KR20130005228A - Method and apparatus for transmitting multicast data - Google Patents

Abstract

PURPOSE: A multicast data transmission method and a device using the same are provided for M2M(Machine to Machine) to reliably transmit multicast data while considering usefulness of radio resource. CONSTITUTION: A connection setup part(820) receives change of transmission method from multicast to unicast from at least one terminal. The connection setup part sets up at least one connection from one terminal. A reception error is detected in at least one terminal of multiple terminals in the same group. A transmission part(830) transmits multicast data based on finally received data to at least one terminal via the unicast connection to at least one terminal. [Reference numerals] (810) Reception part; (820) Connection setup part; (830) Transmission part

Description

METHOD AND APPARATUS FOR TRANSMITTING MULTICAST DATA}

The present invention relates to a multicast data transmission method and apparatus, and more particularly, to a method for multicasting data to a plurality of terminals included in one group in a machine to machine (M2M) communication system, and Relates to a device.

A system for supporting machine to machine (M2M) communication currently under development, for example, the IEEE 802.16p system newly communicates between M2M terminals while minimizing changes in the physical layer of the conventional system, for example, IEEE 802.16m system. Provide a solution.

In a conventional system (IEEE 802.16m), when data transmission between the base station and the terminal is required, a transport connection for transmitting the corresponding service between the base station and the terminal in consideration of the characteristics of the service flow (service flow) related to each data transmission (transport connection) ), And then the data is transmitted and received through the established connection.

Such a forwarding connection includes a unicast connection used when one service is performed between a base station and each specific terminal, and a multicast connection used when one service is performed between a base station and a plurality of terminals. ) Or broadcast connection (broadcast connection). For this connection establishment and management, messages related to Advanced Air Interface-Dynamic Service Addition (AAI-DSA) for establishing a connection, messages related to AAI Dynamic Service Change (AAI-DSC) for changing a connection, and AAI-DSD (for removing connections) AAI Dynamic Service Deletion related messages are used.

In the unicast connection, a specific unicast connection can be received only by a specific terminal, and a multicast connection can be divided into a multicast method in which a plurality of terminals can be simultaneously received and a broadcast method in which all terminals can receive. The multicast scheme and the broadcast scheme are used only for downlink transmission from the base station to the terminal.

In the conventional system, the downlink multicast connection is a multicast transmission method in which the same data is transmitted to multiple terminals at the same time, and is a connection setting applied only to terminals in a connected state, whereas in the M2M communication system, the multicast connection is connected. It is required to apply not only to terminals in a state but also to terminals in an idle mode. In the case of M2M communication, most terminals are in an idle state, and terminals managed by the same group by the group management method require the same data to be simultaneously transmitted to the corresponding terminals. do.

In addition, in the conventional system, multicast transmission is performed only for data for which transmission reliability is not required. Unlike conventional systems, the M2M communication system may have various types of data transmitted by the multicast method. In the M2M communication system, multicast transmission may be used for data transmission where reliability is essential, such as firmware upgrade or group control message delivery. have.

In the multicast scheme for transmitting a plurality of terminals to a target, a method of transmitting the same data (hereinafter, referred to as "multicast data") to the terminal reliably may be as follows.

First, in order to increase the reception success rate of the terminal, the base station retransmits the corresponding multicast data packets each time a predetermined number of times regardless of whether the terminal receives them. In this case, the number of retransmissions may be determined in consideration of the required reception success rate.

Next, when there is a terminal that has not received or received (ACK / NACK) the multicast data packets from the terminal, the base station retransmits the corresponding multicast data packet. In this case, the feedback of the terminal may be made through a common feedback channel of the physical layer that all terminals commonly use, or each terminal uses a feedback channel of the physical layer allocated for each feedback or each terminal receives a message of the MAC layer. By sending it.

In the case of a method in which a base station always retransmits a multicast data packet regardless of whether the terminal receives it, the utilization of radio resources is lowered to provide reliability of transmission.

In addition, when the base station receives the feedback from the terminal through a common feedback channel and retransmits the corresponding multicast data packet, the base station cannot determine the terminal that needs to be retransmitted, and thus the multicast data packet is retransmitted to all terminals. Will be done. Therefore, this method also has a disadvantage in that the utilization of radio resources is lowered like a method of always retransmitting a multicast data packet regardless of whether the terminal receives it.

In addition, a method in which a base station retransmits a corresponding multicast data packet by receiving a feedback from a terminal through an individual feedback channel and a method in which a base station retransmits the corresponding multicast data packet by receiving a feedback through a message of a MAC layer from the terminal are idle terminals. In this case, the state transition to the connected state is required.

