PUCCH Resource Allocation for ACK/NACK Codebook Optimization
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Solution Overview
Problem
In wireless communications, particularly in LTE systems with carrier aggregation, the feedback information sending method results in low PUCCH resource utilization due to a large quantity of NACKs being filled when downlink data occupies only a small part of the configured carriers, leading to inefficient use of PUCCH resources.
Innovation Solution
The method determines the bit quantity of the ACK/NACK codebook and selects a corresponding PUCCH resource, optimizing the codebook generation and resource allocation based on the DAI accumulation and total quantity indications to reduce redundant information and improve resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE generates ACK/NACK codebooks according to all N downlink subframes of M carriers, then the feedback coverage is complete, but PUCCH resource utilization is low due to many filled NACKs
Solution Approach 1:
The patent extracts only the necessary feedback information by identifying and reporting the actual number of downlink subframes that require feedback (through DAI fields), rather than including all N downlink subframes. This removes the redundant NACK fillings and transmits only the essential ACK/NACK bits corresponding to actual data transmissions.
Solution Approach 2:
The patent changes the parameter of feedback codebook size dynamically based on the actual number of scheduled downlink subframes. By using DAI (Downlink Assignment Index) fields that indicate the actual count of subframes requiring feedback, the codebook size adapts to the real transmission load, reducing unnecessary NACKs while maintaining complete feedback coverage for all scheduled subframes.
2Stability of the object's composition
If the UE fills NACK for unscheduled downlink subframes to maintain codebook structure, then the codebook format is standardized, but redundant information increases
Solution Approach 1:
The patent makes the codebook structure dynamic rather than static. Instead of always using a fixed-size codebook covering all N downlink subframes, the codebook size varies based on the actual number of scheduled subframes indicated by DAI fields. This dynamic approach eliminates redundant NACK fillings while ensuring the codebook always includes all necessary feedback positions for scheduled transmissions.
3Adaptability or versatility
If PUCCH resources are allocated for maximum codebook size, then all feedback scenarios are supported, but resource efficiency decreases when downlink data occupies small portion of carriers
Solution Approach 1:
The patent implements dynamic resource allocation where the PUCCH resource selection is based on the actual feedback size determined by DAI fields. The system adapts the codebook size and corresponding PUCCH resources to match the real downlink scheduling load, supporting all possible feedback scenarios while efficiently utilizing resources by avoiding allocation for maximum size when actual data transmission is minimal.
Data Source
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AI summary
Embodiments of the present invention disclose a feedback information sending method, user equipment, and a base station, to select, according to a bit quantity of an ACK/NACK codebook, a PUCCH resource corresponding to the bit quantity of the ACK/NACK codebook, so as to improve PUCCH resource utilization. The method in the embodiments of the present invention includes: receiving, by UE, scheduling information that is sent by a base station by using a downlink control channel, where the downlink control channel belongs to a preconfigured downlink subframe set; receiving downlink data that is on a downlink data channel and that is scheduled according to the scheduling information; determining an uplink subframe, where the uplink subframe is used to send feedback information corresponding to the downlink data, and the preconfigured downlink subframe set is a set of downlink subframes that are associated with the uplink subframe and that are of all carriers configured for the UE by the base station; determining a codebook of the feedback information; performing channel encoding on the feedback information according to the codebook of the feedback information; determining a PUCCH resource according to PUCCH resource indication information; and sending, on the PUCCH resource in the uplink subframe, encoded feedback information.