether or not communication using the 60 GHz band is available. The user of each device may set the communication mode, and although a device supports communication using the 60 GHz band, if the user has set a device to not use communication using the 60 GHz band, communication using the 60 GHz band cannot be performed. 
     The millimeter wave band using device determines whether or not there is a compatible device which is available for communication and uses the 60 GHz band on the basis of the device IDs and communication mode information acquired from the respective ambient devices through the RFID reader (step  409 ). When the millimeter wave band using device determines that there is no compatible device, the millimeter wave band using device outputs a message indicating that there is no ambient device available for communication (step  405 ) and terminates the ambient device list creating process. 
     Meanwhile, when the millimeter wave band using device determines that there is at least one compatible device using the 60 GHz band, the millimeter wave band using device compares the device ID acquired the compatible device with a stored device ID list to determine whether or not the compatible device is a registered device (step  411 ). When the compatible device is determined to be a registered device, the millimeter wave band using device stores it in the list of registered devices to thus update the list of registered devices (step  413 ). When the compatible device is not a registered device, the millimeter wave band using device registers the compatible device as a new device (step  415 ) and terminates the ambient device registration process. 
       FIG. 5  is a flow chart illustrating a pairing process of the device using the millimeter wave band according to another exemplary embodiment of the present invention. In  FIG. 5 , it is illustrated that after the ambient device registration process as illustrated in  FIG. 4  is performed, pairing is intended to communicate with a second device by using the 60 GHz band, and the second device performs pairing in response thereto. 
     With reference to  FIG. 5 , first, a first device displays a list of registered devices of ambient devices which have been registered in response to a user request (step  501 ). The user selects a second device from the displayed list of registered devices, and when the user requests pairing with the selected second device, the first device acquires information according to the user selection and indication (namely, the second device and pairing request information) (step  503 ). 
     For example, when the first device is the mobile terminal  20  illustrated in  FIG. 1  and the list of registered devices includes the display device  10 , the camcorder  30 , and the large capacity storage device  40  illustrated in  FIG. 1 , the mobile terminal  20  displays the information regarding the display device  10 , the camcorder  30 , and the large capacity storage device  40  as registered on the display unit in step  501 , and when the user selects the display device  10  as a second device in step  503 , pairing is performed with the selected display device  10 . 
     Next, the first device determines whether or not a security code of the second device has been registered (step  505 ). Here, when there is communication history between the first and second devices, the security code of the second device has been registered to the first device, so a security code input process is not required. Meanwhile, when the first and second devices communicate with each other for the first time, the security code of the second device must be received from the user for pairing. 
     Thus, when the security code of the second device has not been registered in step  505 , the first device displays a user interface for receiving the security code of the second device and acquires the security code of the second device inputted by the user (step  507 ). 
     And then, the first device transmits an activation (wakeup) command indicating an activation of the 60 GHz communication unit of the second device, a device ID, the security code to the second device through an RFID reader (step  509 ). 
     Meanwhile, when the security code of the second device is determined to have been registered in step  505 , the first device directly performs step  509 , skipping step S 507 . 
     The RFID tag of the second device receives the activation command, the device ID and the security code transmitted from the first device, compares the received security code with a previously stored security code to determine whether or not the two codes are identical (step  511 ). When the security codes are not identical, the second device requests re-transmission of the security code from the first device through the RFID tag (step  513 ). 
     When the re-transmission of the security code is requested from the second device, the first device re-transmits the security code through the RFID reader or the RFID tag (step  515 ), and the RFID tag of the second device determines whether or not the security code re-transmitted from the first device is identical (step  517 ). When the re-transmitted security code is not identical, the second device displays a user interface for receiving a security code from the user and acquires a security code input by the user (step  519 ). 
     Meanwhile, when the security code is identical in step  511  or  517 , power is applied to the 60 GHz communication unit handling communication of the 60 GHz band of the second device to activate the 60 GHz communication unit (step  521 ) and informs the first device that communication using the 60 GHz band is ready (step  523 ). 
     Upon being informed that the second device is ready for communication using the 60 GHz band, the first device activates the 60 GHz communication unit (step  525 ) and transmits and receives data to and from the second device by using the 60 GHz band (step  527 ). 
     As set forth above, in the pairing method using a millimeter wave band and a device performing the method according to exemplary embodiments of the invention, an RFID communication unit is periodically activated to acquire a device ID and communication mode information of a device existing nearby, and generate and manage a list of registered devices based on the acquired information. When a request for pairing with a particular device is provided from the user, the RFID communication unit transmits an activation command instructing an activation of a 60 GHz communication unit, a device ID, and a security code to the particular device to request pairing. Thereafter, when a message indicating that communication using a 60 GHz band is ready is transmitted from the particular device, the 60 GHz communication unit performing communication of the 60 GHz band is activated and data is transmitted and received by using the 60 GHz band. 
     Thus, pairing is performed by using RFID communication, and an element (namely, the 60 GHz communication unit) performing communication by using the 60 GHz band is activated only when it performs high speed data communication and not activated (in a sleep state) when it does not perform communication, thereby conveniently performing pairing. In addition, because power consumption is considerably reduced compared with the related art devices which are periodically activated to respond to a pairing request, the mobile terminal that performs communication by using the 60 GHz band can have a lengthened usage time. 
     While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.