Abstract:
Provided is a session management method of managing a session created between a wireless universal serial bus (USB) host and a wireless USB device through a wireless network, the session management method including: receiving session status messages periodically transmitted for checking a status of the created session; counting a number of continuous reception failures representing a number of the session status messages that are not received; and if the number of the continuous reception failures of session status messages is greater than a reference number, changing the current status of the session to a suspended status if the current status of the session is a connected status, and closing the created session if the current status of the session is a suspended status.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims all benefits accruing under 35 U.S.C. §119 from Korean Patent Application No. 2006-136802 filed on Dec. 28, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Aspects of the present invention relate to a method of creating and managing a session between a wireless universal serial bus (USB) host and a wireless USB device, and provide the wireless USB host and the wireless USB device. 
         [0004]    2. Description of the Related Art 
         [0005]    Conventionally, a wireless universal serial bus (USB) technology is referred to as a certified wireless USB (CWUSB). An operation of connecting a wireless USB host and a wireless USB device generally includes a certification operation, a reconnection operation, a connection close operation, and a sleep/wakeup operation for power management. 
         [0006]    The CWUSB uses an ultra-wideband physical layer (UWB PHY) and is based on a time division multiple access (TDMA). Accordingly, a time scheduling by the wireless USB host is needed such that the wireless USB device can transmit data to the wireless USB host in an allocated time slot. An adaptability of the CWUSB is reduced when dependent on a single wireless technology since mobile devices that apply the wireless USB technology use various wired/wireless networking technologies. 
         [0007]    Moreover, a session connection operation in a session management method of the CWUSB is only started by the wireless USB device. In this case, a usage scenario that can be used by a practical user and the conditions of the wireless USB device that can apply to the CWUSB may be limited. For example, when a single wireless USB device must select a single conceptual association from among several possible conceptual associations, the single wireless USB device displays the conceptual associations and requires a navigation button to select the single conceptual association. However, not all devices employing the wireless USB technology have the navigation button. Therefore, in this case, the role of the wireless USB device must be minimized, while most of the roles must be performed by the wireless USB host. 
         [0008]    Furthermore, when the wireless USB device transmits a connection request and the wireless USB host does not respond thereto, the wireless USB device must retransmit the connection request. Unlike a USB connection in a wired method where power is supplied from the wireless USB host, the wireless USB device using the CWUSB must include a power supply (such as a battery). Therefore, the operation of retransmitting the connection request increases the battery consumption of the wireless USB device. 
         [0009]    Finally, when a momentary loss of connection occurs due to wireless network characteristics, a reconnection operation must be performed. As a result, the load on the wireless USB device may be increased. Moreover, an operation of recognizing the wireless USB device by an operating system has to be performed for every reconnection operation, thereby causing inconvenience to the user. 
       SUMMARY OF THE INVENTION 
       [0010]    Aspects of the present invention provide a method of creating and managing a session between a wireless universal serial bus (USB) host and a wireless USB device, and provide the wireless USB host and the wireless USB device so that a session is created and managed by the wireless USB host, and thus decreasing battery consumption of the wireless USB device and solving the inconvenience to a user of frequent disconnections. 
         [0011]    Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
         [0012]    In accordance with an example embodiment of the present invention, there is provided a session management method of managing a session created between a wireless USB host and a wireless USB device through a wireless network. Such a session management method comprises: receiving session status messages periodically to check a status of the created session; counting a number of continuous reception failures corresponding to a number of session status messages that are not received; changing a current status of the session from a connected status to a suspended status if the current status of the session is the connected status; and closing the created session if the current status of the session is the suspended status and the number of the continuous reception failures is greater than a second predetermined reference number. 
         [0013]    According to an aspect of the present invention, there is provided a computer-readable medium having embodied thereon a computer program for executing the method. 
