Group communication method and device for providing proximity service
The present invention relates to a method and a device for performing group communication based on a proximity service (ProSe) in a wireless communication system. More specifically, the method comprises the steps of: enabling a relay terminal (relay user equipment, relay UE, ProSe UE-to-Network relay) to register group communication in a network node; and enabling the relay terminal to perform the group communication with the network node, wherein the group communication is configured to transmit a downlink signal using a multimedia broadcast and multimedia service (MBMS) if the number of terminals, except for a relayed terminal (relayed user equipment, relayed UE) among a plurality of terminals registered in the network node, is not less than a reference value.
1. A method for performing a group communication based on proximity services (ProSe) by a relay user equipment (UE) for performing a relay operation for a relayed UE communicating with a network node via the relay UE in a wireless communication system, the method comprising:
transmitting, to the network node, a first group communication registration message for the relay UE, including location information of the relay UE, to join the group communication and a second group communication registration message for the relayed UE, received from the relayed UE, to join the group communication;
receiving, from the network node, a downlink signal based on a group communication scheme,
wherein the group communication scheme is determined to be a multimedia broadcast and multimedia service (MBMS) scheme if a number of UEs other than the relayed UE among UEs registered in the network node for the group communication is equal to or greater than a reference value, and the group communication scheme is determined to be a unicast scheme if the number of the UEs other than the relayed UE is smaller than the reference value, and
wherein the relayed UE is implicitly announced to the network node by transmitting the second group communication registration message not including location information for the relayed UE; and
transmitting, to the relayed UE, the downlink signal received from the network node.
2. The method according to claim 1 , wherein the location information includes at least one of a tracking area identity (TAI) and an evolved universal mobile telecommunications services (UMTS) terrestrial radio access network (E-UTRAN) cell global identifier (ECGI).
3. The method according to claim 1 , further comprising receiving MBMS service information from the network node.
4. The method according to claim 3 , wherein the MBMS service information is configured to be transmitted only to at least one relay UE among the at least one relay UE and at least one relayed UE located in a service range of the group communication.
5. The method according to claim 3 , wherein the MBMS service information includes at least one of a service identifier (ID), a temporary mobile group identity (TMGI), and a multicast address of media.
6. The method according to claim 1 , wherein granularity for a service range of the group communication is one of a single cell, a group communication service area, an MBMS service area, a single tracking area, multiple tracking areas, multiple cells, a Multimedia Broadcast multicast service Single Frequency Network (MBSFN) area, an area pre-specified for group communication, and a Public Land Mobile Network (PLMN).
7. The method according to claim 1 , further comprising:
receiving, from the network node, a response to the first group communication registration message and a response to the second group communication registration message;
transmitting, to the relayed UE, the response to the second group communication registration message; and
transmitting, to the relayed UE, the downlink signal from the network node through ProSe communication, if the response to the second group communication registration message is an acknowledgement.
8. The method according to claim 7 , wherein the response to the second group communication registration message includes the location information of the relay UE.
9. The method according to claim 8 , wherein the response to the second group communication registration message includes relay operation information, and
wherein the relay operation information indicates at least one of:
whether the relay UE performs relay operation for the relayed UE,
whether the relayed UE is registered to join the group communication via the relay UE,
whether the relayed UE participates in the group communication via the relay UE,
whether the relayed UE is located in network coverage,
whether the relayed UE is located in evolved universal mobile telecommunications services (UMTS) terrestrial radio access network (E-UTRAN) coverage supporting the group communication, and
whether the relayed UE is located in a service range of the group communication.
10. The method according to claim 8 , wherein the response to the second group communication registration message includes identification information of the relay UE.
11. A relay user equipment (UE) for performing a relay operation for a relayed UE communicating with a network node via the relay UE and performing a group communication based on proximity services (ProSe) in a wireless communication system, the relay UE comprising:
a transceiver; and
a processor,
wherein the processor:
transmits, through the transceiver to the network node, a first group communication registration message for the relay UE, including location information of the relay UE, to join the group communication and a second group communication registration message for the relayed UE, received from the relayed UE, to join the group communication,
receives, through the transceiver from the network node, a downlink signal based on a group communication scheme,
wherein the group communication scheme is determined to be a multimedia broadcast and multimedia service (MBMS) scheme if a number of UEs other than relayed UE among UEs registered in the network node for the group communication is equal to or greater than a reference value, and the group communication scheme is determined to be a unicast scheme if the number of the UEs other than the relayed UE is smaller than the reference value, and
wherein the relayed UE is implicitly announced to the network node by transmitting the second group communication registration message not including location information for the relayed UE, and
transmits, through the transceiver to the relayed UE, the downlink signal received from the network node.
12. A method for supporting a group communication based on proximity services (ProSe) by a network node in a wireless communication system, the method comprising:
receiving, from a relay User Equipment (UE) for performing a relay operation for a relayed UE communicating with the network node via the relay UE, a first group communication registration message for the relay UE, including location information of the relay UE, to join the group communication and a second group communication registration message for the relayed UE, transmitted from the relayed UE, to join the group communication;
determining a group communication scheme to be a multimedia broadcast and multimedia service (MBMS) scheme if a number of UEs other than the relayed UE among UEs registered in the network node for the group communication is equal to or greater than a reference value, and determining the group communication scheme to be a unicast scheme if the number of the UEs other than the relayed UE is smaller than the reference value,
wherein the relayed UE is implicitly announced to the network node by receiving the second group communication registration message not including location information for the relayed UE; and
transmitting, to the relay UE, a downlink signal based on the group communication scheme.