Method and apparatus for configuring sidelink communication in a wireless communication system
A method and apparatus are disclosed from the perspective of a first UE (User Equipment) in RRC_CONNECTED to detect configuration failure. In one embodiment, the method includes the first UE transmitting a first PC5 RRC (Radio Resource Control) message to a second UE, wherein the first PC5 RRC message includes an AS (Access Stratum)-layer configuration for a unicast link established with the second UE. The method also includes the first UE transmitting a fourth RRC message to a network node if a configuration failure of the AS-layer configuration is detected, wherein the fourth RRC message indicates the configuration failure occurs.
1. A method for a first UE (User Equipment) to detect configuration failure, comprising:
transmitting a first PC5-S message to establish a unicast link with a second UE;
receiving a second PC5-S message from the second UE to complete establishment of the unicast link;
transmitting a first PC5 RRC (Radio Resource Control) message including configuration information to the second UE;
receiving a second PC5 RRC failure message directly from the second UE to indicate the second UE cannot comply with the configuration information; and
transmitting a RRC message to a network node to indicate a configuration failure in response to reception of the second PC5 RRC failure message, wherein the RRC message includes a specific failure cause value.
2. The method of claim 1 , wherein the first PC5 RRC message includes an AS (Access Stratum)-layer configuration for the unicast link.
3. The method of claim 2 , wherein the second UE cannot comply with the AS-layer configuration.
4. The method of claim 1 , further comprising:
transmitting a first RRC message to the network node, wherein the first RRC message includes a request for a SLRB (Sidelink Radio Bearer) configuration.
5. The method of claim 4 , further comprising:
receiving a second RRC message from the network node, wherein the second RRC message includes the SLRB configuration.
6. The method of claim 5 , further comprising:
transmitting a third RRC message to the network node, wherein the third RRC message is a complete message in response to reception of the second RRC message.
7. The method of claim 1 , wherein the specific failure cause value is a cause value indicating a configuration failure on the unicast link.
8. The method of claim 1 , wherein the network node is a base station.
9. The method of claim 1 , wherein the first PC5-S message is a Direct Communication Request message.
10. The method of claim 1 , wherein the second PC5-S message is a Direct Communication Accept message.
11. A first UE (User Equipment), comprising:
a processor; and
a memory operatively coupled to the processor, wherein the processor is configured to execute a program code to:
transmit a first PC5-S message to establish a unicast link with a second UE;
receive a second PC5-S message from the second UE to complete establishment of the unicast link;
transmit a first PC5 RRC (Radio Resource Control) message including configuration information to the second UE;
receive a second PC5 RRC failure message directly from the second UE to indicate the second UE cannot comply with the configuration information; and
transmit a RRC message to a network node to indicate a configuration failure in response to reception of the second PC5 RRC failure message, wherein the RRC message includes a specific failure cause value.
12. The first UE of claim 11 , wherein the first PC5 RRC message includes an AS (Access Stratum)-layer configuration for the unicast link.
13. The first UE of claim 12 , wherein the second UE cannot comply with the AS-layer configuration.
14. The first UE of claim 11 , wherein the processor is further configured to execute a program code to:
transmit a first RRC message to the network node, wherein the first RRC message includes a request for a SLRB (Sidelink Radio Bearer) configuration.
15. The first UE of claim 14 , wherein the processor is further configured to execute a program code to:
receive a second RRC message from the network node, wherein the second RRC message includes the SLRB configuration.
16. The first UE of claim 15 , wherein the processor is further configured to execute a program code to:
transmit a third RRC message to the network node, wherein the third RRC message is a complete message in response to reception of the second RRC message.
17. The first UE of claim 11 , wherein the specific failure cause value is a cause value indicating a configuration failure on the unicast link.
18. The first UE of claim 11 , wherein the network node is a base station.
19. The first UE of claim 11 , wherein the first PC5-S message is a Direct Communication Request message.
20. The first UE of claim 11 , wherein the second PC5-S message is a Direct Communication Accept message.