         [0014]    In accordance with another example embodiment of the present invention, there is provided a wireless USB host for managing a session created with a wireless USB device through a wireless network. Such a wireless USB host comprises: a message generating unit to generate a session status message for checking a status of the created session; a wireless transceiving unit to periodically transmit the generated session status message to the wireless USB device and to receive a session status message from the wireless USB device; a counter to count a number of continuous reception failures corresponding to a number of the session status messages that are not received from the wireless USB device; and a session creation management unit to change a current status of the session from a connected status to a suspended status if the current status of the session is the connected status and the number of the continuous reception failures is greater than a predetermined reference number, and to close the created session if the current status is the suspended status and the number of the continuous reception failures is greater than a second predetermined reference number. 
         [0015]    In accordance with yet another example embodiment of the present invention, there is provided a session creation method of creating a session between a wireless USB host and a wireless USB device having wireless IP addresses, respectively, through a wireless network and performed by the wireless USB host. Such a session creation method comprises: retrieving characteristic information including the IP address of the retrieved wireless USB device; transmitting a session creation request message requesting a creation of a session from the wireless USB host to the wireless USB device; transmitting a session creation response message, in response to the session creation request message, from the wireless USB device to the wireless USB host; allocating a session ID to the wireless USB device in response to the session creation response message; transmitting a session creation acknowledgement message including the allocated session ID from the wireless USB host to the wireless USB device; and generating a session between the wireless USB host and the wireless USB device by using the session ID and the IP address of the wireless USB device and the IP address of the wireless USB host. 
         [0016]    According to another aspect of the present invention, there is provided a computer-readable medium having embodied thereon a computer program for executing the method. 
         [0017]    In accordance with yet another example embodiment of the present invention, there is provided a wireless USB device for creating a session with a wireless USB host having an IP address through a wireless network. Such a wireless USB device comprises: a message generating unit generating a session creation response message in response to a session creation request message received from the wireless USB host; a wireless transceiving unit receiving the session creation request message including the IP address of the wireless USB host and a session creation acknowledgement message including a session ID allocated to the wireless USB device through the wireless network and transmitting characteristic information including an IP address of the wireless USB device in response to a received request of the wireless USB host; and a session creating unit creating a session with the wireless USB host by using the received session ID and the IP address of the wireless USB host. 
         [0018]    In accordance with still another example embodiment of the present invention, there is provided a wireless USB host for creating a session with a wireless USB device having an IP address through a wireless network. Such a wireless USB host comprises: a retrieving unit retrieving the wireless USB device connected to the wireless network and acquiring characteristic information including an IP address of the retrieved wireless USB device; a message generating unit generating a session creation request message requesting a creation of a session and a session creation acknowledgement message including a session ID allocated to the wireless USB device; a wireless transceiving unit transmitting the generated session creation request message and the session creation acknowledgement message through the wireless network and receiving a session creation response message in response to the session creation request message; a session ID allocating unit allocating the session ID to the wireless USB device in response to the session creation response message; and a session creating unit creating the session with the wireless USB device by using the session ID and the IP address of the wireless USB device. 
         [0019]    In accordance with another example embodiment of the present invention, there is provided a wireless USB device for managing a session created with a wireless USB host through a wireless network. Such a wireless USB device comprises: a wireless transceiving unit to receive a session status message, periodically transmitted from the wireless USB host, indicating a status of the session; a counter to count a number of continuous reception failures corresponding to a number of the session stat messages that are not received from the wireless USB host; and a session creation management unit to change a current status of the session from a connected status to a suspended status if the current status of the session is the connected status and the number of the continuous reception failures is greater than a first predetermined reference number, and to close the created session if the current status is the suspended status and the number of the continuous reception failures is greater than a second predetermined reference number. 
         [0020]    In accordance with yet another example embodiment of the present invention, there is provided a wireless USB host for managing a session created with a wireless USB device through a wireless network. Such a wireless USB device comprises: a wireless transceiving unit to receive a session status message, periodically transmitted from the wireless USB device, indicating a status of the session; a counter to count a number of continuous reception failures corresponding to a number of the session stat messages that are not received from the wireless USB device; and a session creation management unit to change a current status of the session from a connected status to a suspended status if the current status of the session is the connected status and the number of the continuous reception failures is greater than a first predetermined reference number, and to close the created session if the current status is the suspended status and the number of the continuous reception failures is greater than a second predetermined reference number. 
