Downlink Control Information Transmission in LTE-Advanced Carrier Aggregation
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Solution Overview
Problem
The increase in blind detection complexity and system performance degradation due to cross-carrier scheduling and carrier aggregation in LTE-Advanced systems, particularly in transmitting and detecting downlink control information across multiple carriers.
Innovation Solution
A method where the base station transmits downlink control information on each downlink component carrier within a user equipment's physical downlink shared channel carrier set, either with or without a carrier indicator field, allowing the user equipment to detect this information, and dividing downlink control information formats into groups with varying overheads to standardize detection processes across different bandwidths and transmission modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-carrier scheduling and carrier aggregation are implemented to support wider spectrum configurations in LTE-Advanced, then system bandwidth and data transmission capability are improved, but the number of blind detections and implementation complexity increase
Solution Approach 1:
The patent segments the downlink control information transmission by introducing a carrier indicator field that divides the search space into carrier-specific regions. This allows the UE to separately search for PDCCH on different component carriers rather than performing blind detection across all carriers, thereby reducing overall detection complexity while maintaining support for multiple carriers in carrier aggregation scenarios.
Solution Approach 2:
The carrier indicator field acts as an intermediary that provides explicit signaling about which component carrier the downlink control information pertains to. This intermediary mechanism eliminates the need for the UE to perform exhaustive blind detection across multiple carriers, as the carrier indicator directly identifies the relevant carrier, thus reducing detection complexity while preserving multi-carrier functionality.
2Productivity
If downlink control information is transmitted on multiple component carriers to support carrier aggregation, then system performance and throughput are improved, but the number of blind detections increases
Solution Approach 1:
The carrier indicator field performs preliminary identification of the target component carrier before the UE initiates blind detection. By providing this advance information about which carrier contains the relevant downlink control information, the system prevents the UE from wasting time performing blind detection on unnecessary carriers, thus reducing detection time while maintaining support for multiple active component carriers.
3Quantity of substance
If carrier aggregation is enabled to support LTE-Advanced requirements, then data transmission capacity is improved, but implementation complexity and detection overhead increase
Solution Approach 1:
The patent applies local quality by making the search space characteristics carrier-specific through the carrier indicator field. Each component carrier can have its own designated search space region, allowing the UE to optimize detection parameters for each carrier individually rather than using a unified search approach across all carriers. This reduces detection overhead while maintaining the data transmission capacity benefits of carrier aggregation.
Data Source
Figure 1~3
AI summary
The present invention discloses a method and a system for transmitting downlink control information, wherein when a base station is not configured with a carrier indicator field, the base station transmits a physical downlink control channel bearing the corresponding downlink control information on each downlink component carrier in a user equipment's physical downlink shared channel (PDSCH) carrier set, and the user equipment detects the corresponding downlink control information on each downlink component carrier in the configured PDSCH carrier set. When a base station is configured with a carrier indicator field, the base station transmits the physical downlink control channel bearing the corresponding downlink control information on each downlink component carrier in the configured physical downlink control channel (PDCCH) carrier set, and the user equipment detects the corresponding downlink control information on each downlink component carrier in the PDCCH carrier set. The PDSCH and the PDCCH carrier sets are configured by the base station. The present invention can avoid multiple times of blind detection and can implement the transmission and detection of multi-carrier downlink control information.