Method for transmitting or receiving signal in wireless communication system and apparatus therefor

1. A method of receiving a physical downlink control channel (PDCCH) signal by a user equipment (UE) in a wireless communication system, the method comprising:

determining the number of blind decodings and the number of control channel elements (CCEs) for channel estimation, related to a plurality of search space sets to be monitored during one slot by the UE;

based on that the determined number of blind decodings exceeds a blind decoding limit or the determined number of CCEs exceeds a channel estimation limit, dropping at least one of PDCCH candidates included in the plurality of search space sets; and

attempting to detect a PDCCH signal based on remaining non-dropped PDCCH candidates among the PDCCH candidates,

wherein the UE drops the at least one PDCCH candidate from the plurality of search space sets in a round-robin manner until both the blind decoding limit and the channel estimation limit are satisfied.

2. The method according to claim 1 , wherein the UE drops a PDCCH candidate in a descending order of aggregation levels in each search space set.

3. The method according to claim 2 , wherein the search space set satisfies a nested structure in which a PDCCH candidate is included in a PDCCH candidate of a higher aggregation level than an aggregation level of the PDCCH candidate.

4. The method according to claim 1 , wherein each search space set includes a default PDCCH candidate which is not allowed to be dropped, and

wherein the UE determines the default PDCCH based on at least one of a PDCCH candidate index or a UE identifier (ID).

5. The method according to claim 1 , wherein the UE attempts to detect both a PDCCH signal in a first cell and a PDCCH signal in a second cell in the same search space set.

6. The method according to claim 5 , wherein PDCCH candidates in the first cell are paired with PDCCH candidates in the second cell in the same search space set, and

wherein the UE determines whether to drop PDCCH candidates on a pair basis.

7. The method according to claim 5 , wherein the UE determines which one of the PDCCH candidate in the first cell and the PDCCH candidate in the second cell is to be dropped based on cell indexes in the same search space set.

8. A method of transmitting a physical downlink control channel (PDCCH) signal by a base station (BS) in a wireless communication system, the method comprising:

determining the number of blind decodings and the number of control channel elements (CCEs) for channel estimation, related to a plurality of search space sets to be monitored during one slot by a user equipment (UE);

based on that the determined number of blind decodings exceeds a blind decoding limit or the determined number of CCEs exceeds a channel estimation limit, dropping at least one of PDCCH candidates included in the plurality of search space sets; and

transmitting a PDCCH signal based on remaining PDCCH non-dropped candidates among the PDCCH candidates,

wherein the BS drops the at least one PDCCH candidate from the plurality of search space sets in a round-robin manner until both the blind decoding limit and the channel estimation limit are satisfied.

9. The method according to claim 8 , wherein the BS drops a PDCCH candidate in a descending order of aggregation levels in each search space set.

10. The method according to claim 9 , wherein the search space set satisfies a nested structure in which a PDCCH candidate is included in a PDCCH candidate of a higher aggregation level than an aggregation level of the PDCCH candidate.

11. The method according to claim 8 , wherein each search space set includes a default PDCCH candidate which is not allowed to be dropped, and

wherein the BS determines the default PDCCH based on at least one of a PDCCH candidate index or a UE identifier (ID).

12. The method according to claim 8 , wherein the BS configures the UE to attempt to detect both a PDCCH signal in a first cell and a PDCCH signal in a second cell in the same search space set.

13. The method according to claim 12 , wherein PDCCH candidates in the first cell are paired with PDCCH candidates in the second cell in the same search space set, and

wherein the BS determines whether to drop PDCCH candidates on a pair basis.

14. The method according to claim 12 , wherein the BS determines which one of the PDCCH candidate in the first cell and the PDCCH candidate in the second cell is to be dropped based on cell indexes in the same search space set.

15. A user equipment (UE) for receiving a physical downlink control channel (PDCCH) signal in a wireless communication system, the UE comprising:

a transceiver; and

a processor configured to determine the number of blind decodings and the number of control channel elements (CCEs) for channel estimation, related to a plurality of search space sets to be monitored during one slot by the UE, drop at least one of PDCCH candidates included in the plurality of search space sets, based on that the determined number of blind decodings exceeds a blind decoding limit or the determined number of CCEs exceeds a channel estimation limit, and attempt to detect a PDCCH signal based on remaining non-dropped PDCCH candidates among the PDCCH candidates,

wherein the processor is configured to drop the at least one PDCCH candidate from the plurality of search space sets in a round-robin manner until both the blind decoding limit and the channel estimation limit are satisfied.

16. The UE according to claim 15 , wherein the UE is capable of communicating with at least one of another UE, a UE related to an autonomous driving vehicle, a base station or a network.