KR20130032173A - Method and device for switching transmitting mode for multicast broadcast service - Google Patents

Abstract

PURPOSE: A transmission mode switching method for a multicast broadcasting service and a device thereof are provided to efficiently switch a multicast transmission mode and a unicast transmission mode in a mobile communication system based on Mobile WiMAX. CONSTITUTION: An MBS proxy(23) increases a count value indicating the number of mobile terminals receiving a current service. The MBS proxy determines a service flow type which is a transmission mode based on the count value(S170). When the service flow type is changed, a service flow is generated according to the changed type(S220). The service flow is released according to a previous type. If the service flow type is not changed, a service flow for a newly joined mobile terminal is generated. [Reference numerals] (21) Serving SFA; (22) Anchor SFA; (23) MBS proxy; (S100) MS initial access procedure; (S110) Requesting to join a service; (S140) Executing an authentication/authority verification procedure; (S160) Connection setting procedure; (S170) Determining a service flow type after increasing a count value; (S190) Analyzing a service flow type; (S200) Unicast service flow generating procedure; (S210) Multicast service flow generating procedure; (S220) Multicast service flow generating procedure; (S230) Unicast service flow releasing procedure;

Description

Transmission mode switching method and device therefor for multicast broadcasting service {Method and device for switching transmitting mode for multicast broadcast service}

The present invention relates to a transmission mode switch control method and an apparatus thereof, and more particularly, to a transmission mode switching method and apparatus for a multicast broadcast service.

Multicast and broadcasting services are point-to-multipoint services that transmit data from a single source to multimedia receivers in the form of real-time video, audio, still images, text, and more. The same data is transmitted to multiple receivers through a common wireless channel. Recently, a third generation partnership project (3GPP) multimedia broadcast / multicast service (MBMS) and a mobile WiMAX (MCBCS) multicast broadcast service, or MBS, which supports a multimedia broadcasting service using a wireless network supporting a mobile communication service, are also called. ) Is presented. Mobile WiMAX MCBCS technology provides services using MBS Zone and MBS map.

The specification for WiMAX Release 1.5 has been completed by the WiMAX Forum Network Group. In WiMAX Release 1.5, that is, Phase-1, only the multicast transmission is defined in the radio section in order to provide MCBCS service to the mobile terminal.

However, for the resource efficiency of the radio section, no standard has been standardized on the part of switching the transmission mode to unicast transmission or multicast transmission. Therefore, there is a need for a control method that can effectively switch the transmission mode to reduce radio resource waste and use radio resources as efficiently as possible.

An object of the present invention is to provide a method and apparatus for efficiently switching a multicast transmission mode and a unicast transmission mode in a mobile WiMAX based mobile communication system.

The transmission mode switching method according to an aspect of the present invention for the above problem, in the method for switching the transmission mode in a mobile WiMAX-based mobile communication system, receives a multicast broadcast service transmitted from a mobile terminal If a join request message for receiving is received, increasing a count value indicating the number of mobile terminals currently receiving a service; Determining a service flow type in a transmission mode based on the count value; When the service flow type is changed, generating a service flow according to the changed type and releasing the service flow according to the previous type; And generating a service flow for a newly joined mobile terminal when the service flow type is not changed.

According to another aspect of the present invention, there is provided a transmission mode switching method. In a method of switching a transmission mode in a mobile WiMAX-based mobile communication system, a withdrawal request for terminating a multicast broadcast service transmitted from a mobile terminal If a message is received, decreasing a count value indicating the number of mobile terminals currently being serviced; Determining a service flow type in a transmission mode based on the count value; When the service flow type is changed, generating a service flow according to the changed type and releasing the service flow according to the previous type; And generating a service flow for a newly joined mobile terminal when the service flow type is not changed.

The received message is a type field indicating a number of a service flow type, a length field indicating a length of a message, a value field indicating a service flow type, and a description field indicating a transmission mode between the base station and the mobile terminal. It may include.

In addition, the transmission mode switching method according to another aspect of the present invention, in the method for switching the transmission mode in the gateway of the mobile WiMAX-based mobile communication system, the proxy of the gateway (proxy) multicast broadcast from the anchor SFA If a join request message for the cast service is received, incrementing a count value indicating the number of mobile terminals currently being serviced; When the proxy receives a withdrawal request message for the multicast broadcast service from the anchor SFA, decrementing a count value indicating the number of mobile terminals currently receiving a service; The proxy changing the service flow type from unicast to multicast if the increased count value is greater than a preset threshold; The proxy changing the service flow type from multicast to unicast if the reduced count value is less than a preset threshold; And generating, by the proxy, a join response message including service flow type information or generating a withdrawal response message including the service flow type information to the anchor SFA.

