A method for Physical Downlink Control Channel, PDCCH, monitoring, performed by User Equipment, UE, comprising: being provided a first switching delay before a first switching step and after a first condition is fulfilled, wherein the first switching delay refers to a next available slot boundary that is at least N symbols later than a first starting position, wherein N is a positive integer, and the first starting position is a slot where a timer that has been set to a timer value expires; the first switching step, comprising: switching from monitoring a PDCCH of a serving cell according to a second Search Space Set, SSS, group to monitoring the PDCCH according to a first SSS group, under the first condition based on a time threshold and/or based on a Channel Occupancy Time, COT, duration acquired by a base station of a serving cell; being provided a second switching delay before a second switching step and after a second condition is fulfilled, wherein the second switching delay refers to another next available slot boundary that is at least N symbols later than a second starting position, and the second starting position is a last symbol of a detected PDCCH with a detected Downlink Control information, DCI, format 2_0; and the second switching step, comprising: switching from monitoring the PDCCH according to the first SSS group to monitoring the PDCCH according to the second SSS group, under the second condition based on a monitoring group flag in the detected DCI format 2_0, and/or a detection of a PDCCH by monitoring the PDCCH according to the first SSS group, wherein the time threshold is the timer value in a unit of slot, wherein under the first condition based on the time threshold comprises: a condition of after the timer that has been set to the timer value expires. being provided a first switching delay before a first switching step and after a first condition is fulfilled, wherein the first switching delay refers to a next available slot boundary that is at least N symbols later than a first starting position, wherein N is a positive integer, and the first starting position is a slot where a timer that has been set to a timer value expires; the first switching step, comprising: switching from monitoring a PDCCH of a serving cell according to a second Search Space Set, SSS, group to monitoring the PDCCH according to a first SSS group, under the first condition based on a time threshold and/or based on a Channel Occupancy Time, COT, duration acquired by a base station of a serving cell; being provided a second switching delay before a second switching step and after a second condition is fulfilled, wherein the second switching delay refers to another next available slot boundary that is at least N symbols later than a second starting position, and the second starting position is a last symbol of a detected PDCCH with a detected Downlink Control information, DCI, format 2_0; and the second switching step, comprising: switching from monitoring the PDCCH according to the first SSS group to monitoring the PDCCH according to the second SSS group, under the second condition based on a monitoring group flag in the detected DCI format 2_0, and/or a detection of a PDCCH by monitoring the PDCCH according to the first SSS group, wherein the time threshold is the timer value in a unit of slot, wherein under the first condition based on the time threshold comprises: a condition of after the timer that has been set to the timer value expires.