Therefore, there is a need for a method of reliably transmitting multicast data to M2M terminals while considering the utility of radio resources in an M2M communication system.

The present invention has been made in an effort to provide a multicast data transmission method and apparatus capable of reliably transmitting multicast data to M2M terminals while considering the utility of radio resources.

According to an embodiment of the present invention, a method for transmitting multicast data in a base station is provided. In the multicast data transmission method, multicast data is transmitted to a plurality of terminals in the same group in a multicast manner, and when the reception error of the multicast data is detected at a first terminal among the plurality of terminals, Receiving a request for a change from a multicast transmission to a unicast transmission from a terminal, establishing a unicast connection with the first terminal, and continuously transmitting the multicast data through the unicast connection; And transmitting to the terminal.

If the first terminal is in the idle state before the setting, the setting includes receiving a ranging request message from the first terminal to reenter the network of the first terminal, and the ranging request message. And transmitting a ranging response message to the first terminal, wherein the ranging request message may include information of data finally received by the first terminal.

The ranging request message may further include a transmission purpose indicator in which a value indicating a request for changing a transmission scheme to the base station is displayed.

The ranging request message may further include an identifier of a group to which the first terminal belongs.

The transmitting may include continuously transmitting the multicast data to the first terminal through the unicast connection based on the information of the data finally received by the first terminal.

The setting may further include removing a multicast connection connected to the first terminal.

If the state of the first terminal is in a connected state before the setting by the first terminal, the removing may include receiving a dynamic service delete (DSD) request message from the terminal. And transmitting a DSD response message in response to the DSD request message to the first terminal, wherein the DSD request message may include information of data finally received by the first terminal.

If the state of the first terminal is in the connected state before the setting of the first terminal, the setting includes receiving a dynamic service addition (DSA) request message from the first terminal, and The method may include transmitting a DSA response message for the DSA request message to the terminal, wherein the DSA request message may include information of data finally received by the first terminal.

The setting may include changing the connection between the first terminal and the unicast connection.

If the state of the first terminal is in a connected state before the setting of the first terminal, the changing includes receiving a dynamic service change (DSC) request message from the terminal, and the DSC And transmitting a response message to the request message to the first terminal, wherein the DSC request message may include information of data finally received by the first terminal.

The multicast data transmission method may further include continuously transmitting the multicast data in the multicast manner with the remaining terminals other than the first terminal which has established the unicast connection among the plurality of terminals.

According to another embodiment of the present invention, an apparatus for transmitting multicast data in a base station is provided. The multicast data transmission apparatus includes a connection setting unit and a transmitter. When the connection setting unit receives a request for changing the transmission scheme from the multicast transmission to the unicast transmission from at least one terminal among the plurality of terminals in the same group, in which the reception error of the multicast data is detected, the connection setting unit is connected to the at least one terminal. Set up a cast connection. The transmitter transmits the multicast data to the at least one terminal based on the information of the data finally received by the at least one terminal through the unicast connection.

Each of the plurality of terminals may be in an idle state or a connected state.

The multicast data transmission device may further include a receiver. When the at least one terminal is in an idle state, the receiver receives a ranging request message from the at least one terminal for network reentry. In this case, the ranging request message may include a transmission purpose indicator displaying information on the data finally received by the terminal and a value indicating a request for changing the transmission scheme to the base station.

The connection setting unit may remove the multicast connection respectively established with the at least one terminal before establishing the unicast connection.

When the at least one terminal is in the connected state, the receiver receives a dynamic service delete (DSD) request message from the at least one terminal to remove the multicast connection, respectively, and the DSD request message May include information on the data last received by the terminal.

When the at least one terminal is in the connected state, the receiver receives a dynamic service addition (DSA) request message from the at least one terminal for the unicast connection while maintaining the multicast connection. The DSA request message may include information of data finally received by the terminal.

The receiving unit receives a dynamic service change (DSC) request message from each of the at least one terminal to change the multicast connection to the unicast connection when the at least one terminal is in the connected state. The DSC request message may include information of data finally received by the terminal.

The transmitter continuously transmits the multicast data through the multicast connection with the remaining terminals except at least one terminal that has established the unicast connection among the plurality of terminals.

According to an embodiment of the present invention, by changing the multicast connection of some M2M terminal participating in the multicast transmission to a unicast connection using connection management messages used in a conventional system such as IEEE 802.16m, It is possible to transmit multicast data requiring reliability while improving. In particular, in the M2M communication system, multicast data can be transmitted while improving the utility of radio resources and ensuring reliability to M2M terminals in a plurality of idle and connected states included in one group.