In addition, the transmission mode switching method according to another aspect of the present invention, in the method of switching the transmission mode in the gateway of the mobile WiMAX-based mobile communication system, anchor service flow authorization (SFA) of the gateway (service flow authorization, SFA) Determining a service flow type of the join response message when the message is a join response message for the service request of the mobile terminal received from the proxy; If the determined service flow type is multicast transmission, determining whether the mobile terminal is a newly joined terminal or a terminal in service; Generating a multicast service flow generation procedure when the mobile terminal is a newly joined terminal; And generating a multicast service flow generating procedure and then releasing an existing unicast service flow when the mobile terminal is a serving terminal.

According to another aspect of the present invention, there is provided a method of switching a transmission mode in a method of switching a transmission mode in a gateway of a mobile WiMAX-based mobile communication system. Determining a service flow type of the withdrawal response message when the SFA is a withdrawal response message for the service termination request of the mobile terminal received from the proxy; If the determined service flow type is unicast transmission, determining whether the mobile terminal is leaving the service or is in service; Generating a unicast service flow generation procedure when the mobile terminal is a leaving terminal; And generating a unicast service flow generation procedure and then releasing an existing multicast service flow when the mobile terminal is a serving terminal.

According to an embodiment of the present invention, by providing a service by switching the multicast transmission mode and the unicast transmission mode according to the number of mobile terminals in the mobile WiMAX-based mobile communication system, it is possible to use radio resources more efficiently. As a result, waste of radio resources can be prevented.

1 is a diagram showing the structure of a mobile WiMAX-based mobile communication system according to an embodiment of the present invention.
2 is a flowchart illustrating a process in which a mobile terminal receives a service by accessing a mobile communication system according to an embodiment of the present invention.
3 is a flowchart illustrating a process in which a mobile terminal leaves a mobile communication system to terminate reception of an MCBCS service according to an exemplary embodiment of the present invention.
4 is a flowchart illustrating a process of determining a service flow type according to an embodiment of the present invention.
5 is a flowchart illustrating the operation of an anchor SFA according to an embodiment of the present invention.
6 is a diagram illustrating a service flow parameter used in a service access and service withdrawal process in a transmission mode switching method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

A mobile station (MS) may include a terminal, a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), and a user equipment (UE). ) May be referred to as an access terminal (AT), and may include all or part of the functions of a mobile terminal, a subscriber station, a portable subscriber station, a user device, and the like.

Also, a base station (BS) includes a Node B, an access point (AP), a radio access station (RAS), a base transceiver station (BTS) Multihop Relay-BS, and the like, and may include all or some of the functions of the access point, the radio access station, the node B, the base transceiver station, and the MMR-BS.

Hereinafter, a method and an apparatus for switching a multicast broadcast service transmission mode according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a diagram showing the structure of a mobile communication system based on Mobile WiMAX according to an embodiment of the present invention.

As shown in FIG. 1, a plurality of base stations (BSs) 10 exist in a multimedia broadcast service (MBS) zone. Each base station 10 is connected to a controller / server 30 that provides a service through a gateway, that is, an access service network (ASN-GW) 20, and the controller / server 30 is connected to a content server 40. Provides content from the service. The content server 40 provides the content to be serviced and transmits the content to the controller / server 30.

The controller / server 30 provides a multicast broadcast service (MCBCS) according to an embodiment of the present invention, and may also be referred to as an MCBCS controller / server (MCBCS C / S). For convenience of explanation, we will refer to it as "Controller / Server". The controller / server 30 transmits the session control signal for the MCBCS and the MCBCS contents received from the content server 40 to the gateway 20.

The gateway 20 performs session management on MCBCS content and processes control information for generating a generic routing encapsulation (GRE) tunnel between the base station and the gateway. The gateway 20 transmits the MCBCS content provided from the controller / server 30 to the base station 10 through the GRE tunnel.

The base station 10 schedules the received MCBCS content based on the synchronization information of the radio resource received from the gateway 20, and provides the synchronized content to the mobile station MS 50. The base station 10 provides a point-to-multipoint service to the mobile terminal 50.

