Abstract:
A method and device for content casting services using Wi-Fi communication are disclosed are provided. The device includes a first band communication module for communicating with external devices over a first frequency band and a second band communication module for communicating with external devices over a second frequency band. The method includes detecting occurrence of a cast request event indicating content delivery, selecting, upon detection of the cast request event, a first external device possessing the indicated content, receiving the content from the selected first external device through the first band communication module, and transmitting the received content to a second external device through the second band communication module.

Description:
PRIORITY 
       [0001]    This application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed on May 3, 2012 in the Korean Intellectual Property Office and assigned Serial No. 10-2012-0047040, the entire disclosure of which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a method and device for a Wi-Fi communication system. More specifically, the present invention relates to a method and device that provide content casting services using a Wi-Fi communication system. 
         [0004]    2. Description of the Related Art 
         [0005]    With recent popularization of terminals or devices supporting Wi-Fi communication or Wireless Local Area Network (WLAN) communication, research has been actively conducted into devices that can provide various services using a WLAN communication system. 
         [0006]    In particular, a device may provide a content casting service to another device. For example, a first device may transmit stored content data to a second device such as a Wireless Access Point (WAP) through a first frequency band, and transmit content data to a third device such as a smartphone through a second frequency band. Here, as is widely known, a WAP refers to a device that allows wireless devices to connect to a wired network using Wi-Fi or related standards. 
         [0007]    However, an existing device may use only one of a plurality of frequency bands at a particular time to communicate with external devices. In other words, to simultaneously connect to multiple external devices (for example, first and second external devices), an existing device needs to conduct periodic switching between communication channels (actually used frequency bands) at the PHYsical (PHY) layer. For example, the device may receive content data from a first external device (e.g. WAP) through a channel of a first frequency band (e.g. 2.4 GHz) and store the same. The device then switches the PHY layer channel from the first frequency band to a second frequency band (e.g. 5 GHz) and transmits the stored content data to a second external device (e.g. TV) through the second frequency band channel. Then, to connect back to the first external device, the device needs to switch the PHY layer channel from the second frequency band to the first frequency band. 
         [0008]    An existing device operating as described above may suffer degradation of maximum available throughput at each frequency band according to loss of throughput due to time division and loss of time due to switching between frequency bands. For example, when the device attempts to transmit a large amount of content data through a 5-GHz band while using Voice over Internet Protocol (VoIP) through a 2.4-GHz band, the amount of content data transmittable through the 5-GHz band may be limited. Additionally, the device may experience loss of time owing to periodic switching between frequency bands at the MAC and PHY layers. 
         [0009]    Accordingly, there is a need for a device and method for receiving content data from a first external device through a receive frequency band and simultaneously transmitting the received content data to a second external device through a transmit frequency band. 
         [0010]    The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention. 
       SUMMARY OF THE INVENTION 
       [0011]    Aspects of the present invention are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a method and device for providing content casting services. 
         [0012]    Another aspect of the present invention is to provide a method and device that receives content data from a first external device through a receive frequency band and transmits the received content data to a second external device through a transmit frequency band at the same time. 
         [0013]    Another aspect of the present invention is to provide a method and device that transmit content to external devices through multiple transmit frequency bands. 
         [0014]    In accordance with an aspect of the present invention, a method of providing a content casting service in a device having a first band communication module for communicating with external devices over a first frequency band and a second band communication module for communicating with external devices over a second frequency band is provided. The method includes detecting occurrence of a cast request event, indicating content delivery, selecting, upon detection of the cast request event, a first external device possessing the indicated content, receiving the content from the selected first external device through the first band communication module, and transmitting the received content to a second external device through the second band communication module. 
         [0015]    In accordance with another aspect of the present invention, a method of providing a content casting service in a device having a first band communication module for communicating with external devices over a first frequency band and a second band communication module for communicating with external devices over a second frequency band is provided. The method includes detecting occurrence of a cast request event indicating content delivery, selecting, upon detection of the cast request event, one of content stored in a storage unit, selecting a first external device and a second external device, transmitting the selected content to the first external device through the first band communication module, and transmitting the selected content to the second external device through the second band communication module. 
         [0016]    In accordance with another aspect of the present invention, a method of providing a content casting service in a device having a first band communication module for communicating with external devices over a first frequency band and a second band communication module for communicating with external devices over a second frequency band is provided. The method includes detecting occurrence of a cast request event indicating image delivery, receiving, upon detection of the cast request event, captured images from a first external device through the first band communication module, and transmitting the received captured images to a second external device through the second band communication module. 
         [0017]    In accordance with another aspect of the present invention, a device capable of providing a content casting service is provided. The device includes a touchscreen capable of providing a user interface for user interactions, a first band communication module capable of communicating with a first external device over a first frequency band, a second band communication module capable of communicating with a second external device over a second frequency band, wherein the first band communication module and the second band communication module are integrated into one chip, and a control unit capable of controlling the touchscreen, the first band communication module and the second band communication module, wherein the control unit is capable of controlling a process of detecting occurrence of a cast request event indicating content delivery, selecting, upon detection of the cast request event, the first external device possessing the indicated content, receiving the content from the first external device through the first band communication module, and transmitting the received content to the second external device through the second band communication module. 
         [0018]    In accordance with another aspect of the present invention, a device capable of providing a content casting service is provided. The device includes a touchscreen capable of providing a user interface for user interaction, a first band communication module capable of communicating with a first external device over a first frequency band, a second band communication module capable of communicating with a second external device over a second frequency band, wherein the first band communication module and the second band communication module are integrated into one chip, and a control unit capable of controlling the touchscreen, the first band communication module and the second band communication module, wherein the control unit is capable of controlling a process of detecting occurrence of a cast request event indicating content delivery, selecting, upon detection of the cast request event, one of content stored in a storage unit, selecting a first external device and second external device, transmitting the selected content to the first external device through the first band communication module, and transmitting the selected content to the second external device through the second band communication module. 
         [0019]    In accordance with another aspect of the present invention, a device capable of providing a content casting service is provided. The device includes a touchscreen capable of providing a user interface for user interaction, a first band communication module capable of communicating with a first external device over a first frequency band, a second band communication module capable of communicating with a second external device over a second frequency band, wherein the first band communication module and the second band communication module are integrated into one chip, and a control unit capable of controlling the touchscreen, the first band communication module and the second band communication module, wherein the control unit is capable of controlling a process of detecting occurrence of a cast request event indicating image delivery, receiving, upon detection of the cast request event, captured images from the first external device through the first band communication module, and transmitting the received captured images to the second external device through the second band communication module. 
