Method and apparatus for performing random access in wireless communication system

A base station (BS) in a wireless communication system, the BS comprising:

• a transceiver;
• and
• at least one processor configured to:
• control the transceiver to transmit, to a terminal, a radio resource control (RRC) reconfiguration message comprising a reconfiguration with synchronization,
• control the transceiver to receive, from the terminal, a first message comprising a cell radio network temporary identity (C-RNTI) medium access control (MAC) control element (CE) based on the reconfiguration with synchronization,
• identify whether the BS receives at least one of a physical random access channel (PRACH) or a physical uplink shared channel (PUSCH) via the first message,
• when the BS receives the PRACH and the PUSCH, control the transceiver to transmit, to the terminal, a third message comprising a first physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) comprising an absolute timing advance command MAC CE,
• when the BS receives the PRACH and does not receive the PUSCH, control the transceiver to transmit, to the terminal, a fallback random access response (RAR), and
• control the transceiver to transmit, to the terminal, a second PDCCH,
• wherein the second PDCCH is received by the terminal configured with a discontinuous reception (DRX) during active time, and
• wherein the active time comprises a time while the second PDCCH indicating a new transmission addressed to a C-RNTI corresponding to the C-RNTI MAC CE has not been received after determining by the terminal that a RAR reception is successful.

A method, performed by a terminal, in a wireless communication system, the method comprising:

• receiving, from a base station (BS), a radio resource control (RRC) reconfiguration message comprising a reconfiguration with synchronization;
• transmitting, to the BS, a first message comprising a physical random access channel (PRACH), a physical uplink shared channel (PUSCH), and a cell radio network temporary identity (C-RNTI) medium access control (MAC) control element (CE) based on the reconfiguration with synchronization,
• receiving, from the BS, a first physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH), wherein:
• for the case when the BS receives the PRACH and does not receive the PUSCH, the first PDCCH is a PDCCH addressed to random access RNTI (RA-RNTI) and the PDSCH includes a fallback random access response (RAR);
• and
• for the case when the BS receives the PUSCH, the first PDCCH is a PDCCH addressed to a C-RNTI corresponding to the C-RNTI MAC CE and the PDSCH includes an absolute timing advance command MAC CE,
• determining that a RAR reception is successful based on at least one of the fallback RAR or the PDSCH;
• when a discontinuous reception (DRX) is configured for the terminal via a RRC signalling, determining that active time for the DRX includes a time while a second PDCCH indicating new transmission addressed to the C-RNTI corresponding to the C-RNTI MAC CE has not been received after determining that the RAR reception is successful;
• and
• monitoring the second PDCCH during the active time.

A method, performed by a base station (BS), in a wireless communication system, the method comprising:

• transmitting, to a terminal, a radio resource control (RRC) reconfiguration message comprising a reconfiguration with synchronization;
• receiving, from the terminal, a first message comprising a cell radio network temporary identity (C-RNTI) medium access control (MAC) control element (CE) based on the reconfiguration with synchronization;
• identifying whether the BS receives at least one of a physical random access channel (PRACH) or a physical uplink shared channel (PUSCH) via the first message;
• when the BS receives the PRACH and the PUSCH, transmitting, to the terminal, a third message comprising a first physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) comprising an absolute timing advance command MAC CE;
• when the BS receives the PRACH and does not receive the PUSCH, transmitting, to the terminal, a fallback random access response (RAR);
• and
• transmitting, to the terminal, a second PDCCH,
• wherein the second PDCCH is received by the terminal configured with a discontinuous reception (DRX) during active time, and
• wherein the active time comprises a time while the second PDCCH indicating new transmission addressed to a C-RNTI corresponding to the C-RNTI MAC CE has not been received after determining by the terminal that a RAR reception is successful.