Carrier Scheduling Indication Reducing DCI Overhead
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Solution Overview
Problem
In LTE systems, the existing carrier aggregation technology results in large signaling overheads due to the need for a long Downlink Control Information (DCI) field when a base station configures a large number of carriers, as the Downlink Assignment Indication (DAI2) field must indicate scheduling statuses for all configured carriers except the current scheduled one.
Innovation Solution
A Carrier Assignment Indication (CAI) field is generated by the base station to indicate the total number of scheduled carriers and the accumulative index of the current scheduled carrier, reducing the number of bits required in the DCI field by indicating scheduling information more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the DAI2 field indicates scheduling statuses of all configured carriers different from the current scheduled carrier, then the UE can learn scheduling statuses of all configured carriers, but the quantity of bits of the DAI2 field increases to equal the quantity of configured carriers minus 1, resulting in large signaling overheads
Solution Approach 1:
The patent segments the carrier scheduling indication into two parts: the DAI field (Downlink Assignment Indicator) that provides cumulative scheduling status information, and the CAI field (Carrier Assignment Indicator) that provides compact carrier-specific scheduling information. This segmentation allows the system to avoid transmitting full scheduling status for all carriers while still providing complete scheduling information to the UE, thereby reducing signaling overhead while maintaining information completeness.
Solution Approach 2:
The patent extracts the essential scheduling status information into a compact DAI field that indicates the cumulative number of scheduled carriers, and separates the detailed carrier assignment information into a dedicated CAI field. This extraction allows the main scheduling status to be conveyed with minimal bits, reducing the overall signaling overhead while preserving all necessary scheduling information.
2Area of stationary object
If the base station configures a large quantity of carriers, then the spectral bandwidth increases, but the DAI2 field includes more bits making the DCI relatively long and increasing signaling overheads
Solution Approach 1:
The patent implements dynamic carrier aggregation where the base station can flexibly configure and activate different numbers of carriers based on traffic demands and channel conditions. The DCI format dynamically adapts to indicate only the necessary scheduling information for currently active carriers through the CAI field, rather than maintaining fixed-length fields for all possible carriers. This dynamic approach allows the system to utilize large spectral bandwidth when needed while keeping DCI length manageable by only indicating actively scheduled carriers.
Solution Approach 2:
The patent changes the parameter representation from indicating scheduling status of each individual carrier (which requires multiple bits per carrier) to indicating the cumulative number of scheduled carriers and their identities through the CAI field. This parameter transformation reduces the DCI field length from O(N) bits to O(log N) bits where N is the number of configured carriers, enabling efficient support for large numbers of carriers without proportionally increasing signaling overhead.
Data Source
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AI summary
Embodiments of the present invention disclose a base station, user terminal, and a carrier scheduling indication method, and relate to the communications field, so as to resolve a problem that signaling overheads are relatively large because a quantity of configured carriers of the base station is relatively large. A specific solution is: generating, by a processing unit, a CAI field of a current scheduled carrier according to scheduling statuses of all configured carriers, where the CAI field is used to indicate a total quantity of scheduled carriers in all the configured carriers and an accumulative index value M of the current scheduled carrier, and M represents that the current scheduled carrier is the Mth scheduled carrier from the 1st configured carrier to the current scheduled carrier; or the CAI field is used to indicate a number of a preceding scheduled carrier of the current scheduled carrier and a number of a next scheduled carrier of the current scheduled carrier; andsending, by a sending unit, downlink control information DCI, by carrying the CAI field generated by the processing unit to the DCI, to UE by using the current scheduled carrier The present invention is applied to a carrier scheduling indication process.