HARQ Timing Configuration for TDD Carrier Aggregation
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Solution Overview
Problem
In LTE networks, the hybrid automatic repeat request (HARQ) timing and procedure are disrupted due to overlapping TDD UL/DL subframes in primary and secondary cells with different configurations, leading to blocked feedback and missed UL grants in mobile terminals configured for carrier aggregation.
Innovation Solution
Defining the HARQ timing and procedure to ensure consistent UL or DL HARQ timing, maximum number of HARQ processes, or UL HARQ process mapping for both primary and secondary cells, even when they have different TDD UL/DL subframe configurations, thereby allowing feedback to be provided without being blocked.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different TDD UL/DL subframe configurations are used for primary and secondary cells to provide flexible resource allocation and coverage, then adaptability and resource optimization are improved, but HARQ timing and feedback delivery are disrupted due to overlapping subframes
Solution Approach 1:
The patent applies local quality by allowing different TDD UL/DL subframe configurations for primary and secondary cells based on their specific requirements. Each cell can be independently configured with appropriate UL/DL ratios to optimize its coverage and capacity characteristics, while the HARQ timing is locally adjusted to account for overlapping subframes between cells.
Solution Approach 2:
The patent changes the HARQ timing parameters when overlapping subframes are detected between primary and secondary cells. The system dynamically adjusts the HARQ feedback timing to occur in non-overlapping subframes, ensuring reliable feedback delivery while maintaining the flexibility of different TDD configurations for resource optimization.
2Productivity
If simultaneous reception and transmission are enabled to accommodate overlapping subframes, then communication continuity is improved, but device complexity increases
Solution Approach 1:
The patent implements a dynamic approach where the mobile terminal is configured to enable simultaneous reception and transmission only during overlapping subframe periods. The system dynamically switches between normal operation mode and simultaneous operation mode based on the TDD configuration timing, maintaining communication continuity while minimizing the duration and complexity of the dual operation state.
Data Source
AI summary
Methods, apparatus and computer program products are provided for defining the HARQ functionality for primary and secondary cells having different TDD UL/DL subframe configurations so as to reduce or eliminate instances in which the feedback is blocked and the UL grant is missed. For example, a method is provided that includes providing for communications via a primary cell and at least one secondary cell in a time division duplex (TDD) network that supports carrier aggregation in accordance with different TDD uplink (UL)/downlink (DL) subframe configurations. In this example, the method also defines at least one of: (i) UL or DL hybrid automatic repeat request (HARQ) timing, (ii) a maximum number of DL HARQ processes, (iii) a number of UL HARQ processes or (iv) an UL HARQ process mapping to be the same for each of the primary and secondary cells having different TDD UL/DL subframe configurations.