Dynamic HARQ Block Size Switching for Link Adaptation

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Solution Overview

Problem

Current communication systems face challenges in reducing HARQ retransmission overhead while managing HARQ ACK feedback overhead, especially in high data-rate systems like 5G, where intra-subframe link-quality fluctuations lead to inefficient throughput due to fixed modulation and coding schemes across code blocks.

Innovation Solution

Implementing dynamic switching mechanisms for HARQ block sizes and per-code block link adaptation, allowing for multiple modulation and coding schemes without relying on reference signals, using configurable reporting and adjustment mechanisms to optimize modulation and coding schemes based on real-time feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fixed modulation and coding schemes are used across code blocks, then device complexity is reduced, but throughput deteriorates due to inefficient adaptation to intra-subframe link-quality fluctuations

Engineering Contradiction:

ImprovethroughputVSAvoiddevice complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the code block transmission into multiple groups, each with its own modulation and coding scheme (MCS). Instead of applying a single fixed MCS to all code blocks, the system divides them into groups that can be independently adapted to different link quality conditions, thereby improving throughput while managing complexity through structured segmentation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic switching mechanisms that allow the system to adapt MCS per code block group based on real-time link quality measurements. The system dynamically selects from multiple predefined MCS combinations and switches between them according to observed channel conditions, enabling flexible adaptation without requiring complex real-time optimization algorithms.

Inventive Principle:

Principle #15Dynamics

2Loss of substance

If dynamic switching mechanisms for HARQ block sizes are implemented, then HARQ retransmission overhead is reduced, but device complexity increases

Engineering Contradiction:

ImproveHARQ retransmission overheadVSAvoiddevice complexity

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-defining multiple HARQ block size configurations and MCS combinations before transmission. The system prepares several candidate configurations in advance and selects the appropriate one based on link quality measurements, avoiding the need for complex real-time optimization during transmission while still achieving adaptive optimization.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes key transmission parameters (HARQ block size, MCS) based on measured link quality. By monitoring channel conditions and adjusting these parameters according to predefined thresholds and configurations, the system reduces retransmission overhead while keeping the adjustment mechanism manageable through parameter-based control rather than complex algorithmic optimization.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If per-code block link adaptation is implemented, then adaptability to link-quality fluctuations improves, but control signaling overhead increases

Engineering Contradiction:

ImproveadaptabilityVSAvoidcontrol signaling overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent merges the control of multiple code blocks into groups, where a single MCS applies to each group rather than requiring individual MCS control for every code block. This grouping strategy provides per-code-block adaptation capability while reducing control signaling overhead by consolidating the control information for multiple blocks into fewer group-level parameters.

Inventive Principle:

Principle #5Merging (Combining)

4Productivity

If multiple modulation and coding schemes are used without reference signals, then spectral efficiency improves, but measurement precision deteriorates

Engineering Contradiction:

Improvespectral efficiencyVSAvoidmeasurement precision

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent uses copying by utilizing previously measured link quality data and extrapolating it to determine appropriate MCS selections. Instead of requiring new reference signals for each measurement, the system copies and reuses historical measurement patterns and link quality characteristics to guide MCS selection, maintaining measurement precision while improving spectral efficiency.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS10880047B2Systems, methods and devices for link adaptation and reducing hybrid automatic repeat request overhead

Publication Date: 2020.12.29 INTEL CORP

AI summary

An apparatus, a system and a method use a class of dynamic switching mechanisms with multiple HARQ block sizes to reduce HARQ retransmission overhead while limiting the increase of HARQ ACK feedback overhead. The apparatus includes a first processing unit configured to estimate an intra-subframe fluctuation level of per-codeblock errors; a second processing unit configured to: map the intra-subframe fluctuation level to a hybrid automatic repeat request (HARQ) block size; determine a HARQ acknowledgement (ACK) format based at least in part on the HARQ block size; indicate the selected HARQ block size to a data transmitter; and generate a HARQ ACK. Per-code block link adaptation can be used to support multiple MCSs for a single user in each subframe with fine time-frequency granularity, with low-bandwidth signaling overhead and without a complete dependency on reference signal (RS) structure.