Asynchronous HARQ for Simultaneous Uplink Transmissions
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Solution Overview
Problem
Current HARQ procedures for grant-based uplink transmissions are not suitable for scenarios where a UE simultaneously transmits multiple transport blocks or handles asynchronous HARQ processes, particularly in grant-free uplink transmission schemes where retransmissions may be interrupted by base station grants, leading to asynchronous HARQ processes.
Innovation Solution
The systems and methods described enable HARQ retransmissions, combining, and feedback indication for UEs that simultaneously transmit multiple transport blocks and handle asynchronous HARQ processes by using advanced resource allocation patterns, reference signal sequences, and dedicated feedback channels to manage multiple HARQ processes efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current HARQ procedures for grant-based uplink transmissions are used, then the system maintains simple and standardized HARQ operations, but the system cannot support simultaneous multiple transport block transmissions or asynchronous HARQ processes in grant-free uplink transmission schemes
Solution Approach 1:
The patent segments the HARQ feedback mechanism by introducing separate feedback channels: ACK channels for successfully decoded transport blocks and NACK channels for unsuccessfully decoded transport blocks. This segmentation allows the system to handle multiple TBs simultaneously with different outcomes without requiring complex unified feedback procedures, thus supporting grant-free uplink transmissions while maintaining manageable complexity.
Solution Approach 2:
The patent adds a new dimension to HARQ feedback by implementing asynchronous feedback mechanisms that operate independently from the traditional synchronous grant-based HARQ timeline. This dimensional addition allows feedback to be provided at flexible times suitable for grant-free transmissions, enabling simultaneous multiple TB transmissions without disrupting the underlying HARQ process structure.
2Productivity
If grant-free uplink transmission schemes with autonomous retransmissions are implemented, then the system achieves higher productivity and resource efficiency, but the HARQ processes become asynchronous and incompatible with current uplink HARQ procedures
Solution Approach 1:
The patent creates a universal feedback mechanism that can handle both synchronous grant-based HARQ and asynchronous grant-free HARQ through the same ACK/NACK channel structure. The base station can selectively apply synchronous or asynchronous feedback timing based on the transmission type, making the HARQ procedure multi-functional and compatible with both transmission schemes while maintaining high uplink efficiency.
Solution Approach 2:
The patent introduces dynamic HARQ feedback timing where the base station can adaptively choose between immediate feedback (for grant-based transmissions) and delayed feedback (for grant-free transmissions with autonomous retransmissions). This dynamic approach allows the system to optimize for productivity in grant-free scenarios while maintaining reliability through appropriate feedback timing selection.
3Reliability
If multiple ACK/NACK feedback bits are transmitted for multiple simultaneous TBs, then the system achieves comprehensive error detection and correction, but the feedback channel requires increased bandwidth and complexity
Solution Approach 1:
The patent merges multiple ACK/NACK feedback bits into a unified feedback message structure that can be transmitted through existing uplink control channels. By combining the feedback for multiple TBs into a single structured message with clear identification of which TBs require retransmission, the system achieves comprehensive error detection and correction without proportionally increasing channel complexity, as the merged feedback can be processed efficiently by the base station.
Data Source
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AI summary
Current HARQ procedures for grant-based uplink transmissions may not be suitable for implementations in which a UE can simultaneously transmit multiple transport blocks (TBs) to a base station. However, in some scenarios, such as in some grant-free uplink transmission schemes, a UE may simultaneously transmit multiple TBs. Systems and methods are disclosed herein for performing HARQ for situations in which a UE simultaneously transmits multiple TBs to a base station. By using the systems and methods described herein, HARQ may therefore be performed in such situations.