PDCCH Aggregation Level Design for URLLC Reliability
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Solution Overview
Problem
Current wireless communication standards, such as NR, face challenges in achieving higher reliability for Physical Downlink Control Channel (PDCCH) transmissions, particularly in scenarios like URLLC where traditional aggregation levels (ALs) may not suffice.
Innovation Solution
The introduction of new or additional aggregation levels (ALs) outside of standard-defined levels, allowing for a union of control channel elements (CCEs) in one or more search spaces within a control resource set (CORESET), to enhance PDCCH transmission reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional aggregation levels are used for PDCCH transmission, then the system maintains compatibility with existing standards and simple implementation, but the reliability for URLLC scenarios is insufficient
Solution Approach 1:
The patent introduces dynamic aggregation level selection where the network can configure multiple aggregation levels (including non-standard ones like AL=32, AL=64) and dynamically choose appropriate levels based on channel conditions, UE capability, and service requirements. This dynamic adaptation resolves the contradiction by allowing the system to maintain standard compatibility when needed while achieving higher reliability through extended aggregation levels when required for URLLC.
Solution Approach 2:
The patent changes the aggregation level parameter from fixed standard-defined values to a flexible configurable set that includes both standard and nonstandard levels. By introducing new aggregation level parameters (AL=32, AL=64) and allowing dynamic configuration through RRC signaling, the system can adjust the aggregation level parameter to achieve higher reliability for URLLC while maintaining backward compatibility with existing standards.
2Reliability
If new aggregation levels with union of CCEs are introduced, then PDCCH reception reliability is improved, but the device complexity for handling nonstandard aggregation levels increases
Solution Approach 1:
The patent segments the PDCCH reception process into standardized and nonstandard aggregation level handling. The UE is configured to expect and process standard aggregation levels (AL=1, 2, 4, 8, 16) through conventional blind decoding, while nonstandard levels (AL=32, 64) are handled through specific configured grant mechanisms. This segmentation allows the majority of traffic to use simple standard processing while enabling high-reliability modes only when needed, thus resolving the contradiction between reliability improvement and complexity increase.
Solution Approach 2:
The patent applies partial action by introducing nonstandard aggregation levels only for specific URLLC scenarios rather than universally. The UE performs full blind decoding for standard aggregation levels in common search spaces, while nonstandard levels are used selectively in dedicated search spaces for configured grants. This partial application of extended aggregation levels achieves the necessary reliability improvement for critical services without requiring the UE to handle nonstandard levels in all circumstances, thereby limiting the increase in processing complexity.
Data Source
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AI summary
Certain aspects of the present disclosure relate to methods and apparatus for aggregation level (AL) design for physical downlink control channel (PDCCH) transmissions. New aggregation levels may be used in an effort to improve the reliability for PDCCH transmissions.