         [0020]    Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0022]      FIG. 1  is a block diagram of a device according to an exemplary embodiment of the present invention; 
           [0023]      FIG. 2  illustrates a content casting service according to an exemplary embodiment of the present invention; 
           [0024]      FIGS. 3 and 4  illustrate a time domain relationship between receive and transmit signals during a content casting service of a device according to an exemplary embodiment of the present invention; 
           [0025]      FIG. 5  illustrates a content casting service according to an exemplary embodiment of the present invention; 
           [0026]      FIG. 6  illustrates a content casting service according to an exemplary embodiment of the present invention; 
           [0027]      FIG. 7  illustrates a content casting service according to an exemplary embodiment of the present invention; 
           [0028]      FIG. 8  is a flowchart of a method for providing a content casting service according to an exemplary embodiment of the present invention; 
           [0029]      FIGS. 9 to 11  are screen representations depicting steps in the method of  FIG. 8  according to exemplary embodiments of the present invention; 
           [0030]      FIG. 12  is a flowchart of a method for providing a content casting service according to an exemplary embodiment of the present invention; 
           [0031]      FIGS. 13 and 14  are screen representations depicting steps in the method of  FIG. 12  according to exemplary embodiments of the present invention; 
           [0032]      FIG. 15  is a flowchart of a method for providing a content casting service according to an exemplary embodiment of the present invention; 
           [0033]      FIG. 16  illustrates screen representations depicting steps in the method of  FIG. 15  according to exemplary embodiments of the present invention; 
           [0034]      FIG. 17  is a flowchart of a method for providing a content casting service according to an exemplary embodiment of the present invention; 
           [0035]      FIG. 18  illustrates screen representations depicting steps in the method of  FIG. 17  according to exemplary embodiments of the present invention; 
           [0036]      FIG. 19  illustrates screen representations of a method for providing a content casting service according to exemplary embodiments of the present invention; and 
           [0037]      FIG. 20  is a flowchart of a procedure to determine whether to operate in a dual mode or repeater mode according to an exemplary embodiment of the present invention. 
       
    
    
       [0038]    Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0039]    The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
         [0040]    The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
         [0041]    It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
         [0042]    In the following description, the terms “cast” or “casting” may refer to a unicast where a device sends content to one external device, a multicast where a device sends content to multiple external devices belonging to the same group, or a broadcast where a device sends content to multiple unspecified external devices. 
         [0043]    The method and device according to exemplary embodiments of the present invention are applicable to terminals with a communication function. That is, the exemplary method and device of the present invention can be applied to communication and multimedia appliances such as a smartphone, a tablet computer, a laptop computer, a desktop computer, a TV, a navigation aid, a videophone, and the like. The exemplary method and device may also be applied to convergence appliances such as a refrigerator having a communication function and a TV. 
         [0044]    The description primarily focuses upon the provision of a content casting service using Wireless Local Area Network (WLAN). However, the content casting service may also be provided using a different communication scheme such as Bluetooth. In the following description, only multicasting is described and illustrated. However, it is to be understood that the present invention is also applicable to unicasting or broadcasting. 
         [0045]      FIG. 1  is a block diagram of a device according to an exemplary embodiment of the present invention. 
         [0046]    Referring to  FIG. 1 , the device  100  may include a touchscreen  110  including a touch panel  111  and a display unit  112 , a key input unit  120 , a touch panel controller  125 , a storage unit  130 , an audio processing unit  135  including a speaker (SPK) and microphone (MIC), a first wireless unit  140 , a second wireless unit  145 , and a control unit  180 . 
         [0047]    The touch panel  111  may be placed on the display unit  112 . The touch panel  111  generates touch data (e.g. touch event) corresponding to a touch gesture made by the user and sends the touch data to the control unit  180 . The touch panel  111  may be of an add-on type (e.g., placed on the display unit  112 ) or an on-cell or in-cell type (e.g., inserted in the display unit  112 ). The control unit  180  may control other components on the basis of touch data sent by the touch panel  111 . Touch data or a touch event may be divided into a touch action and touch gesture. A touch action may include a touch, a tap, a double tap, a long tap, a drag, a drag and drop, a flick, a press, and the like. Here, a touch corresponds to single point contact with the screen using a touch means such as a finger or stylus pen; a tap corresponds to touch and release at the same point; a double tap corresponds to two consecutive taps at the same point; a long tap corresponds to a long touch and a release at the same point; a drag corresponds to a touch and a move in one direction; a drag and drop corresponds to a drag and a release; a flick corresponds to a touch, a fast move and a release; and a press corresponds to a touch and a push at the same point. Namely, a touch action may be focused on a state of contact on the screen, and a touch gesture may be focused on a movement of a touch action from a contact on the screen to a release from the screen. The touch panel  111  may include a pressure sensor to sense pressure at a touched point. In that case, sensed pressure information is sent to the control unit  180 , which can distinguish a touch from a press on the basis of the sensed pressure information. The touch panel  111  may be realized using a resistive, a capacitive, or an electromagnetic induction technology. 
         [0048]    The display unit  112  converts video data from the control unit  180  into an analog signal and displays the analog signal under control of the control unit  180 . The display unit  112  may output various screens generated in the course of using the device  100 , such as a lock screen, a home screen, an application (or app) screen, a menu screen, a keypad screen, a message-handling screen, and an Internet access screen. The lock screen is displayed when the display unit  112  is turned on. When a given touch event for unlocking is generated, the control unit  180  may perform a screen transition from the lock screen to the home screen or a preset app screen. The home screen includes a plurality of icons mapped to various apps. When one of the icons is selected by the user, the control unit  180  may execute an app mapped with the selected icon and control the display unit  112  to display the corresponding application screen. The display unit  112  may be realized using a flat display panel composed of Liquid Crystal Display (LCD) devices, Organic Light Emitting Diodes (OLEDs), or Active Matrix Organic Light Emitting Diodes (AMOLEDs). 
         [0049]    The key input unit  120  may include a plurality of alphanumeric and function keys for entering alphanumeric information and for setting various functions. The function keys may include direction, side, and shortcut keys associated with corresponding functions. The key input unit  120  transmits key signals from the user for setting and controlling the device  100  to the control unit  180 . Key signals may be related to power on/off, volume adjustment, and screen on/off. The control unit  180  may control the components according to key signals. The key input unit  120  may include a QWERTY keypad, a 3*4 keypad, or a 4*3 keypad, including multiple keys. When the touch panel  111  is configured to support a full touchscreen feature, the key input unit  120  may include only one or more side keys that are arranged at sides of the case of the device  100  for screen on/off and power on/off. 
