LTE TDD HARQ-ACK Feedback Mechanism for Carrier Aggregation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In LTE TDD systems, the existing carrier aggregation technology limits the number of carriers that can be configured for user equipment (UE), leading to increased feedback delay and degraded feedback performance, especially in uplink-downlink configurations like 5 where transmission of acknowledgement information is limited.
Innovation Solution
The proposed solution involves redefining the HARQ time sequence relationship in carrier aggregation to allow for more carriers to be configured in certain TDD uplink-downlink configurations. This is achieved by determining a specific HARQ time sequence relationship between the physical downlink shared channel (PDSCH) and HARQ acknowledgement (HARQ-ACK) information, allowing HARQ-ACKs to be fed back in multiple uplink subframes, thereby improving feedback performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a maximum of five carriers or serving cells are configured for one UE in LTE TDD system, then the system maintains compatibility with existing standards, but the feedback delay increases and feedback performance degrades when using uplink-downlink configuration 5
Solution Approach 1:
The patent segments the feedback transmission by introducing multiple feedback opportunities within a single uplink subframe. Instead of transmitting all HARQ-ACK bits sequentially, the method divides the feedback into multiple parts that can be transmitted simultaneously through different resources (PUCCH format 3 and PUCCH format 1b/1a), thereby reducing the effective feedback delay while maintaining support for up to 5 carriers
Solution Approach 2:
The patent adds a new dimension to feedback transmission by utilizing both time and resource domain multiplexing. It introduces parallel feedback channels (PUCCH format 3 for carrier aggregation and PUCCH format 1b/1a for additional feedback) that operate simultaneously, transforming the single-dimensional sequential feedback into a multi-dimensional parallel feedback structure, thus reducing feedback delay without increasing the number of carriers beyond 5
2Adaptability or versatility
If PUCCH format 3 transmission mode is used with a maximum of 20 bits in acknowledgement information, then the transmission mode is simple to implement, but the number of supported carriers is limited in certain TDD uplink-downlink configurations
Solution Approach 1:
The patent merges multiple feedback transmission modes (PUCCH format 3 and PUCCH format 1b/1a) into a unified carrier aggregation feedback mechanism. By combining the capabilities of both formats, the system can support up to 5 carriers while distributing the feedback bit load across different formats, thereby increasing adaptability without proportionally increasing device complexity
Solution Approach 2:
The patent changes the feedback transmission parameters by dynamically selecting between different PUCCH formats based on the number of carriers and uplink-downlink configuration. It adjusts the feedback bit allocation and transmission resources according to the specific scenario, allowing the system to adapt to 5-carrier configurations while maintaining reasonable implementation complexity through parameter optimization
3Reliability
If acknowledgement information corresponding to all downlink subframes of a secondary serving cell is fed back in one or several uplink subframes, then the feedback mechanism is simple, but the feedback delay is increased and feedback performance is degraded
Solution Approach 1:
The patent introduces dynamic HARQ timing relationships that adapt to different uplink-downlink configurations. Instead of using fixed feedback timing, the system dynamically determines the appropriate PUCCH format and transmission resources based on the specific downlink subframe and uplink subframe pairing, allowing optimized feedback delay while managing complexity through dynamic adaptation rather than static configuration
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
Embodiments of the present invention provide a method, an apparatus, and a device for transmitting acknowledgement information. The apparatus includes: a transmission module, configured to transmit, in a secondary serving cell, a PDSCH to UE; a determining module, configured to determine an HARQ time sequence relationship corresponding to the secondary serving cell, where the HARQ time sequence relationship is an HARQ time sequence relationship between the PDSCH and an HARQ; and a receiving module, configured to receive, in a primary serving cell according to the HARQ time sequence relationship determined by the determining module, the HARQ-ACK corresponding to the PDSCH; where the primary serving cell is a TDD primary serving cell configured by a base station for the UE, the secondary serving cell is a secondary serving cell in N TDD secondary serving cells configured by the base station for the UE, and N is a natural number that is greater than or equal to 1. In the embodiments of the present invention, more carriers can be configured for UE in some uplink-downlink configurations in an LTE TDD system, an acknowledgement information feedback delay is shortened, and feedback performance is improved.