Carrier Aggregation Terminal DCI Index Mapping
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Solution Overview
Problem
In carrier aggregation systems, user equipment faces challenges in efficiently communicating with a base station due to the difficulty in identifying the correct component carriers for downlink control information, especially when cross-carrier scheduling is applied, leading to ambiguity in uplink signal transmission.
Innovation Solution
A method where user equipment determines indices for multiple downlink and uplink component carriers, receives Downlink Control Information (DCI) through at least one downlink component carrier, and transmits an uplink signal through an uplink component carrier indicated by the DCI, with the option of overlapping or non-overlapping indices, and using cyclic or ascending/descending frequency ordering, and high-layer signaling for linkage and index determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cross-carrier scheduling is applied in carrier aggregation system, then bandwidth and data transfer rate are improved, but ambiguity in identifying correct component carriers increases
Solution Approach 1:
The patent introduces a Carrier Indicator Field (CIF) as an intermediary element within the Downlink Control Information (DCI) to explicitly identify which component carrier the scheduling decision applies to. This mediator resolves the ambiguity caused by cross-carrier scheduling by providing a clear reference that links the control information to the specific data carrier, allowing the user equipment to correctly identify and process scheduling decisions across multiple aggregated carriers.
2Quantity of substance
If multiple component carriers are aggregated, then bandwidth capacity is improved, but complexity of carrier identification and management increases
Solution Approach 1:
The patent segments the identification process by dividing the carrier identification task into distinct components: the Carrier Indicator Field (CIF) for identifying the scheduled carrier and the uplink-downlink component carrier linkage information for mapping between carriers. This segmentation allows the system to manage multiple component carriers systematically, with each segment handling a specific aspect of carrier identification and management, thereby reducing overall complexity despite the increased number of carriers.
Solution Approach 2:
The patent introduces linkage information as an intermediary mechanism that establishes explicit mappings between downlink component carriers and uplink component carriers. This intermediary structure simplifies the management of multiple carriers by providing a clear reference framework that eliminates the need for complex identification logic at the user equipment, allowing efficient handling of carrier aggregation even as the number of carriers increases.
3Loss of substance
If indices for downlink and uplink component carriers overlap, then signaling overhead is reduced, but difficulty in distinguishing carrier types increases
Solution Approach 1:
The patent implements dynamic interpretation of carrier indices based on the context of the received DCI. When cross-carrier scheduling is configured, the system dynamically determines whether an index refers to a downlink or uplink carrier based on the linkage information and the specific DCI content. This dynamic approach allows the use of overlapping indices without causing confusion, as the meaning of each index is determined by the operational context rather than being fixed, thereby maintaining low signaling overhead while avoiding ambiguity.
Data Source
AI summary
The present invention provides a communication method of a terminal in a carrier aggregation system. The method comprises: determining indexes relative to a plurality of downlink component carriers and a plurality of uplink component carriers; receiving, from a base station, DCI through at least one downlink component carrier among the plurality of downlink component carriers; and transmitting an uplink signal to the base station through an uplink component carrier determined on the basis of DCI, wherein the DCI includes an index that indicates the uplink component carrier which transmits the uplink signal among the plurality of uplink component carriers.