Code Block Group Multiplexing for Selective Uplink Retransmission
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in resource utilization during uplink transmissions due to varying payload sizes among user equipment, leading to potential interference and suboptimal retransmission strategies, particularly in two-step random access procedures.
Innovation Solution
The implementation of code block group (CBG) based multiplexing, where payloads are organized into CBGs and mapped to physical uplink shared channel resource units, allowing for efficient multiplexing of CBs from different user equipment, reducing unnecessary retransmissions and optimizing resource use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If entire uplink messages are retransmitted upon decoding failure, then reliability is improved, but resource utilization efficiency deteriorates due to redundant transmissions
Solution Approach 1:
The patent segments the uplink message into multiple code blocks (CBs) and groups them into code block groups (CBGs). Each CBG can be independently acknowledged and retransmitted based on its own decoding status, rather than retransmitting the entire message. This segmentation enables selective retransmission of only the failed CBGs, improving resource utilization while maintaining reliability.
2Productivity
If code block group based multiplexing is implemented, then resource utilization efficiency is improved, but device complexity increases due to additional mapping and management procedures
Solution Approach 1:
The patent establishes universal mapping rules that can handle multiple scenarios (different payload sizes, different numbers of UEs, various CBG configurations) through a single standardized framework. The base station and UE both follow the same mapping procedures, making the system multi-functional and adaptable without requiring separate complex management logic for each scenario.
Solution Approach 2:
The patent dynamically adjusts mapping parameters such as the number of CBGs per UE, the size of each CBG, and the allocation of PRUs based on payload size and channel conditions. By changing these parameters adaptively, the system optimizes resource utilization for different traffic patterns while maintaining manageable complexity through standardized adjustment rules.
3Loss of time
If code block group based multiplexing is implemented, then latency is reduced through minimized retransmissions, but measurement precision deteriorates due to partial feedback information
Solution Approach 1:
The patent implements a feedback mechanism where the base station sends individual acknowledgment bits for each CBG, indicating whether it was successfully decoded or needs retransmission. This granular feedback allows the UE to precisely identify which CBGs require retransmission, reducing unnecessary retransmissions and latency while maintaining accurate information about transmission status through the acknowledgment feedback.
Data Source
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Figure 3A~3C
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may identify a payload for inclusion in an uplink transmission. The UE may organize the payload into a code block group (CBG) that includes one or more code blocks (CB). The EE may map each CB of the CBG to a corresponding uplink shared channel resource unit (e.g., a physical uplink shared channel resource unit) of an uplink transmission occasion of the first EE. The uplink transmission occasion may also be shared with one or more additional EEs such that the CBG of the first EE is multiplexed with additional CBGs from the additional EEs. The EE may transmit, to a base station, the uplink transmission including each uplink shared channel resource unit on which the CBG is organized.