1 is a diagram illustrating an example of a multicast communication system using a multicast transmission scheme according to an embodiment of the present invention.
2 to 7 are diagrams illustrating a multicast data transmission method in a base station according to the first to sixth embodiments of the present invention, respectively.
8 is a diagram illustrating a multicast data transmission apparatus of a base station 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 and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

Throughout the specification, a terminal is a mobile terminal (MT), a mobile station (MS), an advanced MS (AMS), a subscriber station (SS), a portable subscriber station (PSS) ), An access terminal (AT), a user equipment (UE), or the like, and may include all or part of the functions of the MT, MS, SS, PSS, AT, UE, and the like.

In addition, the base station (BS) is a node B (eB), an evolved node B (eNodeB), an access point (AP), a radio access station (radio access station (RAS)), a base transceiver station (base transceiver station, BTS), MMR (mobile multihop relay) -BS, Advanced BS (ABS), It may refer to a relay station (RS), etc., which performs a role of a base station, and may include all or some functions of a node B, an eNodeB, an AP, a RAS, a BTS, an MMR-BS, an RS, and the like.

Now, a multicast data transmission method and apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating an example of a multicast communication system using a multicast transmission scheme according to an embodiment of the present invention.

Referring to FIG. 1, as an example of a multicast communication system, an M2M communication system may include one transmitting apparatus (hereinafter referred to as “base station”) 100 and a plurality of receiving apparatuses (hereinafter referred to as “terminal”) 210a. , 220a, 230a).

In the M2M communication system, the base station 100 transmits the same multicast data to a plurality of terminals 210a, 220a, 230a belonging to the same M2M group 210, 220, 230.

The base station 100 uses an M2M Group Identifier (MGID) assigned to the M2M groups 210, 220, and 230 to transmit multicast data to the same M2M groups 210, 220, and 230. In FIG. 1, three M2M groups 210, 220, and 230 are illustrated for convenience of description, and MGIDs of the three M2M groups 210, 220, and 230 are illustrated as MGID_1, MGID_2, and MGID_3, respectively.

The MGID is uniquely allocated and has a finite size in the base station 100 and is used as an identifier for notifying the corresponding M2M group of the allocated resource. Accordingly, the M2M groups 210, 220, and 230 have different MGIDs MGID_1, MGID_2, and MGID_3.

The base station 100 is a connection management message used in a system such as IEEE 802.16m, for example, AAI-DSA (Advanced Air Interface-Dynamic Service Addition) -related messages, AAI-DSC (AAI Dynamic Service Change) related to the connection change Message, AAI Dynamic Service Deletion (AAI-DSD) -related messages for connection removal when the terminal (210a, 220a, 230a) requires the reliable transmission of the multicast data, the transmission scheme to the terminal is multi- Change from cast transmission to unicast transmission. To this end, the base station 100 changes the connection with the terminal requiring reliable transmission of multicast data from the multicast connection to the unicast connection, and transmits the multicast data to the corresponding terminal through the changed unicast connection. It is possible to transmit reliable multicast data only to the corresponding terminal while improving the utility of radio resources.

In general, the terminals switch to an idle state when there is no data to receive in order to reduce power consumption, and switch to a listening state at a set time to listen for data to be received. In particular, in the case of the M2M system, since most of the terminal is in an idle state (idle state), the base station 100 should be able to transmit reliable multicast data not only to the terminal in the connected state (idle state) but also to the terminal in the idle state. . Accordingly, when the terminal in the connected state as well as the terminal in the idle state requests reliable multicast transmission, the base station 100 changes the state of the terminal to the connected state and changes the transmission method to the terminal to the unicast method.

In the conventional case, when the state of the terminal is changed to the idle state, all the connections maintained in the connected state of the terminal are released. In contrast, the embodiment of the present invention maintains the multicast connection in the connected state even in the idle state. Therefore, data can be transmitted through a multicast connection even in the idle state, and when the idle terminal requires reliable multicast transmission, the state of the terminal is changed to the connected state and the transmission method to the terminal is unicast. You can change it in a way.

2 is a diagram illustrating a multicast data transmission method in a base station according to the first embodiment of the present invention. In particular, FIG. 2 corresponds to a case where the base station transmits multicast data to an idle terminal. In FIG. 2, only one idle terminal 210b belonging to MGID_1 is illustrated. Referring to FIG. 2, the base station 100 performs M2M group paging of MGID_1 (S202), and then transmits multicast data in a multicast transmission method through a multicast connection configured to a plurality of terminals belonging to MGID_1 (S204). ~ S210).

