Detection of beginning of a transmission session in new radio unlicensed spectrum

1. A method, comprising:

detecting, by a processor of a user equipment (UE), presence of an indication from a base station of a wireless network in a New Radio unlicensed spectrum (NR-U);

determining, by the processor, that a transmission opportunity (TXOP) follows the indication responsive to the detecting;

receiving, by the processor, a downlink (DL) transmission in the NR-U from the base station during the TXOP;

monitoring, by the processor, some but not all of a plurality of orthogonal frequency-divisional multiplexing (OFDM) symbols in each slot to detect a leading physical downlink control channel (PDCCH) in a DL TXOP,

wherein the monitoring comprises:

monitoring according to a first PDCCH monitoring behavior during a phase of detection of a beginning of the DL TXOP; and

monitoring according to a second PDCCH monitoring behavior after the phase of detection of the beginning of the DL TXOP, the second PDCCH monitoring behavior being different from the first PDCCH monitoring behavior.

2. The method of claim 1 , wherein the indication comprises a preamble.

3. The method of claim 2 , wherein the preamble comprises a universal preamble used by a plurality of base stations of the wireless network for a same purpose of indicating a DL TXOP.

4. The method of claim 2 , wherein the preamble indicates an identity of the base station, a configuration of the TXOP, or both.

5. The method of claim 1 , wherein the monitoring of some but not all of the plurality of OFDM symbols in each slot comprises monitoring half of the plurality of OFDM symbols in each slot by monitoring every other OFDM symbol of the plurality of OFDM symbols in each slot.

6. The method of claim 1 , wherein the second PDCCH monitoring behavior is pre-configured or configured after the phase of detection of the beginning of the DL TXOP, and wherein, in an event that the second PDCCH monitoring behavior is configured after the phase of detection of the beginning of the DL TXOP, the second PDCCH monitoring behavior is configured via radio resource control (RRC) signaling or via a PDCCH in a detected DL TXOP.

7. The method of claim 1 , wherein the first PDCCH monitoring behavior comprises a first set of control resource set (CORESET) configurations and a first set of search space configurations, and wherein the second PDCCH monitoring behavior comprises one of:

a second set of CORESET configurations, which is different from the first set of CORESET configurations, and a second set of search space configurations, which is different from the first set of search space configurations;

the first set of CORESET configurations and the second set of search space configurations; or

the second set of CORESET configurations and the first set of search space configurations.

8. The method of claim 7 , wherein a resource element group (REG) size of the first set of CORESET configurations is larger than or equal to a REG size of the second set of CORESET configurations, wherein a duration of the first set of CORESET configurations is shorter than or equal to a duration of the second set of CORESET configurations, and wherein a bandwidth of the first set of CORESET configurations is smaller than or equal to a bandwidth of the second set of CORESET configurations.

9. The method of claim 7 , wherein a monitoring periodicity of the first set of search space configurations is shorter than or equal to a monitoring periodicity of the second set of search space configurations, wherein a PDCCH monitoring pattern of the first set of search space configurations is denser than or equal to a PDCCH monitoring pattern of the second set of search space configurations, and wherein a total number of PDCCH candidates of the first set of search space configurations is smaller than or equal to a total number of PDCCH candidates of the second set of search space configurations.

10. The method of claim 1 , wherein the monitoring to detect the leading PDCCH according to the first PDCCH monitoring behavior comprises detecting a beginning of a TXOP by performing one of:

monitoring a group common PDCCH;

detecting a demodulation reference signal (DMRS) of the group common PDCCH; or

detecting a preamble preceding the TXOP.

11. A method, comprising:

detecting, by a processor of a user equipment (UE), presence of an indication from a base station of a wireless network in a New Radio unlicensed spectrum (NR-U);

determining, by the processor, that a transmission opportunity (TXOP) follows the indication responsive to the detecting;

receiving, by the processor, a downlink (DL) transmission in the NR-U from the base station during the TXOP; and

monitoring, by the processor, to detect a leading physical downlink control channel (PDCCH) in a DL TXOP by:

buffering packets of an amount of received signal; and

decoding a physical downlink shared channel (PDSCH) in the buffered packets, the PDSCH preceding the leading PDCCH.

12. The method of claim 11 , wherein the monitoring comprises:

monitoring according to a first PDCCH monitoring behavior during a phase of detection of a beginning of the DL TXOP; and

monitoring according to a second PDCCH monitoring behavior after the phase of detection of the beginning of the DL TXOP, the second PDCCH monitoring behavior being different from the first PDCCH monitoring behavior.

13. The method of claim 12 , wherein the second PDCCH monitoring behavior is pre-configured or configured after the phase of detection of the beginning of the DL TXOP, and wherein, in an event that the second PDCCH monitoring behavior is configured after the phase of detection of the beginning of the DL TXOP, the second PDCCH monitoring behavior is configured via radio resource control (RRC) signaling or via a PDCCH in a detected DL TXOP.

14. The method of claim 12 , wherein the first PDCCH monitoring behavior comprises a first set of control resource set (CORESET) configurations and a first set of search space configurations, and wherein the second PDCCH monitoring behavior comprises one of:

a second set of CORESET configurations, which is different from the first set of CORESET configurations, and a second set of search space configurations, which is different from the first set of search space configurations;

the first set of CORESET configurations and the second set of search space configurations; or

the second set of CORESET configurations and the first set of search space configurations.

15. The method of claim 14 , wherein a resource element group (REG) size of the first set of CORESET configurations is larger than or equal to a REG size of the second set of CORESET configurations, wherein a duration of the first set of CORESET configurations is shorter than or equal to a duration of the second set of CORESET configurations, and wherein a bandwidth of the first set of CORESET configurations is smaller than or equal to a bandwidth of the second set of CORESET configurations.

16. The method of claim 14 , wherein a monitoring periodicity of the first set of search space configurations is shorter than or equal to a monitoring periodicity of the second set of search space configurations, wherein a PDCCH monitoring pattern of the first set of search space configurations is denser than or equal to a PDCCH monitoring pattern of the second set of search space configurations, and wherein a total number of PDCCH candidates of the first set of search space configurations is smaller than or equal to a total number of PDCCH candidates of the second set of search space configurations.

17. The method of claim 12 , wherein the monitoring to detect the leading PDCCH according to the first PDCCH monitoring behavior comprises detecting a beginning of a TXOP by performing one of:

monitoring a group common PDCCH;

detecting a demodulation reference signal (DMRS) of the group common PDCCH; or

detecting a preamble preceding the TXOP.

18. A method, comprising:

detecting, by a processor of a user equipment (UE), a leading physical downlink control channel (PDCCH) in a downlink (DL) transmission opportunity (TXOP) from a base station of a wireless network in a New Radio unlicensed spectrum (NR-U); and

receiving, by the processor, a DL transmission in the NR-U from the base station during the DL TXOP,

wherein the detecting comprises monitoring some but not all of a plurality of orthogonal frequency-divisional multiplexing (OFDM) symbols in each slot;

wherein the monitoring comprises:

monitoring according to a first PDCCH monitoring behavior during a phase of detection of a beginning of the DL TXOP; and

monitoring according to a second PDCCH monitoring behavior after the phase of detection of the beginning of the DL TXOP, the second PDCCH monitoring behavior being different from the first PDCCH monitoring behavior.