CNN Weight Pruning and Quantization for Mobile Deployment

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Solution Overview

Problem

Deep learning convolutional neural networks (CNNs) face challenges in deployment on resource-limited platforms due to large model size and high computational complexity, hindering their use on battery-powered mobile devices.

Innovation Solution

The method involves regularizing spatial domain weights, providing quantization, pruning small or zero weights, fine-tuning a quantization codebook, compressing the output, and utilizing sparse spatial domain or Winograd convolution to reduce memory and computational requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If deep convolutional neural networks are deployed on resource-limited platforms, then computational capability and accuracy are improved, but model size and computational complexity increase memory and energy consumption beyond available resources

Engineering Contradiction:
Improvecomputational capabilityVSAvoidmodel size
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent segments the CNN model into multiple components that can be independently compressed: spatial domain weights, Winograd domain weights, and activation maps. Each component undergoes separate pruning and quantization operations, allowing selective compression without compromising overall model functionality. This segmentation enables the model to be divided into manageable parts that can be optimized for resource-constrained environments.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies parameter changes through quantization, transforming high-precision floating-point weights into lower-precision representations (e.g., 32-bit float to 8-bit integer or binary). This parameter transformation significantly reduces model size while maintaining acceptable accuracy. The method also changes the sparsity parameters by applying different pruning thresholds to different weight components, optimizing the balance between compression ratio and model performance.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If deep convolutional neural networks are deployed on resource-limited platforms, then computational capability is improved, but computational complexity increases energy consumption beyond available power

Engineering Contradiction:
Improvecomputational capabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts and removes redundant computational elements from the CNN model through pruning operations. By identifying and eliminating small or zero-valued weights in both spatial and Winograd domains, the method reduces the total number of multiply-accumulate operations required during inference. This extraction of unnecessary computations directly lowers energy consumption while preserving the essential computational capabilities needed for accurate predictions.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by performing pruning and quantization on only the most critical weight components rather than uniformly processing all parameters. The method selectively applies compression techniques to spatial domain weights and Winograd domain weights based on their contribution to model accuracy, avoiding excessive compression that would degrade performance. This selective approach optimizes the trade-off between energy savings and computational effectiveness.

Inventive Principle:
Principle #16Partial or excessive action

3Quantity of substance

If model compression techniques are applied to reduce model size, then memory requirements are reduced, but model accuracy may deteriorate

Engineering Contradiction:
Improvememory requirementsVSAvoidmodel accuracy
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent performs preliminary quantization and pruning operations during the model training and compression phase, before deployment on resource-constrained devices. By pre-computing quantized weight values and pruning masks, the method prepares an optimized model structure that maintains accuracy characteristics. The preliminary action includes computing sensitivity metrics and determining optimal pruning thresholds in advance, ensuring that compression does not significantly degrade model accuracy when deployed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent incorporates feedback mechanisms through iterative pruning and quantization processes. After each compression operation, the model performance is evaluated, and pruning thresholds or quantization parameters are adjusted based on accuracy metrics. This feedback loop allows the method to identify the optimal compression level that maintains acceptable accuracy while achieving desired memory reduction targets. The feedback-driven approach ensures that compression operations do not push the model beyond its accuracy tolerance thresholds.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS11423312B2Method and apparatus for universal pruning and compression of deep convolutional neural networks under joint sparsity constraints
Publication Date: 2022.08.23 SAMSUNG ELECTRONICS CO LTD
  • US11423312B2 patent drawing
  • US11423312B2 patent drawing
  • US11423312B2 patent drawing

AI summary

A method and system for constructing a convolutional neural network (CNN) model are herein disclosed. The method includes regularizing spatial domain weights, providing quantization of the spatial domain weights, pruning small or zero weights in a spatial domain, fine-tuning a quantization codebook, compressing a quantization output from the quantization codebook, and decompressing the spatial domain weights and using either sparse spatial domain convolution and sparse Winograd convolution after pruning Winograd-domain weights.