The terminal 210b in the idle state among the plurality of terminals receives the multicast data when there is multicast data to be received after switching to the listening state after a time set as the start time of the multicast transmission. Here, the multicast transmission start time may be included in the paging message.

If the terminal 210b detects a reception error while receiving the multicast data, and determines that the reliability of the multicast data cannot be guaranteed (S212), the terminal 210b stops the reception of the multicast data (S214) and transmits the corresponding service. The method determines the change from the multicast transmission method to the unicast transmission method (S216).

The terminal 210b requests the base station 100 to switch the transmission method of the corresponding service from the multicast transmission method to the unicast transmission method. In this case, the request for changing the transmission method to the base station 100 by the idle terminal 210b is made through a ranging request (RNG-REQ) message used for network re-entry.

Specifically, the terminal 210b transmits the ranging code to the base station 100 before the ranging request (Advanced Air Interface-RNG-REQ, AAI-RNG-REQ) message is transmitted to the base station 100 through AAI-RNG-. A resource for transmitting a REQ message is allocated (S218).

The terminal 210b transmits an AAI-RNG-REQ message to the base station 100 in order to perform the network reentry procedure of the terminal 210b (S220). In this case, the AAI-RNG-REQ message transmitted by the terminal 210b may include a Routing Purpose Indication (RPI) of the corresponding message, and the terminal 210b multicasts the transmission purpose indicator (RPI). A value indicating a transmission mode change request to the base station 100 for reliable reception of a service is indicated. For example, when 0b1110 is used as a value indicating a request for changing a transmission method to the base station 100, 0b1110 may be displayed as a transmission purpose indicator (RPI). In addition, the AAI-RNG-REQ message transmitted by the terminal 210b may further include an indicator of a service requesting a change of a transmission method and a sequence number (SN) of reception related information of the corresponding service. MGID_1, which is an identifier of the M2M group of the terminal 210b, may be displayed on the indicator of the service requesting to change the transmission method, and the serial number of the finally received MAC PDU may be displayed on the serial number of the reception related information.

AAI-RNG-REQ message may be defined as shown in Table 1.

Field Size Value condition Ranging Purpose Indication 4 0b0000 = initial network entry
... .
0b1110 = network reentry for reliable multicast data reception (switch to unicast) ... . Else f (Ranging Purpose Indication == 0b1110) { MGID 15 M2M Group ID SN of latest successful MDPUs 10 Sequence number of latest  successful MPDUs When an AAI-RNG -REQ message is sent by a M2M device for reliable multicast data reception }

When the base station 100 receives a request for changing a transmission method from the terminal 210b through an AAI-RNG-REQ message, an AAI-Ranging Response (AAI-RNG-RSP) message for the AAI-RNG-REQ message is received. To transmit to the terminal 210b (S222).

Upon receiving the AAI-RNG-RSP message, the terminal 210b performs network re-entry procedures to switch from an idle state to a connected state (S224).

Thereafter, the base station 100 changes the connection for the multicast service from a multicast connection to a unicast connection. To this end, the base station 100 transmits an AAI-Dynamic Service Deletion Request (AAI-DSD-REQ) message to the terminal 210b to remove the multicast connection (S226). The AAI-DSD-REQ message can use the message format used in the existing system. The AAI-DSD-REQ message used in the existing system includes an identifier of a multicast connection to remove the connection.

 When the terminal 210b receives the AAI-DSD-REQ message from the base station 100, the terminal 210b removes the corresponding multicast connection and performs a dynamic service removal response (AAI-DAI-DSQ) for the AAI-DSD-REQ message. The DSD-RSP) message is transmitted to the base station 100 (S228).

Next, when the base station 100 receives the AAI-DSD-RSP message from the terminal 210b, the base station 100 transmits an advanced air interface-dynamic service addition request (AAI-DSA-REQ) message for unicast connection. Transmit to 210b (S230). The AAI-DSA REQ message can use the message format used in the existing system. The AAI-DSA-REQ message used in the existing system includes a newly established connection, for example, an identifier of a unicast connection. .

When the terminal 210b receives the AAI-DSA-REQ message from the base station 100, the terminal 210b receives an Advanced Air Interface-Dynamic Service Addition Response (AAI-DSA-RSP) message to the AAI-DSA-REQ message. It transmits to the base station 100 (S232).

When the base station 100 receives the AAI-DSA-RSP message from the terminal 210b, the base station 100 receives an advanced air interface-dynamic service addition acknowledgment (AAI-DSA-ACK) message for the unicast connection establishment. 210b) and set the unicast connection with the terminal 210b (S236).

