Dynamic HARQ Codebook for Multi-TRP Wireless Networks
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Solution Overview
Problem
Existing wireless communication systems face challenges in providing reliable HARQ-ACK feedback for multi-TRP deployments, especially in scenarios with different backhaul conditions, which affects the accuracy and efficiency of downlink communications.
Innovation Solution
The implementation of a dynamic hybrid automatic repeat request (HARQ) codebook that uses counter downlink assignment indicators (DAIs) and total DAIs to determine HARQ-ACK payloads, allowing for joint or separate counting methods across TRPs, enabling accurate feedback on DCI reception and transmission identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dynamic HARQ codebook is implemented for multi-TRP communication, then the reliability of HARQ-ACK feedback is improved, but the device complexity increases due to the need to process counter DAI and total DAI values from multiple TRPs
Solution Approach 1:
The patent segments the HARQ-ACK feedback mechanism by introducing separate counter DAI and total DAI fields in DCI formats for each TRP. This segmentation allows the UE to independently track and identify DCI transmissions from different TRPs, resolving the complexity of managing unified feedback across multiple TRPs while improving reliability through structured acknowledgment.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the UE with TRP-specific parameters and DAI tracking rules before multi-TRP communication begins. The UE is prepared with the ability to distinguish and count DCI transmissions from different TRPs using separate counter DAI values, enabling reliable feedback without increasing runtime processing complexity.
2Measurement precision
If separate counting methods are used for each TRP, then the accuracy of DCI reception detection is improved, but the loss of time increases due to extended feedback processing duration
Solution Approach 1:
The patent implements a feedback mechanism where the UE sends HARQ-ACK responses that include information about received and missed DCI transmissions from each TRP. The base station uses this feedback to identify missed DCI and retransmit only the necessary data, improving detection accuracy while minimizing time loss through targeted retransmissions rather than comprehensive re-sending.
Solution Approach 2:
The patent replaces complex mechanical tracking of multiple DCI transmissions with a systematic use of counter DAI and total DAI fields embedded in the DCI messages themselves. This substitution allows the UE to automatically detect missed DCI by comparing DAI values without requiring complex external tracking mechanisms, reducing processing time while maintaining high detection accuracy.
3Productivity
If joint counting of DCI transmissions across TRPs is implemented, then the productivity of downlink communication is improved, but the loss of information increases due to difficulty in identifying which TRP transmitted which DCI
Solution Approach 1:
The patent applies local quality by assigning distinct characteristics (TRP-specific counter DAI values and association rules) to each TRP's DCI transmissions. This allows the system to maintain joint counting for productivity while preserving the ability to identify which TRP transmitted each DCI through localized quality markers embedded in the DCI structure, preventing information loss.
4Adaptability or versatility
If multiple DCI transmissions from different TRPs are monitored in the same PDCCH monitoring occasion, then the versatility of multi-TRP communication is improved, but the difficulty of detecting and measuring increases due to overlapping monitoring requirements
Solution Approach 1:
The patent resolves the detection difficulty by adding another dimension to the monitoring structure - TRP-specific counter DAI values that operate independently within each PDCCH monitoring occasion. This dimensional addition allows the UE to distinguish and detect DCI transmissions from multiple TRPs simultaneously without increasing the inherent difficulty of monitoring, as each DCI carries its own unique identifier in the DAI field.
Data Source
AI summary
This disclosure provides systems, methods and apparatus for wireless communication. In one aspect, a multi-transmit-receive point (TRP) approach for hybrid automatic repeat request (HARQ) acknowledgment (ACK) feedback using counter downlink assignment indicators (DAIs) (cDAIs) and total DAIs (tDAIs) is provided. For example, some techniques and apparatuses described herein may provide a joint counting method in which cDAIs and tDAIs are implemented and tracked jointly between the TRPs of a multi-TRP group. This may be useful in the ideal backhaul scenario when the multi-TRP group is jointly scheduled, and may be more robust against errors than a separate counting method. Some techniques and apparatuses described herein may provide a separate counting method, in which cDAIs and tDAIs are implemented and tracked separately by the respective TRPs of a multi-TRP group.