HARQ-ACK Mapping for TDD-FDD Carrier Aggregation
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Solution Overview
Problem
In carrier aggregation systems, there is a lack of mechanisms for transmitting and receiving HARQ-ACK information across cells with different frame structure types, leading to inefficient communication.
Innovation Solution
A communication method that enables appropriate transmission and reception of HARQ-ACK information by mapping it to PUCCH resources and coordinating subframe patterns between TDD and FDD cells, allowing for efficient communication in systems with mixed frame structure types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is performed by aggregating TDD and FDD component carriers, then communication speed and data rate are improved, but communication reliability deteriorates due to lack of HARQ-ACK transmission mechanism across different frame structure types
Solution Approach 1:
The patent introduces a mapping mechanism that acts as an intermediary between TDD and FDD frame structures. Specifically, it maps HARQ-ACK timing from FDD to TDD by using a reference FDD subframe and determining corresponding TDD subframes through a mapping table or formula, enabling reliable feedback transmission across different duplex modes without requiring separate mechanisms for each type.
Solution Approach 2:
The patent changes the timing parameter representation from FDD-based subframe indices to TDD-based subframe indices through a mapping function. By transforming the timing relationship parameters (k values) between different frame structures, the system maintains HARQ-ACK reliability while supporting carrier aggregation across TDD and FDD component carriers.
2Device complexity
If HARQ-ACK information is transmitted without a mapping mechanism between different frame structures, then device complexity is reduced, but information loss occurs due to inability to properly transmit feedback across TDD and FDD cells
Solution Approach 1:
The patent creates a universal HARQ-ACK transmission mechanism that works across both TDD and FDD frame structures through a unified mapping approach. The same mapping table and timing relationship formulas can be applied regardless of whether the component carriers are TDD or FDD, eliminating the need for separate handling logic and preventing information loss while maintaining manageable complexity.
3Reliability
If separate HARQ-ACK mechanisms are implemented for TDD and FDD cells, then communication reliability is improved, but device complexity increases due to multiple transmission mechanisms
Solution Approach 1:
The patent merges the HARQ-ACK transmission mechanisms for TDD and FDD into a unified framework. By combining the timing relationship definitions and using a common mapping approach that accommodates both frame structures, the system achieves reliable transmission without requiring separate independent mechanisms, thus reducing overall complexity while maintaining reliability.
Data Source
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AI summary
A terminal communicating with a base station by using an FDD cell and a TDD cell includes a reception unit that performs reception over a PDCCH transmitted using a DCI format. In a case where the TDD cell is configured as a primary cell for the terminal, a first uplink reference UL-DL configuration used for determining an interval between reception of the PDCCH indicating transmission of a PUSCH and the transmission of the PUSCH is configured for the TDD cell, and a second uplink reference UL-DL configuration used for determining whether or not to use DAI included in the DCI format of the PDCCH indicating the transmission of the PUSCH is configured for the FDD cell.