         [0021]    In accordance with still another example embodiment of the present invention, there is provided a session creation method of creating a session between a wireless USB host and a wireless USB device having wireless IP addresses, respectively, through a wireless network and performed by the wireless USB device. Such a session creation method comprises: transmitting a session creation request message requesting a creation of a session from the wireless USB device to the wireless USB host; receiving a session creation response message, in response to the session creation request message, from the wireless USB host, the session creation response message including a session ID; and generating a session between the wireless USB host and the wireless USB device by transmitting a data connection request from the wireless USB device to the wireless USB host. 
         [0022]    In addition to the example embodiments and aspects as described above, further aspects and embodiments will be apparent by reference to the drawings and by study of the following descriptions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    A better understanding of the present invention will become apparent from the following detailed description of example embodiments and the claims when read in connection with the accompanying drawings, all forming a part of the disclosure of this invention. While the following written and illustrated disclosure focuses on disclosing example embodiments of the invention, it should be clearly understood that the same is by way of illustration and example only and that the invention is not limited thereto. The spirit and scope of the present invention are limited only by the terms of the appended claims. The following represents brief descriptions of the drawings, wherein: 
           [0024]      FIG. 1  is a block diagram illustrating a wireless universal serial bus (USB) host and a wireless USB device according to an example embodiment of the present invention; 
           [0025]      FIG. 2  is a session status transition diagram according to an example embodiment of the present invention; 
           [0026]      FIG. 3  is a flowchart of a session creation operation performed by a device according to an example embodiment of the present invention; 
           [0027]      FIG. 4  is a flowchart of a session creation operation performed by a host according to another example embodiment of the present invention; 
           [0028]      FIG. 5  is a flowchart of a session close operation according to an example embodiment of the present invention; 
           [0029]      FIG. 6  is a flowchart of a session maintenance operation according to an example embodiment of the present invention; 
           [0030]      FIG. 7  is a view illustrating a session status bitmap included in a session status message according to an example embodiment of the present invention; 
           [0031]      FIG. 8  is a flowchart of session stop and restart operations according to an example embodiment of the present invention; 
           [0032]      FIG. 9  is a view illustrating a wireless USB host and a plurality of USB devices according to an example embodiment of the present invention; and 
           [0033]      FIG. 10  is a view illustrating session information stored in a wireless USB host according to an example embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0034]    Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
         [0035]      FIG. 1  is a block diagram of a wireless USB host  100  and a wireless USB device  110  according to an example embodiment of the present invention. The wireless USB host  100  includes a user interface  101 , a counter  102 , a session information storage unit  103 , a session creation management unit  104 , a message generating unit  105 , a session identification (ID) allocating unit  106 , a retrieving unit  107 , and a wireless transceiving unit  108 . The wireless USB device  110  includes a user interface  111 , a counter  112 , a session information storage unit  113 , a session creation management unit  114 , a message generating unit  115 , and a wireless transceiving unit  116 . 
         [0036]    Referring to  FIG. 1 , the user interface  101  of the wireless USB host  100  displays characteristic information on one or more wireless USB devices  110  connected through at least one wireless network. Thereafter, the user interface  101  receives a selection signal (from a user, for example) to select a wireless USB device  110  in order to create a session therewith. The wireless network may be one or more of a wireless ad hoc network (such as a mobile ad hoc network (MANET)), a wireless mesh network, and the like. The characteristic information may include a type, a performance, or a wireless Internet Protocol (IP) address of the wireless USB device  110 . A session may refer to a USB over mobile ad hoc network (UOM) session. 
         [0037]    The counter  102  manages a session created with the wireless USB device  110  and counts the number of reception failures of session status messages received from the wireless USB device  110 . The counted number of reception failures is used to renew a session status of the wireless USB device  110 . 
         [0038]    The session information storage unit  103  stores session information on the wireless USB device  110 . The session information on the wireless USB device  110  may include one or more of a session ID, a wireless IP address of the wireless USB device  110 , a session status, and the like.  FIG. 10  illustrates a structure of session information on the wireless USB device  110  according to an example embodiment of the present invention. 
