NR DCI Precoding Field Configuration for 5G Uplink Power
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Solution Overview
Problem
In 5G NR systems, user equipment (UEs) face challenges in determining the correct codebook for full power transmission due to ambiguity in decoding downlink control information (DCI) from the 5th generation NodeB (gNB), leading to inefficient power control and reduced PDCCH decoding performance.
Innovation Solution
The introduction of padding bits in the TPMI precoding information within the DCI and joint encoding between the SRI and TPMI/number of MIMO layer precoding information helps to resolve the ambiguity, ensuring fixed field sizes for precoding information and number of layers, thereby enabling full power uplink transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable field sizes for precoding information are used in DCI, then adaptability to different codebook configurations is improved, but ambiguity in decoding DCI increases leading to reduced PDCCH decoding performance
Solution Approach 1:
The patent applies parameter changes by introducing a fixed field size for precoding information in DCI format 0_1, specifically setting the field size to 5 bits regardless of the actual codebook configuration. This fixed parameter eliminates decoding ambiguity while maintaining adaptability through the use of codebookSubsetRestriction to indicate available codebook subsets. The fixed 5-bit field size ensures reliable PDCCH decoding while the codebookSubsetRestriction mechanism provides the necessary adaptability to different codebook configurations.
2Measurement precision
If full power transmission is enabled, then power control accuracy is improved, but ambiguity in determining codebook for full power transmission increases
Solution Approach 1:
The patent uses codebookSubsetRestriction as an intermediary mechanism to resolve the ambiguity in codebook determination for full power transmission. The codebookSubsetRestriction field provides additional information that mediates between the fixed 5-bit precoding information field and the actual codebook selection, enabling the UE to correctly determine the codebook for full power transmission without ambiguity. This intermediary structure allows full power transmission with accurate power control while eliminating the information loss related to codebook determination.
3Reliability
If fixed field size is used for precoding information, then PDCCH decoding performance is improved, but flexibility in codebook configuration is reduced
Solution Approach 1:
The patent segments the precoding information indication into two parts: a fixed 5-bit field in DCI format 0_1 for reliable decoding, and a separate codebookSubsetRestriction field for flexible codebook configuration. This segmentation allows the fixed field to provide reliable PDCCH decoding performance while the codebookSubsetRestriction segment maintains the flexibility needed for different codebook configurations. The two segments work together to resolve the contradiction between fixed field size and configuration flexibility.
Data Source
AI summary
Systems and methods for transmission of full power uplink transmission in 5G networks are described. The gNB provides TPMI precoding information in DCI of a PDCCH in which the field size for precoding information and number of layers are fixed irrespective of the SRI. The gNB indicates in RRC signaling the use of codebook-based transmission for UL. If different SRS resources with different number of antenna ports are configured, the bitwidth of the SRI field is the maximum number of ports among the configured SRS resources in an SRS resource set with usage set to ‘codebook’. If the number of ports for a configured SRS resource in the set is less than the maximum number of ports, the most significant bits of the field have a value of ‘0’. The bitwidth is dependent on UE coherence capabilities and a maxrank of the UE.