NACK Feedback HARQ for V2V Groupcast Reliability
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Solution Overview
Problem
Current wireless communication technologies face challenges in achieving high reliability and low latency for groupcast communications in New Radio (NR) V2V applications, particularly in supporting diverse use cases with varying frequency ranges and deployment options, due to limitations in resource allocation and error correction mechanisms.
Innovation Solution
A NACK feedback based HARQ retransmission scheme is implemented, where NACK time-frequency resources are signaled in the SCI for V2V groupcast communications, allowing for retransmissions based on feedback and beamforming adjustments to enhance reliability and control interference, with the option to signal a maximum repetition level and use beam-specific reference signals for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback based HARQ scheme is applied for sidelink communication, then reliability is improved, but device complexity increases due to additional feedback signaling and resource management
Solution Approach 1:
The feedback mechanism is segmented into two distinct types: NACK-only feedback for groupcast communications and ACK/NACK feedback for unicast communications. This segmentation allows the system to apply the appropriate feedback type based on the communication scenario, reducing unnecessary signaling complexity while maintaining reliability where needed
Solution Approach 2:
The feedback mechanism dynamically adapts to different communication scenarios (groupcast vs. unicast) by selecting different feedback types. The system can switch between NACK-only and ACK/NACK feedback based on the traffic type, making the complexity dynamic rather than static, thus optimizing resource usage
2Reliability
If NACK feedback is transmitted for every failed decoding, then reliability is improved, but uplink resource consumption increases
Solution Approach 1:
The patent extracts only the essential feedback signal (NACK) for groupcast communications, removing the redundant ACK signaling. By taking out only the necessary negative acknowledgment when decoding fails, the system reduces uplink resource consumption while maintaining the reliability needed for successful data delivery
Solution Approach 2:
Instead of requiring full dual-directional feedback (ACK and NACK), the system applies partial action by implementing NACK-only feedback for groupcast. This partial feedback mechanism is sufficient for the reliability requirements of groupcast while significantly reducing the quantity of uplink resources consumed compared to complete feedback schemes
3Object-generated harmful factors
If beamforming is used for retransmission, then interference control is improved, but device complexity increases due to beam management overhead
Solution Approach 1:
Beamforming is applied locally and selectively only during retransmission phases rather than continuously for all transmissions. The system uses beam-specific reference signals and beam indicators to apply directional transmission precisely where needed (during retransmission to specific receiving UEs), improving interference control in localized areas without requiring complex continuous beam management across all communication scenarios
Data Source
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AI summary
The present disclosure includes methods and devices for NACK feedback based HARQ retransmission scheme in a wireless communication network. The method includes receiving mobile radio communication terminal devices transmitting NACK feedback signaled time-frequency resources and transmitting mobile radio communication terminal devices performing retransmission of the previously sent messages based on receiving NACK feedback.