         [0039]    The session creation management unit  104  creates and manages the session with the wireless USB device  110 . The wireless USB host  100  or the wireless USB device  110  may create the session. Accordingly, the session creation management  104  creates the session when the wireless USB device  110  does not create the session. 
         [0040]    When the wireless USB host  100  creates the session, the message generating unit  105  generates a session creation request message requesting a creation of a session and a session creation acknowledgement message including a session ID allocated to the wireless USB device  110 . The session creation request message and/or the session creation acknowledgement message may include characteristic information including an IP address of the wireless USB host  100 . The generated session creation request message is transmitted to the wireless USB device  110  through the wireless transceiving unit  108 . 
         [0041]    When the wireless USB device  110  creates the session, the message generating unit  105  generates a session creation response message as a message about characteristic information including the IP address of the wireless USB host  100 . The generated session creation response message is transmitted to the wireless USB device  110  through the wireless transceiving unit  108 . The session creation response message may include a TRUE value permitting the creation of the session or a FALSE value not permitting the creation of the session. In addition, after the session with the wireless USB device  110  is created, a session status message is generated and periodically transmitted by the wireless transceiving unit  108  to the wireless USB device  110 . The session status message indicates that the session is active. 
         [0042]    The session ID allocating unit  106  allocates a session ID to the wireless USB device  110 . The session ID allocating unit  106  may allocate the session ID when the session creation response message from the wireless USB device  110  is received. Specifically, the session ID allocating unit  106  may determine whether the session ID that is to be allocated to the wireless USB device  110  already exists in the session information storage unit  103 . If the session ID that is to be allocated already exists, the session ID allocating unit  103  may use the session ID that is already stored in the session information storage unit  103 . 
         [0043]    The retrieving unit  107  retrieves one or more wireless USB devices  110  connected to the wireless network in the session creation operations performed by the wireless USB host  100  and acquires the characteristic information (including the IP address) of the retrieved wireless USB device  110 . The acquired characteristic information is displayed on the user interface  101  in order to be used to select a wireless USB device  110 . 
         [0044]    The wireless transceiving unit  108  transmits and receives messages to and from the wireless USB device  110 . 
         [0045]    The user interface  111  of the wireless USB device  110  displays characteristic information on one or more wireless USB hosts  100  connected through the wireless network and receives a selection signal (from a user, for example) to select the wireless USB host  100  in order to create a session. The wireless USB device  110  may create a session with a single wireless USB host  110 . The characteristic information on the wireless USB host  100  may include a type, a performance, or a wireless IP address of the wireless USB host  100 . 
         [0046]    The counter  112  manages a session created with the wireless USB host  100  and counts the number of reception failures of session status messages received from the wireless USB host  100 . The counted number of reception failures is used to renew the session status of the wireless USB device  100 . 
         [0047]    The session information storage unit  113  stores session information on the wireless USB host  100 . The session information may include one or more of a wireless IP address of the wireless USB host  100 , a session status, and the like. Unlike the session information stored in the session information storage unit  103  of the wireless USB host  100  according to aspects of the present invention, the session information stored in the session information storage unit  113  may not include the session ID. 
         [0048]    The session creation management unit  114  creates and generates the session with the wireless USB host  100 . The wireless USB host  100  or the wireless USB device  110  may create the session. Accordingly, the session creation management unit  114  creates the session when the wireless USB host  100  does not create the session. 
         [0049]    When the wireless USB device  110  creates the session, the message generating unit  115  generates a session creation request message requesting the creation of the session as a message about characteristic information including the IP address of the wireless USB device  110 . The generated session creation request message is transmitted through the wireless transceiving unit  116 . When the wireless USB host  100  creates the session, the message generating unit  115  generates a session creation response message in response to the session creation request message of the wireless USB host  100 . The generated session creation response message is transmitted to the wireless USB host  100  through the wireless transceiving unit  116 . In addition, after the session with the wireless USB host  100  is created, a session status message, indicating that the session is active, is generated. The generated session status message is periodically transmitted to the wireless USB host  100  through the wireless transceiving unit  116 . 
