Abstract:
A mobile communication system for supporting a Multimedia Broadcast/Multicast Service (MBMS) is provided. More particularly, an apparatus and a method for applying a direct tunnel feature in order to reduce a transmission delay of a mobile communication system for providing an MBMS. The system includes a Gateway GPRS Support Node (GGSN). The GGSN omits transmission of data to a Serving GPRS Support Node (SGSN) and transmits data to a Radio Network Controller (RNC) using the direct tunnel feature when transmitting data.

Description:
PRIORITY 
       [0001]    This application claims priority to an application filed as PCT/KR2010/000425 on Jan. 22, 2010 claiming priority of the Korean Application filed in Korean Intellectual Property Office on Jan. 23, 2009 and assigned Serial No. 10-2009-0005945, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a mobile communication system for supporting a multimedia broadcast/multicast service. More particularly, the present invention relates to an apparatus and a method for applying a direct tunnel feature in order to reduce a transmission delay of a mobile communication system for providing a Multimedia Broadcast/Multicast Service (MBMS). 
         [0004]    2. Description of the Related Art 
         [0005]    Today, with development of a communication technology, a service provided by a Code Division Multiple Access (CDMA) mobile communication system is evolving into multicasting multimedia communication for transmitting a large capacity data such as packet data, circuit data, etc. as well as a voice service. Therefore, to support the multicasting multimedia communication, a broadcast/multicast service for providing a service from one data source to a plurality of user terminals has been proposed. The broadcast/multicast service may be divided into a Cell Broadcast Service (CBS) which is a message dominant service, and a Multimedia Broadcast/Multicast Service (MBMS) for supporting a multimedia type such as real-time images and voices, still images, characters, etc. 
         [0006]    Here, a mobile communication system for providing the MBMS is described below. 
         [0007]    First, a Multicast/Broadcast-Service Center (MB-SC) which is a source providing an MBMS stream schedules a stream for an MBMS service and transfers the same to a transmission network. The transmission network denotes a network existing between the MB-SC and a Serving GPRS Support Node (SGSN), and transfers a stream for an MBMS service transferred from the MB-SC to the SGSN. Here, the SGSN may be configured using a Gateway GPRS Support Node (GGSN) and an external network, and assuming that a plurality of terminals that desire to receive an MBMS service at an arbitrary point exist, the SGSN that has received a stream for the MBMS service from the transmission network plays a role of controlling an MBMS related service of subscribers (terminals) that desire to receive the MBMS service. For example, the SGSN manages MBMS service billing related data of each subscriber and selectively transmits MBMS service related data to a specific Radio Network Controller (RNC). Accordingly, the Base Station Controller (BSC) transmits relevant service data to relevant terminals to allow the terminals to use the MBMS service. 
         [0008]    That is, in the above-described MBMS service providing method, the GGSN transmits traffic to the BSC by way of the SGSN. The GGSN, SGSN, and BSC perform a session start process of transmitting/receiving a MBMS Session Start Request/Response message to/from a neighbor node, and then sequentially transfer data received from the GGSN to a node that has transmitted a previous MBMS session start response. 
         [0009]    Accordingly, lots of nodes exist unnecessarily between terminals and the MB-SC in the mobile communication system while an MBMS service is provided, so that a transmission delay increases and a signal control is concentrated on the SSGN and so a load of the SSGN occurs. 
       SUMMARY OF THE INVENTION 
       [0010]    An aspect of the present invention is 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 an apparatus and a method for reducing a transmission delay that occurs when providing an MBMS in a mobile communication system. 
         [0011]    Another aspect of the present invention is to provide an apparatus and a method for reducing a transmission delay using a direct tunnel feature when providing an MBMS in a mobile communication system. 
         [0012]    Still another aspect of the present invention is to provide an apparatus and a method for generating a session update request message including information of a relevant terminal in order to provide an MBMS using a direct tunnel feature in a mobile communication system. 
         [0013]    In accordance with an aspect of the present invention, an apparatus for providing a Multimedia Broadcast/Multicast Service (MBMS) in a mobile communication system is provided. The apparatus includes a Gateway GPRS Support Node (GGSN) for omitting data transmission to a Service GPRS Support Node (SGSN) and allowing data transmission to a Base Station Controller (BSC) to be performed using a direct tunnel feature when transmitting data. 
