PDSCH Redundancy Gap Feedback for Reliable Low-Latency Retransmissions
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing redundancy versions (RVs) for Physical Downlink Shared Channel (PDSCH) transmissions, leading to suboptimal performance in scenarios requiring ultra-reliable low-latency communications (URLLC) and massive Machine-Type Communications (mMTC) in 5G networks.
Innovation Solution
Implementing a method for generating and utilizing Hybrid Automatic Repeat Request (HARQ) feedback to indicate a redundancy gap associated with PDSCH, enabling enhanced feedback mechanisms for retransmissions and channel state information (CSI) to optimize RV sequences and slot aggregation, thereby improving transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HARQ feedback mechanisms are used for PDSCH transmissions, then system compatibility is maintained, but transmission reliability is insufficient for URLLC and mMTC applications
Solution Approach 1:
The patent implements dynamic HARQ feedback mechanisms where the UE can adaptively select between different feedback types (ACK/NACK only, or ACK/NACK with redundancy gap indication) based on channel conditions and application requirements. The base station dynamically adjusts retransmission parameters including RV sequence selection and slot aggregation levels based on received feedback, enabling the system to adapt to varying reliability requirements of different 5G applications such as URLLC and mMTC
Solution Approach 2:
The patent introduces new parameters including redundancy gap indication values and enhanced HARQ feedback structures that provide more granular control over retransmission behavior. By changing parameters such as the number of redundancy versions, RV sequence patterns, and slot aggregation levels, the system can optimize transmission reliability for specific application scenarios while maintaining compatibility with existing protocols
2Reliability
If multiple retransmissions are performed to ensure reliable data reception, then transmission reliability is improved, but latency increases
Solution Approach 1:
The patent employs preliminary actions by pre-configuring multiple RV sequences and slot aggregation patterns before transmission. The base station prepares alternative retransmission strategies in advance, and the UE provides early feedback on channel conditions and decoding status. This allows the base station to select the most efficient retransmission path before actual retransmissions begin, reducing the time required for multiple retry cycles
Solution Approach 2:
The patent implements enhanced feedback mechanisms where the UE provides not only ACK/NACK but also redundancy gap indications that inform the base station about the amount of additional redundancy needed for successful decoding. This feedback enables the base station to adjust subsequent retransmissions more efficiently, potentially reducing the number of retransmission rounds required and thereby lowering overall latency while maintaining high reliability
3Productivity
If redundancy gap indication is added to HARQ feedback, then transmission efficiency is improved, but feedback complexity increases
Solution Approach 1:
The patent designs the enhanced HARQ feedback structure to serve multiple functions: it provides ACK/NACK indication, redundancy gap information, and channel quality feedback all within a unified feedback message framework. The base station can interpret the feedback according to different application requirements, making the system versatile without requiring separate feedback channels for each function, thereby managing complexity while improving transmission efficiency
Data Source
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AI summary
Techniques discussed herein can facilitate successful decoding of Physical Downlink Shared Channel (PDSCH) based on a reduced number of retransmissions. Based on a given PDSCH, embodiments discussed herein can communicate feedback (e.g., Hybrid Automatic Repeat reQuest (HARQ) feedback, Channel State Information (CSI) feedback) that indicates an amount of additional information that can allow a User Equipment (UE) to successfully decode the PDSCH. In some embodiments, the feedback can indicate a requested Redundancy Version (RV) sequence that can allow the UE to successfully decode the PDSCH. In other embodiments, the feedback can indicate the amount of additional information, based on which a receiving Base Station (BS) can select a RV sequence.