         [0050]    The touch panel controller  125  is connected to the touch panel  111 . The touch panel controller  125  receives analog touch data from the touch panel  111 , converts the analog touch data into digital touch data, and sends the digital touch data to the control unit  180 . The control unit  180  identifies a touch gesture from the received touch data. That is, the control unit  180  may extract information regarding a touch point, a distance, a direction and speed of the touch and movement, and a touch pressure. 
         [0051]    The storage unit  130  may include a high-speed random access memory, nonvolatile memory, optical storage medium, and flash memory (NAND or NOR type). The storage unit  130  stores various kinds of software such as an operating system, a communication program, a graphics program, a user interface program, and other applications. Modules or components of particular software include a set of instructions. The operating system (for example, Windows, Linux, Darwin, RTXC, UNIX, OS X, or VxWorks) includes various software modules for controlling the device  100 . The communication program includes instructions enabling the device  100  to communicate with external devices through the first wireless unit  140  and second wireless unit  145 . More particularly, the communication program may include a routine for determining whether to activate a content casting service on the basis of detected user input, and a routine for actually providing a content casting service. The graphics program includes various components for displaying graphics data on the touchscreen  110 . Here, graphics data may be composed at least one of text, web pages, icons, digital images, video and animation. The graphics program includes a routine for controlling an operation to display graphics data corresponding to a function executed by the control unit  180  on the touchscreen  110 . The user interface program includes various routines for managing interactions between the device  100  and the user. Application programs may perform operations related to Web browsing, electronic mail, instant messaging, word processing, keyboard emulation, address books, widgets, Digital Rights Management (DRM), speech recognition, position determination, location based services, content casting services, and the like. The storage unit  130  may further store other programs or routines, or may not store one or more of programs or routines described above. 
         [0052]    The audio processing unit  135  inputs and outputs audio signals for speech recognition, voice reproduction, digital recording, and call processing by means of the speaker and microphone. The audio processing unit  135  outputs an audio signal through the speaker and receives an audio signal through the microphone. The audio processing unit  135  converts audio data from the control unit  180  into an electrical signal and outputs the electrical signal to the speaker, and converts an electrical signal from the microphone into audio data and outputs the audio data to the control unit  180 . The speaker converts an electrical signal from the audio processing unit  135  into a sound wave for output. The microphone converts a sound wave propagated from a sound source such as a person into an electrical signal. 
         [0053]    The first wireless unit  140  and the second wireless unit  145  perform communication operations to send and receive signals (e.g. carrying content data) to and from external devices. The first wireless unit  140  may include at least one of a radio frequency transceiver and an optical (e.g. infrared) transceiver. For example, the first wireless unit  140  may support one of Global System for Mobile Communications (GSM) network, Enhanced Data Rates for GSM Evolution (EDGE) network, Code Division Multiple Access (CDMA) network, Wideband Code Division Multiple Access (WCDMA) network, Long Term Evolution (LTE) network, Orthogonal Frequency Division Multiple Access (OFDMA) network, and Bluetooth network. 
         [0054]    The second wireless unit  145  supports Wi-Fi communication. The second wireless unit  145  may include a first band communication module  150  and a second band communication module  160  that are physically separated to send and receive signals using different frequency bands. For example, the first band communication module  150  and second band communication module  160  may respectively support 2.4 GHz and 5 GHz, and may support other frequency bands according to design. The first band communication module  150  and second band communication module  160  may each include an RF section, a PHY layer, and a MAC layer. Hence, the second wireless unit  145  may receive a signal through a first frequency band and send a signal through a second frequency band at the same time. The second wireless unit  145  may simultaneously receive signals or simultaneously send signals through a first frequency band and a second frequency band at the same time. The frequency bands (for example, 2.4 GHz and 5 GHz) supported respectively by the first band communication module  150  and second band communication module  160  may be independent of one another. Thereby, interference between receive and transmit signals can be avoided and RF performance degradation can be prevented. 
         [0055]    The first band communication module  150  may include a first RF section  151 , a first PHY layer  152 , a first MAC layer  153  and a first antenna  154  to process a first frequency band signal. The second band communication module  160  may include a second RF section  161 , a second PHY layer  162 , a second MAC layer  163  and a second antenna  164  to process a second frequency band signal. 
         [0056]    The first band communication module  150  and the second band communication module  160  may be configured as physically separate entities in the same chip. That is, a signal received by the first antenna  154  is delivered through the first RF section  151 , first PHY layer  152  and first MAC layer  153  to an application processor  181 ; and a transmit signal from the application processor  181  is delivered through the first MAC layer  153 , first PHY layer  152  and first RF section  151  to the first antenna  154 . A signal received by the second antenna  164  is delivered through the second RF section  161 , second PHY layer  162  and second MAC layer  163  to the application processor  181 ; and a transmit signal from the application processor  181  is delivered through the second MAC layer  163 , second PHY layer  162  and second RF section  161  to the second antenna  164 . Under control of the application processor  181 , the first band communication module  150  and the second band communication module  160  may receive signals at the same time; the first band communication module  150  and the second band communication module  160  may transmit signals at the same time; the first band communication module  150  may receive a signal and the second band communication module  160  may transmit a signal at the same time; or the first band communication module  150  may transmit a signal and the second band communication module  160  may receive a signal at the same time. 
         [0057]    The first frequency band (for example, 2.4 GHz) supported by the first band communication module  150  and the second frequency band (for example, 5 GHz) supported by the second band communication module  160  may not overlap with each other. Hence, interference between a first frequency band signal and a second frequency band signal can be avoided, preventing RF performance degradation. 
         [0058]    The first RF section  151  (the second RF section  161 ) receives an RF signal from the first antenna  154  (the second antenna  164 ), converts the RF signal into a baseband signal, and outputs the baseband signal to the first PHY layer  152  (the second PHY layer  162 ). The first RF section  151  (the second RF section  161 ) receives a baseband signal from the first PHY layer  152  (the second PHY layer  162 ), converts the baseband signal into an RF signal, and outputs the RF signal to the first antenna  154  (the second antenna  164 ). The first RF section  151  and the second RF section  161  may each include an amplifier, mixer, oscillator, DAC, and filter. 
