A method performed by a user equipment, UE , in a wireless communication system, the method comprising: receiving configuration information related to a message A comprising a physical random access channel, PRACH, preamble, a physical uplink shared channel, PUSCH, and a demodulation reference signal, DM-RS, for the PUSCH; performing a 2-step random access procedure; after performing the 2-step random access procedure, monitoring a physical downlink control channel, PDCCH, in an on duration based on configured discontinuous reception, DRX; and receiving a physical downlink shared channel, PDSCH, based on the PDCCH, wherein performing the 2-step random access procedure comprises: transmitting the message A based on the configuration information; and in response to the message A, receiving a message B comprising a random access response, RAR, wherein a scrambling sequence for scrambling the PUSCH is initialized based on a random access-radio network temporary identifier, RA-RNTI, a random access preamble identifier, RAPID, of the PRACH preamble and a certain value, wherein the certain value is configured by a higher layer parameter, wherein the PRACH preamble is included in a first plurality of PRACH preambles which are mapped to a first plurality of valid PUSCH occasions among a plurality of valid PUSCH occasions, and wherein a PRACH preamble included in a second plurality of PRACH preambles which are not mapped to any of the first plurality of valid PUSCH occasions is available to be transmitted. receiving configuration information related to a message A comprising a physical random access channel, PRACH, preamble, a physical uplink shared channel, PUSCH, and a demodulation reference signal, DM-RS, for the PUSCH; performing a 2-step random access procedure; after performing the 2-step random access procedure, monitoring a physical downlink control channel, PDCCH, in an on duration based on configured discontinuous reception, DRX; and receiving a physical downlink shared channel, PDSCH, based on the PDCCH, wherein performing the 2-step random access procedure comprises: transmitting the message A based on the configuration information; and in response to the message A, receiving a message B comprising a random access response, RAR, wherein a scrambling sequence for scrambling the PUSCH is initialized based on a random access-radio network temporary identifier, RA-RNTI, a random access preamble identifier, RAPID, of the PRACH preamble and a certain value, wherein the certain value is configured by a higher layer parameter, wherein the PRACH preamble is included in a first plurality of PRACH preambles which are mapped to a first plurality of valid PUSCH occasions among a plurality of valid PUSCH occasions, and wherein a PRACH preamble included in a second plurality of PRACH preambles which are not mapped to any of the first plurality of valid PUSCH occasions is available to be transmitted. transmitting the message A based on the configuration information; and in response to the message A, receiving a message B comprising a random access response, RAR, wherein a scrambling sequence for scrambling the PUSCH is initialized based on a random access-radio network temporary identifier, RA-RNTI, a random access preamble identifier, RAPID, of the PRACH preamble and a certain value, wherein the certain value is configured by a higher layer parameter, wherein the PRACH preamble is included in a first plurality of PRACH preambles which are mapped to a first plurality of valid PUSCH occasions among a plurality of valid PUSCH occasions, and wherein a PRACH preamble included in a second plurality of PRACH preambles which are not mapped to any of the first plurality of valid PUSCH occasions is available to be transmitted. <EOS>