HARQ-ACK Resource Timing for Low-Latency Dynamic TDD Feedback
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Solution Overview
Problem
The existing HARQ ACK/NACK timing configurations in NR-TDD systems lead to latency due to semi-static configurations, especially in dynamic TDD scenarios and SBFD schemes, which do not efficiently utilize uplink transmission opportunities.
Innovation Solution
A wireless transmit/receive unit (WTRU) is configured to transmit HARQ-ACK using second time and frequency resources within SBFD download time units, allowing for opportunistic transmission based on implicit, explicit, or semi-static indications, and can transmit NACK using first time and frequency resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If semi-static HARQ ACK/NACK timing configuration is used, then configuration simplicity is maintained, but transmission latency increases and uplink opportunity utilization is reduced
Solution Approach 1:
The patent applies dynamics by transitioning from semi-static HARQ timing configuration to dynamic configuration. The network can now dynamically indicate second time and frequency resources for HARQ-ACK transmission based on current TDD uplink/downlink slot configurations and SBFD settings, allowing the timing to adapt to changing network conditions rather than being fixed semi-statically.
Solution Approach 2:
The patent changes the timing parameter from a fixed semi-static configuration to a dynamic parameter that can be indicated through higher layer signaling. The second time and frequency resources are determined based on current system state including TDD configuration and SBFD patterns, allowing parameter adjustment to optimize latency and uplink utilization.
2Stability of the object's composition
If semi-static HARQ ACK/NACK timing is used, then configuration stability is maintained, but uplink transmission opportunity utilization is reduced
Solution Approach 1:
The system dynamically determines second time and frequency resources based on current TDD uplink/downlink slot configurations and SBFD patterns. This dynamic approach allows the network to maximize uplink transmission opportunities by adapting to changing slot configurations while maintaining stability through structured indication mechanisms.
Solution Approach 2:
The patent creates a universal mechanism that works across different TDD configurations and SBFD patterns. The higher layer indication mechanism can accommodate various time and frequency resource allocations, making the system adaptable to multiple network configurations without requiring separate handling for each scenario.
3Productivity
If dynamic TDD and SBFD are implemented, then uplink transmission opportunities increase, but timing indication complexity increases
Solution Approach 1:
The patent introduces higher layer indication as an intermediary mechanism between the complex dynamic TDD/SBFD configuration and the HARQ timing determination. This intermediary layer simplifies the timing indication by providing structured parameters that the WTRU can process to determine the second time and frequency resources without needing to directly interpret complex slot configurations.
Solution Approach 2:
The patent segments the timing indication into distinct components: first time and frequency resources for NACK transmission, and second time and frequency resources for HARQ-ACK transmission. This segmentation allows each component to be independently configured and processed, reducing the overall complexity of handling dynamic TDD and SBFD timing indications.
4Loss of time
If earlier HARQ-ACK transmission time is used, then latency is reduced, but collision risk with NACK transmission increases
Solution Approach 1:
The patent segments the feedback transmission into two distinct time and frequency resource sets: first resources for NACK transmission and second resources for HARQ-ACK transmission. By separating these transmissions temporally and spectrally, the system enables earlier HARQ-ACK transmission to reduce latency while preventing collisions with NACK transmissions through proper resource allocation.
Solution Approach 2:
The patent applies local quality by assigning different time and frequency characteristics to NACK and HARQ-ACK transmissions. The first time and frequency resources are optimized for NACK transmission, while the second resources are optimized for HARQ-ACK transmission, allowing each type of feedback to have dedicated resources with appropriate timing and frequency characteristics.
Data Source
AI summary
A wireless transmit/receive unit (WTRU) may receive a plurality of downlink signals. The WTRU may receive first configuration information indicating first time and frequency resources for transmission of hybrid automatic repeat request (HARQ) acknowledgment (ACK). The WTRU may receive second configuration information indicating second time and frequency resources for transmission of HARQ-ACK. The second configuration information may indicate one or more sequences to be transmitted using the second time and frequency resources. The WTRU may transmit at least one sequence of the one or more sequences using the second time and frequency resources. The at least one sequence of the one or more sequences may be transmitted using the second time and frequency resources to indicate an ACK associated with the plurality of downlink signals.