Compact DCI 0_2 Signaling for Reliable NR-U Downlink Feedback
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Solution Overview
Problem
In 5G NR systems operating in unlicensed spectrum, the use of DCI format 0_1 for downlink feedback information (DFI) increases UE blind detection complexity and decreases CG DFI reliability due to the need to monitor both DCI formats 0_1 and 0_2, which is not supported by some UEs.
Innovation Solution
Transmission of downlink feedback information using a compact DCI format 0_2 frame structure to address LBT failures in NR-U operation, enhancing PDCCH reliability in URLLC systems, and harmonizing UL CG enhancements for unlicensed spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DCI format 0_1 is used for downlink feedback information transmission, then the feedback information can be transmitted, but UE blind detection complexity increases
Solution Approach 1:
The patent segments the DCI format into two versions: DCI format 0_1 for comprehensive feedback and DCI format 0_2 for compact feedback. This segmentation allows UEs to choose the appropriate format based on their capabilities and channel conditions, reducing blind detection complexity while maintaining transmission reliability.
Solution Approach 2:
The patent changes the parameter set of DCI format 0_2 by removing optional fields present in DCI format 0_1, such as certain scheduling information and redundancy versions. This parameter reduction creates a compact format that decreases UE blind detection complexity while still conveying essential downlink feedback information.
2Adaptability or versatility
If both DCI formats 0_1 and 0_2 are monitored, then comprehensive feedback coverage is achieved, but CG DFI reliability decreases
Solution Approach 1:
The patent introduces dynamic format selection where the gNB can dynamically choose between DCI format 01 and 02 based on channel conditions, UE capabilities, and traffic requirements. This dynamic approach ensures that the most reliable format is used for each transmission, improving CG DFI reliability while maintaining comprehensive coverage.
Solution Approach 2:
The patent creates DCI format 02 as a simplified copy of DCI format 01, retaining only the essential fields needed for downlink feedback. This copying approach allows UEs to monitor a compact format that provides the same core functionality with reduced complexity and improved reliability.
3Loss of information
If DCI format 01 is used, then complete scheduling information is provided, but some UEs cannot support monitoring both formats
Solution Approach 1:
The patent extracts only the essential downlink feedback fields from DCI format 01 to create DCI format 02. By taking out non-essential fields such as detailed scheduling information and optional parameters, the compact format becomes operable for all UEs while still providing complete downlink feedback functionality.
Solution Approach 2:
The patent designs DCI format 02 to be universally supported by all UEs, making it a multi-functional format that can serve both as a standalone compact feedback format and as a complementary format to DCI 01. This universality ensures ease of operation across different UE implementations while maintaining information completeness through selective field inclusion.
Data Source
AI summary
Apparatus, methods, and computer-readable media for transmission of downlink feedback information using downlink control information format 0_2 are disclosed herein. A user equipment (UE) may receive, from a base station on a first subband, a downlink control information (DCI) having a first predetermined DCI format or a second predetermined DCI format, in which the second predetermined DCI format has a length smaller than the first predetermined DCI format. The UE also may determine that the DCI indicates a downlink feedback information (DFI) based on one or more of an indication in the DCI or a first predetermined scrambling code associated with the DCI, when the DCI is received with the second predetermined DCI format.