Polar Coding Retransmission with Variable CBG HARQ-ACK
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current radio communication systems face challenges in efficiently supporting retransmissions with variable code block group sizes and high reliability requirements for ultra-reliable low latency communications (URLLC) and enhanced massive mobile broadband (eMBB) services, particularly in adapting modulation and coding schemes and channel quality indicators to ensure reliable data transmission.
Innovation Solution
The implementation of polar coding for URLLC data, dynamic code block group (CBG) size management, and variable length Hybrid Automatic Repeat Request (HARQ) acknowledgments (ACKs) to optimize retransmissions, along with modulation and coding scheme (MCS) selection and channel quality indicator (CQI) values, tailored to the specific characteristics of URLLC and eMBB data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable code block group sizes are used for retransmissions, then retransmission efficiency is improved, but system complexity increases
Solution Approach 1:
The patent implements dynamic code block group (CBG) size adjustment where the CBG size is not fixed but varies based on transmission conditions. The system dynamically selects CBG sizes from a set of predefined sizes (e.g., 1, 2, 4, 8 code blocks) depending on channel conditions, traffic type (URLLC vs eMBB), and retransmission history, allowing optimal adaptation without rigid complexity
Solution Approach 2:
The patent changes the parameter of code block group size from a fixed value to a variable parameter that can take different values based on transmission requirements. By introducing variable CBG size as a controllable parameter alongside variable HARQ-ACK length, the system achieves flexible retransmission efficiency improvement while managing complexity through standardized parameter sets
2Measurement precision
If variable length HARQ-ACK feedback is implemented, then feedback accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent segments the HARQ-ACK feedback into variable-length bit sequences where each bit corresponds to specific code block groups. Instead of using fixed-length feedback for all transmissions, the system segments the feedback to match the actual number of CBGs being acknowledged, improving precision while using standardized segmentation patterns to manage complexity
Solution Approach 2:
The variable length HARQ-ACK mechanism serves multiple functions: it accurately acknowledges different numbers of CBGs, supports both initial transmissions and retransmissions, and adapts to different service types (URLLC and eMBB). This multi-functionality reduces the need for separate feedback mechanisms for different scenarios, managing overall processing complexity
3Reliability
If polar coding is used for URLLC data, then reliability is improved, but computational complexity increases
Solution Approach 1:
The patent segments the URLLC data into multiple code blocks that are then encoded using polar coding. By dividing the data into manageable code block groups (CBGs) with sizes of 1, 2, 4, or 8 code blocks, the system makes polar coding computationally feasible while maintaining the reliability benefits through systematic segmentation and group-wise processing
Solution Approach 2:
The patent applies polar coding selectively to code block groups that require high reliability (such as initial URLLC transmissions or critically important retransmissions) rather than uniformly to all data blocks. This partial application of polar coding to only the most reliability-critical segments reduces overall computational complexity while maintaining the reliability improvements where they are most needed
4Adaptability or versatility
If dynamic CBG size adjustment is implemented, then transmission adaptability is improved, but control overhead increases
Solution Approach 1:
The patent merges the CBG size indication with existing downlink control information (DCI) fields rather than introducing separate dedicated signaling. The CBG size information is combined with HARQ process information and other control elements, allowing dynamic adaptation of CBG sizes while minimizing additional control overhead through efficient information packing
Data Source
AI summary
Systems, methods, and instrumentalities are described herein for supporting CBG-based retransmission with variable CBG size using variable length HARQ-ACK. A WTRU may receive a configuration to use a first table. The first table may be associated with a maximum number of code block groups per transport block (maxCBG/TB). The WTRU may determine a number of HARQ-ACK bits to send for code blocks. The determination may depend on whether an indication is received to switch from the first table to a second table. On a condition that the indication to switch from the first table to the second table is received, the WTRU may send a number of HARQ-ACK bits that is equal to two times the maxCBG/TB. The WTRU may receive a retransmission of a number of code blocks, wherein a code block group size depends on a sent number of HARQ-ACK bits.