HARQ Timing Configuration for FDD-TDD Carrier Aggregation
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Solution Overview
Problem
Current 3GPP standards do not address the possibility of a user equipment being served by simultaneously aggregated FDD and TDD carriers, lacking mechanisms for downlink scheduling and HARQ control timing in such networks.
Innovation Solution
The proposed solution involves determining a control timing configuration for a base station and user equipment to manage downlink HARQ-ACK control timing in a multiple cell communications network, where the user equipment is served by both TDD and FDD based cells, by selecting an applicable reference configuration based on the used FDD or TDD UL/DL configuration, and implementing this configuration for HARQ and scheduling timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a user equipment is served by simultaneously aggregated FDD and TDD carriers, then network capacity and spectral efficiency are improved, but the complexity of downlink scheduling and HARQ control timing increases significantly
Solution Approach 1:
The patent segments the carrier aggregation into a primary cell (PCell) and secondary cell (SCell), where the PCell handles control signaling and the SCell handles data transmission. This segmentation allows the system to manage the complexity of FDD-TDD aggregation by separating control and data functions across different cells with different duplexing modes.
Solution Approach 2:
The patent introduces an intermediary mechanism where the PCell acts as a mediator between the FDD and TDD carriers. The PCell provides the reference timing configuration that reconciles the different HARQ timing requirements of FDD and TDD modes, enabling coordinated operation without requiring separate timing mechanisms for each carrier type.
2Measurement precision
If separate HARQ timing mechanisms are implemented for FDD and TDD carriers, then timing accuracy is improved, but the overall system complexity and signaling overhead increase
Solution Approach 1:
The patent implements a universal HARQ timing mechanism where a single timing configuration from the PCell serves both FDD and TDD SCells. This multi-functional approach allows the same timing reference to be used across different duplexing modes, maintaining timing accuracy while avoiding the complexity of separate timing mechanisms.
Solution Approach 2:
Instead of having each carrier type (FDD and TDD) provide its own timing reference, the patent inverts the approach by having the control cell (PCell) provide a unified timing reference that both FDD and TDD data cells must follow. This inversion simplifies the system by centralizing timing control rather than distributing it across multiple independent sources.
Data Source
AI summary
Some of the example embodiments are directed towards a base station for determining a control timing configuration in order to provide a subframe timing setting for configuring downlink HARQ-ACK control timing for a cell serving a user equipment in a multiple cell communications network. The user equipment is served a TDD based cell and a FDD based cell. Some example embodiments are directed towards the user equipment the control timing configuration as discussed above.