Blind Detection of Common and UE-Specific Search Spaces
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Solution Overview
Problem
In LTE systems, existing technologies face challenges in enabling a new carrier type based on OFDM to work stand-alone, particularly in blindly detecting common and UE-specific search spaces, which limits the flexibility and efficiency of resource allocation and interference management.
Innovation Solution
A method and apparatus for blindly detecting common and UE-specific search spaces are developed, allowing the new carrier type to operate independently by pre-defining resource allocation parameters, such as the number and type of EPDCCH sets, PRB pairs, and ECCE locations, enabling flexible configuration and improved interference management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the new carrier type uses EPDCCH for UE specific search space only (as in ETE release 11), then system power saving performance is improved and interference is decreased, but the new carrier type cannot work as a stand-alone cell
Solution Approach 1:
The search space is segmented into two distinct types: common search space (CSS) and UE-specific search space (USS). The CSS is configured using traditional PDCCH, while the USS uses EPDCCH. This segmentation allows the system to maintain backward compatibility for common control information while enabling advanced features for user-specific control, thus allowing the new carrier type to function as a stand-alone cell without requiring full dual-configuration complexity.
Solution Approach 2:
The system dynamically selects which search space type to use based on operational mode. When operating as a stand-alone cell, the new carrier type can configure both CSS and USS. When operating as a secondary cell, it can use only USS. This dynamic adaptability resolves the contradiction by allowing the system to have stand-alone capability when needed while maintaining simpler operation in other scenarios.
2Adaptability or versatility
If the new carrier type configures both common search space and UE specific search space with EPDCCH, then it can work stand-alone, but resource allocation overhead and blind detection complexity increase
Solution Approach 1:
Different quality levels of control channels are applied to different search spaces. The CSS uses the more robust PDCCH transmission suitable for all UEs, while the USS uses the more resource-efficient EPDCCH for individual user communication. This local differentiation allows stand-alone operation with reduced overall resource overhead compared to using EPDCCH universally.
Solution Approach 2:
Instead of requiring full EPDCCH configuration for both CSS and USS to achieve stand-alone capability, the system applies EPDCCH partially - only for the USS portion. This partial action is sufficient to enable stand-alone operation while avoiding the excessive resource overhead that would result from configuring EPDCCH for both search space types.
3Adaptability or versatility
If the new carrier type uses PDCCH for common search space and EPDCCH for UE specific search space, then flexibility is improved, but blind detection complexity increases due to tracking multiple PDCCH candidates across different search spaces
Solution Approach 1:
The blind detection complexity is extracted and isolated to specific search spaces with defined candidate numbers. The CSS has a limited set of candidates (4 or 8 CCEs), and the USS has its own defined candidates. By separating the detection processes and defining explicit candidate limits for each search space type, the overall complexity is managed while maintaining flexibility.
Solution Approach 2:
The system changes parameters such as aggregation level and number of candidates based on the search space type and transmission conditions. For CSS, parameters are optimized for reliability with more candidates, while for USS, parameters are adjusted for efficiency with fewer candidates. This parameter adaptation allows flexible operation while controlling blind detection complexity through conditional parameter selection.
Data Source
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AI summary
Methods and apparatus are provided for blindly detecting a common search space and a UE specific search space. A location of a candidate EPDCCH occupied by a common search space is determined. A blind detection is performed for the candidate EPDCCH occupied by the common search space. A location of a candidate enhanced EPDCCH occupied by a UE specific search space is determined. A blind detection is performed for the candidate EPDCCH occupied by the UE specific search space.