Method for forming bearer for public safety in wireless communication system and device therefor

1. A bearer establishment method of a mobility management entity (MME), the method comprising:

receiving a service request message for a public safety service, the service request message including information on a mission critical push to talk over long-term evolution (MCPTT) type;

determining a type of an MCPTT service based on the information on the MCPTT type; and

establishing a bearer with a priority higher than a priority of a preconfigured bearer based on the type of the MCPTT service.

2. The method of claim 1 , wherein the service request message includes information on an MCPTT capability of a terminal, and wherein establishing of the bearer comprises establishing the bearer with the priority higher than the priority of the preconfigured bearer based on the MCPTT capability of the terminal.

3. The method of claim 1 , wherein establishing the bearer comprises:

inquiring to a home subscriber server (HSS) about quality of service (QoS) information for use of the MCPTT service based on the type of the MCPTT service; and

modifying a context of a first default bearer for a terminal based on the QoS information acquired from the HSS.

4. The method of claim 3 , wherein establishing the bearer comprises:

storing a secondary default bearer context for the MCPTT service before receiving the service request message from the terminal;

determining a bearer context based on the type of the MCPTT service in the secondary default bearer context; and

activating a secondary default bearer based on the determined bearer context.

5. The method of claim 1 , wherein receiving the first service request message comprises receiving a downlink data notification (DDN) message including information on a public safety network from a packet data network gateway (P-GW).

6. The method of claim 5 , wherein establishing the bearer comprises:

transmitting a paging signal including a public safety network identifier to a base station;

receiving, when a terminal receives the paging signal via the base station and transmits a response to the base station, a message including a bearer configuration request from the base station; and

determining a bearer context to configure the bearer according to the bearer configuration request,

or

wherein the DDN message is an update bearer request message including a quality of service (QoS) value for establishing the bearer for the public safety network determined by the P-GW according to a signal transmitted by an application server, and

establishing the bearer comprises:

establishing the bearer based on the QoS value included in the update bearer request message.

7. The method of claim 1 , wherein the service request message is an attach request message, and establishing the bearer comprises:

determining a bearer context based on information included in the attach request message; and

establishing the bearer based on the determined bearer context.

8. A mobility management entity (MME) comprising:

a transceiver configured to transmit and receive signals; and

a controller configured to:

control the transceiver to receive a service request message for a public safety service, the service request message including information on a mission critical push to talk over long-term evolution (MCPTT) type,

determine a type of an MCPTT service based on the information on the MCPTT type, and

establish a bearer with a priority higher than a priority of a preconfigured bearer based on the type of the MCPTT service.

9. The MME of claim 8 , wherein the service request message includes information on an MCPTT capability of a terminal, and wherein the controller is further configured to establish the bearer with the priority higher than the priority of the preconfigured bearer based on the MCPTT capability of the terminal.

10. The MME of claim 8 , wherein the controller is further configured to:

inquire to a home subscriber server (HSS) about quality of service (QoS) information for use of the MCPTT service based on the type of the MCPTT service, and

modify a context of a first default bearer for a terminal based on the QoS information acquired from the HSS.

11. The MME of claim 9 , wherein the controller is further configured to:

store a secondary default bearer context for the MCPTT service before receiving the service request message from the terminal,

determine a bearer context based on the type of the MCPTT service in the secondary default bearer context, and

activate a secondary default bearer based on the determined bearer context.

12. The MME of claim 8 , wherein the controller is further configured to control the transceiver to receive a downlink data notification (DDN) message including information on a public safety network from a packet data network gateway (P-GW).

13. The MME of claim 8 , wherein the controller is further configured to:

control the transceiver to transmit a paging signal including a public safety network identifier to a base station,

control the transceiver to receive, when a terminal receives the paging signal via the base station and transmits a response to the base station, a message including a bearer configuration request from the base station, and

determine a bearer context to configure the bearer according to the bearer configuration request.

14. The MME of claim 12 , wherein the DDN message is an update bearer request message including a quality of service (QoS) value for establishing the bearer for the public safety network determined by the P-GW according to a signal transmitted by an application server, and

the controller is further configured to establish the bearer based on the QoS value included in the update bearer request message.

15. The MME of claim 8 , wherein the first service request message is an attach request message, and

the controller is further configured to determine a bearer context based on information included in the attach request message and establish the bearer based on the determined bearer context.