HARQ-ACK Codebook Generation for Missed PDSCH Detection
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Solution Overview
Problem
Inconsistent understanding between base stations and user equipment (UE) regarding the generation mechanism of Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) codebooks leads to incorrect reception of HARQ-ACK codebooks, particularly when UE misses detection of Dynamic Scheduling PDSCHs, resulting in different bit orders and sizes of the codebooks.
Innovation Solution
The method involves determining the HARQ-ACK codebook generation mechanism at the UE based on the Downlink Assignment Index (DAI) value in the uplink grant information, allowing consistent generation mechanisms between the base station and UE, and handling overlapping PDSCHs by prioritizing and grouping them for accurate feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE generates HARQ-ACK codebook using SPS codebook mechanism when only SPS PDSCHs are received, then the codebook is generated according to SPS index and downlink slot order, but the base station may use TDRA table codebook mechanism expecting different bit order and size
Solution Approach 1:
The patent introduces a feedback mechanism where the base station sends indication information (via PDCCH or RRC signaling) to tell the UE which codebook generation mechanism to use. The UE then generates the HARQ-ACK codebook according to the indicated mechanism (SPS codebook or TDRA table codebook), ensuring both sides use the same mechanism and avoid bit order/size mismatches.
Solution Approach 2:
The indication information acts as an intermediary between the base station and UE, conveying the intended codebook generation mechanism from the base station to the UE. This intermediary ensures both parties align their understanding without direct negotiation, resolving the inconsistency problem.
2Reliability
If the UE misses detection of DS PDSCHs, then the UE generates codebook based on received SPS PDSCHs only, but the base station expects codebook to include all scheduled PDSCHs
Solution Approach 1:
The base station performs preliminary action by sending indication information before the UE generates the HARQ-ACK codebook. This indication tells the UE which codebook generation mechanism to use, allowing the UE to prepare the correct codebook structure in advance, even if some PDSCHs are missed during detection.
Solution Approach 2:
The patent changes the parameter of codebook generation mechanism from being implicitly determined (based on what the UE receives) to being explicitly controlled (by base station indication). This parameter change allows the base station to control whether the UE uses SPS codebook or TDRA table codebook mechanism, ensuring consistency even when detection fails.
3Adaptability or versatility
If multiple SPS PDSCHs and DS PDSCHs are multiplexed in one HARQ-ACK codebook, then the codebook size and bit order become complex to manage
Solution Approach 1:
The patent segments the HARQ-ACK codebook generation into two distinct mechanisms: SPS codebook (for SPS PDSCHs only) and TDRA table codebook (for DS PDSCHs or mixed). The base station indicates which segment to use, avoiding the complexity of managing mixed multiplexing while maintaining the capability to handle both types separately when needed.
Data Source
AI summary
Provided are an HARQ-ACK codebook generation method, an HARQ-ACK codebook transmission method, and a PDSCH reception method. The HARQ-ACK codebook generation method includes: receiving UL grant information sent by a base station, wherein a PUSCH scheduled by the UL grant information is used for the UE to transmit an HARQ-ACK codebook; and according to a value of a Downlink Assignment Index (DAI) in the UL grant information and a situation that the UE receives PDSCHs, determining a corresponding mechanism to generate the HARQ-ACK codebook.