Parallel Codeblock Group Retransmission for Latency Minimization
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Solution Overview
Problem
Wireless communications systems with multi-level coding and multi-level sequential demodulation and decoding face increased latency due to hierarchical HARQ procedures, which lead to inefficiencies in retransmissions across decoding levels, especially for latency-sensitive data.
Innovation Solution
The system transmits multiple codeblock groups (CBGs) across the same channel resources, allowing for parallel retransmissions of all CBGs if any fail, rather than sequential retransmissions based on decoding levels, thereby reducing latency and improving system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hierarchical HARQ procedure is used for multi-level coding, then reliability is improved, but latency increases
Solution Approach 1:
The transmission is divided into multiple codeblock groups (CBGs), each associated with a specific decoding level. This segmentation allows the system to identify and retransmit only the specific CBGs that failed decoding, rather than retransmitting all CBGs sequentially across multiple decoding levels, thereby reducing latency while maintaining reliability.
Solution Approach 2:
All CBGs for all decoding levels are transmitted in parallel in the initial transmission period, rather than sequentially. This preliminary parallel transmission allows the receiver to decode CBGs at different levels simultaneously, and only failed CBGs are retransmitted in subsequent periods, significantly reducing overall latency.
2Device complexity
If sequential retransmissions are used based on decoding levels, then device complexity is reduced, but productivity decreases
Solution Approach 1:
The system dynamically adapts the retransmission strategy based on decoding outcomes. After initial parallel transmission of all CBGs, the system identifies which specific CBGs failed and schedules retransmissions only for those failed CBGs in subsequent time periods. This dynamic approach improves productivity by avoiding unnecessary retransmissions while maintaining manageable device complexity through selective feedback and retransmission scheduling.
Data Source
AI summary
Methods, systems, and devices for latency minimization in wireless communications employing multi-level coding and multi-level sequential demodulation and decoding are described. A user equipment (UE) receive a set of codeblock groups in a first time period. Each codeblock group jointly sharing same channel resources may be associated with a respective decoding level of a set of decoding levels. The UE may determine a first outcome for a first codeblock group and a second outcome for a second codeblock group. The UE may then transmit a feedback message that is based on the first outcome and the second outcome. In case that the feedback message indicates that the first outcome or the second outcome is a failed decoding procedure, the UE may receive, in a second time period, a retransmission of all the codeblock groups. These retransmissions may continue on additional time periods until all related codeblock groups are successfully decoded.