         [0050]    The wireless transceiving unit  116  transmits and receives messages to and from the wireless USB host  100 . 
         [0051]      FIG. 2  is a session status transition diagram according to an example embodiment of the present invention. The session status includes a null status  200 , a connected status  210 , a suspended status  220 , and a closed status  230 . 
         [0052]    Referring to  FIG. 2 , if a session between the wireless USB host  100  and the wireless USB device  110  is created during the initial null status  200 , the null status  200  is changed to the connected status  210 . 
         [0053]    When in the connected status  210 , it is determined whether the session status message periodically transmitted from the wireless USB device  110  and/or the wireless USB host  100  is received in order to check that the session is active. If a number of reception failures of session status messages is greater than a reference number, the connected status  210  is changed to the suspended status  220 . Alternatively, if a session status message is not received for a predetermined amount of time, the connected status  210  is changed to the suspended status  220 . Furthermore, if a session close message informing that the session is to be closed is externally received while in the connected status  210  or the suspended status  220 , the session is forcibly closed and the connected status  210  or the suspended status  220  is changed to the closed status  230 . When the session is closed, the session information is deleted. 
         [0054]    In the suspended status  220 , the number of reception failures of session status messages is also counted. Accordingly, if the number of reception failures of the session status messages while in the suspended status  220  is more than the reference number of reception failures in the suspended status  220 , the suspended status  220  is changed to the closed status  230 . However, it is understood that according to other aspects, the suspended status  220  may only be changed to the closed status  230  when a session close message is received, or the suspended status  220  may be changed to the closed status  230  according to other methods (such as after a predetermined period of time irrespective of a number of reception failures of session status messages). When the session status message is received in the suspended status  220 , the suspended status  220  is changed back to the connected status  210 . 
         [0055]    The session status transition diagram in  FIG. 2  may apply to both of the wireless USB host  100  and the wireless USB device  110  or may apply to one of the wireless USB host  100  and the wireless USB device  110 . 
         [0056]      FIG. 3  is a flowchart of a session creation operation performed by the wireless USB device  110  according to an example embodiment of the present invention. When the wireless USB device  110  creates the session, the wireless USB device  110 —transmits the session creation request message. When the wireless USB host  100  creates the session, the wireless USB host  100  transmits the session creation request message. 
         [0057]    Referring to  FIG. 3 , in operation S 300 , an initialization is performed such that the wireless USB host  100  and a channel are set, and the wireless USB host  100  and the wireless USB device  110  set their wireless IP addresses, respectively. 
         [0058]    In operation S 301 , the wireless USB device  110  generates a session creation request message having characteristic information including the wireless IP address of the wireless USB device  110 , and broadcasts (i.e., transmits) the generated session creation request message to the wireless USB host  100 . In  FIG. 3 , Broadcasting is abbreviated as BC. 
         [0059]    In operation S 302 , the characteristic information on the wireless USB device  110  is displayed to a user  300 . In operation S 303 , the user  300  selects the wireless USB device  110  in order to set the session. When a plurality of the wireless USB devices are used, the user  300  may select the wireless USB device  110  device from among the plurality of wireless USB devices in order to set the session. 
         [0060]    Thereafter, in operation S 304 , the wireless USB host  100  allocates a session ID to the selected wireless USB device  110  and generates a session creation response message including the allocated session ID and the wireless IP address of the USB host  100 . The generated session creation response message is transmitted to the wireless USB device  110  in order to create the session with the wireless USB host  100 . The session may be a UOM session. 
         [0061]    In operation S 305 , the wireless USB host  100  registers the wireless IP address of the wireless USB device  110 , and waits for a data connection request from the wireless USB device  110 . 
         [0062]    Thereafter, in operation S 306 , if the data connection is requested from the wireless USB device  110 , the data connection between the wireless USB host  100  and the wireless USB device  110  is set. 
         [0063]    In operation S 307 , USB data transmission between the wireless USB host  100  and the wireless USB device  110  is performed. 
