PDCCH Candidate Differentiation in CSS and USS Search Spaces
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Solution Overview
Problem
In the context of LTE and NR cellular communication systems, there is a challenge in efficiently determining the size and interpreting information related to PDCCH and PDSCH, particularly when multiple PDCCH candidates are present in CSS and USS, with similar resource elements and DCI format sizes, leading to ambiguity in transmission and reception.
Innovation Solution
A terminal apparatus and base station apparatus are configured to process PDCCH and PDSCH by determining the correct transmission or reception based on the type of search space, resource element alignment, and higher-layer parameters, specifically using DCI formats 0_0 and 1_0, to differentiate between PDCCH candidates in CSS and USS, ensuring accurate communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple PDCCH candidates are configured in CSS and USS with similar resource elements and DCI format sizes, then the terminal apparatus can monitor control channels in multiple search spaces, but it becomes difficult to determine which PDCCH candidate actually transmits the DCI format
Solution Approach 1:
The patent divides the PDCCH candidates into distinct groups based on search space type (CSS vs USS) and applies different RIV interpretation rules to each group. This segmentation allows the terminal to clearly identify which search space type transmitted the DCI by checking whether the decoded RIV falls within the valid range for that search space type, thereby resolving the ambiguity without limiting multi-search space monitoring capability
Solution Approach 2:
The patent introduces the search space type as an intermediary parameter that mediates between the PDCCH candidate and the RIV interpretation. By using the search space type to select the appropriate RIV interpretation rule, the system enables clear determination of the transmitting PDCCH candidate while maintaining the ability to monitor multiple search spaces simultaneously
2Device complexity
If the DCI format size is made the same for different PDCCH candidates, then the processing complexity is reduced, but the ability to differentiate between candidates is lost
Solution Approach 1:
The patent applies different local quality rules for RIV interpretation based on the search space type. While the DCI format size remains uniform, the interpretation of the RIV field differs between CSS and USS candidates, allowing reliable differentiation. Specifically, CSS candidates use one RIV interpretation rule while USS candidates use another, enabling the terminal to identify the transmitting candidate without increasing overall processing complexity
3Reliability
If the terminal apparatus monitors both CSS and USS PDCCH candidates, then the coverage and reliability of control channel reception is improved, but the determination of which candidate transmitted the DCI becomes ambiguous
Solution Approach 1:
The patent implements a dynamic determination process where the terminal sequentially tests each monitored PDCCH candidate against the appropriate RIV interpretation rule based on its search space type. The first candidate that successfully decodes a DCI format with a valid RIV according to its search space type's rules is identified as the transmitting candidate. This dynamic approach maintains high reception reliability while preserving complete information about which specific candidate transmitted the DCI
Data Source
AI summary
The present invention can perform communication efficiently. In a case that (1) the terminal apparatus is configured to monitor a first PDCCH candidate in a CSS and a second PDCCH candidate in a USS according to a DCI format with a C-RNTI, (2) a set of resource elements constituting the first PDCCH candidate is the same as a set of resource elements constituting the second PDCCH candidate, (3) a higher layer parameter is not set, and/or (4) the size of the DCI format corresponding to the first PDCCH candidate is the same as the size of the DCI format corresponding to the second PDCCH candidate, a terminal apparatus regards that a PDCCH with the DCI format is transmitted or received in the first PDCCH candidate when the PDCCH with the DCI format is received in the second PDCCH candidate.