HARQ-ACK Feedback Multiplexing on Unlicensed Spectrum
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Solution Overview
Problem
In wireless communication, especially in 3GPP 5G NR, HARQ-ACK feedback transmission on unlicensed spectrum faces challenges such as LBT procedure failures and interference from hidden network nodes, leading to unnecessary downlink retransmissions and performance degradation due to failed HARQ-ACK reception.
Innovation Solution
The method involves configuring multiple transmission opportunities for HARQ-ACK feedback using radio resource control signaling and multiplexing HARQ-ACK feedback information by modulating additional bits into existing HARQ-ACK codebooks, allowing transmission on unlicensed carriers even after initial LBT failures, and using specific DM RS positions and orthogonal sequences to carry additional information bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HARQ-ACK feedback is transmitted on unlicensed spectrum, then transmission efficiency is improved, but reliability deteriorates due to LBT failures and interference
Solution Approach 1:
The patent applies preliminary action by performing LBT procedure in advance before HARQ-ACK transmission. The system determines whether the channel is available before attempting transmission, and if LBT fails, it schedules alternative resources in advance to ensure feedback delivery, thus preventing transmission failures while maintaining efficient unlicensed spectrum utilization
Solution Approach 2:
The patent implements beforehand cushioning by preparing alternative transmission resources and mechanisms in advance. When LBT failure or interference occurs, pre-configured alternative paths and resources are activated to cushion the impact on reliability, ensuring that HARQ-ACK feedback can still be delivered even when initial transmission attempts fail
2Reliability
If multiple transmission opportunities are provided for HARQ-ACK feedback, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by combining multiple transmission opportunities into a unified HARQ-ACK codebook structure. Instead of treating each transmission opportunity as a separate complex process, the system merges them into a single codebook that can be transmitted across multiple opportunities, simplifying the device complexity while maintaining improved reliability through redundant transmission chances
3Quantity of substance
If HARQ-ACK codebooks are multiplexed in the same slot, then channel resources are saved, but transmission precision deteriorates due to resource conflicts
Solution Approach 1:
The patent applies local quality by assigning different spatial or frequency resources to different HARQ-ACK codebooks within the same slot. Instead of uniform resource allocation, the system provides localized resource differentiation that allows multiple codebooks to coexist in the same time slot without interfering with each other, thus maintaining transmission precision while improving resource utilization
Data Source
AI summary
The present application is related to a method and apparatus for transmitting HARQ-ACK feedback on unlicensed spectrum. A method for HARQ-ACK multiplexing includes receiving a plurality of downlink transmissions, generating a HARQ-ACK codebook corresponding to the plurality of downlink transmissions, wherein the HARQ-ACK codebook is to be transmitted in a slot, receiving another plurality of downlink transmissions; generating another HARQ-ACK codebook corresponding to the another plurality of downlink transmissions, wherein the another HARQ-ACK codebook is to be transmitted in the slot, and transmitting the HARQ-ACK codebook on an uplink channel in the slot.