UE Frame-Based Uplink Access in Unlicensed Bands
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Solution Overview
Problem
Existing frame-based equipment (FBE) operations in unlicensed bands face challenges in determining channel occupancy and clear channel assessment, particularly for user equipment (UE) in next-generation wireless communication systems like 5G NR, leading to inefficiencies and potential misalignment in channel occupancy initiation.
Innovation Solution
A method and system for FBE operation in an unlicensed band where UE receives DCI scheduling a physical uplink shared channel (PUSCH) with an indicated fixed frame period (FFP) initiator, initiates channel occupancy by transmitting within the FFP after ensuring no downlink signal is detected, and transmits the scheduled PUSCH within the FFP, aligning start and end times with FFP boundaries, and performing clear channel assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE initiates channel occupancy by transmitting configured PUSCH in the second FFP, then the UE can secure uplink transmission opportunities in unlicensed bands, but this may cause interference with downlink signals from the base station operating in the first FFP
Solution Approach 1:
The base station transmits downlink signals in the first FFP before the UE initiates uplink transmission in the second FFP. This preliminary downlink transmission allows the UE to detect and avoid interfering with ongoing base station operations while securing subsequent uplink opportunities.
Solution Approach 2:
The frame structure is divided into separate first FFP and second FFP periods, with the downlink portion in the first FFP and uplink portion in the second FFP. This segmentation allows independent control and detection of downlink and uplink transmissions, preventing interference while maintaining both transmission directions.
2Reliability
If the UE performs clear channel assessment before transmitting configured PUSCH, then the UE can avoid transmitting on occupied channels, but this adds detection time and complexity to the transmission process
Solution Approach 1:
The UE autonomously performs clear channel assessment by detecting downlink signals from the base station in the first FFP and independently determining whether to proceed with uplink transmission in the second FFP. This self-service approach eliminates the need for complex centralized coordination while ensuring reliable channel access.
Solution Approach 2:
The UE uses feedback from detecting downlink signals in the first FFP to make informed decisions about uplink transmission in the second FFP. This feedback mechanism ensures reliable channel access by preventing transmissions that would interfere with ongoing base station operations.
3Productivity
If the UE aligns configured PUSCH transmission with the start time of the second FFP, then the UE can efficiently utilize frame-based equipment operation, but this requires precise timing synchronization between overlapping first and second FFP
Solution Approach 1:
Both the first FFP (base station) and second FFP (UE) operate on periodic timelines with defined start and end times. This periodic structure allows the UE to align its uplink transmissions with the second FFP start times while the base station operates independently in the first FFP, achieving efficient frame-based operation without requiring continuous synchronization.
Data Source
AI summary
A UE and a method for FBE operation in an unlicensed band are provided. The method receives DCI scheduling a PUSCH and indicating that an initiator of a CO of a FFP for the scheduled PUSCH is the UE. The method initiates the CO by transmitting a configured PUSCH within the CO when a DL signal has not been detected within a second FFP before a start time of the configured PUSCH, wherein the scheduled PUSCH is immediately after the configured PUSCH. The method transmits the scheduled PUSCH within the CO after receiving the DCI. The start time of the configured PUSCH is aligned with a start time of the FFP, an end time of the configured PUSCH is before start times of idle periods of both FFPs, and the second FFP overlaps the FFP and is used when the BS operates as an initiating device for the FBE operation.