Next, the base station 100 continuously transmits multicast data to the terminal 210b through a newly established unicast connection based on the corresponding service reception related information received from the terminal 210b through an AAI-RNG-REQ message ( S238). That is, the base station 100 transmits data after the data transmitted without error in the multicast manner to the terminal 210b through a unicast connection.

On the other hand, the base station 100 continuously transmits multicast data in a multicast transmission method through a multicast connection to the other terminals except for the terminal 210b which has established a unicast connection among the terminals belonging to MGID_1.

3 is a diagram illustrating a multicast data transmission method in a base station according to a second embodiment of the present invention. In particular, FIG. 3 corresponds to a case where the base station transmits multicast data to a terminal in a connected state through a multicast connection. do. 3 illustrates only the terminal 210b of one connection state belonging to MGID_1.

Referring to FIG. 3, since the state of the terminal 210b is a connected state, there is no group paging procedure and a network re-entry procedure of the terminal 210b, and the request for switching the transmission scheme of the terminal 210b to the base station 100 is AAI. It differs from the multicast transmission method according to the first embodiment in that it is made through -DSD-REQ message.

Specifically, the base station 100 transmits multicast data in a multicast manner through a multicast connection set up with a plurality of terminals belonging to MGID_1 (S304 to S310).

The terminal 210b receives the multicast data transmitted by the base station 100.

When the terminal 210b detects a reception error while receiving the multicast data, and determines that the reliability of the multicast data cannot be guaranteed (S312), the terminal 210b stops receiving the multicast data (S314) and transmits the corresponding service. The method determines the switching from the multicast transmission method to the unicast transmission method (S316).

The terminal 210b transmits the AAI-DSD-REQ message to the base station 100 and requests the switching of the transmission method of the corresponding service (S318). In this case, the AAI-DSD-REQ message transmitted by the terminal 210b may include a serial number (SN) of the reception related information of the corresponding service, as shown in Table 2, to indicate a request for the change of the transmission method of the corresponding service. In the serial number SN of the reception related information, the serial number of the finally received MAC PDU may be displayed.

Field Size Value / Description Condition ... . SN of latest successful MDPUs 10 Sequence number of latest successful MPDUs When an AAI-DSD-REQ message is sent by a M2M device to switch a multicast service flow from the multicast connection to the unicast connection.

When the base station 100 receives the request for changing the transmission method from the terminal 210b through the AAI-DSD-REQ message, the base station 100 removes the corresponding multicast connection and transmits the AAI-DSD-RSP message to the terminal 210b (S320). ).

Next, the base station 100 transmits an AAI-DSA-REQ message for unicast connection to the terminal 210a in the same manner as the multicast transmission method according to the first embodiment (S322).

When the terminal 210b receives the AAI-DSA-REQ message from the base station 100, the terminal 210b transmits the AAI-DSA-RSP message to the base station 100 (S324).

When the base station 100 receives the AAI-DSA-RSP message from the terminal 210b, the base station 100 transmits an AAI-DSA-ACK message for the unicast connection establishment to the terminal 210b (S326), and transmits the corresponding unicast connection to the terminal. It sets between 210b and S328.

Next, the base station 100 continuously transmits multicast data to the terminal 210b through a newly established unicast connection based on the corresponding service reception related information received from the terminal 210b through an AAI-DSD-REQ message ( S330).

On the other hand, the base station 100 continuously transmits multicast data in a multicast transmission method through a multicast connection to the other terminals except for the terminal 210b which has established a unicast connection among the terminals belonging to MGID_1.

Meanwhile, in the first and second multicast transmission methods described with reference to FIGS. 2 and 3, the multicast connection is removed through an AAI-DSD-REQ message and an AAI-DSD-RSP message for establishing a unicast connection. You can also switch to unicast without the need to remove the multicast connection. This method will be described with reference to FIGS. 4 and 5.

4 is a diagram illustrating a multicast transmission method according to a third embodiment of the present invention. In particular, FIG. 4 corresponds to a case where a base station transmits multicast data to an idle terminal. In FIG. 3, only one idle terminal 210b belonging to MGID_1 is illustrated.

4 is different from the multicast transmission method according to the first embodiment in that there is no multicast connection removal procedure through the AAI-DSD-REQ message and the AAI-DSD-RSP message.

First, since the steps S402 to S424 in FIG. 4 are the same as the steps S202 to S224 described in FIG. 2, descriptions of the steps S402 to S424 will be omitted.

