Downlink Assignment Index for HARQ-ACK Clarity in Control Repetition
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing control channel repetition schemes, leading to ambiguities in HARQ-Ack feedback due to multiple DCI messages scheduling the same PDSCH, which can result in misinterpreted feedback and inefficient resource utilization.
Innovation Solution
Implementing techniques for determining and transmitting HARQ-Ack feedback by associating multiple DCI messages with a control channel repetition scheme, where the feedback codebook includes a single position or separate positions based on linked or unlinked DCI, using reference control channel monitoring occasions to interpret downlink assignment indexes, thereby clarifying the decoding status of multiple DCI messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control channel repetition scheme is implemented to improve reliability, then control channel reliability is improved, but feedback codebook ambiguity increases
Solution Approach 1:
The feedback codebook is segmented into separate positions for each DCI message. When multiple DCI messages are received, each DCI is assigned a distinct position in the codebook based on its DAI value, allowing the UE to provide separate feedback for each scheduled PDSCH without ambiguity
Solution Approach 2:
The downlink assignment index (DAI) acts as an intermediary parameter that mediates between multiple DCI messages and the feedback codebook. The DAI value determines the specific position in the codebook where feedback for each DCI should be placed, resolving the ambiguity caused by control channel repetition
2Reliability
If multiple DCI messages schedule the same PDSCH to improve reliability, then control channel reliability is improved, but resource utilization efficiency decreases
Solution Approach 1:
The feedback codebook structure dynamically adapts based on the number of DCI messages received. The UE determines the codebook size and position allocation based on the DAIs present in the received DCI messages, allowing flexible resource usage that matches actual transmission needs rather than allocating fixed resources for potential repetitions
3Measurement precision
If separate feedback positions are allocated for each DCI message to eliminate ambiguity, then feedback precision is improved, but feedback overhead increases
Solution Approach 1:
The feedback codebook structure serves multiple functions: it provides separate feedback positions when needed (when multiple DCI messages are received) while maintaining compatibility with single-DCI scenarios. The same codebook framework adapts to different numbers of DCI messages, eliminating the need for separate feedback mechanisms
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may monitor a first control channel candidate for first downlink control information (DCI) scheduling a data channel and a second control channel candidate for second DCI scheduling the data channel, wherein the first control channel candidate and the second control channel candidate are associated with a control channel repetition scheme. The UE may transmit a feedback codebook regarding the data channel based at least in part on monitoring the first control channel candidate and the second control channel candidate, wherein the feedback codebook includes one of: a single position corresponding to the data channel, or a first position corresponding to the first DCI on the first control channel candidate and a second position corresponding to the second DCI on the second control channel candidate. Numerous other aspects are provided.