User Terminal Uplink Control for Multi-TRP HARQ-ACK Feedback
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Solution Overview
Problem
Current radio communication systems, particularly in the context of next-generation mobile communication systems like 5G, do not adequately address the control and transmission of uplink signals when multiple transmission/reception points (TRPs) are used, leading to inefficiencies in controlling uplink control information.
Innovation Solution
The implementation of a method that allows for appropriate uplink transmission control by using a shared or separate reporting of Downlink Assignment Index (DAI) fields in the Downlink Control Information (DCI) for multiple TRPs, enabling joint or separate counting of counter DAI and total DAI, and applying a dynamic HARQ-ACK codebook for simultaneous or separate feedback of HARQ-ACKs across TRPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-TRPs are used for downlink transmission to increase capacity and throughput, then system capacity and data rates are improved, but uplink transmission control becomes complex and undefined
Solution Approach 1:
The patent segments the DAI counting mechanism into separate counters for each TRP (first counter for first TRP, second counter for second TRP) rather than using a joint counter. This segmentation allows independent tracking of downlink assignments from multiple TRPs, resolving the control complexity while maintaining the capacity benefits of multi-TRP operation.
Solution Approach 2:
The patent introduces a new dimension to the DAI structure by adding TRP-specific counters (cDAI and tDAI) to the existing framework. This dimensional extension allows the system to track multiple TRP assignments simultaneously without collapsing into a single complex counter, thus managing uplink control complexity while supporting multi-TRP productivity gains.
2Ease of operation
If joint counting of DAI is used across multiple TRPs, then uplink control is simplified, but accuracy of HARQ-ACK feedback decreases due to counting errors
Solution Approach 1:
The patent divides the DAI counting function into separate segmented counters for each TRP, ensuring that each TRP's downlink assignments are tracked independently. This segmentation prevents counting errors from propagating across TRPs while maintaining sufficient control simplicity through standardized counter management procedures.
Solution Approach 2:
The patent implements enhanced feedback mechanisms where the UE reports HARQ-ACK information based on separately tracked counters for each TRP. This feedback approach ensures that acknowledgment accuracy is maintained by comparing expected versus actual DAI values for each TRP independently, preventing feedback errors while preserving operational ease.
3Measurement precision
If separate DAI reporting is implemented for each TRP, then HARQ-ACK feedback accuracy is improved, but signaling overhead and processing complexity increase
Solution Approach 1:
The patent merges the separate DAI reporting for multiple TRPs into a unified DCI structure where cDAI and tDAI fields convey TRP-specific counting information. This merging approach reduces signaling overhead by consolidating multiple counter reports into standardized field formats while maintaining the precision benefits of separate TRP tracking.
Solution Approach 2:
The patent creates a universal DAI reporting mechanism that handles multiple TRPs through standardized counter fields (cDAI for counter DAI, tDAI for total DAI) that can accommodate any number of TRPs. This multi-functional approach allows the same signaling structure to serve both single-TRP and multi-TRP scenarios, reducing overhead while preserving feedback accuracy.
4Adaptability or versatility
If dynamic HARQ-ACK codebook is used for multi-TRP, then adaptability to different TRP configurations is improved, but determination complexity of codebook increases
Solution Approach 1:
The patent implements a dynamic HARQ-ACK codebook where the codebook size and structure adapt to the actual number of TRPs and their assignment patterns. The dynamic nature allows the system to scale with TRP configurations while the standardized counter-based determination method keeps the complexity manageable through systematic calculation rules.
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~3B
AI summary
One aspect of a user terminal according to the present invention includes: a receiving section that receives a downlink shared channel transmitted from a plurality of transmission/reception points; and a control section that controls transmission of a transmission confirmation signal for the downlink shared channel, based on at least one of a count value of DL assignment jointly controlled between the plurality of transmission/reception points, and an index of the transmission/reception points and a count value of DL assignment separately controlled between the plurality of transmission/reception points.