         [0059]    The first PHY layer  152  (the second PHY layer  162 ) may act as a modem for performing conversion between a baseband signal and a bit string according to the physical layer specification of Wi-Fi communication. For example, when Wi-Fi communication employs Orthogonal Frequency Division Multiplexing (OFDM) the first PHY layer  152  (the second PHY layer  162 ) converts a bit string to be sent into complex symbols through coding and modulation, and converts the complex symbols into OFDM symbols through complex symbol-to-subcarrier mapping, Inverse Fast Fourier Transform (IFFT) and Cyclic Prefix (CP) insertion for data transmission. For data reception, the first PHY layer  152  (the second PHY layer  162 ) separates a baseband signal into OFDM symbols, and converts the OFDM symbols into a bit string through subcarrier-to-complex symbol mapping, Fast Fourier Transform (FFT), demodulation, and decoding. 
         [0060]    The first MAC layer  153  (the second MAC layer  163 ) may use various communication-related algorithms in relation to network access control (or addressing), channel sharing between multiple nodes (or collision avoidance), packet encryption, fragmentation, power saving mode, and flow control. 
         [0061]    In the above description, for signal transmission and reception, the first band communication module  150  and second band communication module  160  are depicted as each having one antenna (i.e. the first antenna  154  or second antenna  164 ). However, the first band communication module  150  and second band communication module  160  may be designed to share a single antenna by employing a diplexer to separate the path of the first RF section  151  from that of the second RF section  161 . 
         [0062]    The second wireless unit  145  may further include a third band communication module  170 , which acts similarly to the first and second band communication modules  150  and  160  but uses a different frequency band. The third band communication module  170  may include a third RF section  171 , a third PHY layer  172 , a third MAC layer  173  and a third antenna  174  to process a signal of a second frequency band. 
         [0063]    The control unit  180  controls the overall operation of the device  100 , controls signal exchange between the internal components thereof, and performs data processing. The control unit  180  also controls power supply from a battery to other components. The control unit  180  executes an application in response to a touch gesture. To achieve this, the control unit  180  may include the application processor  181 . 
         [0064]    The application processor  181  may determine the receive frequency band and the transmit frequency band when a casting request event (e.g., a touch on a “Cast” button on the screen) is detected. For example, the application processor  181  may determine to use a first frequency band and a second frequency band respectively for reception and transmission, or use the first frequency band and the second frequency band respectively for transmission and reception. The first frequency band and the second frequency band may be in the same frequency range of, for example, 2.4 GHz. In this case, the first frequency band and the second frequency band may correspond to non-overlapping orthogonal channels. For example, the first frequency band and the second frequency band may be assigned in the frequency range of 2.4 GHz. In the 2.4 GHz range, 14 channels may be defined (channel bandwidth of 22 MHz and channel separation of 5 MHz), and three non-overlapping channels (Channels  1 ,  6  and  11 ) are possible. Then, the first frequency band may be related to Channel  1  and the second frequency band may be related to Channel  6  or  11 . The application processor  181  may determine to use both the first frequency band and the second frequency band for transmission, or use both the first frequency band and the second frequency band for reception. 
         [0065]    The application processor  181  may set the receive frequency band and the transmit frequency band to a preset frequency range, or determine the receive frequency band and the transmit frequency band according to a function used in a content casting service and external devices involved in the content casting service. That is, the application processor  181  may determine the receive frequency band and the transmit frequency band in consideration of frequencies used by an executed function or supported by external devices during a content casting service. For example, when a Web browsing function and a display function are used in a content casting service, the application processor  181  may determine the receive frequency band and the transmit frequency band according to frequencies used by the Web browsing function and the display function. Here, the device  100  may execute the Web browsing function to receive Web pages through an external device such as a wireless Access Point (AP), and execute the display function to display content on an external device such as a TV by sending content data (e.g. received Web pages) to the external device. For another example, when the device  100  is already connected with an access point, to initiate a content casting service, the application processor  181  may determine the receive frequency band and the transmit frequency band in consideration of a frequency band used to connect to the access point. Here, the receive frequency band may be set to the frequency band used to connect to the access point, and the transmit frequency band may be set to a different frequency band. 
         [0066]    The application processor  181  controls an operation to receive content through the first band communication module  150  and send the received content through the second band communication module  160  at the same time. The application processor  181  may determine to operate in a dual mode or a repeater mode according to characteristics of the current content casting service. In the repeater mode, content received by the first band communication module  150  is forwarded directly to the second band communication module  160  (the application processor  181  is bypassed). In the dual mode, content received by the first band communication module  150  is sent to the application processor  181 , which processes the content (for example, resolution adjustment or resizing) and forwards the processed content to the second band communication module  160 . The application processor  181  may send content stored in the device  100  to both the first band communication module  150  and second band communication module  160 . The application processor  181  may receive content through both the first band communication module  150  and the second band communication module  160  from the outside. 
         [0067]    The exemplary device  100  of the present invention may further include an external port, a vibration motor, a Global Positioning Sensor (GPS) receiver, a camera module, and the like (not shown). With the trend towards digital convergence, it should be apparent that the exemplary device  100  of the present invention may further include a unit comparable to the above-described units, and one unit of the device  100  may be removed or replaced with another unit. 
         [0068]      FIG. 2  illustrates a content casting service according to an exemplary embodiment of the present invention. 
         [0069]    In the following description, a “main owner” refers to a device that casts content to other devices. A “contents group” refers to one or more devices that are capable of providing content to the main owner. A “casting group” refers to one or more devices that receive content from the main owner. One or more casting groups may be present according to frequency bands. For example, a casting group communicating with the main owner through a first frequency band may be referred to as a first casting group, and a casting group communicating with the main owner through a second frequency band may be referred to as a second casting group. The contents group may communicate with the main owner through a frequency band not used by the casting group. 
         [0070]    Referring to  FIG. 2 , a main owner  210  may include the above-described components  181 ,  150  and  160 . The main owner  210  may connect to an access point through the first band communication module  150 . After being connected to the access point, the main owner  210  may detect a user input for connecting to a contents group  220  (for example, selection of a YouTube icon on the touchscreen). Here, the contents group  220  may include a cloud server, a Social Networking Service (SNS) server such as Twitter or Facebook, a moving image database server such as YouTube, and the like. In response to a user input, the main owner  210  may connect to an external device in the contents group  220  through the access point, receive content from the external device, and play back the received content in real time. 