The mobile terminal 50 accesses the base station 10 to perform radio channel transmission and reception according to a radio access standard, supports activation or deactivation of MCBCS bearer transmission, and maintains an MCBCS user context related to MCBCS session contents. Do this.

In this structure, the mobile terminal 50 and the base station 10 are connected to the R1 interface, and the base station 10 and the gateway 20 are connected to the R6 interface. The connectivity service network (CSN) including the controller / server 30 and the gateway 20 are connected by an R3 interface.

Next, a transmission mode switching method for a multicast broadcast service according to an embodiment of the present invention will be described based on a mobile WiMAX-based mobile communication system having such a structure.

First, a process of receiving a service by accessing a mobile communication system to receive a MCBCS service will be described.

2 is a flowchart illustrating a process in which a mobile terminal receives a service by accessing a mobile communication system according to an embodiment of the present invention.

The mobile terminal 50 performs an initial access procedure to access the mobile communication network (S100). The mobile terminal 50 is connected to the CSN through the base station 10 and the gateway 20.

In order to receive the MCBCS service, the mobile terminal 50 transmits a service join message to the gateway 20 of the ASN connected to the serving base station 10 through the R3 interface (S110).

The serving service flow authorization (SFA) 21 of the serving gateway 20 receiving the service join message delivers an MBS join request message (MBS_Join_Req) to the anchor SFA 22 of the mobile terminal. (S120). At this time, the MBS join request message transmitted also includes an identifier (MS ID) of the mobile terminal. The anchor SFA 22 of the gateway 20 stores the mobile terminal identifier, and then transmits an MBS join response message MBS_Join_Rsp to the serving SFA 21 (S130). In this case, the anchor SFA 22 stores and manages the identifier of the mobile terminal that receives the join response message so that the transmission mode can be switched for the mobile terminal that has already joined when the service flow type is changed.

Next, an authentication / authorization verification procedure is performed between the anchor SFA 22 and the AAA (Authentication, Authorization, Accounting) server 60 of the CSN to determine whether the mobile terminal requesting the MCBCS service is a mobile terminal capable of receiving a service ( S140). After the authentication / authorization verification procedure is performed, the anchor SFA 22 transmits an MBS join request message (MBS_Join_Req) to the MBS proxy 23 (S150). The MBS join request message transmitted from the anchor SFA 22 to the MBS proxy 23 may include a packet data flow identifier (PDFID). The MBS proxy 23 receiving the MBS join request message performs a procedure for establishing a connection with the controller / server 30. At this time, the MBS proxy 23 receives information on MCBCS services from the controller / server 30 (S160).

When the MBS proxy 23 receives the MBS join request message, the MBS proxy 23 increments a count value indicating the number of mobile terminals currently being serviced. The increased count value is compared with a preset threshold value, and a service flow type to be used as a transmission mode of the wireless section is determined according to the comparison result (S170).

If the message sent from the anchor SFA 22 is an MBS join request message, the service flow type is changed from unicast to multicast, and vice versa, no change occurs from multicast to unicast. In addition, even if the mobile terminal identifier is not included in the MBS join request message, the MBS proxy 23 may determine the number of mobile terminals using the number of times the MBS join request message is received from the anchor SFA 22.

The MBS proxy 23 transmits an MBS join response message MBS_Join_Rsp including the determined service flow type to the anchor SFA 22 (S180). The anchor SFA 22 checks the service flow type included in the received MBS join response message and checks whether the service flow type has been changed (S190).

If the service flow type is not changed, a service flow generation procedure for the joined mobile terminal is performed according to the service flow type included in the MBS join response message (S220 and S210). If the service flow type is changed, a service flow generation and release procedure for changing a transmission mode in a wireless section is performed for mobile terminals managed by the anchor SFA 22 (S220).

Next, a process of leaving the mobile terminal from the mobile communication system based on the mobile WiMAX will be described.

3 is a flowchart illustrating a process in which a mobile terminal leaves a mobile communication system to terminate reception of an MCBCS service according to an embodiment of the present invention.

In order to end the MCBCS service reception, the mobile terminal 50 transmits a service withdrawal message (S300). The service withdrawal message is received to the serving SFA 21 of the serving gateway 20 through the serving base station 10, and the serving SFA 21 transmits an MBS withdrawal request message (MBS_Leave_Req) to the anchor SFA 22 of the mobile terminal. (S310). At this time, the MBS withdrawal request message also includes the identifier of the mobile terminal.

