HARQ Feedback via Multiple Uplink Channels
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Solution Overview
Problem
Wireless communication devices with multiple antenna sets face challenges in decoding signals due to varying channel conditions, limited timelines, and hardware complexity, making it difficult to combine multiple sets of least-likelihood ratios (LLRs) for hybrid automatic repeat request (HARQ) feedback within strict reporting timelines.
Innovation Solution
The implementation of multiple uplink control channels allows for separate feedback transmissions based on different decoding attempts using different sets of LLRs, enabling additional decoding attempts and reducing device complexity by providing soft feedback on the likelihood of successful decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple sets of LLRs are combined for decoding, then receive diversity is improved, but device complexity and processing requirements increase beyond what can be handled within HARQ feedback timelines
Solution Approach 1:
The patent segments the feedback transmission into multiple separate uplink control channels (PUCCHs) instead of combining all decoding attempts into a single feedback message. This allows the UE to transmit feedback from multiple decoding attempts independently, reducing the processing burden for generating a single comprehensive feedback while maintaining the benefits of multiple decoding attempts with different antenna panels
Solution Approach 2:
The patent performs preliminary decoding attempts using different antenna panels before the HARQ feedback deadline, generating multiple sets of LLRs in advance. By preparing these decoding results beforehand and transmitting them through separate PUCCH channels, the system avoids last-minute processing complexity while ensuring receive diversity benefits are realized within the required timeline
2Reliability
If multiple decoding attempts are performed before feedback deadline, then decoding reliability improves, but the timeline constraint cannot be met
Solution Approach 1:
The patent employs periodic action by scheduling multiple decoding attempts at different time points before the HARQ feedback deadline, with each attempt using a different antenna panel. The results are then transmitted through separate PUCCH channels at their respective scheduled times, allowing the system to perform multiple decoding operations without missing the overall feedback deadline
3Reliability
If additional demodulator instances are added for multiple LLR generation, then decoding performance improves, but hardware complexity and cost increase
Solution Approach 1:
The patent makes the single demodulator multi-functional by time-division multiplexing its operation across different antenna panels. Instead of requiring separate demodulator instances for each antenna panel, the same demodulator is reused sequentially to generate LLRs for different panels, reducing hardware complexity while maintaining the capability to perform multiple decoding attempts with diverse antenna configurations
Data Source
AI summary
Some techniques and apparatuses described herein provide reporting of multiple feedbacks for a same transport block (TB) or a same code block group (CBG) of a signal, such as a physical downlink shared channel. Thus, in case of a failure to decode a signal via a first set of antennas, a user equipment (UE) can perform a second decoding attempt via a second set of antennas (before or after transmitting first feedback). The UE may report a result of the first decoding attempt in a first feedback, and may report a result of the second decoding attempt in a second feedback. Some techniques and apparatuses described herein also provide soft feedback (e.g., information other than a binary acknowledgment (ACK) or negative ACK (NACK)) for a transmission, such as information indicating whether a second attempt to decode the transmission is likely to be successful.