Patent ID: 11895737
Assignee: SAMSUNG ELECTRONICS CO., LTD.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method performed by a terminal in a communication system, the method comprising:
receiving, at a packet data convergence protocol (PDCP) entity associated with a signaling radio bearer (SRB) or a data radio bearer (DRB), a first PDCP data protocol data unit (PDU) from a lower layer, wherein the SRB is used for transmission of a radio resource control (RRC) message and the DRB is used for transmission of user plane data;
determining, at the PDCP entity, a first count value of the first PDCP data PDU based on a state variable used in the PDCP entity;
performing, at the PDCP entity, deciphering and integrity verification of the first PDCP data PDU based on the first count value;
in case that the integrity verification of the first PDCP data PDU is not failed, updating the state variable; and
in case that the integrity verification of the first PDCP data PDU fails, indicating a failure of the integrity verification to an upper layer and discarding the first PDCP data PDU, at the PDCP entity,
wherein, in case that the PDCP entity is associated with the SRB, a procedure for an RRC connection re-establishment is triggered based on the indication of the failure of the integrity verification,
wherein, in case that the PDCP entity is associated with the DRB, the discarded first PDCP data PDU is considered as not received at the PDCP entity, based on the indication of the failure of the integrity verification,
wherein the state variable is not updated based on considering the first PDCP data PDU as not received and a count value of a second PDCP data PDU which is received by the PDCP entity from the lower layer is determined as the first count value based on the state variable, and
wherein, in case that integrity verification performed for the second PDCP data PDU is not failed, the second PDCP data PDU is stored in a reception buffer.