Method and apparatus for inter-UE coordination in SL CA
Methods and apparatuses for inter-user equipment (UE) coordination in sidelink (SL) carrier aggregation (CA) in a wireless communication system. A method of operating a UE includes: receiving, from a base station (BS), configuration information about multiple SL carriers for a SL CA operation; determining whether a SL radio link failure (RLF) is detected for a SL carrier among the multiple SL carriers; and starting a timer for the SL carrier based on a determination that the SL RLF is detected, wherein an activation or a deactivation of the SL carrier is determined based on a status of the timer.
1 . A user equipment (UE) comprising:
a transceiver configured to receive, from a base station (BS), configuration information about multiple sidelink (SL) carriers for a SL carrier aggregation (CA) operation; and
a processor operably coupled to the transceiver, the processor configured to:
determine whether a SL radio link failure (RLF) is detected for a SL carrier among the multiple SL carriers, and
start a timer for the SL carrier based on a determination that the SL RLF is detected, wherein an activation or a deactivation of the SL carrier is determined based on a status of the timer.
2 . The UE of claim 1 , wherein:
the transceiver is further configured to receive, via a UE dedicated radio resource control (RRC) message or system information, information about the multiple SL carriers and the timer, or
the processor is further configured to identify the multiple SL carriers and the timer based on predetermined parameters.
3 . The UE of claim 1 , wherein the processor is further configured to identify the multiple SL carriers based on a destination layer 2 (L2) identification (ID).
4 . The UE of claim 1 , wherein the processor is further configured to identify the multiple SL carriers based on a set of parameters associated with a required quality of service (QoS).
5 . The UE of claim 1 , wherein:
the transceiver is further configured to receive a value for a threshold number of consecutive hybrid automatic repeat request (HARQ) discontinuous transmission (DTX); and
the processor is further configured to detect the SL RLF of the SL carrier based on a comparison between an actual number of consecutive HARQ DTX and the threshold number of consecutive HARQ DTX.
6 . The UE of claim 1 , wherein the transceiver is further configured to transmit, to a peer UE via a PC5-RRC message or a SL medium access control control element (MAC CE), a SL carrier deactivation signal or a SL carrier release signal for the SL carrier.
7 . The UE of claim 1 , wherein the processor is further configured to:
determine the status of the timer;
determine that the SL carrier is activated or configured based on a determination that the status of the timer is not running;
determine that the SL carrier is deactivated or released based on a determination that the status of the timer is running;
maintain a PC5-RRC connection based on a determination that at least one SL carrier among the multiple SL carriers is activated or configured; and
release the PC5-RRC connection based on a determination that each SL carrier among the multiple SL carriers is released or deactivated.
8 . The UE of claim 1 , wherein the processor is further configured to not start the timer for the SL carrier when the SL RLF is detected based on at least one of:
a maximum number of radio link control (RLC) retransmissions;
expiry of timer 400 (T400); or
an integrity check failure for a destination layer 2 (L2) identification (ID).
9 . A method of a user equipment (UE), the method comprising:
receiving, from a base station (BS), configuration information about multiple sidelink (SL) carriers for a SL carrier aggregation (CA) operation;
determining whether a SL radio link failure (RLF) is detected for a SL carrier among the multiple SL carriers; and
starting a timer for the SL carrier based on a determination that the SL RLF is detected, wherein an activation or a deactivation of the SL carrier is determined based on a status of the timer.
10 . The method of claim 9 , further comprising:
receiving, via a UE dedicated radio resource control (RRC) message or system information, information about the multiple SL carriers and the timer, or
identifying the multiple SL carriers and the timer based on predetermined parameters.
11 . The method of claim 9 , further comprising identifying the multiple SL carriers based on a destination layer 2 (L2) identification (ID).
12 . The method of claim 9 , further comprising identifying the multiple SL carriers based on a set of parameters associated with a required quality of service (QoS).
13 . The method of claim 9 , further comprising:
receiving a value for a threshold number of consecutive hybrid automatic repeat request (HARQ) discontinuous transmission (DTX); and
detecting the SL RLF of the SL carrier based on a comparison between an actual number of consecutive HARQ DTX and the threshold number of consecutive HARQ DTX.
14 . The method of claim 9 , further comprising transmitting, to a peer UE via a PC5-RRC message or a SL medium access control control element (MAC CE), a SL carrier deactivation signal or a SL carrier release signal for the SL carrier.
15 . The method of claim 9 , further comprising:
determining the status of the timer;
determining that the SL carrier is activated or configured, based on a determination that the status of the timer is not running;
determining that the SL carrier is deactivated or released based on a determination that the status of the timer is running;
maintaining a PC5-RRC connection based on a determination that at least one SL carrier among the multiple SL carriers is activated or configured; and
releasing the PC5-RRC connection based on a determination that each SL carrier among the multiple SL carriers is released or deactivated.
16 . The method of claim 9 , further comprising not starting the timer for the SL carrier when the SL RLF is detected based on at least one of:
a maximum number of radio link control (RLC) retransmissions;
expiry of timer 400 (T400); or
an integrity check failure for a destination layer 2 (L2) identification (ID).
17 . A base station (BS) comprising:
a processor configured to generate configuration information about multiple sidelink (SL) carriers; and
a transceiver operably coupled to the processor, the transceiver configured to transmit, to a use equipment (UE), the configuration information about the multiple SL carriers for a SL carrier aggregation (CA) operation,
wherein:
a detection of SL radio link failure (RLF) is determined based on the configuration information, for a SL carrier among the multiple SL carriers, and
a timer for the SL carrier is started based on a determination when the SL RLF is detected, wherein an activation or a deactivation of the SL carrier being determined based on a status of the timer.
18 . The BS of claim 17 , wherein the transceiver is further configured to transmit, via a UE dedicated radio resource control (RRC) message or system information, information about the multiple SL carriers and the timer.
19 . The BS of claim 17 , wherein:
the transceiver is further configured to transmit a value for a threshold number of consecutive hybrid automatic repeat request (HARQ) discontinuous transmission (DTX); and
the SL RLF of the SL carrier is detected based on a comparison between an actual number of consecutive HARQ DTX and the threshold number of consecutive HARQ DTX.
20 . The BS of claim 17 , wherein:
the multiple SL carriers are identified based on a destination layer 2 (L2) identification (ID) or
the multiple SL carriers are determined based on a set of parameters associated with a required quality of service (QoS).