Channel access enhancements for ultra-reliable low-latency communication (URLLC) in unlicensed spectrum
Embodiments of a user equipment (UE) configurable for unlicensed band operation in a 5G NR system (5GS), when operating in semi-static channel access mode, for a UE-initiated channel-occupancy time (COT), is configured to transmit an uplink (UL) transmission burst, as an initiating device, starting at a beginning of fixed frame period (FFP) and ending at a symbol before an idle period of the FFP after a successful clear-channel assessment (CCA).
1. An apparatus of a user equipment (UE) configurable for unlicensed band operation in a fifth-generation new radio (SG NR) system (5GS), the apparatus comprising: processing circuitry; and memory,
wherein when operating in semi-static channel access mode, the processing circuitry is configured to:
decode downlink control information (DCI) that schedules an uplink grant for a physical uplink shared channel (PUSCH), the DCI indicating whether the uplink grant is to be performed with a UE-initiated channel-occupancy time (COT) or with a generation Node B (gNB) initiated COT that is to be shared with the UE,
wherein when the DCI indicates that the uplink grant is to be performed for the VE initiated COT, the processing circuitry is configured to cause the UE to transmit an uplink (UL) transmission burst carrying the PUSCH, as an initiating device, starting at a beginning of fixed frame period (FFP) and ending at a symbol before an idle period of the FFP after a successful clear-channel assessment (CCA),
wherein when the DCI indicates that the uplink grant is to be performed with the gNB-initiated COT that is to be shared with the UE, the processing circuitry is configured to cause the UE to transmit the UL transmission burst carrying the PUSCH within a predetermined time period after detection of a downlink (DL) transmission burst within the gNB-initiated COT without first performing the CCA,
wherein the UL transmission burst within the gNB-initiated COT indicates a time-domain resource utilization by the UE within the gNB-initiated COT.
2. The apparatus of claim 1 , wherein in the semi-static channel access mode, the processing circuitry is configured to:
decode radio-resource control (RRC) signalling received from a generation node B (gNB) to determine the FFP for the UE-initiated COT, the FFP having a periodicity comprising one of 1 millisecond (ms), 2 ms, 2.5 ms, 4 ms, Sms and 10 ms.
3. The apparatus of claim 2 , wherein the periodicity of the FFP for the UE-initiated COT (UE FFP) is configurable to be an integer multiple of or inter-factor of a periodicity of an FFP for the gNB-initiated COT (gNB FFP).
4. The apparatus of claim 3 , wherein an offset between the FFP for the UE-initiated COT (UE FFP) and the FFP for the gNB-initiated COT (gNB FFP) is a starting point of a first UE FFP relative to a radio frame boundary.
5. The apparatus of claim 4 , wherein when a configured UL transmission is aligned with a UE FFP boundary and ends before an idle period of the UE FFP, the UE is configured to assume that a scheduled UL transmission is to be performed as if the UE is the initiating device unless:
the scheduled UL transmission is confined within the gNB FFP before an idle period of the gNB FFP; and
the UE has determined that the gNB has initiated the gNB FFP.
6. The apparatus of claim 5 , wherein when the scheduled UL transmission is to start after the UE FFP boundary and ends before the idle period of the UE FFP, the UE is configured to assume that the scheduled UL transmission is to be performed as if the UE is the initiating device when the UE has already initiated the UE FFP by transmission of an earlier UL burst starting from the UE FFP boundary after successfully performing the CCA; and
wherein when the scheduled UL transmission is to start after the UE FFP boundary and ends before the idle period of the UE FFP, the UE is configured to assume that the scheduled UL transmission corresponds to a gNB-initiated COT when the scheduled UL transmission is confined within the gNB FFP before the idle period of the gNB FFP and when the UE has determined that the gNB has initiated the gNB FFP.
7. The apparatus of claim 5 , wherein the processing circuitry is configured to determine whether the scheduled UL transmission belongs to the UE-initiated COT or to the gNB-initiated COT based on whether the scheduled UL transmission is confined within the gNB FFP and ends before an idle period of the gNB-initiated COT, and whether the gNB FFP 1 s active.
8. The apparatus of claim 1 , wherein the processing circuitry is to configure the UE to perform a CCA within an idle period immediately before a start of the UE-initiated COT, and
wherein the processing circuitry is to further configure the UE to perform the CCA before an UL transmission within the UE-initiated COT if a gap with a prior burst is larger than a predefined time period, and
wherein the UE is configured to assume that the CCA is successful if the channel is assessed to be idle within at least a predetermined observations period.
9. The apparatus of claim 1 , wherein the processing circuitry is configured to decode a system information block 1 (SIB1), the SIB1 to include the FFP for the UE-initiated COT (UE FFP),
wherein in response to the SIB1, the processing circuitry is to configure the UE in the semi-static channel access mode when the SIB1 indicates an FFP for the gNB-initiated COT (gNB FFP), and
wherein the processing circuitry is to configure the UE to operate as the initiating device when configured in the semi-static channel access mode and is to configure the UE to refrain from operating as the initiating device when not configured in the semi-static channel access mode.