         [0064]    According to aspects of the present invention, the creation of the session operation may further include an operation of periodically transmitting a session status message indicating to the wireless USB host  100  or the wireless USB device  100  that the session is active. 
         [0065]      FIG. 4  is a flowchart of a creation of the session operation performed by the wireless USB host  100  according to another example embodiment of the present invention. In  FIG. 4 , Broadcasting is abbreviated as BC and Unicasting is abbreviated as UC. 
         [0066]    Referring to  FIG. 4 , in operation S 400 , an initialization is performed such that the wireless USB host  100  and a channel are set, and the wireless USB host  100  and the wireless USB device  110  set their wireless IP addresses, respectively. 
         [0067]    In operation S 401 , the wireless USB host  100  broadcasts a device retrieving request message to retrieve wireless USB devices  110  connected to the wireless network. 
         [0068]    In operation S 402 , the wireless USB device  110  that receives the device retrieving request message transmits a device retrieving response message including characteristic information of the wireless USB device  110  to the wireless USB host  100 . 
         [0069]    In operation S 403 , the characteristic information of the wireless USB device  110  is displayed to the user  300 . If a plurality of wireless USB devices transmit a device retrieving response message (operation S 402 ), then the characteristic information of each of the plurality of wireless USB device is displayed to the user  300 . 
         [0070]    In operation S 404 , the user  300  selects a wireless USB device  110  to set a session. If a plurality of the wireless USB devices transmits a device retrieving response message, the user  300  may select the wireless USB device  110  from among the plurality of wireless USB device to set the session. 
         [0071]    In operation S 405 , the wireless USB host  100  generates a session creation request message requesting a creation of the session as a message about characteristic information including the wireless IP address of the wireless USB host  100 . Then, in operation S 405 , the generated session creation message is transmitted to the wireless USB device  110 . 
         [0072]    In operation S 406 , the wireless USB device  110  displays the characteristic information on the wireless USB host  100 . In operation S 407 , the wireless USB host  100  may be selected by a selection of the user  310 . It is understood that operation S 406  and operation S 407  are optional. 
         [0073]    In operation S 408 , the wireless USB device  110  that receives the session creation request message generates a session creation response message in response to the received session creation request and transmits the generated session creation response to the wireless USB host  100 . 
         [0074]    In operation S 409 , the wireless USB host  100  that receives the session creation response message allocates a session ID to the wireless USB device  110  and generates a session creation acknowledgement message including the allocated session ID. The generated session creation acknowledgement message is transmitted to the wireless USB device  110  in order to create a session with the wireless USB host  100 . The session may be a UOM session. 
         [0075]    In operation S 410 , apart from the creation of the session, a data connection with the wireless USB device  110  is set. Thereafter, in operation S 411 , USB data transmission between the wireless USB host  100  and the wireless USB device  110  is performed. 
         [0076]    According to aspects of the present invention, the creation of the session operation may further include an operation of periodically transmitting a session status message indicating to the wireless USB host  100  or the wireless USB device  110  that the session is active. In addition, an operation of storing the session information may also be further included. 
         [0077]      FIG. 5  is a flowchart of a session close operation according to an example embodiment of the present invention. The session close operation may be performed in a case where a session close message is received from the user  300  or a session status message is not received for a predetermined time that has been exceeded. 
         [0078]    Referring to  FIG. 5 , in operations S 500  to S 505 , the session close operation is performed by the wireless USB host  100 . First, if the session close message instructing to close a created session is received from the user  300  in operation S 500 , or the session status message is detected as not received for a predetermined amount of time that has been exceeded in operation S 501 , the session is closed. 
         [0079]    In operation S 502 , the wireless USB host  100  may transmit the session close message to the wireless USB device  110 . Otherwise, in operations S 503  and S 504 , the wireless USB host  100  and the wireless USB device  110  may delete the session information. Thereafter, in operation S 505 , additional operations are performed to close the data connection. 
