Extended Common Search Space for Uplink-Downlink Configuration
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Solution Overview
Problem
In LTE TDD systems, the limited size of the common search space (CSS) can lead to difficulties in finding an idle PDCCH to carry uplink-downlink configuration information, causing UE to fail in acquiring current configuration information and resulting in disrupted data transmission.
Innovation Solution
The method involves configuring a larger first CSS by adding a newly added CSS with more control channel elements (CCEs) beyond the initial 16 CCEs, allowing for a larger aggregation level and flexible distribution, ensuring that a PDCCH for carrying uplink-downlink configuration information can be identified, and dynamically adjusting the size and location based on preset rules to accommodate varying channel conditions and cell loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CSS size is increased to accommodate multiple DCI types, then the reliability of PDCCH transmission is improved, but the device complexity increases
Solution Approach 1:
The common search space is segmented into a reference CSS (first 16 CCEs) and a newly added CSS (additional N CCEs). This segmentation allows the system to maintain the original CSS structure for backward compatibility while adding extra resources to accommodate multiple DCI types, thereby improving reliability without completely redesigning the existing framework.
Solution Approach 2:
The patent extends the CSS size from the traditional 16 CCEs to L CCEs (L>16) by adding a new dimension of capacity. This dimensional expansion in the CCE space allows multiple DCI types to coexist in the same subframe without interfering with each other, resolving the contradiction between reliability and complexity.
2Productivity
If the CSS size is increased to ensure idle PDCCH availability, then the productivity of configuration updates is improved, but the loss of time for UE detection increases
Solution Approach 1:
The base station proactively configures the extended CSS with L CCEs (L>16) in advance, ensuring that sufficient idle PDCCH resources are available before needing to transmit uplink-downlink configuration information. This preliminary preparation eliminates the need for UE to perform extensive blind detection across multiple subframes, reducing detection time while maintaining high productivity.
3Adaptability or versatility
If the CSS size is increased to carry multiple DCI types, then the adaptability of the system is improved, but the device complexity increases
Solution Approach 1:
The extended CSS with L CCEs (L>16) serves multiple functions: it can carry traditional DCI formats, uplink-downlink configuration information, and other control messages simultaneously. This multi-functional design allows the same search space structure to adapt to various DCI types without requiring separate configurations for each type, thereby improving adaptability while managing complexity.
Data Source
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AI summary
Embodiments of the present invention relate to the communications field, and provide a method, an apparatus, and a system for configuring a search space, to implement that a PDCCH carrying uplink-downlink configuration information can be sent normally, so that user equipment UE can receive uplink-downlink configuration information of a base station in time, thereby ensuring that the UE can complete data transmission according to the uplink-downlink configuration information, and improving user experience. The method includes: configuring, by a base station, a first subframe set, where a subframe in the first subframe set is a downlink subframe or a special subframe; configuring, by the base station, a first common search space CSS in the subframe in the first subframe set; and sending, by the base station to user equipment UE, a physical downlink control channel PDCCH carrying uplink-downlink configuration information, where the PDCCH is a PDCCH in the first CSS. The present invention is applicable to a scenario in which uplink-downlink configuration information is transmitted.