UE Error Reason Feedback for Downlink Decoding Failure
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Solution Overview
Problem
In wireless communications systems, base stations lack sufficient information to determine efficient retransmission parameters when user equipment (UE) experiences decoding failures, leading to inefficient or ineffective radio link adaptations.
Innovation Solution
User equipment (UE) is configured to identify the reason for decoding failures by measuring signal strength parameters and comparing them to thresholds, then indicates the failure reason to the base station, allowing for targeted radio link adaptations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the base station uses standard retransmission procedures without additional error reason information, then the system maintains simple operation and low overhead, but the base station lacks sufficient information to determine efficient retransmission parameters
Solution Approach 1:
The UE performs measurements of signal strength parameters (L1 or L3) and compares them to configured thresholds before transmitting the NACK, preliminarily determining the error reason (full beam blocking, partial beam blocking, interference, fast frequency fading). This preliminary action enables the UE to include specific error reason information in the NACK feedback, providing the base station with valuable diagnostic data without requiring complex post-failure analysis procedures.
Solution Approach 2:
The patent implements an enhanced feedback mechanism where the NACK transmission includes additional error reason indication information beyond the standard decoding failure notification. The UE feeds back not only that decoding failed but also the specific reason determined through measurement and comparison, enabling the base station to adapt retransmission parameters based on the root cause of failure rather than using generic retransmission procedures.
2Reliability
If the base station implements generic retransmission without error reason-based adaptation, then the system maintains low processing overhead, but the retransmission efficiency and success rate are reduced
Solution Approach 1:
The patent applies local quality by tailoring the retransmission parameters specifically to the detected error reason. Instead of uniform retransmission strategies, the base station adjusts modulation and coding schemes, beam selection, and resource allocation based on the specific local condition identified (full beam blocking requires beam change, partial blocking may tolerate current beam with different parameters, interference requires different time/frequency resources). This localized adaptation improves retransmission success rates while maintaining reasonable processing overhead through rule-based decisions.
3Adaptability or versatility
If the UE transmits detailed error reason information, then the base station can optimize link adaptation parameters, but the uplink feedback transmission requires additional processing and resources
Solution Approach 1:
The UE performs measurements and determines the error reason preliminarily before feedback transmission, so that when the NACK is sent, the error reason information is already prepared and ready for immediate transmission. This eliminates the need for time-consuming post-failure analysis at the UE and allows the base station to receive ready-to-use diagnostic information, reducing overall feedback processing time while maintaining high adaptability.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may fail to successfully receive (e.g., fail to receive, or decode) a downlink transmission. In order to suggest a solution for the reception issue to a base station, the UE may detect a reason for the failed reception. The UE may transmit, to the base station, an indication that the UE failed to decode the transmission and may receive, in response, a grant for transmission of a channel state information (CSI) report including resources allocated for an indication of the error reason. The UE may use these resources to indicate the error reason to the base station, and the base station may perform a radio link adaptation action to mitigate the error based on the error reason. In some examples, the UE may suggest the radio link adaptation action to the base station.