         [0080]    In operations S 510  to S 515 , the session close operation is performed by the wireless USB device  110 . First, if a session close message instructing to close the created session is received from the user  310  in operation S 510 , or the session status message is detected as not received for a predetermined amount of time that has been exceeded in operation S 511 , the session is closed. 
         [0081]    In operation S 512 , the wireless USB device  110  may transmit the session close message to the wireless USB host  100 . Otherwise, in operations S 513  and S 514 , the wireless USB host  100  and the wireless USB device  110  may delete the session information. Thereafter, in operation S 515 , additional operations are performed to close the data connection. 
         [0082]      FIG. 6  is a flowchart of a session maintenance operation according to an example embodiment of the present invention.  FIG. 7  is a view of a session status bitmap included in a session status message according to an example embodiment of the present invention. 
         [0083]    Referring to  FIG. 6 , in operation S 600 , the wireless USB host  100  periodically transmits a session status message after a creation of a session. The session status message transmitted from the wireless USB host  100  includes a session status bitmap as shown in  FIG. 7 . 
         [0084]    Referring to  FIG. 7 , the session status bitmap according to an example embodiment of the present invention has  128  bits. This value is determined in consideration of a specification of the USB connection. Therefore, a maximum of  128  wireless USB devices may be connected to the wireless USB host  100 . Each bit represents a session activation status of the wireless USB device corresponding to the allocated session ID such that the session activation status of the wireless USB device can be “1” or “0.” 
         [0085]    Referring to  FIG. 6 , in operation S 601 , the wireless USB device  110  that receives the session status message from the wireless USB host  100  renews the session status of the wireless USB host  100  from the session information in the session information storage unit  113  (illustrated in  FIG. 1 ). 
         [0086]    In operations S 602  and S 603 , the wireless USB host  100  that receives the session status message from the wireless USB device  110  renews the session status of the device in the session information stored in the session information storage unit  103  (illustrated in  FIG. 1 ). Due to characteristics of the performance of the USB connection, a plurality of wireless USB devices may be connected to a single wireless USB host, however, a single wireless USB device can only be connected to a single wireless USB host. Therefore, the session status bitmap of the wireless USB device  110  only has 1-bit (unlike the session status bitmap shown in  FIG. 7 ). 
         [0087]      FIG. 8  is a flowchart of session stop and restart operations according to an example embodiment of the present invention. Referring to  FIG. 8 , in operations S 800  to S 803 , the session status message is not received and the status of the session is suspended. 
         [0088]    After the creation of the session, the wireless USB device  110  periodically transmits the session status message to the wireless USB host  100 . In operation S 800 , the wireless USB host  100  counts the number of reception failures of the session status messages and determines whether the number of reception failures counted for a predetermined time is greater than a reference number. 
         [0089]    In operation S 801 , when the number of reception failures of the session status message is greater than the reference number, the wireless USB host  100  changes the session status of the wireless USB device  110  from a connected status to a suspended status. 
         [0090]    Similarly, after the creation of the session, the wireless USB host  100  periodically transmits the session status message to the wireless USB device  110 . It is assumed that in operation S 802 , the session status message is not received, or the session status message is received but a bit corresponding to a session ID from among the bits of the session activation bitmap included in the received session status message is “0.” 
         [0091]    In operation S 803 , it is determined whether operation S 802  is repeatedly performed more than N times. According to a result of the determination, if operation S 802  has been performed more than N times, the wireless USB device  110  changes the session status of the wireless USB host  100  in the session information stored in the session information storage unit  113  (illustrated in  FIG. 1 ) from the connected status to the suspended status. 
         [0092]    In operations S 804  to S 807 , the wireless USB host  100  or the wireless USB device  110  receives the session status message in the suspended status, so that the session status is renewed. 
         [0093]    It is assumed that in operation S 804 , the current session status is the suspended status, and the wireless USB host  100  receives a session status message in which the session status of the session status bitmap is “1.” In operation S 805 , the wireless USB host  100  changes the session status of the wireless USB device  110  from the suspended status to the connected status. 
