Method and apparatus for group communication in proximity-based service

1. A method of supporting a group communication by a first user equipment (UE) in a wireless communication system, the method comprising:

establishing a communication connection with a second UE via a first relay UE; and

receiving, from the first relay UE, a message including a request for a relay connection, the message including first information indicating a current hop count, second information indicating a maximum number of allowed hops, and third information on a capacity profile which indicates a maximum number of allowed subordinated UEs,

wherein if a condition is satisfied, the relay connection is provided between the first relay UE and a third UE via a second relay UE, the second relay UE being the first UE,

wherein if the condition is not satisfied, the request for the relay connection is rejected, and

wherein the condition includes: the current hop count is less than the maximum number of allowed hops, and a number of UEs served by the first UE is less than the maximum number of allowed subordinated UEs.

2. The method of claim 1 , wherein the capacity profile further indicates a relay mode of the first UE, and the condition further includes: the relay mode allows that relay UEs are mutually served from each other.

3. The method of claim 1 , wherein fourth information indicating a cause for the relay connection is further received from a network node using a paging message, and the condition further includes: the cause for the relay connection is allowed by the first UE.

4. The method of claim 1 , wherein the message requesting the relay connection is received from the first relay UE using a physical shared channel, and the physical shared channel is scrambled using a group Identifier (ID) or a service ID.

5. The method of claim 4 , wherein the physical shared channel is scrambled using a scrambling sequence having an initialization value of the following expression:

c init =h· 2 13 +└n s /2┘·2 9 +ID

where c is the current hop number, h is a current hop count, n s is a slot number in a radio frame, ID is the group ID or the service ID, and └ ┘ is a flooring function.

6. A first user equipment (UE) configured to support a group communication in a wireless communication system, the first UE comprising:

a radio frequency (RF) unit; and

a processor operably coupled with the RF unit,

wherein the processor is configured to:

establish a communication connection with a second UE via a first relay UE, and

receive, from the first relay UE, a message including a request for a relay connection, the message including first information indicating a current hop count, second information indicating a maximum number of allowed hops, and third information on a capacity profile which indicates a maximum number of allowed subordinated UEs,

wherein if a condition is satisfied, the relay connection is provided between the first relay UE and a third UE via a second relay UE, the second relay UE being the first UE,

wherein if the condition is not satisfied, the request for the relay connection is rejected,

wherein the condition includes: the current hop count is less than the maximum number of allowed hops, and a number of UEs served by the first UE is less than the maximum number of allowed subordinated UEs.

7. The wireless device of claim 6 , wherein the capacity profile further indicates a relay mode of the first UE, and the condition further includes: the relay mode allows that relay UEs are mutually served from each other.

8. The first UE of claim 6 , wherein fourth information indicating a cause for the relay connection is further received from a network node using a paging message, and the condition further includes: the cause for the relay connection is allowed by the first UE.

9. The first UE of claim 6 , wherein the message requesting the relay connection is received from the first relay UE using a physical shared channel, and the physical shared channel is scrambled using a group Identifier (ID) or a service ID.

10. The first UE of claim 9 , wherein the physical shared channel is scrambled using a scrambling sequence having an initialization value of the following expression:

c init =h· 2 13 +└n s /2┘·2 9 +ID

where c is the current hop number, h is a current hop count, n s is a slot number in a radio frame, ID is the group ID or the service ID, and └ ┘ is a flooring function.