After transmitting the AAI-RNG-RSP message, the base station 100 transmits an AAI-DSA-REQ message for unicast connection to the terminal 210b (S426). The AAI-DSA REQ message can use the message format used in the existing system.

When the terminal 210b receives the AAI-DSA-REQ message from the base station 100, the terminal 210b transmits the AAI-DSA-RSP message to the base station 100 (S428).

When the base station 100 receives the AAI-DSA-RSP message from the terminal 210b, the base station 100 transmits an AAI-DSA-ACK message for the unicast connection establishment to the terminal 210b (S430), and transmits the corresponding unicast connection to the terminal. It sets between 210b and S432.

Next, the base station 100 continuously transmits multicast data to the terminal 210b through a newly established unicast connection based on the corresponding service reception related information received from the terminal 210b through an AAI-RNG-REQ message ( S434).

5 is a diagram illustrating a multicast data transmission method in a base station according to a fourth embodiment of the present invention. In particular, FIG. 5 corresponds to a case in which the base station transmits multicast data to a terminal in a connected state through a multicast connection. do. In FIG. 5, only the terminal 210b of one connection state belonging to MGID_1 is illustrated.

Referring to FIG. 5, there is no procedure for removing a multicast connection through an AAI-DSD-REQ message and an AAI-DSD-RSP message. In this regard, a request for changing a transmission method of a corresponding service is made through an AAI-DSA-REQ message. It is different from the multicast transmission method according to the second embodiment. In this case, in the second embodiment, the parameters included in the AAI-DSD-REQ message may be included in the AAI-DSA-REQ message as shown in Table 3.

First, since steps S504 to S516 in FIG. 5 are the same as steps S304 to S316 described in FIG. 3, descriptions of steps S504 to S516 will be omitted.

After determining the change of the transmission method from the multicast transmission to the unicast transmission, the terminal 210b transmits the AAI-DSA-REQ message for the unicast connection to the base station 100, thereby changing the transmission method of the corresponding service. Request (S518). In this case, the AAI-DSA-REQ message transmitted by the terminal 210b includes a MAC PDU of the last received MAC as a serial number (SN) of reception related information of the corresponding service, as shown in Table 3, to indicate a request for a change in the transmission method of the corresponding service. The serial number may be displayed.

Field Size Value / Description Condition ... . SN of latest successful MDPUs 10 Sequence number of latest  successful MPDUs When an AAI - DSA - REQ message is  sent by  a M2M device to switch  a multicast service flow from  the multicast connection to the  unicast connection .

When the base station 100 receives the request for changing the transmission scheme of the corresponding service through the reception of the AAI-DSA-REQ message, the base station 100 transmits the AAI-DSA-RSP message to the terminal 210b (S520).

When the terminal 210b receives the AAI-DSA-RSP message from the base station 100, the terminal 210b transmits an AAI-DSA-ACK message for unicast connection establishment to the base station 100 (S522).

The base station 100 establishes a corresponding unicast connection with the terminal 210b (S524).

Next, the base station 100 continuously transmits multicast data to the terminal 210b through the newly established unicast connection based on the corresponding service reception related information received from the terminal 210b through an AAI-DSA-REQ message ( S526).

Since the multicast transmission method according to the third and fourth embodiments of the present invention establishes a new unicast connection with the terminal 210b while maintaining the multicast connection, the previously established multicast connection is newly established. It can be kept separate from the unicast connection.

On the other hand, unlike the multicast transmission method according to the first to fourth embodiments may be changed to a unicast method using an AAI-Dynamic Service Change (AAI-DSC) message. This method will be described with reference to FIGS. 6 and 7.

6 is a diagram illustrating a multicast connection method according to a fifth embodiment of the present invention. In particular, FIG. 6 corresponds to a case in which a base station transmits multicast data to an idle terminal. In FIG. 6, only one idle terminal 210b belonging to MGID_1 is illustrated.

Referring to FIG. 6, a third implementation is performed in that an AAI-DSC message is used instead of an AAI-DSA-REQ message, an AAI-DSA-RSP message, and an AAI-DSA-ACK message to change to a unicast connection. It is different from the multicast transmission method according to the example.

In FIG. 6, steps S602 to S624 are the same as steps S402 to S424 described in FIG. 4, and thus descriptions of steps S602 to S624 are omitted.

After transmitting the AAI-RNG-RSP message, the base station 100 sends a dynamic service change request (AAI-DSC Request, AAI-DSD-REQ) message to change the connection for the corresponding multicast service into a unicast connection. Transmission to the terminal 210b (S626). At this time, the AAI-DSC-REQ message can use the message type used in the existing system as it is.

