SCB-Based MIMO Layer Mapping for Lower HARQ Complexity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing New Radio (NR) multiple MIMO layer scheme is limited by mapping codewords to up to 8 MIMO layers with separate modulation and coding schemes, leading to inefficient link adaptation and high HARQ complexity, especially in scenarios with a large number of layers, which affects spectral efficiency and latency.

Innovation Solution

Perform MIMO layer mapping per set of code blocks (SCBs) with independent modulation and coding scheme adaptation for each SCB, allowing cross-CB coding without separate HARQ processes, and transmit/receive hybrid automatic repeat request (HARQ) feedback on a per TB basis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate HARQ processes are used for each codeword in existing NR multiple MIMO layer scheme, then link adaptation can be performed per codeword, but HARQ complexity increases significantly

Engineering Contradiction:

Improvelink adaptation flexibilityVSAvoidHARQ complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple codeword-level HARQ processes into a unified transport block-level HARQ process. Multiple code blocks are grouped into code block groups (CBGs), and HARQ feedback is provided at the CBG or TB level rather than per codeword, reducing the number of parallel HARQ processes while maintaining link adaptation capability through CBG-based selective retransmission

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the transport block into code block groups (CBGs) as an intermediate structure between code blocks and the entire transport block. This segmentation allows selective HARQ feedback and retransmission at the CBG level, providing fine-grained control without requiring separate HARQ processes for each codeword, thus reducing overall HARQ complexity

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If codeword-level mapping to MIMO layers is used, then modulation and coding scheme can be adapted per codeword, but signaling overhead increases

Engineering Contradiction:

ImproveMCS adaptation granularityVSAvoidsignaling overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent makes the code block group (CBG) a universal structure that serves multiple functions: it enables selective HARQ feedback, supports code block grouping for efficient retransmission, and provides a basis for MCS adaptation. This multi-functional design eliminates the need for separate signaling structures for different purposes, reducing overall signaling overhead while maintaining adaptation capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent applies partial action by providing HARQ feedback at the CBG level rather than requiring full transport block-level feedback or per-codeword feedback. This partial feedback mechanism reduces signaling overhead by only reporting status for individual CBGs that need retransmission, rather than signaling for entire codewords or the complete transport block

Inventive Principle:

Principle #16Partial or excessive action

3Measurement precision

If per-codeword HARQ feedback is implemented, then decoding accuracy improves, but system complexity and latency increase

Engineering Contradiction:

Improvedecoding accuracyVSAvoidHARQ feedback latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent introduces a new hierarchical dimension for HARQ feedback by organizing code blocks into code block groups (CBGs) and providing feedback at the CBG level rather than strictly at the code block or codeword level. This dimensional change in the feedback hierarchy reduces the total number of feedback signals required, thereby reducing latency and processing complexity while maintaining sufficient decoding accuracy through selective CBG retransmission

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20250330274A1System, apparatus, and method of joint coding and MIMO optimization

Publication Date: 2025.10.23 HUAWEI TECH CO LTD

AI summary

A framework, corresponding methods, network devices, and apparatus for joint coding and MIMO optimization are provided that includes one or more of: a) MIMO layer mapping is performed per set of CB (SCB) rather than at the transport block (TB) level. An SCB may include one or more CB. In some cases, all SCBs include only one CB. b) Each SCB can have independent link adaptation (e.g. MCS and CB size) without a separate HARQ process and/or HARQ feedback per SCB; thus, the granularity of the HARQ process and/or HARQ feedback is at the TB level. c) Cross-CB coding may be applied over multiple SCBs, with the outputs of cross-CB coding mapped to separate MIMO layers to maximize performance, but without the use of per layer feedback or multiple TBs or HARQ processes; thus, the granularity of the HARQ process and HARQ feedback is at the TB level.