US 12,149,998 B2
Handover method performed by user equipment, and user equipment
Ningjuan Chang, Shanghai (CN); and Renmao Liu, Shanghai (CN)
Assigned to SHARP KABUSHIKI KAISHA, Sakai (JP)
Appl. No. 17/424,142
Filed by SHARP KABUSHIKI KAISHA, Sakai (JP)
PCT Filed Jan. 20, 2020, PCT No. PCT/CN2020/073181
§ 371(c)(1), (2) Date Jul. 19, 2021,
PCT Pub. No. WO2020/151653, PCT Pub. Date Jul. 30, 2020.
Claims priority of application No. 201910061161.4 (CN), filed on Jan. 22, 2019.
Prior Publication US 2022/0104089 A1, Mar. 31, 2022
Int. Cl. H04W 36/08 (2009.01); H04W 36/00 (2009.01); H04W 76/20 (2018.01); H04W 76/30 (2018.01)
CPC H04W 36/08 (2013.01) [H04W 36/0079 (2018.08); H04W 76/20 (2018.02); H04W 76/30 (2018.02)] 10 Claims
OG exemplary drawing
 
1. A User Equipment (UE), comprising:
receiving circuitry configured to receive a first Radio Resource Control (RRC) message for an RRC configuration from a source base station, and to receive a second RRC message including a release command from a target base station; and
handover circuitry configured to apply the RRC configuration based on the first RRC message in which separate indications are configured for Data Radio Bearers (DRBs), and to perform a source base station release based on the release command, wherein
the RRC configuration is applied before a successful completion of a random access procedure,
the application of the RRC configuration includes:
establishing a Medium Access Control (MAC) entity for the target base station,
for each of the DRBs configured with the separate indications, on a basis of a radio resource configuration dedicated information element carried in the first RRC message, establishing a Radio Link Control (RLC) entity for the target base station and reconfiguring a Packet Data Convergence Protocol (PDCP) entity to establish a security function, and
for a Signaling Radio Bearer (SRB), on the basis of the radio resource configuration dedicated information element carried in the first RRC message, establishing a PDCP entity for the target base station and establishing an RLC entity for the target base station,
the separate indications indicate that the UE maintains a source base station communication and a target base station communication during a handover for the DRBs,
the source base station release includes, for each of the DRBs, releasing an RLC entity for the source base station, and releasing a security function for the source base station, and
for each of the DRBs, the release command causes a PDCP layer to send a PDCP status report to the target base station.