         [0071]    The main owner  210  may connect to a casting group  230  through the second band communication module  160 . Here, the second band communication module  160  may directly connect to the casting group  230  without an intermediate medium such as an access point. Direct connection between the main owner  210  and casting group  230  may be achieved using, for example, Wi-Fi Direct. As Wi-Fi Direct is known in the art, a detailed description thereof is omitted herein. 
         [0072]    When the user enters an input for a content casting service (for example, touch on the “Cast” button on the touchscreen), the main owner  210  may transmit the content received from the external device of the contents group  220  to the casting group  230 . 
         [0073]    As described above, the main owner  210  may receive content from the contents group  220  through the access point and transmit the received content to the casting group  230 . In  FIG. 2 , the user may use a smartphone (main owner  210 ) to view a moving image received from YouTube (contents group  220 ) and share the moving image with nearby friends (casting group  230 ). Hence, the user may view and enjoy a moving image together with friends. 
         [0074]    The main owner  210  may determine whether to operate in a repeater mode  240  or dual mode  250 . For example, when content is a document file or a compressed file, the main owner  210  may determine to operate in the repeater mode  240 . On the other hand, when content is a moving image, the main owner  210  may determine to operate in the dual mode  250 . In the repeater mode  240 , the main owner  210  uses the first band communication module  150  to receive content through the access point and uses the second band communication module  160  to transmit the received content in real time. In the dual mode  250 , the main owner  210  uses the first band communication module  150  to receive content through the access point, processes the received content through the application processor  181  (for example, resolution adjustment or resizing) and uses the second band communication module  160  to transmit the processed content in real time. In the dual mode  250 , the content delivered to the casting group  230  may be content received through the access point, or be content generated by or stored in the main owner  210  (for example, camera-captured images). 
         [0075]      FIGS. 3 and 4  illustrate a time domain relationship between receive and transmit signals during a content casting service of a device according to an exemplary embodiment of the present invention. 
         [0076]    Referring to  FIGS. 3 and 4 , since the main owner  210  includes the two communication modules  150  and  160  that operate independently on different frequency bands within the same chip as described in connection with  FIG. 2 , the main owner  210  may simultaneously receive content from the contents group  220  and transmit the received content to the casting group  230 . Hence, as shown in  FIG. 3 , the device  100  does not need a separate switching time for receiving content and transmitting the received content, and can simultaneously perform content reception as indicated by reference numeral  300  or  302  and content transmission as indicated by reference numeral  310  or  312 . As content reception and content transmission are simultaneously performed (without time delay due to switching between frequency bands), exemplary embodiments of the present invention have an advantage over related art techniques in terms of real-time playback. Delay indicated by reference numeral  320  or  322  in  FIG. 3  has no relation to switching between frequency bands, and is merely a time needed for the main owner  210  to transmit content received through the first band communication module  150  from the access point to the casting group  230  through the second band communication module  160 . 
         [0077]    When a single host interface is used for communication between the application processor  181  and the communication modules  150  and  160 , the application processor  181  has to alternately communicate with the first band communication module  150  and the second band communication module  160 . In this case, the first band communication module  150  and second band communication module  160  may fragment one transmit or receive frame into multiple packets under control of the application processor  181 . The application processor  181  may alternately communicate with the first band communication module  150  and the second band communication module  160  on the basis of fragmented packets. As shown in  FIG. 4 , the application processor  181  may process receive packets indicated by reference numerals  400 ,  401 ,  402 ,  403  and  404  alternately with transmit packets indicated by reference numerals  410 ,  411 ,  412 ,  413  and  414 . As the application processor  181  does not have to switch between frequency bands at the MAC or PHY layer (no time delay due to switching between frequency bands), exemplary embodiments of the present invention are more advantageous to real-time playback in comparison to a related art technique. 
         [0078]      FIG. 5  illustrates a content casting service according to an exemplary embodiment of the present invention. 
         [0079]    Referring to  FIG. 5 , a main owner  510  may include the above-described components  181 ,  150  and  160 . The main owner  510  may simultaneously receive content from a contents group  520  through the first band communication module  150  and an access point and transmit the received content to a casting group  530 . In  FIG. 5 , the main owner  510  is a home network server. The casting group  530  includes user appliances connected to the home network. Such home network appliances may be connected with the home network server using Wi-Fi Direct techniques. The home network appliances may include a smartphone, a TV, a tablet computer, a laptop computer, a refrigerator having a TV, and the like. 
         [0080]      FIG. 6  illustrates a content casting service according to an exemplary embodiment of the present invention. 
         [0081]    Referring to  FIG. 6 , a main owner  610  may include the above-described components  181 ,  150  and  160 . The main owner  610  may connect to an access point through the first band communication module  150 , and connect to a second casting group  630  through the access point. The main owner  610  may also connect to a first casting group  620  through the second band communication module  160 . Here, the main owner  610  may connect directly to the first casting group  620  through, for example, Wi-Fi Direct. Thereafter, the main owner  610  may detect a user input requesting a content casting service (for example, a tap on a “Cast” button of a music player application screen). 
         [0082]    In response to the user input, the main owner  610  may display information regarding the first casting group  620  and the second casting group  630 . The information on the first casting group  620  may include identification information of external devices within the first casting group  620  (for example, phone numbers, user names, user images, device names, and the like). Here, the identification information may include information that is received by the main owner  610  from external devices of the first casting group  620  during connection establishment. The identification information may also include information pre-stored in the main owner  610  (for example, phonebook information). The information on the second casting group  630  may include identification information of external devices within the second casting group  630 . 
         [0083]    When the user selects external devices from the first casting group information and the second casting group information displayed on the screen, the main owner  610  transmits the current content (for example, a music file being played back) to the selected external devices of the second casting group  630  through the first band communication module  150  and transmits the current content to the selected external devices of the first casting group  620  through the second band communication module  160 . In  FIG. 6 , the user may listen to music played back by the smartphone (main owner  610 ) and allow both nearby friends (first casting group  620 ) and friends at a distance (second casting group  630 ) to listen to music in real time. In other cases, the user may allow nearby friends and friends at a distance to view images being captured by the smartphone in real time. Also, the user may allow nearby friends and friends at a distance to hear the speech of a counterpart in a call in real time. 
         [0084]    In the above description, the device  100  is depicted as having two physically separated communication modules to support two frequency bands. If necessary, an exemplary device of the present invention may include three or more physically separated communication modules to support three or more frequency bands. 
         [0085]      FIG. 7  illustrates a content casting service according to an exemplary embodiment of the present invention. 
