PDCCH Search Space Overlap Resolution in LTE-A Carrier Aggregation
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Solution Overview
Problem
In the LTE-Advanced network, the overlap of common and user-specific search spaces for PDCCH monitoring causes detection challenges, especially when scheduling across carriers, leading to block rate issues and difficulties in defining the search space for user equipment (UE) to effectively monitor downlink control information.
Innovation Solution
The method involves determining user-specific search spaces for PDCCH monitoring based on component carrier indexes, adjusting the control channel element (CCE) calculation formula to account for component carrier indexes and aggregation levels, and configuring these indexes to ensure distinct starting positions and sizes for each carrier, allowing for independent or shared search spaces depending on bandwidth and CRC scrambling conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If common search space and user-specific search space are used for PDCCH monitoring in carrier aggregation, then scheduling flexibility across carriers is improved, but search space overlap occurs causing detection challenges and block rate issues
Solution Approach 1:
The patent segments the search space by introducing component carrier indexes to differentiate search spaces for different carriers. The user-specific search space is divided into multiple instances, each associated with a specific component carrier index, allowing the UE to monitor PDCCH candidates on different carriers without confusion from overlapping search spaces.
Solution Approach 2:
The patent applies local quality by configuring different starting positions and sizes for user-specific search spaces based on component carrier indexes. Each carrier's search space has locally optimized parameters (starting CCE index, number of CCEs) tailored to its specific bandwidth and scheduling requirements, rather than using a uniform configuration across all carriers.
2Measurement precision
If search space parameters are configured for each component carrier, then accurate PDCCH monitoring across carriers is improved, but device complexity increases
Solution Approach 1:
The patent achieves universality by using a single set of configuration parameters (component carrier indexes, aggregation levels) that serve multiple component carriers simultaneously. The same configuration mechanism and formula structures are reused across all carriers, reducing the need for entirely separate configuration sets for each carrier while still providing carrier-specific customization.
Data Source
Figure 1~3
AI summary
The present invention discloses a method for detecting downlink control information, including: when scheduling across carriers is enabled, determining by user equipment (UE) user-specific search space monitoring a physical downlink control channel (PDCCH) according to component carrier indexes, wherein the component carrier indexes include component carrier indexes corresponding to various component carriers implementing scheduling across carrier and being scheduled across carriers. Also the present invention also provides an apparatus for detecting downlink control information, a user equipment and a network side device. The present invention solve the overlap problem of common search space and user-specific search space in Release 10 and solves the problem of determining a search space for the PDCCH in the situation of scheduling across carriers is enabled in Release 10.