         [0014]    In accordance with another aspect of the present invention, a method for providing an MBMS in a mobile communication system is provided. The method includes a data transmission process of a Gateway GPRS Support Node (GGSN) that omits data transmission to a Service GPRS Support Node (SGSN) and transmits data to a Base Station Controller (BSC) using a direct tunnel feature when transmitting data. 
         [0015]    Exemplary embodiments of the present invention provide an apparatus and a method for providing an MBMS, that omits data transmission to an SGSN using a direct tunnel feature in order to reduce a transmission delay of a mobile communication system providing an MBMS, so that a transmission delay that occurs in the conventional mobile communication system is reduced and a load of the SGSN is reduced and so a great advantage is provided to real-time data transmission. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    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: 
           [0017]      FIG. 1  is a block diagram illustrating a mobile communication system for reducing a transmission delay when providing an MBMS service according to an exemplary embodiment of the present invention; 
           [0018]      FIG. 2  is a flowchart illustrating a process for providing an MBMS in an SGSN according to an exemplary embodiment of the present invention; 
           [0019]      FIG. 3  is a flowchart illustrating a process for providing an MBMS in a GGSN according to an exemplary embodiment of the present invention; 
           [0020]      FIG. 4  is a view illustrating a construction of a message for providing an MBMS in a mobile communication system according to an exemplary embodiment of the present invention; and 
           [0021]      FIG. 5  is a view illustrating a process for providing an MBMS in a mobile communication system according to an exemplary embodiment of the present invention. 
       
    
    
       [0022]    Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0023]    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. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
         [0024]    Exemplary embodiments of the present invention provide an apparatus and a method for providing an MBMS using a direct tunnel feature in order to reduce a transmission delay of a mobile communication system providing the MBMS. The direct tunnel feature denotes a feature where a GGSN or a PDN-GW directly connects a GTP tunnel to an RNC or a BSC to transmit traffic by bypassing an SGSN. 
         [0025]      FIG. 1  is a block diagram illustrating a mobile communication system for reducing a transmission delay when providing an MBMS service according to an exemplary embodiment of the present invention. 
         [0026]    Referring to  FIG. 1 , the mobile communication system may include an SGSN  100  and a GGSN  110 . 
         [0027]    First, the SGSN  100  may include a controller  102 , a message generator  104 , and a communication unit  106 . The GGSN  110  may include a controller  112 , a message reader  114 , and a communication unit  116 . 
         [0028]    The controller  102  of the SGSN  100  controls an overall operation of the SGSN  100 . According to an exemplary embodiment of the present invention, to reduce a transmission delay via a direct tunnel feature, the controller  102  performs a session start process with a relevant node, and when radio resource setup is completed, the controller  102  receives information of a terminal that desires to use an MBMS service, that is, an ID of a specific terminal and Tunnel Endpoint Identifier User Plane (TEID) information which is information regarding an address of an RNC from the RNC, and generates a session update request message including the information. 
         [0029]    After that, the controller  102  processes to transmit the generated session update request message to the GGSN  110 . Accordingly, the GGSN  110  that has received the information of the terminal that desires to use the MBMS service directly transmits data to the terminal using the above information by bypassing the SGSN. 
         [0030]    The message generator  104  generates a session update request message under control of the controller  102 . That is, the message generator  104  generates the session update request message which is a message including information of the RNC for allowing the GGSN  110  to directly transmit data to the RNC using the direct tunnel feature. 
         [0031]    The communication unit  106  communicates with a relevant node to perform a session start process. According to an exemplary embodiment of the present invention, the communication unit  106  receives information of a terminal that desires to use the MBMS service, that is, information regarding an ID of a specific terminal and an address of an RNC from the RNC. 
         [0032]    The controller  112  of the GGSN  110  controls an overall operation of the GGSN  110 . According to an exemplary embodiment of the present invention, to reduce a transmission delay via a direct tunnel feature, the controller  112  performs a session start process with a relevant node, and when radio resource setup is completed, the controller  112  receives information of a terminal that desires to use an MBMS service, that is, an ID of a specific terminal and a session update request message including information regarding an address of an RNC from the SSGN  110  to analyze the received session update request message. The controller  112  that has analyzed the message and determined the ID of the specific terminal and the address of the RNC processes to directly transmit data to the RNC corresponding to the information using the above information by bypassing the SGSN. 
         [0033]    The message reader  114  determines information of the terminal that desires to use the MBMS service, that is, information regarding the ID of the specific terminal and information regarding the address of the RNC, included in the received session update request message, and provides the same to the controller  112  under control of the controller  112 . 
