Method and apparatus for supporting ue-to-network relay communication in a wireless communication system

Abstract

A method and device are disclosed from the perspective of a second UE. The second UE initiates a first procedure of establishing the one-to-one connection with the first UE for a unicast communication between the first UE and the second UE or for a UE-to-UE communication between the first UE and a third UE via the second UE or a second procedure of establishing the one-to-one connection with the first UE for a UE-to-Network communication between the first UE and a network node via the second UE. The second UE transmits a first PC5-S message to the first UE for completing the first procedure of establishing the one-to-one connection with the first UE for the unicast communication or the UE-to-UE communication if the first procedure is initiated, wherein the first PC5-S message includes QoS information for the unicast communication or the UE-to-UE communication.

1 . A method for a second User Equipment (UE) to establish one-to-one connection between a first UE and the second UE, comprising:
 receiving a first PC5-S message from the first UE for initiating a procedure of establishing the one-to-one connection; and   transmitting a second PC5-S message to the first UE for completing the procedure of establishing the one-to-one connection, wherein a presence of Quality of Service (QoS) information in the second PC5-S message is defined as optional.   
     
     
         2 . The method of  claim 1 , wherein the second PC5-S message includes a QoS information if the one-to-one connection is used for a unicast communication between the first UE and the second UE or a UE-to-UE communication between the first UE and a third UE via the second UE, and the second PC5-S message does not include any QoS information if the one-to-one connection is used for a UE-to-Network communication between the first UE and a network node via the second UE. 
     
     
         3 . The method of  claim 1 , wherein the first PC5-S message is a Direct Communication Request message or a Direct Link Establishment Request message, and the second PC5-S message is a Direct Communication Accept message or a Direct Link Establishment Accept message. 
     
     
         4 . The method of  claim 1 , further comprising:
 transmitting a third PC5-S message to the first UE for establishing a security context between the first UE and the second UE in the procedure of establishing the one-to-one connection.   
     
     
         5 . The method of  claim 4 , wherein the third PC5-S message is a Security Mode Command message or a Direct Link Security Mode Command message. 
     
     
         6 . The method of  claim 1 , further comprising:
 receiving a fourth PC5-S message from the first UE for completing establishment of the security context in the procedure of establishing the one-to-one connection.   
     
     
         7 . The method of  claim 6 , wherein the fourth PC5-S message is a Security Mode Complete message or a Direct Link Security Mode Complete message. 
     
     
         8 . A second UE (User Equipment), 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 PC5-S message from a first UE for initiating a procedure of establishing a one-to-one connection between the first UE and the second UE; and 
 transmit a second PC5-S message to the first UE for completing the procedure of establishing the one-to-one connection, wherein a presence of Quality of Service (QoS) information in the second PC5-S message is defined as optional. 
   
     
     
         9 . The second UE of  claim 8 , wherein the second PC5-S message includes a QoS information if the one-to-one connection is used for a unicast communication between the first UE and the second UE or a UE-to-UE communication between the first UE and a third UE via the second UE, and the second PC5-S message does not include any QoS information if the one-to-one connection is used for a UE-to-Network communication between the first UE and a network node via the second UE. 
     
     
         10 . The second UE of  claim 8 , wherein the first PC5-S message is a Direct Communication Request message or a Direct Link Establishment Request message, and the second PC5-S message is a Direct Communication Accept message or a Direct Link Establishment Accept message. 
     
     
         11 . The second UE of  claim 8 , wherein the processor is further configured to execute a program code stored in the memory to:
 transmit a third PC5-S message to the first UE for establishing a security context between the first UE and the second UE in the procedure of establishing the one-to-one connection.   
     
     
         12 . The second UE of  claim 11 , wherein the third PC5-S message is a Security Mode Command message or a Direct Link Security Mode Command message. 
     
     
         13 . The second UE of  claim 8 , wherein the processor is further configured to execute a program code stored in the memory to:
 receive a fourth PC5-S message from the first UE for completing establishment of the security context in the procedure of establishing the one-to-one connection.   
     
     
         14 . The second UE of  claim 13 , wherein the fourth PC5-S message is a Security Mode Complete message or a Direct Link Security Mode Complete message.