TDD Inter-band Carrier Aggregation HARQ Timing Conflict Resolution
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Solution Overview
Problem
In wireless communication systems, particularly in E-UTRAN networks, TDD inter-band carrier aggregation faces challenges due to subframe conflicts between cells with different UL-DL configurations, leading to potential collisions during HARQ feedback reception, which can result in suspended or erroneous UL transmissions.
Innovation Solution
The method involves aggregating multiple cells with different TDD UL-DL configurations, addressing subframe conflicts by setting HARQ feedback to ACK, flushing the HARQ buffer, or changing the HARQ feedback subframe to resolve collisions, ensuring efficient PUSCH transmission and avoiding retransmission errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple cells with different TDD UL-DL configurations are aggregated, then data rate and network capacity are improved, but subframe conflicts occur between cells leading to HARQ feedback reception collisions
Solution Approach 1:
The patent applies dynamics by making the HARQ feedback timing configurable and adaptable. The system dynamically selects from multiple possible PDSCH-to-HARQ feedback timing values (e.g., 4, 7, 8 subframes) based on the specific TDD UL-DL configuration and cell aggregation scenario, allowing the timing to be optimized for each situation rather than being fixed, thus resolving subframe conflicts while maintaining high data rates
Solution Approach 2:
The patent changes the parameter of HARQ feedback timing offset to resolve conflicts. By modifying the PDSCH-to-HARQ feedback timing parameter to be configurable across multiple values, the system can adjust the timing to avoid collisions with UL subframes in other cells, thereby maintaining reliability while supporting cell aggregation for improved productivity
2Device complexity
If HARQ feedback timing is fixed according to standard specifications, then system complexity is reduced, but subframe collisions cannot be avoided in inter-band carrier aggregation scenarios
Solution Approach 1:
The patent segments the HARQ timing configuration into cell-specific or configuration-specific timing values. Instead of using a single fixed timing for all cells, the system applies different PDSCH-to-HARQ feedback timing values to different cells or different TDD configurations, allowing each cell to have optimized timing that avoids conflicts while maintaining overall system manageability
Solution Approach 2:
The system transitions from static fixed timing to dynamic configurable timing, where the HARQ feedback timing can be adjusted based on the specific TDD UL-DL configuration and cell aggregation scenario, enabling conflict avoidance without significantly increasing system complexity through standardized configuration mechanisms
3Productivity
If simultaneous TX and RX operations are enabled in TDD inter-band carrier aggregation, then network capacity and data throughput are improved, but subframe conflicts between cells cause erroneous retransmissions
Solution Approach 1:
The patent applies preliminary action by pre-configuring appropriate PDSCH-to-HARQ feedback timing values for different TDD UL-DL configurations and cell aggregation scenarios. The system determines in advance which timing value (e.g., 4, 7, or 8 subframes) should be used for each cell configuration, preventing subframe collisions and erroneous retransmissions before they occur, thus maintaining both high network capacity and transmission accuracy
Data Source
AI summary
A method and apparatus for TDD inter-band carrier aggregation in a wireless communication system includes performing aggregating multiple cells with different TDD UL-DL configurations, transmitting a PUSCH transmission on a first cell, the subframe for HARQ feedback reception for the PUSCH in a first cell colliding with a UL subframe in a second cell, and performing one of setting the corresponding HARQ feedback to ACK, flushing the corresponding HARQ buffer, and changing the corresponding HARQ feedback subframe for the PUSCH to another subframe.