Joint HARQ Feedback Codebook for Multi-Cell Carrier Scheduling
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing feedback for single-downlink control information (DCI) across multiple component carriers (CCs) in multi-cell scheduling scenarios, particularly in dynamic spectrum sharing environments.
Innovation Solution
A user equipment (UE) is configured with a joint feedback codebook to provide unified feedback for multiple CCs, including a virtual CC, based on cross-carrier scheduling and a joint feedback configuration, enabling efficient ACK/NACK feedback for downlink transmissions across multiple CCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate feedback mechanisms are used for each component carrier, then feedback accuracy for individual CCs is maintained, but feedback overhead and system complexity increase significantly
Solution Approach 1:
The patent combines feedback for multiple component carriers into a single unified feedback message. The UE generates one joint feedback codebook that includes HARQ-ACK information for PDSCHs scheduled by multiple DCIs across different CCs, rather than generating separate feedback messages for each CC. This merging approach maintains feedback accuracy while significantly reducing feedback overhead and simplifying the feedback mechanism.
Solution Approach 2:
The unified feedback codebook serves multiple functions simultaneously: it provides HARQ-ACK feedback for multiple CCs, supports both single-DCI and multi-DCI scheduling modes, and handles dynamic spectrum sharing scenarios. This multi-functional design eliminates the need for separate feedback mechanisms for different scheduling scenarios, reducing overall system complexity.
2Productivity
If unified feedback codebook is used for multiple CCs, then feedback overhead is reduced and efficiency improves, but complexity in managing feedback for different CCs increases
Solution Approach 1:
The unified feedback codebook is segmented into multiple parts, each corresponding to a specific CC or scheduling instance. The UE identifies separate HARQ-ACK information segments for different DCIs and CCs within the single feedback message. This segmentation allows the system to manage complexity through structured organization while maintaining the efficiency benefits of unified feedback.
Solution Approach 2:
The patent introduces an intermediary mapping mechanism that associates each HARQ-ACK information element in the unified codebook with its corresponding DCI and CC. This intermediary structure (using indicators like CI field and mapping rules) enables the system to manage the complexity of multi-CC feedback while maintaining unified feedback efficiency.
3Adaptability or versatility
If multiple DCIs schedule PDSCHs on different CCs, then resource allocation flexibility is improved, but feedback coordination and timing synchronization become more difficult
Solution Approach 1:
The patent establishes preliminary mapping rules and timing relationships between DCIs and their corresponding HARQ-ACK feedback elements before actual transmission occurs. The UE and gNB agree on mapping configurations (such as PDSCH-to-HARQ feedback timing) in advance, enabling reliable feedback synchronization even when multiple DCIs are transmitted at different times on different CCs.
Solution Approach 2:
The unified feedback codebook incorporates feedback elements from multiple DCIs in a coordinated manner, with each element's timing and position determined by pre-established mapping rules. This feedback mechanism ensures that all HARQ-ACK information is collected and transmitted in a synchronized manner, maintaining reliability despite the flexibility of multi-DCI scheduling.
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AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may communicate over multiple component carriers (CCs). The UE may receive control signaling indicating a joint feedback codebook configuration for jointly reporting feedback for a first CC, a second CC, and a virtual CC that may be mapped to a third CC and a fourth CC. The UE may then receive downlink control information (DCI) scheduling a first downlink transmission via the first CC and a second downlink transmission on the second CC, or both downlink transmissions may be scheduled via the virtual CC. The UE may transmit a joint feedback message for the first CC, the second CC, and the virtual CC based on the joint codebook configuration.