ACK/NACK Feedback Bundling for Multi-TRP Wireless Systems
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Solution Overview
Problem
Current wireless communication systems, particularly in 5G NR, face challenges in efficiently managing acknowledgement (ACK)/negative ACK (NACK) feedback across multiple transmission reception points (TRPs), which affects the reliability and efficiency of data transmission.
Innovation Solution
The system configures base stations and user equipment (UE) to send and receive information on physical downlink control channel (PDCCH) monitoring occasions, allows ACK/NACK feedback bundling, and provides definitions for interpreting downlink assignment indices (DAIs), enabling joint or individual ACK/NACK feedback transmission based on specific rules and DAI configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACK/NACK feedback is provided for each TRP independently, then feedback reliability is improved, but feedback complexity and overhead increase
Solution Approach 1:
The feedback mechanism is segmented into two independent parts: a joint ACK/NACK feedback component that provides common feedback across all TRPs, and individual TRP-specific feedback components that provide TRP-specific information. This segmentation allows the system to maintain feedback reliability through multiple components while reducing overall complexity by avoiding redundant feedback for each TRP independently.
Solution Approach 2:
The patent merges the feedback from multiple TRPs into a unified joint ACK/NACK feedback structure. Instead of treating each TRP's feedback independently, the system combines them into a single feedback message that includes both joint and individual feedback components, thereby reducing feedback overhead and complexity while maintaining reliability.
2Quantity of substance
If ACK/NACK feedback bundling is implemented across multiple TRPs, then feedback overhead is reduced, but feedback processing complexity increases
Solution Approach 1:
The feedback processing is segmented into distinct stages: first determining joint feedback based on common conditions across TRPs, then determining individual feedback for each TRP, and finally combining them into the final feedback message. This segmentation simplifies the processing complexity by breaking down the bundling operation into manageable steps.
Solution Approach 2:
The system performs preliminary actions by first evaluating joint feedback conditions and pre-determining the joint ACK/NACK status before processing individual TRP-specific feedback. This preliminary processing reduces the overall complexity by establishing common feedback decisions early in the process.
3Reliability
If multiple PUCCH resources are configured for feedback transmission, then feedback reliability is improved, but resource allocation complexity increases
Solution Approach 1:
The PUCCH resource allocation is segmented into two types: a first PUCCH resource for transmitting joint feedback and a second PUCCH resource for transmitting individual TRP feedback. This segmentation allows the system to improve reliability through multiple resources while reducing allocation complexity by clearly defining the purpose and usage of each resource type.
Solution Approach 2:
The system dynamically selects which PUCCH resources to use based on feedback configuration parameters. The base station determines whether to use joint feedback, individual feedback, or both, and dynamically allocates resources accordingly. This dynamic approach improves reliability when needed while simplifying resource management when configurations are simpler.
Data Source
AI summary
Various aspects related to ACK/NACK feedback for multi-TRP transmission scenarios are described. A base station, may send, to a UE, information indicating PDCCH monitoring occasions for each of a plurality of TRPs. In one aspect, the base station may send information indicating whether ACK/NACK feedback across the plurality of TRPs is allowed. The base station may send rules to the UE for performing ACK/NACK feedback bundling for providing feedback to the plurality of TRPs. The base station may also send information indicating a DAI definition for interpreting DAIs transmitted by the plurality of TRPs in corresponding PDCCH transmissions indicating whether the DAIs are independent or joint. The base station may receive a joint ACK/NACK feedback from the UE in a PUCCH based on the rules, or may receive multiple ACK/NACK feedback from the UE in a PUCCH for a first TRP independent from a second TRP.