         [0034]    The communication unit  116  communicates with a relevant node to perform a session start process. According to an exemplary embodiment of the present invention, the communication unit  116  receives a session update request message including information of a terminal that desires to use the MBMS service, that is, information regarding an ID of a specific terminal and an address of an RNC from the RNC, and transmits a response message thereto. 
         [0035]    Up to now, an apparatus for reducing a transmission delay of a mobile communication system providing an MBMS service according to an exemplary embodiment of the present invention has been described. Hereinafter, a method for providing an MBMS service using a direct tunnel feature in order to reduce a transmission delay of a mobile communication system providing the MBMS service using the above apparatus according to an exemplary embodiment of the present invention is described. 
         [0036]      FIG. 2  is a flowchart illustrating a process for providing an MBMS in an SGSN according to an exemplary embodiment of the present invention. 
         [0037]    Referring to  FIG. 2 , first, the SGSN performs a session start process with a GGSN in step  201 . That is, the SGSN performs the session start process while giving/taking an address for providing the service to/from the GGSN. 
         [0038]    The SSGN proceeds to step  203  to determine whether a direct tunnel is supported. Here, the direct tunnel denotes applying a direct tunnel feature of the conventional PDP context to an MBMS bearer context. The direct tunnel is for allowing the GGSN (or PDN-GW) to transmit traffic to a base station by bypassing the SGSN when transmitting real-time traffic, thereby reducing a transmission delay. 
         [0039]    When determining that the direct tunnel is not supported in step  203 , the SGSN proceeds to step  211  to provide the MBMS service using the conventional method. 
         [0040]    In contrast, when determining that the direct tunnel is supported in step  203 , the SGSN proceeds to step  205  to determine TEID information from the RNC, and proceeds to step  207  to generate a session update request message including the TEID information. Here, the TEID information is information for supporting the direct tunnel feature according to an exemplary embodiment of the present invention. The TEID information denotes information of a terminal that desires to use the MBMS service, that is, information regarding an ID of a specific terminal and an address of an RNC. The session update request message may be represented in the form of  FIG. 4A . 
         [0041]    The SGSN proceeds to step  209  to transmit the generated session update request message to the GGSN to transmit information of the RNC that should transmit data to the GGSN. 
         [0042]    After that, the SGSN ends the present algorithm. 
         [0043]      FIG. 3  is a flowchart illustrating a process for providing an MBMS in a GGSN according to an exemplary embodiment of the present invention. 
         [0044]    Referring to  FIG. 3 , first, the GGSN performs a session start process with a SGSN and an MB-SC in step  301 . That is, the GGSN performs the session start process while giving/taking an address for providing the service to/from the SGSN and the MB-SC. 
         [0045]    The GGSN proceeds to step  303  to receive a session update request message from the SGSN and then proceeds to step  305  to determine whether a direct tunnel is supported. Here, the session update request message is information for supporting the direct tunnel feature according to an exemplary embodiment of the present invention. The session update request message denotes a message including information of a terminal that desires to use the MBMS service, that is, information regarding an ID of a specific terminal and an address of an RNC. The session update request message may be represented in the form of  FIG. 4A . 
         [0046]    In addition, the direct tunnel denotes applying a direct tunnel feature of the conventional PDP context to an MBMS bearer context. The direct tunnel is for allowing the GGSN (or PDN-GW) to directly transmit traffic to the RNC by bypassing the SGSN when transmitting real-time traffic, thereby reducing a transmission delay. 
         [0047]    When determining that the direct tunnel is not supported in step  305 , the GGSN proceeds to step  313  to delete the received session update request message, and proceeds to step  315  to provide the MBMS service using the conventional method. That is, when the direct tunnel is not supported, the GGSN performs a general operation of passing through the SGSN when transmitting traffic in real-time. At this point, when the direct tunnel is not supported, the received session update request message becomes an undefined message, so that the GGSN deletes the received message, and the SGSN cannot receive a response message from the GGSN within a predetermined time. Accordingly, the GGSN does not perform the direct tunnel feature and provides the MBMS service using the conventional method. 
         [0048]    In contrast, when determining the direct tunnel feature is supported in step  305 , the GGSN proceeds to step  307  to analyze the session update request message, and proceeds to step  309  to determine information included in the session update request message. Here, the GGSN determines information of an RNC that will directly transmit relevant data in order to perform a direct tunnel feature. 
