TDD Carrier Aggregation ACK/NACK Rebalancing Across Component Carriers
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Solution Overview
Problem
In TDD networks with carrier aggregation, the different TDD UL/DL subframe configurations of primary and secondary cells can lead to unbalanced DL association sets, resulting in increased transmission and reception (TP) loss due to unnecessary retransmissions, which existing technologies have not adequately addressed.
Innovation Solution
The method involves balancing the number of ACK/NACK bits by modifying the number of DL subframes in the DL association sets for component carriers with different TDD UL/DL subframe configurations, thereby reducing unnecessary retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different TDD UL/DL subframe configurations are used for primary and secondary cells to provide different coverage and resource amounts, then the adaptability and coverage are improved, but the DL association sets become unbalanced causing increased TP loss due to unnecessary retransmissions
Solution Approach 1:
The patent modifies the parameters of DL association sets by adjusting the number of DL subframes included in each set for different component carriers. Specifically, it changes the configuration parameters to balance the association set sizes across carriers with different TDD UL/DL configurations, thereby reducing unnecessary retransmissions and TP loss while maintaining the adaptability benefits of different subframe configurations
Solution Approach 2:
The patent intentionally introduces asymmetry in the modification process by applying different adjustment rules to different component carriers. The first component carrier's DL association set is modified differently than the second component carrier's set, creating an asymmetric solution that balances the overall system performance while respecting the asymmetric nature of different TDD configurations
2Adaptability or versatility
If different TDD UL/DL subframe configurations are used for primary and secondary cells to support inter-band carrier aggregation, then the versatility is improved, but the device complexity increases due to unbalanced ACK/NACK bit requirements
Solution Approach 1:
The patent changes the parameters of DL association sets to balance the number of ACK/NACK bits across component carriers with different TDD configurations. By modifying the association set configurations rather than changing the fundamental TDD UL/DL subframe configurations, the patent maintains versatility for inter-band carrier aggregation while reducing the complexity introduced by unbalanced ACK/NACK bit requirements
3Ease of operation
If the number of DL subframes in DL association sets is not adjusted for different TDD configurations, then the ease of operation is maintained, but the productivity decreases due to increased retransmissions and reduced communication throughput
Solution Approach 1:
The patent modifies the parameters of DL association sets by adjusting the number of DL subframes included in each set. This parameter change directly addresses the productivity issue by reducing unnecessary retransmissions and improving communication throughput, while the modifications are applied in a systematic manner that maintains ease of operation through defined adjustment rules for different component carriers
Data Source
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AI summary
Methods, apparatus and computer program products are provided for rebalancing the sizes of downlink (DL) association sets for component carriers having different time division duplex subframe configurations. A method is provided that includes determining DL subframes that are included in a DL association set for each of a plurality of component carriers. In an instance in which the number of acknowledgement (ACK)/negative acknowledgement (NACK) bits corresponding to the DL subframes included in the DL association sets for respective component carriers differ by at least a predetermined amount, the method modifies the number of ACK/NACK bits corresponding to the DL subframes that are included in the DL association sets for each of the respective component carriers. The method may also cause transmission of the ACK/NACK bits in accordance with the DL association sets, as modified, via the respective component carriers. Corresponding apparatus and computer program products are also provided.