Carrier Aggregation Feedback Delay Reduction via Subframe Deviation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The Carrier Aggregation TDD system has a feedback delay that is equal to or greater than the Carrier Aggregation FDD system, with no effective solution existing to address this issue.
Innovation Solution
The method involves aggregating multiple Time Division Duplexing (TDD) serving cells with subframe deviations to obtain PCells and SCells, where the transmission node transmits information based on these deviations, allowing the terminal to adjust HARQ-ACK feedback timing to match the FDD system's delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If TDD serving cells are aggregated using conventional methods, then the system supports TDD operation, but the feedback delay becomes equal to or greater than FDD system delay
Solution Approach 1:
The patent applies preliminary action by pre-configuring subframe deviation values (D_s) for different TDD uplink-downlink configurations before actual carrier aggregation operation. The network pre-calculates and signals these deviation values to the terminal, allowing the terminal to proactively adjust HARQ-ACK feedback timing without real-time computation delays, thus reducing feedback delay while maintaining TDD configuration flexibility
Solution Approach 2:
The patent changes the timing parameter by introducing subframe deviation values (D_s) that shift the HARQ-ACK feedback timing from the conventional n+k relationship to n+k-D_s. This parameter modification allows the feedback delay to be reduced from 4 subframes (FDD equivalent) to potentially fewer subframes, while the network can dynamically adjust D_s based on different TDD configuration scenarios
2Productivity
If HARQ-ACK feedback timing follows conventional TDD specifications, then the system maintains standard compliance, but transmission performance deteriorates due to increased delay
Solution Approach 1:
The patent modifies the HARQ-ACK feedback timing parameter by introducing subframe deviation D_s, changing the timing relationship from conventional n+k to n+k-D_s. This parameter change reduces feedback delay while maintaining compatibility with TDD frame structure, thereby improving transmission performance without sacrificing standard compliance
Solution Approach 2:
The patent introduces dynamic adjustment capability where the subframe deviation D_s can be differently configured for primary and secondary cells (D_s,P and D_s,S), allowing the system to adaptively optimize feedback timing based on specific carrier aggregation scenarios and TDD configurations, thus improving transmission performance
3Adaptability or versatility
If multiple TDD serving cells with different uplink-downlink configurations are aggregated, then system versatility improves, but intercell interference increases
Solution Approach 1:
The patent applies local quality by allowing different subframe deviation values (D_s,P and D_s,S) to be configured for primary and secondary cells respectively. This enables each cell to have optimized feedback timing tailored to its specific TDD configuration, reducing timing misalignment and intercell interference while maintaining the ability to aggregate cells with different uplink-downlink configurations
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The present invention discloses a Carrier Aggregation (CA) method and device for a communication system. Herein, the CA method for the communication system includes that: multiple serving cells with subframe deviations are aggregated to obtain K Primary Cells (PCells) and M Secondary Cells (SCells), herein K and M are positive integers; and a transmission node transmits information on the multiple aggregated serving cells according to the subframe deviations. By the present invention, a transmission delay of a Long Term Evolution Time Division Duplex (LTE TDD) system may be reduced.