Method and apparatus for relay user equipment (UE) adding multiple target end UEs for UE-to-UE relay communication in a wireless communication system

A relay User Equipment (UE), comprising:

• a control circuit;
• a processor installed in the control circuit;
• and
• a memory installed in the control circuit and operatively coupled to the processor;
• wherein the processor is configured to execute a program code stored in the memory to:
• receive a first message from a source end UE, wherein the first message is to establish a 1st hop PC5 connection with the relay UE for supporting UE-to-UE (U2U) relay communication with any target end UE;
• establish at least a first 2nd hop PC5 connection with a first target end UE for supporting the U2U relay communication with the source end UE;
• send, in response to completion of the first 2nd hop PC5 connection, a second message to the source end UE, wherein the second message is to complete establishment of the 1st hop PC5 connection;
• establish a second 2nd hop PC5 connection with a second target end UE for supporting the U2U relay communication with the source end UE;
• and
• send, in response to completion of the second 2nd hop PC5 connection, a third message to the source end UE for request of modifying the 1st hop PC5 connection to add the second target end UE for the U2U relay communication.

A method for a relay User Equipment (UE), comprising:

• the relay UE receives a first message from a source end UE, wherein the first message is to establish a 1st hop PC5 connection with the relay UE for supporting UE-to-UE (U2U) relay communication with any target end UE;
• the relay UE establishes a first 2nd hop PC5 connection with a first target end UE for supporting the U2U relay communication with the source end UE;
• the relay UE establishes a second 2nd hop PC5 connection with a second target end UE for supporting the U2U relay communication with the source end UE;
• and
• the relay UE sends a second message to the source end UE, wherein the second message is to complete establishment of the 1st hop PC5 connection and includes a user info of the first target end UE and a user info of the second target end UE.

A relay User Equipment (UE), comprising:

• a control circuit;
• a processor installed in the control circuit;
• and
• a memory installed in the control circuit and operatively coupled to the processor;
• wherein the processor is configured to execute a program code stored in the memory to:
• receive a first message from a source end UE, wherein the first message is to establish a 1st hop PC5 connection with the relay UE for supporting UE-to-UE (U2U) relay communication with any target end UE;
• establish a first 2nd hop PC5 connection with a first target end UE for supporting the U2U relay communication with the source end UE;
• establish a second 2nd hop PC5 connection with a second target end UE for supporting the U2U relay communication with the source end UE;
• and
• send a second message to the source end UE, wherein the second message is to complete establishment of the 1st hop PC5 connection and includes a user info of the first target end UE and a user info of the second target end UE.