         [0086]    Referring to  FIG. 7 , a main owner  710  may include the above described components  181 ,  150  and  160  and may further include the third band communication module  170  supporting a third frequency band. The main owner  710  may connect to a contents group  720  through the first band communication module  150 . Here, the contents group  720  is composed of accessories that are directly connectable to the main owner  710  through, for example, Wi-Fi Direct (such as a camera, a CCTV, a remote-controllable miniature car or helicopter with a camera, and the like). The main owner  710  may play back, in real-time, content received through the first band communication module  150  from the contents group  720  (for example, images captured from a miniature helicopter). 
         [0087]    The main owner  710  may directly connect to a first casting group  730  through the second band communication module  160 . The main owner  710  may connect to an access point through the third band communication module  170  and connect to a second casting group  740  through the access point. Thereafter, the main owner  710  may detect a user input requesting a content casting service (for example, a touch on a “Cast” button of a captured image screen). 
         [0088]    In response to the user input, the main owner  710  may display information regarding the first casting group  730  and the second casting group  740 . When the user selects external devices from the first casting group information and the second casting group information displayed on the screen, the main owner  710  transmits content received from the contents group  720  to the first casting group  730  through the second band communication module  160  and transmits the content to the second casting group  740  through the third band communication module  170 . 
         [0089]      FIG. 8  is a flowchart of a method for providing a content casting service according to an exemplary embodiment of the present invention, and  FIGS. 9 to 11  are screen representations depicting steps in the method of  FIG. 8  according to exemplary embodiments of the present invention. 
         [0090]    Referring to  FIGS. 1 and 8  to  11 , the control unit  180  of the device  100  may control the display unit  112  to display a home screen. When an icon associated with a chatting application is selected on the home screen (for example, a tap on the icon), the control unit  180  executes a chatting application associated with the selected icon in step  801 . The control unit  180  may control the touchscreen  110  to display a chatting application screen as indicated by reference numeral  901  in  FIG. 9 . 
         [0091]    The control unit  180  detects a touch input on the chatting application screen  901  in step  802 . For example, the control unit  180  may detect selection of a first object  902  associated with an option menu on the chatting application screen  901  (e.g., a touch on the first object  902 ). Upon selection of the first object  902 , the control unit  180  controls the touchscreen  110  to display an option menu  903 . 
         [0092]    The control unit  180  determines whether a cast request event is detected in step  803 . When a cast request event is detected (for example, when a second object  904  (a cast music object) associated with content casting is selected on the option menu  903 ), the control unit  180  controls the touchscreen  110  to display a playlist  905  in step  804 . 
         [0093]    The control unit  180  selects music to be cast from the playlist  905  according to a user manipulation in step  805 . After music selection, the control unit  180  controls the first band communication module  150  and the second band communication module  160  to transmit the selected music (content) to external devices connected respectively therewith (for example, first and second external devices) in step  806 . 
         [0094]    More specifically for step  806 , when music to be cast is selected, as shown in  FIG. 10 , the control unit  180  controls the touchscreen  110  to display a message  1001  notifying of initiation of music casting in a chat window. The control unit  180  controls the first band communication module  150  to send a cast invite message to the first casting group. The first band communication module  150  may be directly connected to the first casting group by means of, for example, Wi-Fi Direct without an intermediate medium such as an access point under control of the control unit  180 . Alternatively, the first band communication module  150  may be connected to the first casting group through an access point. 
         [0095]    The control unit  180  controls the second band communication module  160  to send a cast invite message to the second casting group. Here, the second band communication module  160  may be directly connected to the second casting group without an access point or be connected thereto through an access point. 
         [0096]    The control unit  180  may control an operation to send cast invite messages according to a preset priority. For example, when the first band communication module  150  is actively engaged in communication, the control unit  180  may control the second band communication module  160  to send a cast invite message to the second casting group first and then control the first band communication module  150  to send a cast invite message to the first casting group. When the first band communication module  150  and the second band communication module  160  are both available, that is, not engaged in communication, the control unit  180  may control the first band communication module  150  to send a cast invite message to the first casting group first and then control the second band communication module  160  to send a cast invite message to the second casting group. 
         [0097]    A cast invite message  1002  is displayed in a chat window of the first casting group. A cast invite message  1003  is displayed on a chat window of the second casting group. A first external device of the first casting group may detect selection of a “Join” button in response to the cast invite message  1002 . Upon selection of the “Join” button, the first external device sends a cast join message to the device  100  (main owner). When a second external device of the second casting group detects selection of a “Join” button in response to the cast invite message  1003 , it sends a cast join message to the device  100 . 
         [0098]    As shown in  FIG. 11 , the control unit  180  controls the touchscreen  110  to display a cast wait message  1101 . When cast join messages are received from the first and second casting groups, the control unit  180  controls the touchscreen  110  to display a music cast screen  1102 . The control unit  180  sends the selected music data to the first casting group through the first band communication module  150 , and sends the music data to the second casting group through the second band communication module  160 . After sending a cast join message to the device  100 , the first external device of the first casting group displays a cast wait message  1103 . When music data is received from the device  100 , the first external device displays a music cast screen  1104  and plays back the received music data. After sending a cast join message to the device  100 , the second external device of the second casting group displays a cast wait message  1105 . When music data is received from the device  100 , the second external device displays a music cast screen  1106  and plays back the received music data. Among the music cast screens  1102 ,  1104  and  1106 , the music cast screen  1102  of the device  100  may include buttons  1107  and  1108  for controlling music playback. The user may add or delete music to be cast using such buttons. 
         [0099]    As described above in connection with  FIGS. 1 and 8  to  11 , the user may introduce favorite content such as music to acquaintances nearby or far away during a chat session. 
         [0100]      FIG. 12  is a flowchart of a method for providing a content casting service according to an exemplary embodiment of the present invention, and  FIGS. 13 and 14  are screen representations depicting steps in the method of  FIG. 12  according to exemplary embodiments of the present invention. 
         [0101]    Referring to  FIGS. 1 and 12  to  14 , the control unit  180  of the device  100  executes an SNS application according to a user selection (for example, a tap on an icon mapped to the SNS application on the home screen) in step  1201 . The control unit  180  may control the touchscreen  110  to display an SNS application screen  1301 . 
         [0102]    The control unit  180  detects a touch input on the SNS application screen  1301  in step  1202 . For example, the control unit  180  may detect selection of a first object  1302  associated with an option menu on the SNS application screen  1301  (e.g. a touch on the first object  1302 ). Upon selection of the first object  1302 , the control unit  180  controls the touchscreen  110  to display an option menu  1303 . 