When the terminal 210b receives the AAI-DSC-REQ message from the base station 100, the terminal 210b transmits the AAI-DSC-RSP message to the base station 100 (S628).

Next, when the base station 100 receives the AAI-DSC-RSP message from the terminal 210b, the base station 100 changes the connection method with the terminal 210b from a multicast connection to a unicast connection (S630).

When the connection method between the base station 100 and the terminal 210b is changed to a unicast connection, the base station 100 is newly set based on the corresponding service reception related information received from the terminal 210b through an AAI-RNG-REQ message. The multicast data is continuously transmitted to the terminal 210b through the unicast connection (S632).

FIG. 7 is a diagram illustrating a multicast data transmission method in a base station according to a sixth embodiment of the present invention. In particular, FIG. 7 corresponds to a case in which the base station transmits multicast data to a terminal in a connected state through a multicast connection. do. In FIG. 7, only the terminal 210b of one connection state belonging to MGID_1 is illustrated.

Referring to FIG. 7, a fourth implementation is performed in that an AAI-DSC message is used instead of an AAI-DSA-REQ message, an AAI-DSA-RSP message, and an AAI-DSA-ACK message to change to a unicast connection. It is different from the multicast transmission method according to the example.

In FIG. 7, steps S704 to S716 are the same as steps S504 to S516 described in FIG. 5, and thus descriptions of steps S704 to S716 are omitted.

After determining the change of the transmission method of the corresponding service from the multicast transmission method to the unicast transmission method, the terminal 210b transmits the AAI-DSC-REQ message to the base station 100 (S718), and then transmits the service. Request a change. In this case, the AAI-DSC-REQ message transmitted by the terminal 210b includes a MAC PDU of the last received MAC as the serial number (SN) of the reception related information of the corresponding service, as shown in Table 4, to indicate a request for the change of the transmission method of the corresponding service. The serial number may be displayed.

Field Size (bits) Value / Description Conditions ... SN of latest successful MDPUs 10 Sequence number of latest successful MPDUs When an AAI-DSC-REQ message is sent by a M2M device to switch a multicast service flow from the multicast connection to the unicast connection

When the base station 100 receives a request for changing the transmission method from the terminal 210b through the AAI-DSC-REQ message, the base station 100 transmits an AAI-DSC-RSP message to the terminal 210b (S720) and the terminal 210b. Change the connection method from the multicast connection to the unicast connection (S722).

When the connection method between the base station 100 and the terminal 210b is changed to a unicast connection, the base station 100 is newly set based on the corresponding service reception related information received from the terminal 210b through an AAI-DSC-REQ message. The multicast data may be continuously transmitted to the terminal 210b through the unicast connection (S724).

As described above, according to the multicast transmission method according to an embodiment of the present invention, when reliable multicast data transmission is required to a plurality of idle and connected M2M terminals included in one group in an M2M communication system, By changing the transmission method to some M2M terminals whose reliability of data reception is not satisfied by the multicast method, from multicast transmission to unicast transmission, multicast data is transmitted to the corresponding M2M terminal while improving the efficiency of radio resources and ensuring reliability. Can be transmitted.

8 is a diagram illustrating a multicast data transmission apparatus of a base station according to an embodiment of the present invention.

Referring to FIG. 8, the multicast transmission apparatus 800 of the base station 100 includes a receiver 810, a connection setup unit 820, and a transmitter 830.

The receiver 810 receives a connection management message and ranging messages for network reentry from a plurality of terminals of the same group.

The connection setting unit 820 manages a multicast connection with terminals to transmit the same data, that is, multicast data, to a plurality of terminals of the same group in a multicast manner, and at least one terminal among a plurality of terminals of the same group. When receiving a request for changing the transmission scheme from the multicast transmission to the unicast transmission, the connection with the corresponding terminal is established as a unicast connection.

As described with reference to FIGS. 2 and 3, the connection setting unit 820 may remove the multicast connection established with the corresponding terminal and establish a unicast connection with the corresponding terminal.

As described with reference to FIGS. 3 and 4, the connection setting unit 820 may establish a unicast connection with the corresponding terminal while maintaining the multicast connection established with the corresponding terminal.

The connection setting unit 820 may change the multicast connection established between the terminal 210b and the unicast connection as described with reference to FIGS. 6 and 7.

The transmitter 830 transmits the connection management message and the ranging message used to change the transmission method of the terminal to the unicast method to the terminal.

The transmitter 830 may transmit multicast data to a plurality of terminals of the same group through a multicast connection established with the corresponding terminal in a multicast manner, and the corresponding terminal through a unicast connection established with the corresponding terminal. Only 210b can continuously transmit multicast data.

