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 first User Equipment (UE) to establish one-to-one connection between the first UE and a second UE. In one embodiment, the method includes the first UE initiating a first procedure of establishing the one-to-one connection with the second 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 second UE for a UE-to-Network communication between the first UE and a network node via the second UE. The method also includes the first UE transmitting a first PC5-S message to the second UE for completing establishment of a first security context in the first procedure of establishing the one-to-one connection with the second UE for the unicast communication or the UE-to-UE communication if the first procedure is initiated, wherein the first PC5-S message includes Quality of Service (QoS) information for the unicast communication or the UE-to-UE communication. The method further includes the first UE transmitting a second PC5-S message to the second UE for completing establishment of a second security context in the second procedure of establishing the one-to-one connection with the second UE for the UE-to-Network communication if the second procedure is initiated, wherein the second PC5-S message does not include any QoS information for the UE-to-Network communication.

What is claimed is: 
     
         1 . A method of a first User Equipment (UE) for establishing a one-to-one connection between the first UE and a second UE, comprising:
 transmitting a first PC5 Signaling (PC5-S) message to the second UE for completing establishment of a first security context, wherein the first PC5-S message optionally includes Quality of Service (QoS) information for a unicast communication; and   transmitting a second PC5-S message to the second UE for completing establishment of a second security context, wherein the second PC5-S message does not include QoS information for a UE-to-Network relay communication.   
     
     
         2 . The method of  claim 1 , further comprising:
 transmitting a third PC5-S message to the second UE for establishing the one-to-one connection; and   receiving a fourth PC5-S message from the second UE for completing establishing the one-to-one connection.   
     
     
         3 . The method of  claim 2 , wherein the third PC5-S message is a Direct Communication Request message or a Direct Link Establishment Request message, and the fourth PC5-S message is a Direct Communication Accept message or a Direct Link Establishment Accept message. 
     
     
         4 . The method of  claim 1 , further comprising:
 receiving a fifth PC5-S message from the second UE for establishment of the first or the second security context.   
     
     
         5 . The method of  claim 4 , wherein the fifth PC5-S message is a Security Mode Command message or a Direct Link Security Mode Command message, and wherein the first or the second PC5-S message is a Security Mode Complete message or a Direct Link Security Mode Complete message. 
     
     
         6 . The method of  claim 1 , wherein a presence of a field used to indicate the QoS information in the first PC5-S message is defined as optional. 
     
     
         7 . The method of  claim 6 , wherein the field used to indicate the QoS information is present in the first PC5-S message. 
     
     
         8 . The method of  claim 1 , wherein a presence of a field used to indicate the QoS information in the second PC5-S message is defined as optional. 
     
     
         9 . The method of  claim 8 , wherein the field used to indicate the QoS information is absent in the second PC5-S message. 
     
     
         10 . A method for a first User Equipment (UE) to establish a one-to-one connection between the first UE and a second UE, comprising:
 transmitting a first PC5 Signaling (PC5-S) message to the second UE for initiating a procedure of establishing the one-to-one connection with the second UE;   receiving a second PC5-S message from the second UE for establishing a security context between the first UE and the second UE in the procedure of establishing the one-to-one connection;   transmitting a third PC5-S message to the second UE for completing establishment of the security context, wherein a field used to indicate Quality of Service (QoS) information in the third PC5-S message is defined as optional; and   receiving a fourth PC5-S message from the second UE for completing the procedure of establishing the one-to-one connection.   
     
     
         11 . The method of  claim 10 , wherein the third PC5-S message includes the field used to indicate QoS information when the one-to-one connection is used for a unicast communication between the first UE and the second UE, and the third PC5-S message does not include the field used to indicate QoS information when the one-to-one connection is used for a UE-to-Network relay communication between the first UE and a network node via the second UE. 
     
     
         12 . The method of  claim 10 , wherein the first PC5-S message is a Direct Communication Request message or a Direct Link Establishment Request message, and the fourth PC5-S message is a Direct Communication Accept message or a Direct Link Establishment Accept message. 
     
     
         13 . The method of  claim 10 , wherein the second PC5-S message is a Security Mode Command message or a Direct Link Security Mode Command message, and the third PC5-S message is a Security Mode Complete message or a Direct Link Security Mode Complete message. 
     
     
         14 . A first User Equipment (UE) configured to establish a one-to-one connection between the first UE and a second UE, comprising:
 a memory; and   a processor operatively connected to the memory, wherein the processor is configured to execute a program code to:
 transmit a first PC5 Signaling (PC5-S) message to the second UE for completing establishment of a first security context, wherein the first PC5-S message optionally includes Quality of Service (QoS) information for a unicast communication; and 
 transmit a second PC5-S message to the second UE for completing establishment of a second security context, wherein the second PC5-S message does not include QoS information for a UE-to-Network relay communication. 
   
     
     
         15 . The first UE of  claim 14 , wherein the processor is further configured to execute a program code to:
 transmit a third PC5-S message to the second UE for establishing the one-to-one connection; and   receive a fourth PC5-S message from the second UE for completing establishing the one-to-one connection.   
     
     
         16 . The first UE of  claim 15 , wherein the third PC5-S message is a Direct Communication Request message or a Direct Link Establishment Request message, and the fourth PC5-S message is a Direct Communication Accept message or a Direct Link Establishment Accept message. 
     
     
         17 . The first UE of  claim 14 , wherein the processor is further configured to execute a program code to:
 receive a fifth PC5-S message from the second UE for establishing the first or the second security context for the one-to-one connection.   
     
     
         18 . The first UE of  claim 17 , wherein the fifth PC5-S message is a Security Mode Command message or a Direct Link Security Mode Command message, and wherein the first or the second PC5-S message is a Security Mode Complete message or a Direct Link Security Mode Complete message. 
     
     
         19 . The first UE of  claim 14 , wherein a presence of a field used to indicate the QoS information in the first PC5-S message is defined as optional and the field used to indicate the QoS information is present in the first PC5-S message. 
     
     
         20 . The first UE of  claim 14 , wherein a presence of a field used to indicate QoS information in the second PC5-S message is defined as optional and the field used to indicate QoS information is absent in the second PC5-S message.