Feedback Timing for Carrier Aggregation with Different TDD Configurations

The patent segments the feedback transmission by introducing a primary carrier and secondary carrier distinction. Feedback for the primary cell (PCell) is transmitted on the primary carrier, while feedback for secondary cells (SCells) is transmitted on the primary carrier as well, but with different timing requirements. This segmentation allows different TDD configurations to be handled separately, resolving the timing conflict that arises when multiple carriers with different uplink-downlink configurations are aggregated.

The patent introduces a timing indication mechanism as an intermediary. The network side configures and indicates specific timing relationships between downlink data reception and uplink feedback transmission for each carrier. This intermediary timing indication layer mediates between the conflicting TDD configurations of different carriers, allowing the system to maintain multiple aggregated carriers with different configurations while ensuring proper feedback timing for each.

The patent implements dynamic feedback timing adjustment. Instead of using fixed feedback timing rules that work for a single TDD configuration, the system dynamically determines feedback timing based on the specific TDD configuration of each carrier and the indicated timing relationships. The UE adjusts its feedback transmission timing dynamically according to the configured timing indications, allowing reliable feedback transmission across carriers with different and changing TDD configurations.

The patent changes the feedback transmission parameters (timing offset, uplink subframe selection) based on the TDD configuration parameters of each carrier. The network side configures different timing parameters for different carriers, and the UE applies these parameter changes to ensure that feedback is transmitted at appropriate times that satisfy both the TDD configuration constraints and the timing requirements for reliable communication.