The anchor SFA 22 stores the identifier of the mobile terminal and then transmits an MBS withdrawal response message (MBS_Leave_Rsp) to the serving SFA 21 (S320). The next anchor SFA 22 transmits an MBS withdrawal request message MBS_Leave_Req to the MBS proxy 23 (S330). The MBS withdrawal request message transmitted from the anchor SFA 22 to the MBS proxy 23 may include a PDFID. When the MBS proxy 23 receives the MBS exit request message, the MBS proxy 23 decreases the count value indicating the number of mobile terminals currently being serviced by a predetermined value. The reduced count value is compared with a preset threshold value, and a service flow type to be used as a transmission mode of the wireless section is determined according to the comparison result (S340).

If the message sent from the anchor SFA 22 is an MBS leave request message, the service flow type is changed from multicast to unicast, and vice versa, no change occurs from unicast to multicast. . Even in this case, even if the mobile terminal identifier is not included in the MBS withdrawal request message, the MBS proxy 23 can determine the number of mobile terminals currently using the service by using the number of times the MBS withdrawal request message is received from the anchor SFA.

 The MBS proxy 23 transmits the MBS leave response message (MBS_Leave_Rsp) including the determined service flow type to the anchor SFA 22 (S350). The anchor SFA 22 receiving the MBS leave response message is the AAA server 60. In step S360, the anchor SFA 22 determines whether the service flow type has been changed based on the service flow type included in the MBS withdrawal response message. If the flow type has not been changed, a service flow release procedure for the mobile terminal withdrawn according to the service flow type is performed (S380 and S390) If the service flow type is changed, mobile terminals managed by the anchor SFA are changed. A service flow generation and release procedure for changing a transmission mode in a wireless section is performed for S400 and S410.

Next, a process of determining a service flow type in the transmission mode switch method as described above will be described in more detail.

4 is a flowchart illustrating a process of determining a service flow type according to an embodiment of the present invention, and in particular, illustrates an operation flowchart after an MBS proxy receives a message from an anchor SFA.

The MBS proxy 23 is initially waiting for message reception (S500). In the waiting state, the MBS proxy 23 receives a message from the anchor SFA 22 (S510). The MBS proxy 23 determines the received message type (S520). If the received message is an MBS join request message, a count value indicating the number of mobile terminals currently being serviced is increased by a predetermined value (S530). If the received message is an MBS exit request message, the number of mobile terminals currently being serviced is increased. The indicated count value is decreased by a predetermined value (S530).

Next, the MBS proxy 23 compares the count value with the threshold value (S550). If the count value is larger than the threshold value, the MBS proxy 23 changes the service flow type from unicast to multicast (S560). On the other hand, if the count value is less than the threshold value, the MBS proxy 23 changes the service flow type from multicast to unicast (S570). On the other hand, if the increased count value is smaller than the preset threshold, the previous service flow type is maintained, and if the reduced count value is greater than the preset threshold, the previous service flow type is maintained.

If the service flow type is determined, the MBS proxy 23 generates a response message including the information of the determined service flow type. That is, when the MBS join request message is received, the MBS join response message is generated (S580). When the MBS withdrawal request message is received, the MBS withdrawal response message is generated (S590). The MBS proxy 23 transmits the generated response message to the anchor SFA 22 (S600), and then returns to the message reception waiting state.

Next, the operation of the anchor SFA in the mode switching method according to the service connection and service withdrawal as described above will be described in more detail.

5 is a flowchart illustrating an operation of an anchor SFA according to an embodiment of the present invention. In particular, FIG. 5 is a diagram illustrating an operation flow after an anchor SFA receives a message from an MBS proxy.

As shown in FIG. 5, the anchor SFA 22 is initially in a message reception waiting state (S700). In the reception waiting state, the anchor SFA 22 receives a message from the MBS proxy 23 (S710). The anchor SFA 22 determines the type of the received message (S720), and if the determined message type is the MBS join response message, determines the service flow type (S730).

