HARQ-ACK Codebook Segmentation for Configured Grant PUSCH
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing HARQ-ACK feedback mechanisms in wireless communication systems, particularly in NR Rel-15, face inefficiencies due to high overhead and complex codebook management for CBG-level retransmissions in configured grant scenarios, which complicates the retransmission process and increases latency.
Innovation Solution
The proposed solution involves reducing the HARQ-ACK codebook overhead by aligning the configured grant DFI with existing UL grant formats, such as DCI format 0_0 or 0_1, and configuring the maximum number of uplink HARQ processes with CBG-level feedback to match the payload size, allowing for efficient CBG-based retransmissions without additional blind detection complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CBG-level HARQ-ACK feedback is implemented for configured grant PUSCH, then retransmission efficiency is improved, but HARQ-ACK codebook overhead increases
Solution Approach 1:
The patent segments the HARQ-ACK codebook into two parts: a first codebook for dynamically scheduled PUSCH and a second codebook for configured grant PUSCH. This segmentation allows independent optimization of each codebook, enabling CBG-level feedback for configured grant without forcing CBG-level feedback for all PUSCH transmissions, thus controlling overall overhead while improving retransmission efficiency for configured grant scenarios.
Solution Approach 2:
The patent introduces dynamic configuration for the second codebook size based on higher layer parameters and DCI indicators. The size of the second codebook can be dynamically adjusted according to the actual number of configured grant PUSCH transmissions and CBG configurations, allowing the system to adapt the overhead to actual needs rather than always using maximum CBG-level feedback.
2Productivity
If CBG-level HARQ-ACK feedback is used, then retransmission efficiency is improved, but system complexity increases
Solution Approach 1:
By segmenting the HARQ-ACK codebook into two separate codebooks with different management rules, the patent simplifies codebook management for each type of PUSCH. The first codebook follows existing dynamic scheduling rules while the second codebook is specifically designed for configured grant with its own independent size determination and feedback mechanisms, reducing the overall complexity compared to a unified CBG-level approach.
Solution Approach 2:
The patent applies different codebook management strategies to different PUSCH types: dynamic PUSCH uses the first codebook with traditional management, while configured grant PUSCH uses the second codebook with CBG-level feedback. This local differentiation allows CBG-level efficiency where needed without imposing CBG-level complexity on all transmissions.
3Measurement precision
If the HARQ-ACK codebook size is increased to support CBG-level feedback, then feedback precision is improved, but transmission overhead increases
Solution Approach 1:
The patent implements dynamic codebook size determination for the second codebook based on the actual number of configured grant PUSCH transmissions, HARQ process IDs, and CBG configurations. The codebook size is not fixed at maximum but adapts to actual transmission needs, allowing high feedback precision when CBG-level feedback is required while minimizing overhead when fewer transmissions occur or when TB-level feedback suffices.
Solution Approach 2:
The patent changes the parameter of codebook size from a static maximum value to a dynamically determined value based on multiple factors including the number of configured grant PUSCH transmissions, HARQ process IDs, CBG configurations, and higher layer parameters. This parameter change enables the system to achieve high feedback precision when needed while reducing overhead in other scenarios.
Data Source
AI summary
Methods, a remote unit and abase unit are disclosed. According to one embodiment, a remote unit comprising a transceiver; a memory; and a processor coupled to the transceiver and the memory and configured to: control the transceiver to transmit, to a base unit, an indicator in an uplink control information (UCI), wherein the UCI is associated to a configured grant uplink data channel, and the indicator requests code block group (CBG)-level hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback for the configured grant uplink data channel, and control the transceiver to receive, from the base unit, first downlink control information (DCI) which includes a HARQ-ACK codebook, wherein the first DCI has the same size as one uplink grant scheduling uplink data transmission, and wherein the HARQ-ACK codebook includes CBG-level HARQ-ACK feedback information bits for the configured grant uplink data channel.