Polar Code Decoding With Reed-Muller Nodes for Lower Latency

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Solution Overview

Problem

Polar codes used in 5G NR decoding suffer from high decoding latency due to their serial nature, particularly in successive cancellation list (SCL) decoding, which increases computational complexity and latency, despite improvements from multidimensional and list decoding methods.

Innovation Solution

The implementation of a Simplified Successive Cancellation List (SSCL) decoding tree that identifies and employs Reed-Muller codes within its nodes, utilizing Hadamard decoders to reduce latency by performing maximum likelihood decoding efficiently and outputting hard decision values, thereby reducing the complexity from O(LN log N) to O(N log N).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If successive cancellation list (SCL) decoding is used to improve block error rate performance, then decoding reliability is improved, but decoding latency and computational complexity increase significantly

Engineering Contradiction:

Improveblock error rate performanceVSAvoiddecoding latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The decoding process is segmented by identifying and separating Reed-Muller code nodes from other nodes in the polar code decoding tree. These Reed-Muller nodes are then decoded using a specialized Hadamard transform-based decoder rather than the general SCL decoding process, allowing parallel processing and reducing overall latency while maintaining reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the decoding parameter approach by switching from sequential SCL decoding to a hybrid approach where Reed-Muller nodes use Hadamard transform decoding. This parameter change enables these specific nodes to be decoded in parallel with other nodes, reducing the L-fold complexity increase while maintaining the reliability benefits of list decoding.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If list decoding with size L is used to achieve better decoding performance, then reliability is improved, but computational complexity increases by a factor of L

Engineering Contradiction:

Improvedecoding performanceVSAvoidcomputational complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The decoding tree is segmented to identify Reed-Muller code nodes, which are then processed using a dedicated Hadamard transform decoder. This segmentation allows these specific nodes to be decoded with reduced complexity while other nodes continue with standard SCL decoding, achieving a balance between reliability and computational complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention substitutes the general-purpose SCL decoding mechanism with a specialized Hadamard transform-based decoding mechanism for Reed-Muller nodes. This substitution replaces the complex sequential list decoding operations with an efficient transform-based approach, reducing computational complexity by a factor of L for these nodes while maintaining decoding performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Speed

If multidimensional polar decoding is used to reduce decoding latency, then speed is improved, but the serial nature of SCD still results in large latency

Engineering Contradiction:

Improvedecoding speedVSAvoiddecoding latency

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The decoding process is segmented to identify Reed-Muller code nodes within the multidimensional polar decoding structure. These segmented nodes are then decoded using parallel Hadamard transform operations, further reducing latency beyond what standard multidimensional decoding achieves alone.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention adds another dimension to the decoding process by applying Hadamard transform decoding to Reed-Muller nodes. This dimensional change allows these nodes to be decoded in parallel with the multidimensional polar decoding process, further reducing latency through additional parallelization opportunities.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly reduces decoding latency in polar codes without compromising block error rate performance, improving throughput by leveraging the symmetric structure of Reed-Muller codes within the SSCL decoding tree.

Implementation Method 1

utilizing Hadamard decoders to reduce latency by performing maximum likelihood decoding efficiently

Methodology Applied

Scientific EffectHadamard transform:

Data Source

PatentUS11271596B2System and method for identifying and decoding Reed-Muller codes in polar codes

Publication Date: 2022.03.08 SAMSUNG ELECTRONICS CO LTD

AI summary

A method and an apparatus are provided for decoding a polar code. A simplified successive cancellation list (SSCL) decoding tree for the polar code is generated. The SSCL decoding tree includes a plurality of nodes. One or more nodes of the plurality of nodes are identified as employing Reed-Muller codes for decoding. Decoding of received log-likelihood ratios (LLRs) is performed using Reed-Muller codes at the one or more nodes. Hard decision values are output from the one or more nodes.