         [0103]    The control unit  180  determines whether a cast request event is detected in step  1203 . When a cast request event is detected (for example, when a second object  1304  (a cast music object) associated with content casting is selected on the option menu  1303 ), the control unit  180  controls the touchscreen  110  to display a playlist  1305  in step  1204 . 
         [0104]    The control unit  180  selects music to be cast from the playlist  1305  according to a user manipulation in step  1205 . After music selection, the control unit  180  determines recipient devices to receive music (for example, first and second external devices) in step  1206 . 
         [0105]    More specifically for step  1206 , when music to be cast is selected from the playlist  1305 , the control unit  180  controls the touchscreen  110  to display first casting group information  1401  and second casting group information  1402 . Here, the first casting group information  1401  includes identification information of external devices connected with, for example, the first band communication module  150  of the device  100 . The identification information may include photographs and names of users of the external devices. The identification information may be information received from the external devices or information pre-stored in the device  100 . The external devices may be directly connected to the first band communication module  150  without an access point or be connected thereto through an access point. The second casting group information  1402  may be displayed when, for example, the second band communication module  160  of the device  100  is connected to an access point. The second casting group information  1402  may be not displayed when the device  100  is not connected with an access point. The second casting group information  1402  may be obtained from contact information stored in the storage unit  130 . When the user selects external devices from the displayed first casting group information  1401  and second casting group information  1402 , the control unit  180  determines the selected external devices as recipient devices to receive content (music). 
         [0106]    The control unit  180  controls the first band communication module  150  and the second band communication module  160  to transmit the selected content (music) to the recipient devices (for example, a first external device connected with the first band communication module  150  and a second external device connected with the second band communication module  160 ) in step  1207 . 
         [0107]    More specifically for step  1207 , when an “Invite” button  1403  is selected, the control unit  180  controls the first band communication module  150  to send a cast invite message to a selected external device of the first casting group. The first band communication module  150  may be directly connected to the first casting group or be connected thereto through an access point under control of the control unit  180 . In addition, the control unit  180  controls the second band communication module  160  to send a cast invite message to a selected external device of the second casting group. The second band communication module  160  may be directly connected to the second casting group or be connected thereto through an access point under control of the control unit  180 . As described before, the control unit  180  may send cast invite messages according to a preset priority. 
         [0108]    The selected external device of the first casting group displays a cast invite message  1404 . The selected external device of the second casting group displays a cast invite message  1405 . When a “Join” button is selected on the cast invite message  1404 , the external device of the first casting group sends a cast join message to the device  100 . When a “Join” button is selected on the cast invite message  1405 , the external device of the second casting group sends a cast join message to the device  100 . Subsequent steps are substantially the same as described in connection with  FIG. 11 , and a description thereof is omitted. 
         [0109]    As described above in connection with  FIGS. 1 and 12  to  14 , the user may introduce favorite content such as music to acquaintances nearby or far away during an SNS session. 
         [0110]      FIG. 15  is a flowchart of a method for providing a content casting service according to an exemplary embodiment of the present invention, and  FIG. 16  illustrates representations depicting steps in the method of  FIG. 15  according to exemplary embodiments of the present invention. 
         [0111]    Referring to  FIGS. 1 ,  15  and  16 , the control unit  180  of the device  100  may control the display unit  112  to display a home screen. Here, the home screen may include icons associated with playback applications for stored content (for example, a music player and video player). When an icon is selected (for example, a tap on the icon), the control unit  180  executes a content playback application associated with the selected icon and controls the touchscreen  110  to display a content playback screen  1601  correspondingly in step  1501 . When a “Play” button  1608  on the content playback screen  1601  is selected, the control unit  180  plays back content (e.g. music). Here, the content may be the last one played back by the corresponding application or one selected by the user from a playlist. 
         [0112]    The control unit  180  detects a touch input on the content playback screen  1601  in step  1502 . The control unit  180  determines whether the touch input is a cast request event in step  1503 . For example, when a “Cast” button is selected on the content playback screen  1601 , the control unit  180  determines recipient devices to receive content (music) (for example, first and second external devices) in step  1504 . More specifically for step  1504 , when the “Cast” button  1602  is selected, the control unit  180  controls the touchscreen  110  to display first casting group information  1603  and second casting group information  1604 . When the user selects external devices from the displayed first casting group information  1603  and second casting group information  1604 , the control unit  180  determines the selected external devices as recipient devices to receive content (music). 
         [0113]    The control unit  180  controls the first band communication module  150  and the second band communication module  160  to transmit the content (music) to the recipient devices (for example, a first external device connected with the first band communication module  150  and a second external device connected with the second band communication module  160 ) in step  1505 . More specifically, in step  1505 , when an “Invite” button  1605  is selected, the control unit  180  controls the first band communication module  150  to send a cast invite message to a selected external device of the first casting group. In addition, the control unit  180  controls the second band communication module  160  to send a cast invite message to a selected external device of the second casting group. As described before, the control unit  180  may send cast invite messages according to a preset priority. Accordingly, the selected external device of the first casting group displays a cast invite message  1606 . The selected external device of the second casting group displays a cast invite message  1607 . When a “Join” button is selected on the cast invite message  1606 , the external device of the first casting group sends a cast join message to the device  100 . When a “Join” button is selected on the cast invite message  1607 , the external device of the second casting group sends a cast join message to the device  100 . Subsequent steps are substantially the same as described in connection with  FIG. 11 , and a description thereof is omitted. 
         [0114]    As described above in connection with  FIGS. 1 ,  15  and  16 , the user listening to music using a player application on the smartphone may introduce the music to acquaintances nearby or far away. 
         [0115]      FIG. 17  is a flowchart of a method for providing a content casting service according to an exemplary embodiment of the present invention, and  FIG. 18  illustrates screen representations depicting steps in the method of  FIG. 17  according to exemplary embodiments of the present invention. 
         [0116]    Referring to  FIGS. 1 ,  17  and  18 , the control unit  180  of the device  100  may control the display unit  112  to display a home screen. Here, the home screen may include icons associated with streaming applications such as a music player, a video player, a mobile browser, and the like. When an icon is selected (for example, the icon is tapped), the control unit  180  executes a streaming application associated with the selected icon and controls the touchscreen  110  to display a streaming application screen  1801  correspondingly in step  1701 . 
