MAC Layer Erasure Code for Adaptive Modulation Stability

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Solution Overview

Problem

Adaptive Coding and Modulation (ACM) methods in wireless data transmission systems face limitations due to high memory requirements for storing error probability data and instability in control loops, leading to reduced useful bit rate and spectral efficiency, especially when transitioning between modulation/coding pairs.

Innovation Solution

Applying a second MDS (Maximum Distance Separable) erasure code at the MAC layer to generate redundancy bits, determining the maximum error rate while minimizing throughput and spectral efficiency drops, and selecting the optimal modulation/coding pairs to maximize transmission efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a large number of modulation/coding pairs are used to achieve fine throughput/protection optimization, then adaptability to channel variations is improved, but memory resources required for storing error probability data increases significantly

Engineering Contradiction:

Improveadaptability to channel variationsVSAvoidmemory resources

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent extracts the error probability calculation functionality from pre-stored charts and implements it through a mathematical formula (equation 1) that computes error probability directly from signal-to-noise ratio and code rate parameters. This eliminates the need to store large charts in memory while maintaining the ability to determine error probabilities for any modulation/coding pair.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the approach from storing discrete chart data to using a continuous mathematical model where error probability is determined by parameters (signal-to-noise ratio, code rate, modulation type) rather than pre-computed lookup tables. This allows dynamic calculation for any parameter combination without increasing memory resources.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a large number of modulation/coding pairs are used to achieve fine throughput/protection optimization, then adaptability to channel variations is improved, but control loop stability deteriorates and processing delays increase

Engineering Contradiction:

Improveadaptability to channel variationsVSAvoidcontrol loop stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent reduces the number of discrete modulation/coding pairs from many fine-grained options to a smaller set of carefully selected pairs. The mathematical error probability formula enables precise performance prediction for each pair, allowing optimal selection with fewer options. This reduces control loop complexity and improves stability while maintaining adaptability through accurate error rate prediction.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If high granularity modulation/coding pairs are used in ACM method, then error rate constraint compliance is improved, but useful bit rate and spectral efficiency decrease due to added redundancy

Engineering Contradiction:

Improveerror rate constraint complianceVSAvoiduseful bit rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes from fine-grained discrete modulation/coding pairs to a continuous mathematical model that can precisely predict error probabilities. This enables selection of optimal pairs that meet error rate constraints with minimal redundancy, improving spectral efficiency while maintaining reliability through accurate error rate calculation rather than conservative over-protection.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If high granularity modulation/coding pairs are used in ACM method, then error rate constraint compliance is improved, but spectral efficiency decreases due to added redundancy

Engineering Contradiction:

Improveerror rate constraint complianceVSAvoidspectral efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent extracts the error probability determination from conservative pre-stored charts to a precise mathematical formula, enabling accurate prediction of actual error rates. This allows optimization of redundancy levels to meet error rate constraints with minimal spectral efficiency loss, eliminating the need for excessive protection that characterized high-granularity ACM approaches.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP2704344B1Method for optimising resources of a data transmission and device implementing the method

Publication Date: 2020.11.11 THALES SA

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AI summary

The method involves applying one of correcting codes at a level of a medium access layer to generate packets of redundancy bits on basis of packets of data bits received and supplemented with padding sections such that all of the sections have same size. Information representative of a ratio between number of bits at input of the layer and number of actually transmitted bits or representative of transmission bitrate required for a set of solutions associating modulation correcting codes is evaluated. One among a set of solution codes is selected to maximize the ratio or minimize the bitrate. Independent claims are also included for the following: (1) a data-transmission system (2) a computer program product comprising a set of instructions for executing a method for optimizing resources.