         [0094]    It is assumed that in operation S 806 , the current session status is the suspended status, and the wireless USB device  110  receives a session status message in which the session status of the session status bitmap is “1.” In operation S 807 , the wireless USB device  110  changes the session status of the wireless USB host  100  from the suspended status to the connected status. 
         [0095]      FIG. 9  is a view of a wireless USB host  100  and a plurality of wireless USB devices  110   a,    110   b,  and  110   c  according to an example embodiment of the present invention.  FIG. 10  is a view of session information stored in the wireless USB host  100  in  FIG. 9 , according to an example embodiment of the present invention. 
         [0096]    Referring to  FIG. 9 , session IDs  1 ,  2 , and  3  are allocated to the wireless USB devices  110   a,    110   b,  and  110   c,  respectively. The wireless USB host  100  transmits the session status message including the session status bitmap shown in  FIG. 7 , and the USB devices  110   a,    110   b,  and  110   c  transmit session status messages having a host status bit of 1-bit, so that the session activation status can be informed. 
         [0097]      FIG. 10  illustrates the session information stored in the wireless USB host  100  including session IDs, wireless IP addresses of the wireless USB devices, and session statuses, according to an example embodiment of the present invention. The wireless USB device  110  may store similar information. However, the wireless USB device  110  creates a session with a single wireless USB host  100 . Accordingly, the wireless USB device  110  includes the IP address of the wireless USB host  100  and the session status, but does not include a session ID. 
         [0098]    As described above, according to aspects of the present invention, the creating and managing of a session can be performed by the wireless USB host. As a result, a battery consumption of the wireless USB device and an inconvenience to a user due to frequent loss of connections decrease. In addition, the creating and managing of the session can be symmetrically performed by the wireless USB host and the wireless USB device, so that various usage scenarios can be created according to type and characteristics of the wireless USB device. In addition, IP-based technology is used, so that aspects of the present invention can be applied to any network technology and also to a personal area network (PAN) region and a wireless local area network (WLAN) region. 
         [0099]    Various components of the apparatus as shown in  FIG. 1 , such as the session creation management unit  104  and the message generating unit  105 , can be integrated into a single control unit, or alternatively, can be implemented in software or hardware, such as, for example, an application specific integrated circuit (ASIC). As such, it is intended that the processes described herein be broadly interpreted as being equivalently performed by software, hardware, or a combination thereof. Software modules can be written via a variety of software languages, including C, C++, Java, Visual Basic, and many others. These software modules may include data and instructions which can also be stored on one or more machine-readable storage media, such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; magnetic disks such as fixed, floppy and removable disks; other magnetic media including tape; and optical media such as compact discs (CDs) or digital video discs (DVDs). Instructions of the software routines or modules may also be loaded or transported into the wireless cards or any computing devices on the wireless network in one of many different ways. For example, code segments including instructions stored on floppy discs, CD or DVD media, a hard disk, or transported through a network interface card, modem, or other interface device may be loaded into the system and executed as corresponding software routines or modules. In the loading or transport process, data signals that are embodied as carrier waves (transmitted over telephone lines, network lines, wireless links, cables, and the like) may communicate the code segments, including instructions, to the network node or element. Such carrier waves may be in the form of electrical, optical, acoustical, electromagnetic, or other types of signals. 
         [0100]    While there have been illustrated and described what are considered to be example embodiments of the present invention, it will be understood by those skilled in the art and as technology develops that various changes and modifications, may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the present invention. Many modifications, permutations, additions and sub-combinations may be made to adapt the teachings of the present invention to a particular situation without departing from the scope thereof. For example, if a session status message is not received for a predetermined amount of time (as opposed to if a number of received reception failures is greater than a reference number), the connected status is changed to the suspended status. Also, the suspended status may only be changed to the closed status when a session close message is received (as opposed to changing the suspended status to a closed status if a number of received reception failures during the suspended status is greater than a predetermined number), or the suspended status may be changed to the closed status according to other methods (such as after a predetermined period of time irrespective of a number of reception failures of session status messages). Accordingly, it is intended, therefore, that the present invention not be limited to the various example embodiments disclosed, but that the present invention includes all embodiments falling within the scope of the appended claims.