LTE Control Channel Overlap Resolution via DCI Format Identification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In LTE wireless communication systems, mobile stations struggle to identify DCI formats when common and user equipment-specific search spaces overlap, due to shared CCE candidates and identical RNTI and bit numbers, leading to ambiguity in decoding.
Innovation Solution
The system allocates control information only in the common search space, scrambles it with C-RNTI, and includes information indicating the corresponding CC, allowing the mobile station to determine the correct search space for reception, even when payload sizes are the same, by inserting additional bits in specific DCI formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the common search space and user equipment-specific search space are configured to overlap with the same CCE candidates, then resource utilization is improved, but the mobile station cannot identify DCI format types due to ambiguity
Solution Approach 1:
The patent applies local quality by making the DCI format identification method dependent on the search space location. When the search space is determined to be a common search space, the mobile station uses one identification method (checking payload size and considering overlap conditions); when it is a user equipment-specific search space, a different method is used. This localized approach to identification resolves the ambiguity while maintaining overlapping search spaces for improved resource utilization.
2Reliability
If the mobile station performs blind decoding of all CCE candidates in both common and user equipment-specific search spaces, then the probability of successful DCI detection is improved, but the decoding complexity and processing time increase
Solution Approach 1:
The patent implements partial action by having the mobile station perform blind decoding with full complexity only in the common search space, while using a simplified identification approach in the user equipment-specific search space. The mobile station leverages the determined search space type (common vs. user equipment-specific) to apply appropriate decoding strategies, reducing overall processing complexity while maintaining reliable detection through the enhanced common search space decoding.
3Adaptability or versatility
If the base station allocates control information in both common and user equipment-specific search spaces with the same RNTI and payload size, then search space flexibility is improved, but DCI format discrimination becomes impossible
Solution Approach 1:
The patent introduces an intermediary mechanism - the search space type determination (common vs. user equipment-specific) based on CCE candidate analysis - that acts as a mediator to preserve DCI format type information. By using the search space classification as an intermediary layer, the system can allocate control information flexibly in both search spaces with the same RNTI and payload size while still enabling the mobile station to discriminate DCI format types through the known relationship between search space type and format type.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
When a common search space and a user equipment-specific search space overlap with each other, and bit numbers of DCI formats transmitted in the common search space and the user equipment-specific search space, respectively are the same as each other, a mobile station apparatus identifies a type of the DCI format. When the common search space and the user equipment-specific search space overlap with each other, and a bit number of a DCI format allocated in the common search space and a bit number of a DCI format allocated in the user equipment-specific search space are the same as each other, a base station apparatus 3 does not allocate the DCI format allocated in the user equipment-specific search space in the overlapped space, and a mobile station apparatus 1 performs blind decoding only of the DCI format allocated in the common search space in the overlapped space.