HARQ Feedback Carrier Aggregation FDD TDD Mapping
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing HARQ feedback for carrier aggregation of FDD and TDD carriers, leading to increased bundling, larger DCI formats, and reduced spectral efficiency, particularly in TDD configurations where uplink subframes are fewer than downlink subframes.
Innovation Solution
The method involves providing HARQ feedback on the uplink FDD carrier, associating each downlink subframe and special subframe in the TDD carrier with an uplink subframe in a one-to-one manner, and using QPSK modulated sequences to form HARQ messages, thereby reducing bundling and optimizing resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation of FDD and TDD carriers is implemented, then spectral efficiency is improved, but HARQ feedback management complexity increases
Solution Approach 1:
The patent segments HARQ feedback management by separating FDD and TDD carrier feedback handling. FDD carriers use continuous uplink subframes for feedback, while TDD carriers map multiple downlink subframes to specific uplink subframes. This segmentation allows each duplexing mode to be managed independently, reducing overall complexity while maintaining high spectral efficiency through carrier aggregation.
Solution Approach 2:
The patent implements a universal HARQ feedback mechanism that works across both FDD and TDD carriers. The system uses a common uplink FDD carrier for HARQ feedback transmission regardless of which downlink carrier (FDD or TDD) the feedback corresponds to. This multi-functional approach simplifies the feedback management architecture while supporting carrier aggregation of different duplexing modes.
2Productivity
If TDD carrier is used with more downlink subframes than uplink subframes, then downlink capacity is improved, but HARQ feedback resource allocation becomes difficult
Solution Approach 1:
The patent introduces an intermediary FDD uplink carrier that mediates between TDD downlink subframes and the uplink feedback resources. Multiple TDD downlink subframes are mapped to specific uplink subframes on the FDD carrier, which has sufficient uplink capacity. This intermediary approach resolves the resource allocation difficulty by providing a dedicated feedback channel that is not constrained by the TDD uplink subframe limitation.
Solution Approach 2:
The patent moves HARQ feedback transmission to a different time-frequency dimension by using the FDD uplink carrier instead of TDD uplink subframes. The feedback resources are allocated in the frequency domain on the FDD carrier, allowing multiple TDD downlink subframes to be acknowledged without being limited by the TDD uplink subframe count. This dimensional change enables efficient feedback resource allocation.
Data Source
Figure 1A~1B
Figure 1C~1E
Figure 2~3
AI summary
Method (500) in a radio network node (110), a radio network node (110), method (700) in a recipient (120) and a recipient (120), for data transmission and assignment of uplink control channel resources (310) in an uplink FDD carrier (300), for enabling a recipient (120) to provide HARQ feedback for data transmitted in the downlink using carrier aggregation of a downlink FDD carrier (350) and at least one TDD carrier (200). The method (500) comprises associating (501) each downlink subframe (360) in the downlink FDD carrier (350) with an uplink control channel subframe (310) in the uplink FDD carrier (300). Further, the method (500) comprises associating (502) each downlink subframe (210) and special subframe (220) in the TDD carrier (200) with an uplink control channel subframe (310) in the uplink FDD carrier (300). The method (500) also comprises assigning (503) uplink control channel resources (310) in the uplink FDD carrier (300) to the recipient (120), according to the made associations (501, 502). In addition, the method also comprises transmitting (504) data on said downlink FDD carrier (350) and/ or TDD carrier (200), to be received by the recipient (120).