A method for sending discovery reference signals, DRSs, in an NR unlicensed-carrier of a new radio unlicensed, NR-U, system, the method comprising: configuring, by a base station, a DRS, wherein the DRS is used for cell search, synchronization and measurement and wherein the DRS comprises a synchronization signal/physical broadcast channel, SS/PBCH, block, SSB, a control resource set, CORESET, and a physical downlink shared channel, PDSCH, wherein signals or channels in the DRS are limited to use a same subcarrier spacing, SCS, and wherein the SSB and the CORESET are multiplexed in time domain according to the multiplexing pattern 1 specified in 3GPP TS38.231-f00; determining, by the base station, a specified time window for sending the DRS, the specified time window is determined to be equal to 5 ms; configuring, by the base station, at least one candidate SSB position for sending the SSB in each slot of the specified time window, wherein a new candidate SSB position is configured in a time unit in which no candidate SSB position is defined in the specified time window, the time unit including one of a slot or an OFDM symbol, wherein SSB positions in the specified time window are indexed from 0 to L, wherein the indices from 0 to L1 refer to the SSB positions as specified in 3GPP TS38.231-f00 and further newly added candidate SSB positions in the specified time window are indexed consecutively from L1+1 to L, wherein when the carrier frequency is less than or equal to 3GHz, L1=3 and for SCS equal to 15 kHz, L=9, for SCS equal to 30 kHz, L=19, when the carrier frequency is greater than 3GHz and less than or equal to 6GHz, L1=7 and for SCS equal to 15 kHz, L=9, for SCS equal to 30 kHz, L=19, when the carrier frequency is greater than 6GHz, for SCS equal to 120 kHz or 240 kHz, L1 = 63 and L is an integer greater than or equal to 64, and wherein each SSB candidate position is a candidate position of the DRS and the DRS has the same sequence number as the SSB; and sending, by the base station, the DRS to a terminal at any configured SSB candidate position in the specified time window, wherein when a channel contention fails at a first configured SSB candidate position of the specified time window, a second configured SSB candidate position after the first configured SSB candidate position is set to a candidate position for sending the DRS. configuring, by a base station, a DRS, wherein the DRS is used for cell search, synchronization and measurement and wherein the DRS comprises a synchronization signal/physical broadcast channel, SS/PBCH, block, SSB, a control resource set, CORESET, and a physical downlink shared channel, PDSCH, wherein signals or channels in the DRS are limited to use a same subcarrier spacing, SCS, and wherein the SSB and the CORESET are multiplexed in time domain according to the multiplexing pattern 1 specified in 3GPP TS38.231-f00; determining, by the base station, a specified time window for sending the DRS, the specified time window is determined to be equal to 5 ms; configuring, by the base station, at least one candidate SSB position for sending the SSB in each slot of the specified time window, wherein a new candidate SSB position is configured in a time unit in which no candidate SSB position is defined in the specified time window, the time unit including one of a slot or an OFDM symbol, wherein SSB positions in the specified time window are indexed from 0 to L, wherein the indices from 0 to L1 refer to the SSB positions as specified in 3GPP TS38.231-f00 and further newly added candidate SSB positions in the specified time window are indexed consecutively from L1+1 to L, wherein when the carrier frequency is less than or equal to 3GHz, L1=3 and for SCS equal to 15 kHz, L=9, for SCS equal to 30 kHz, L=19, for SCS equal to 15 kHz, L=9, for SCS equal to 30 kHz, L=19, when the carrier frequency is greater than 3GHz and less than or equal to 6GHz, L1=7 and for SCS equal to 15 kHz, L=9, for SCS equal to 30 kHz, L=19, for SCS equal to 15 kHz, L=9, for SCS equal to 30 kHz, L=19, when the carrier frequency is greater than 6GHz, for SCS equal to 120 kHz or 240 kHz, L1 = 63 and L is an integer greater than or equal to 64, and wherein each SSB candidate position is a candidate position of the DRS and the DRS has the same sequence number as the SSB; and sending, by the base station, the DRS to a terminal at any configured SSB candidate position in the specified time window, wherein when a channel contention fails at a first configured SSB candidate position of the specified time window, a second configured SSB candidate position after the first configured SSB candidate position is set to a candidate position for sending the DRS.