Method and apparatus for supporting RACH-less mobility with pre-allocated beams in wireless communication system
摘要
說明書
In step S1000, the UE receives a mobility command message which includes information on a pre-allocated UL resource for UL transmission with pre-allocated beams. In step S1010, the UE synchronizes to a target cell. In step S1020, the UE performs the UL transmission to the target cell via the pre-allocated beams based on the pre-allocated UL resource for UL transmission to transmit a mobility complete message via a UL grant.
The information on the pre-allocated UL resource may be a pre-allocated UL grant, and the UL transmission may be a PUSCH transmission. In this case, the pre-allocated UL resource may be UL resource for the PUSCH transmission which is pre-allocated based on the pre-allocated UL grant.
The UE may determine that a quality of the pre-allocated beams meets the criterion. The criterion may be indicated by the target cell. In this case, the UE may perform initial PUSCH transmission and/or a PUSCH retransmission for a MAC PDU including the mobility complete message to the target cell via at least one beam among the pre-allocated beams based on the pre-allocated UL grant in response to the mobility command message. The UE may perform PUSCH retransmission of the MAC PDU including the mobility complete message to the target cell via another beam among the pre-allocated beams based on the pre-allocated UL grant, until an acknowledgment is received and/or the maximum number of retransmissions is reached.
When the UE determines that there is no pre-allocated beam of which quality meets the criterion, the UE may perform a random access procedure towards the target cell. In the random access procedure, the UE may transmit a RACH preamble with a beam and then may (re-)transmit the MAC PDU upon receiving a random access response in response to the RACH preamble.