         [0049]    The GGSN proceeds to step  311  to transmit the data to the relevant RNC, that is, the RNC corresponding to the information included in the session update request message. That is, the GGSN uses the direct tunnel feature that directly connects a GTP tunnel to the RNC and transmits traffic by bypassing the SGSN when transmitting data. 
         [0050]    After that, the GGSN ends the present algorithm. 
         [0051]      FIG. 4  is a view illustrating a construction of a message for providing an MBMS in a mobile communication system according to an exemplary embodiment of the present invention. 
         [0052]      FIG. 4A  is a view illustrating a construction of a session update request message for providing an MBMS in a mobile communication system according to an exemplary embodiment of the present invention. 
         [0053]    Referring to  FIG. 4A , the session update request message includes “Tunnel Endpoint Identifier User Plane” information representing a unique ID of a terminal that is provided with an MBMS service and “RNC address for User Plane” information representing an address of a relevant RNC for directly transferring the MBMS data to the RNC by bypassing the SGSN. 
         [0054]    That is, the SGSN transfers the information of the unique ID of the terminal received from the RNC to the GGSN, so that the GGSN directly transfers the MBMS data to the RNC, thereby reducing a transmission delay. 
         [0055]      FIG. 4B  is a view illustrating a construction of a session update request response message for providing an MBMS in a mobile communication system according to an exemplary embodiment of the present invention. 
         [0056]    Referring to  FIG. 4B , the session update request response message denotes a response message that the GGSN that has received a session update request message from the SGSN transmits to the SGSN. 
         [0057]      FIG. 5  is a view illustrating a process for providing an MBMS in a mobile communication system according to an exemplary embodiment of the present invention. 
         [0058]    Referring to  FIG. 5 , the mobile communication system may include a User Equipment (UE)  501 , an RNC  503 , an SGSN  505 , a GGSN  507 , and an MB-SC  509 . 
         [0059]    First, the RNC  503 , the SGSN  505 , the GGSN  507 , and the MB-SC  509  perform ( 510 ) a session start process for giving and taking a session start request and a response thereto between them, and then set ( 512 ) a radio resource between the terminal  501  and the RNC  503 . 
         [0060]    The session start process  510  and the radio resource setup process  512  are the same as the MBMS service providing process of the conventional mobile communication system. 
         [0061]    However, a difference between the mobile communication system according to an exemplary embodiment of the present invention and the conventional mobile communication system is as follows. 
         [0062]    First, after the conventional mobile communication system performs the above process, when transmitting data, the MB-SC transmits the data to the GGSN, and accordingly, the GGSN transmits the received data to the SGSN. After that, the SGSN transfers the data received from the GGSN to the RNC to transmit the same to relevant terminals. That is, to transmit data to be received to respective terminals, the conventional mobile communication system sequentially transmits the data to relevant nodes, so that a transmission delay may occur. 
         [0063]    However, the mobile communication system according to an exemplary embodiment of the present invention uses a direct tunnel feature where the GGSN that has received ( 514 ) a session update request message including information representing a unique ID of a terminal, received from the SGSN  505  directly transfers relevant data instead of transmitting the relevant data to the SGSN  505 , thereby reducing a transmission delay. 
         [0064]    In more detail, the mobile communication system according to an exemplary embodiment of the present invention completes the radio resource setup, and then the RNC  503  provides ( 514 ) information of a specific terminal that receives data to the SGSN  505 . Accordingly, the SGSN  505  generates ( 516 ) a session update request message including the information of the specific terminal, received from the RNC  503 , and then transmits ( 518 ) the generated session update request message to the GGSN  507 . 
         [0065]    Accordingly, the GGSN  507  that has received the session update request message transmits a response thereto to the SGSN  505  and analyzes the request message to determine ( 520 ) information of the relevant RNC  503 , that is, an address of the RNC  503  that will directly transmit data. 
         [0066]    After that, the GGSN  507  directly transfers data  522  provided from the MB-SC  509  to the relevant RNC  503  using the direct tunnel feature instead of transmitting the data to the SGSN  505 . 
         [0067]    Accordingly, the mobile communication system according to an exemplary embodiment of the present invention may solve a transmission delay that occurs when providing an MBMS service. 
         [0068]    Although 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. Therefore, the scope of the present invention should not be limited to the above-described embodiments but should be determined by not only the appended claims but also the equivalents thereof.