         [0117]    The control unit  180  controls the first band communication module  150  to connect to a first external device providing a streaming service (for example, a YouTube server) in step  1702 . Here, the first band communication module  150  may connect to the first external device through an access point. The control unit  180  may control the first band communication module  150  to download content (e.g. moving image or music) from the first external device and control the touchscreen  110  to play back the downloaded content in real time. 
         [0118]    The control unit  180  detects a touch input on the streaming application screen  1801  in step  1703 . The control unit  180  determines whether the touch input is a cast request event in step  1704 . For example, when a “Cast” button  1802  is selected on the streaming application screen  1801 , the control unit  180  determines recipient devices to receive content (for example, second external device) among external devices connected with the second band communication module  160  in step  1705 . 
         [0119]    More specifically for step  1705 , under control of the control unit  180 , the second band communication module  160  may be directly connected with one or more nearby external devices through, for example, Wi-Fi Direct without an intermediate medium such as an access point. The control unit  180  controls the touchscreen  110  to display first casting group information  1803  regarding external devices connected to the second band communication module  160 . The control unit  180  may detect user selection on the first casting group information  1803 . The control unit  180  may control the touchscreen  110  to display second casting group information  1804 . Here, the second casting group information  1804  may be displayed when the third band communication module  170  is connected to an access point. The second casting group information  1804  may be not displayed when the third band communication module  170  is not connected to an access point. The second casting group information  1804  may be, for example, contact information stored in the storage unit  130 . The control unit  180  may detect a user selection on the second casting group information  1804 . When an “Invite” button  1805  is selected, the control unit  180  controls the second band communication module  160  to send a cast invite message to a selected external device of the first casting group. In addition, the control unit  180  controls the third band communication module  170  to send a cast invite message to a selected external device of the second casting group. Accordingly, the selected external device of the first casting group displays a cast invite message  1806 . The selected external device of the second casting group displays a cast invite message  1807 . When a “Join” button is selected on the cast invite message  1806 , the external device of the first casting group sends a cast join message to the device  100 . When a “Join” button is selected on the cast invite message  1807 , the external device of the second casting group sends a cast join message to the device  100 . The control unit  180  determines the external device of the first casting group having sent a cast join message (a second external device) as a recipient device to receive content. The control unit  180  determines the external device of the second casting group having sent a cast join message (a third external device) as a recipient device to receive content. 
         [0120]    After determining recipient devices, the control unit  180  controls the first band communication module  150  to receive streaming content (e.g. moving images or music) from the first external device in step  1706 . The control unit  180  plays back the received streaming content, and transmits the streaming content to the second external device through the second band communication module  160  in step  1707 . The control unit  180  may also transmit the received streaming content to the third external device through the third band communication module  170 . 
         [0121]    As described above in connection with  FIGS. 1 ,  17  and  18 , the user viewing, for example, a YouTube video using a moving image player on the smartphone may introduce the video to acquaintances nearby or far away. 
         [0122]      FIG. 19  illustrates screen representations of a method for providing a content casting service according to exemplary embodiments of the present invention. 
         [0123]    Referring to  FIGS. 1 and 19 , the control unit  180  of the device  100  may control the touchscreen  110  to display a camera application screen  1901 . For example, the control unit  180  may activate a camera module and display images captured by the camera module on the touchscreen  110 . For another example, the control unit  180  may control the first band communication module  150  to connect to an accessory (e.g. a miniature helicopter that has a Wi-Fi Direct capability and a camera module and that is controlled remotely by the control unit  180 ) and receive captured images from the accessory, and control the touchscreen  110  to display the received images. 
         [0124]    When a “Cast” button  1902  is selected on the camera application screen  1901 , the control unit  180  controls the touchscreen  110  to display first casting group information  1903  and second casting group information  1904 . 
         [0125]    The user may select external devices from the displayed first casting group information  1903  and second casting group information  1904 . When an “Invite” button  1905  is selected, the control unit  180  controls the second band communication module  160  to send a cast invite message to a selected external device of the first casting group. In addition, the control unit  180  controls the third band communication module  170  to send a cast invite message to a selected external device of the second casting group. Accordingly, the selected external device of the first casting group displays a cast invite message  1906 . The selected external device of the second casting group displays a cast invite message  1907 . Subsequent steps are substantially the same as described in connection with  FIG. 11 , and a description thereof is omitted. 
         [0126]    As described above in connection with  FIGS. 1 and 19 , the user viewing moving images captured by a camera module installed in the smartphone or an external accessory may introduce the moving images to acquaintances nearby or far away. 
         [0127]      FIG. 20  is a flowchart of a procedure to determine whether to operate in a dual mode or repeater mode according to an exemplary embodiment of the present invention. 
         [0128]    Referring to  FIGS. 1 and 20 , the control unit  180  of the device  100  controls the first band communication module  150  supporting a receive frequency band to receive content from a first external device (such as a YouTube server) in step  2001 . The control unit  180  determines an operating mode for a content casting service in step  2003 . The operating mode may be determined in consideration of the type of the received content. For example, when the received content is a document file or a compressed file, the operating mode may be set to a repeater mode. When the received content is a moving image, the operating mode may be set to a dual mode. 
         [0129]    When the operating mode is determined to be a repeater mode, the control unit  180  controls the second band communication module  160  to send the received content to a second external device in step  2005 . When the operating mode is determined to be a dual mode, the control unit  180  processes the content received through the first band communication module  150  (for example, resolution adjustment) in step  2007 , and controls the second band communication module  160  to send the processed content to a second external device in step  2009 . 
         [0130]    In an exemplary feature of the present invention, a method and device that support content casting services are provided. Content data may be received from a first external device through a receive frequency band and be transmitted to a second external device through a transmit frequency band at the same time. Content can be simultaneously transmitted to external devices through multiple transmit frequency bands. 
         [0131]    The exemplary methods of the present invention may be implemented as computer programs and may be stored in various computer readable storage media. The computer readable storage media may store program instructions, data files, data structures and combinations thereof The program instructions may include instructions developed specifically for the present invention and existing general-purpose instructions. The computer readable storage media may include magnetic media such as a hard disk and floppy disk, optical media such as a CD-ROM and DVD, magneto-optical media such as a floptical disk, and memory devices such as a ROM and RAM. The program instructions may include machine codes produced by compilers and high-level language codes executable through interpreters. Each hardware device may be replaced with one or more software modules to perform operations according to the present invention, and vice versa. 
         [0132]    While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.