10. A non-transitory computer-readable storage medium that stores instructions for execution by processing circuitry of a user equipment (UE) configurable for unlicensed band operation in a 5G NR system (5GS),
wherein when operating in semi-static channel access mode, the processing circuitry is configured to:
decode downlink control information (DCI) that schedules an uplink grant for a physical uplink shared channel (PUSCH), the DCI indicating whether the uplink grant is to be performed with a UE-initiated channel-occupancy time (COT) or with a generation Node B (gNB) initiated COT that is to be shared with the UE,
wherein when the DCI indicates that the uplink grant is to be performed for the VE initiated COT, the processing circuitry is configured to cause the UE to transmit an uplink (UL) transmission burst carrying the PUSCH, as an initiating device, starting at a beginning of fixed frame period (FFP) and ending at a symbol before an idle period of the FFP after a successful clear-channel assessment (CCA),
wherein when the DCI indicates that the uplink grant is to be performed with the gNB-initiated COT that is to be shared with the UE, the processing circuitry is configured to cause the UE to transmit the UL transmission burst carrying the PUSCH within a predetermined time period after detection of a downlink (DL) transmission burst within the gNB-initiated COT without first performing the CCA,
wherein the UL transmission burst within the gNB-initiated COT indicates a time-domain resource utilization by the UE within the gNB-initiated COT.
11. The non-transitory computer-readable storage medium of claim 10 , wherein in the semi-static channel access mode, the processing circuitry is configured to:
decode radio-resource control (RRC) signalling received from a generation node B (gNB) to determine the FFP for the UE-initiated COT, the FFP having a periodicity comprising one of 1 millisecond (ms), 2 ms, 2.5 ms, 4 ms, Sms and 10 ms.
12. The non-transitory computer-readable storage medium of claim 11 , wherein the periodicity of the FFP for the UE-initiated COT (UE FFP) is configurable to be an integer multiple of or inter-factor of a periodicity of an FFP for the gNB-initiated COT (gNB FFP).
13. The non-transitory computer-readable storage medium of claim 12 , wherein an offset between the FFP for the UE-initiated COT (UE FFP) and the FFP for the gNB-initiated COT (gNB FFP) is a starting point of a first UE FFP relative to a radio frame boundary.
14. The non-transitory computer-readable storage medium of claim 13 , wherein when a configured UL transmission is aligned with a UE FFP boundary and ends before an idle period of the UE FFP, the UE is configured to assume that a scheduled UL transmission is to be performed as if the UE is the initiating device unless:
the scheduled UL transmission is confined within the gNB FFP before an idle period of the gNB FFP; and
the UE has determined that the gNB has initiated the gNB FFP.
15. The non-transitory computer-readable storage medium of claim 14 , wherein when the scheduled UL transmission is to start after the UE FFP boundary and ends before the idle period of the UE FFP, the UE is configured to assume that the scheduled UL transmission is to be performed as if the UE is the initiating device when the UE has already initiated the UE FFP by transmission of an earlier UL burst starting from the UE FFP boundary after successfully performing the CCA; and
wherein when the scheduled UL transmission is to start after the UE FFP boundary and ends before the idle period of the UE FFP, the UE is configured to assume that the scheduled UL transmission corresponds to the gNB-initiated COT when the scheduled UL transmission is confined within a gNB FFP before the idle period of the gNB FFP and when the UE has determined that the gNB has initiated the gNB FFP.
16. The non-transitory computer-readable storage medium of claim 14 , wherein the processing circuitry is configured to determine whether the scheduled UL transmission belongs to the UE-initiated COT or to the gNB-initiated COT based on whether the scheduled UL transmission is confined within the gNB FFP and ends before an idle period of the gNB-initiated COT, and whether the gNB FFP is active.
17. The non-transitory computer-readable storage medium of claim 10 , wherein the processing circuitry is to configure the UE to perform a CCA within an idle period immediately before a start of the UE-initiated COT, and
wherein the processing circuitry is to further configure the UE to perform the CCA before an UL transmission within the UE-initiated COT if a gap with a prior burst is larger than a predefined time period, and
wherein the UE is configured to assume that the CCA is successful if the channel is assessed to be idle within at least a predetermined observations period.
18. An apparatus of a generation node B (gNB) configurable for unlicensed band operation in a 5G NR system (5GS), the apparatus comprising: processing circuitry; and memory,
wherein the processing circuitry is configured to encode a system information block 1 (SIB1), the SIB1 encoded to include a fixed frame period (FFP) for a user equipment (UE) UE-initiated channel-occupancy time (COT) (UE FFP);
wherein to configure the UE to operate in a semi-static channel access mode, the processing circuity is to encode the SIB1 to further indicate an FFP for a gNB-initiated COT (gNB FFP),
wherein the processing circuitry is further configured to encode downlink control information (DCI) that schedules an uplink grant for a physical uplink shared channel (PUSCH), the DCI indicating whether the uplink grant is to be performed with the UE-initiated channel-occupancy time (COT) or with the gNB initiated COT that is to be shared with the UE;
wherein when the DCI is encoded to indicate that the uplink grant is to be performed for the UE initiated COT, and when the UE is configured to operate in the semi-static channel access mode, the gNB is configured to receive an uplink (UL) transmission burst from the UE operating as an initiating device, the UL transmission burst starting at a beginning of the UE FFP after a successful clear-channel assessment (CCA) by the UE,
wherein when the DCI is encoded to indicate that the uplink grant is to be performed with the gNB-initiated COT that is to be shared with the UE, the processing circuitry is to configure the gNB to receive the UL transmission burst carrying the PUSCH within a predetermined time period after detection of a downlink (DL) transmission burst within the gNB-initiated COT without first performing the CCA,
wherein the UL transmission burst within the gNB-initiated COT indicates a time-domain resource utilization by the UE within the gNB-initiated COT.
19. The apparatus of claim 18 , wherein the FFP for the UE-initiated COT has a periodicity comprising one of 1 millisecond (ms), 2 ms, 2.5 ms, 4 ms, 5 ms and 10 ms.