Multi-TRP PDCCH Repetition Linking for HARQ-ACK Accuracy
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Solution Overview
Problem
Existing MIMO transmission schemes for PDCCH in multi-TRP systems face challenges in efficiently linking repeated PDCCHs across search space sets and managing PDCCH candidate linkage, leading to incorrect HARQ-ACK codebook payload sizes and increased UE complexity in processing multiple TCI states.
Innovation Solution
A method for explicitly linking repeated PDCCHs across search space sets and CORESETs using multi-TRP repetition or multi-chance schemes, with enhanced methods for PDCCH candidate linkage, HARQ-ACK codebook construction, and prioritization of PDCCH reception to manage multiple TCI states, ensuring correct payload size and reduced UE complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If repeated PDCCHs are transmitted across multiple search space sets in multi-TRP systems, then reliability of control channel transmission is improved, but UE complexity in processing and linking PDCCH candidates increases
Solution Approach 1:
The patent segments PDCCH candidates into different search space sets (CSS and USS) with distinct linkage rules. CSS PDCCH candidates are linked within the same CSS, while USS PDCCH candidates are linked across USS based on candidate index mapping. This segmentation reduces UE processing complexity by providing clear, structured linkage rules for different search space types, preventing the need to handle all PDCCH candidates uniformly.
Solution Approach 2:
The patent establishes preliminary linkage rules between PDCCH candidates in different search space sets before actual PDCCH reception. By pre-defining that PDCCH candidate i in CSS is linked to PDCCH candidate i in USS, and establishing candidate index mapping relationships, the UE can efficiently identify and process repeated PDCCHs without complex real-time analysis, thus reducing processing complexity while maintaining reliability.
2Productivity
If PDCCH candidates are linked across search space sets, then efficient HARQ-ACK codebook construction is achieved, but incorrect payload sizes occur due to improper linkage
Solution Approach 1:
The patent applies different linkage quality rules to different search space sets. CSS PDCCH candidates use one-to-one linkage within the same CSS, while USS PDCCH candidates use index-based mapping across USS. This local differentiation ensures that each search space set has appropriate linkage rules tailored to its characteristics, preventing incorrect payload size calculations that would result from uniform linkage rules.
Solution Approach 2:
The patent implements feedback mechanisms where the UE determines HARQ-ACK codebook payload size based on the linkage relationship between PDCCH candidates. By using the established linkage rules to identify which PDCCH candidates are repetitions of each other, the UE can accurately count the number of unique PDCCH candidates and construct the HARQ-ACK codebook with the correct payload size, avoiding both overcounting and undercounting.
3Adaptability or versatility
If multiple TCI states are used for PDCCH transmission from different TRPs, then multi-TRP system capability is enhanced, but UE complexity in managing multiple TCI states increases
Solution Approach 1:
The patent creates a universal PDCCH candidate linkage mechanism that works across different search space sets and TRPs. By establishing that PDCCH candidates with the same index in different search space sets are linked, the system provides a unified approach to handling multiple TCI states from different TRPs, reducing UE complexity by avoiding the need for TRP-specific processing rules.
Solution Approach 2:
The patent extends the PDCCH candidate linkage concept from the traditional single-search-space dimension to a multi-dimensional space spanning multiple search space sets and TRPs. By mapping PDCCH candidates across search space sets using candidate indices as the linking dimension, the system enables efficient multi-TRP operation without increasing UE complexity, as the linkage rules operate consistently across all dimensions.
Data Source
AI summary
A method and a user equipment (UE) are provided for explicitly linking repeated physical downlink control channels (PDCCHs). The UE receives the repeated PDCCHs from a network. Each of the repeated PDCCHs include downlink control information (DCI) that schedules reception of a same physical downlink shared channel (PDSCH) at the UE. The UE links the repeated PDCCHs having common PDCCH candidate numbers across search space (SS) sets of a control resource set (CORESET). The repeated PDCCHs are received in accordance with the UE and the network communicating using a multi-transmission and reception point (TRP) repetition scheme or a multi-TRP multi-chance scheme.