If the service flow type included in the received MBS join response message is unicast transmission, a unicast service flow generation procedure is performed for the joined mobile terminal (S740). Meanwhile, if the service flow type included in the received MBS join response message is multicast transmission, the anchor SFA 22 determines whether the mobile terminal is a newly joined mobile terminal or a mobile terminal currently in service (S750). In this case, when the identifier of the mobile terminal included in the MBS join request message is included in the previously stored identifiers, the anchor SFA 22 determines that the mobile terminal is a serviced terminal, If not included, the mobile terminal determines that the newly joined terminal.

If the mobile terminal is a newly joined mobile terminal, a multicast service flow generation procedure is performed for the corresponding mobile terminal (S760).

On the other hand, when the mobile terminal is currently receiving the service, not the joined mobile terminal, and the transmission mode is changed, that is, changed from unicast transmission to multicast transmission, the anchor SFA 22 is multicast to minimize the MCBCS service disconnection After the service flow generation procedure is first performed (S770), the procedure of releasing the existing unicast service flow is performed (S780). This multicast service flow generation and unicast service flow release procedure is repeated as many times as the number of mobile terminals currently receiving MCBCS services. After all of these procedures have been performed, anchor SFA 22 returns to the message waiting state.

Meanwhile, in the above message type determination step (S720), if the received message is an MBS withdrawal response message, the anchor SFA 22 determines the service flow type (S790). If the service flow type of the received MBS withdrawal response message is unicast transmission, the anchor SFA 22 determines whether the mobile terminal is leaving the mobile terminal or is currently receiving a service (S800).

If the mobile terminal is a mobile terminal that is currently leaving, the unicast service flow release procedure is performed on the mobile terminal (S810). On the other hand, if the mobile terminal is currently receiving the service, not leaving the mobile terminal and the transmission mode is changed, that is, when the transmission mode is changed from multicast transmission to unicast transmission, the anchor SFA 22 to minimize the MCBCS service disconnection After the unicast service flow generation procedure is first performed (S820), the procedure for releasing the existing multicast service flow is performed (S830). This unicast service flow generation and multicast service flow release procedure is repeated as many times as the number of mobile terminals currently receiving MCBCS services.

On the other hand, if the service flow type of the MBS withdrawal response message received in the above step (S790) is multicast transmission, the anchor SFA 22 performs a multicast service flow release procedure for the mobile terminal to leave (S840). After performing the processes as described above, the anchor SFA is in a message reception waiting state (S850).

In FIG. 6, in the transmission mode switching method according to the embodiment of the present invention as described above, the service flow parameters used in the service access and service withdrawal process are shown.

The service flow parameter according to an embodiment of the present invention is included in the MBS join response message or MBS withdrawal response message that the MBS proxy sends to the anchor SFA in the mobile WiMAX-based mobile communication system.

As shown in FIG. 6, the type field F1 indicates a number of a service flow type. The length in octets field F2 indicates the length of a message and may be defined as 1 byte. The value field F3 indicates a service flow type, for example, 0x00 indicates a unicast transmission mode, 0x01 indicates a multicast transmission mode, and the remaining bits are defined as reserved. The description field F4 describes that this flag indicates a transmission mode between the base station and the mobile terminal for MCBCS service. The Parent TLV (type length value) field F5 indicates that the service flow type parameter belongs to the SF Info parameter.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention, a recording medium on which the program is recorded And such an embodiment can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (19)