An embodiment of the present invention is not implemented only through the above-described apparatus and / or method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Such an implementation can be easily implemented by those skilled in the art to which the present invention pertains based on the description of the above-described embodiments.

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)

A method for transmitting multicast data at a base station,
Transmitting multicast data in a multicast manner to a plurality of terminals in the same group;
Receiving a request for a change from multicast transmission to unicast transmission when the reception error of the multicast data is detected at a first terminal of the plurality of terminals;
Establishing a unicast connection with the first terminal, and
Continuously transmitting the multicast data to the first terminal through the unicast connection
Multicast data transmission method comprising a. In claim 1,
If the first terminal is idle before the setting step,
The setting step
Receiving a ranging request message from the first terminal for network reentry of the first terminal, and
Transmitting a ranging response message for the ranging request message to the first terminal;
The ranging request message is a multicast data transmission method including the information of the data finally received by the first terminal. In claim 2,
The ranging request message further includes a transmission purpose indicator indicating a value indicating a request for changing a transmission scheme to the base station. 4. The method of claim 3,
The ranging request message further includes an identifier of a group to which the first terminal belongs. In claim 2,
The transmitting may include continuously transmitting the multicast data to the first terminal through the unicast connection based on the information of the data finally received by the first terminal. In claim 2,
The setting may further include removing a multicast connection connected to the first terminal. The method of claim 6,
When the state of the first terminal is connected state (connected state) before the setting step, the first terminal,
The removing step
Receiving a dynamic service delete (DSD) request message from the terminal, and
Transmitting a DSD response message for the DSD request message to the first terminal;
The DSD request message includes information on the data finally received by the first terminal. In claim 2,
If the state of the first terminal before the setting step of the first terminal is connected state,
The setting step
Receiving a dynamic service addition (DSA) request message from the first terminal, and
Transmitting a DSA response message for the DSA request message to the terminal;
The DSA request message includes information on the data last received by the first terminal. In claim 2,
The setting may include changing the connection with the first terminal to the unicast connection. The method of claim 9,
If the state of the first terminal before the setting step of the first terminal is connected state,
The changing step
Receiving a dynamic service change (DSC) request message from the terminal, and
Sending a response message to the first terminal to the DSC request message,
The DSC request message is a multicast data transmission method comprising the information of the data finally received by the first terminal. In claim 1,
Continuously transmitting multicast data in the multicast manner with the remaining terminals except the first terminal which has established the unicast connection among the plurality of terminals.
The multicast data transmission method further comprising. An apparatus for transmitting multicast data at a base station,
When a request for changing the transmission scheme from multicast transmission to unicast transmission is received from at least one terminal among the plurality of terminals connected to the multicast in which the reception error of the multicast data is detected, the at least one terminal and the at least one terminal. A connection establishment section for establishing a unicast connection, and
Transmitting unit for transmitting the multicast data to each of the at least one terminal on the basis of the information of the data finally received by each of the at least one terminal through the unicast connection
Multicast data transmission apparatus comprising a. The method of claim 12,
And the plurality of terminals are each in an idle state or a connected state. In claim 13,
Receiving unit for receiving a ranging request message from each of the at least one terminal for the network re-entry when the at least one terminal is idle
Further comprising:
The ranging request message includes a transmission purpose indicator which displays information on the data finally received by the terminal and a value indicating a request to change the transmission scheme to the base station. The method of claim 14,
And the connection establishment unit removes the multicast connection established with each of the at least one terminal before establishing the unicast connection. 16. The method of claim 15,
When the at least one terminal is in the connected state, the receiving unit receives a dynamic service delete (DSD) request message from each of the at least one terminal to remove the multicast connection,
The DSD request message is a multicast data transmission device including information on the data last received by the terminal. The method of claim 12,
When the at least one terminal is in the connected state, the receiver receives a dynamic service addition (DSA) request message from the at least one terminal for the unicast connection while maintaining the multicast connection. and,
The DSA request message is a multicast data transmission device including information on the data last received by the terminal. The method of claim 12,
The receiving unit receives a dynamic service change (DSC) request message from each of the at least one terminal to change the multicast connection to the unicast connection when the at least one terminal is in the connected state. ,
The DSC request message is a multicast data transmission apparatus including the information of the data last received by the terminal. The method of claim 12,
And the transmitter is configured to continuously transmit the multicast data through the multicast connection with the remaining terminals except the at least one terminal that has established the unicast connection among the plurality of terminals.

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