HARQ Timing for TDD-FDD Carrier Aggregation

The patent segments the HARQ process into separate timing relationships for TDD and FDD component carriers. Specifically, it defines independent HARQ timing parameters (k1, k2, k3) for each carrier type, allowing the system to handle the different frame structures of TDD and FDD separately rather than requiring unified complex coordination. This segmentation resolves the contradiction by maintaining high data transmission capacity through carrier aggregation while simplifying HARQ timing coordination through carrier-specific timing rules.

The patent introduces a carrier indicator field (CIF) as an intermediary mechanism in the downlink control information (DCI) to enable cross-carrier scheduling. The CIF carries the index of the scheduled carrier, allowing the scheduler to flexibly allocate resources across different component carriers while maintaining a unified scheduling structure. This intermediary approach provides the adaptability of cross-carrier scheduling without proportionally increasing complexity, as the CIF adds minimal signaling overhead while enabling versatile resource allocation.

The patent applies local quality by defining carrier-specific HARQ timing parameters (k1 for FDD, k2 for TDD) that are optimized for each carrier type's frame structure. The system allows different timing relationships to coexist on different carriers, with each carrier having its own optimized timing characteristics. This resolves the contradiction by achieving high transmission efficiency through carrier-optimized timing while maintaining timing synchronization through the unified uplink-downlink association rules defined in the patent.