In the method of switching the transmission mode in the mobile WiMAX based mobile communication system,
When a join request message for receiving a multicast broadcast service transmitted from the mobile terminal is received, increasing a count value indicating the number of mobile terminals currently being serviced;
Determining a service flow type in a transmission mode based on the count value;
When the service flow type is changed, generating a service flow according to the changed type and releasing the service flow according to the previous type; And
If the service flow type is not changed, creating a service flow for the newly joined mobile terminal
The transmission mode switching method comprising a. The method of claim 1, wherein
Determining the service flow type
Comparing the increased count value with a preset threshold value; And
Determining a service flow type from unicast to multicast when the incremented count value is greater than the threshold value
The transmission mode switching method comprising a. The method according to claim 2, wherein
Generating the service flow, and releasing the service flow according to the previous type,
Performing a multicast service flow generation procedure according to the determined service flow type; And
After performing the generation procedure, performing the unicast service flow release procedure
The transmission mode switching method comprising a. The method according to claim 2, wherein
The determining of the service flow type may include performing only a change from unicast to multicast when a change of a service flow type is required when the received message is a join request message. In the method of switching the transmission mode in the mobile WiMAX based mobile communication system,
When a withdrawal request message for terminating a multicast broadcast service received from the mobile terminal is received, decreasing a count value indicating the number of mobile terminals currently being serviced;
Determining a service flow type in a transmission mode based on the count value;
When the service flow type is changed, generating a service flow according to the changed type and releasing the service flow according to the previous type; And
If the service flow type is not changed, creating a service flow for the newly joined mobile terminal
The transmission mode switching method comprising a. The method of claim 5, wherein
Determining the service flow type
Comparing the reduced count value with a preset threshold value; And
If the reduced count value is less than the threshold, determining a service flow type from multicast to unicast
The transmission mode switching method comprising a. The method of claim 6, wherein
Generating the service flow, and releasing the service flow according to the previous type,
Performing a unicast service flow generation procedure according to the determined service flow type; And
Performing the multicast service flow release procedure after performing the generation procedure
The transmission mode switching method comprising a. The method of claim 6, wherein
The determining of the service flow type may include performing only a change from multicast to unicast when a change of the service flow type is required when the received message is a withdrawal request message. The method according to claim 1 or 5
The received message includes the identifier of the mobile terminal,
And counting the number of mobile terminals currently being serviced based on the identifier of the mobile terminal. The method according to claim 1 or 5
And counting the number of mobile terminals currently being serviced based on the number of times the message is received. The method according to claim 1 or 5
The received message includes a type field indicating a number of a service flow type, a length field indicating a length of a message, a value field indicating a service flow type, and a description field indicating a transmission mode between a base station and a mobile terminal. Including a transmission mode switching method. In the method of switching the transmission mode in the gateway of the mobile WiMAX based mobile communication system,
When a proxy of the gateway receives a join request message for a multicast broadcast service from an anchor SFA, increasing a count value indicating a number of mobile terminals currently receiving a service;
When the proxy receives a withdrawal request message for the multicast broadcast service from the anchor SFA, decrementing a count value indicating the number of mobile terminals currently receiving a service;
The proxy changing the service flow type from unicast to multicast if the increased count value is greater than a preset threshold;
The proxy changing the service flow type from multicast to unicast if the reduced count value is less than a preset threshold; And
Generating, by the proxy, a join response message including service flow type information or generating an exit response message including the service flow type information to the anchor SFA;
Transmission mode switching method comprising a. The method of claim 11, wherein
The proxy maintaining the previous service flow type if the increased count value is less than a preset threshold; And
The proxy maintaining the previous service flow type if the reduced count value is greater than a preset threshold;
The transmission mode switching method comprising a. In the method of switching the transmission mode in the gateway of the mobile WiMAX based mobile communication system,
Determining a service flow type of the join response message when the anchor service flow authorization (SFA) of the gateway is a join response message for a service request of a mobile terminal received from a proxy;
If the determined service flow type is multicast transmission, determining whether the mobile terminal is a newly joined terminal or a terminal in service;
Generating a multicast service flow generation procedure when the mobile terminal is a newly joined terminal; And
If the mobile terminal is a serving terminal, generating a multicast service flow generation procedure and then performing a procedure of releasing an existing unicast service flow
The transmission mode switching method comprising a. The method of claim 14, wherein
If the determined service flow type is unicast transmission, determining that the mobile terminal is a newly joined terminal and generating a unicast service flow generation procedure. The method of claim 14, wherein
After generating the multicast service flow generation procedure, the step of releasing an existing unicast service flow is repeated as many times as the number of mobile terminals in service. In the method of switching the transmission mode in the gateway of the mobile WiMAX based mobile communication system,
Determining a service flow type of the withdrawal response message when the anchor service flow authorization (SFA) of the gateway is a withdrawal response message for the service termination request of the mobile terminal received from the proxy;
If the determined service flow type is unicast transmission, determining whether the mobile terminal is leaving the service or is in service;
Generating a unicast service flow generation procedure when the mobile terminal is a leaving terminal; And
If the mobile terminal is a serving terminal, generating a unicast service flow generation procedure and then performing a procedure of releasing an existing multicast service flow
The transmission mode switching method comprising a. The method of claim 17, wherein
If the determined service flow type is multicast transmission, determining that the mobile terminal is leaving the terminal and generating a multicast service flow generation procedure. The method of claim 17, wherein
After generating the unicast service flow generation procedure, the step of releasing an existing multicast service flow is repeated as many times as the number of mobile terminals in service.

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