Recursive Bit Likelihood Calculation for High-Order Modulation

Solution Overview

Problem

Conventional bitwise likelihood calculation methods experience performance deterioration due to increased approximation errors as the number of multi-levels in a modulation scheme increases, leading to higher computational complexity and memory requirements.

Innovation Solution

A bit-likelihood calculating apparatus that employs an initial-bit-likelihood calculating unit to determine inter-transmission-signal-point distances and region numbers, and an i-th-bit-likelihood calculating unit to recursively calculate bit likelihood using a recurrence formula, reducing approximation errors and computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional likelihood calculation formulas are used with high multi-level modulation schemes, then computational complexity and memory requirements increase, but approximation errors increase leading to performance deterioration

Engineering Contradiction:

Improvebitwise likelihood calculation accuracyVSAvoidcomputational complexity and memory requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the likelihood calculation into two distinct parts: a first likelihood value calculated using a first formula, and a second likelihood value calculated using a second formula. This segmentation allows each formula to be optimized for specific purposes, reducing overall computational complexity while maintaining accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different likelihood calculation formulas (different local qualities) to different aspects of the calculation. The first formula is used for calculating the first likelihood value, and the second formula is used for calculating the second likelihood value, allowing each to be optimized for its specific function rather than using a single complex formula for all cases.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If a single likelihood calculation formula is used irrespective of reception data values, then memory requirements are reduced, but approximation errors increase as modulation multi-levels increase

Engineering Contradiction:

Improvememory requirementsVSAvoidlikelihood calculation accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent segments the likelihood calculation into two distinct parts: a first likelihood value calculated using a first formula, and a second likelihood value calculated using a second formula. This segmentation allows each formula to be optimized for specific purposes, reducing overall computational complexity while maintaining accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different likelihood calculation formulas (different local qualities) to different aspects of the calculation. The first formula is used for calculating the first likelihood value, and the second formula is used for calculating the second likelihood value, allowing each to be optimized for its specific function rather than using a single complex formula for all cases.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If likelihood calculation formulas are selectively used based on reception data values, then calculation accuracy is maintained, but computational complexity and memory requirements increase

Engineering Contradiction:

Improvelikelihood calculation accuracyVSAvoidcomputational efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the likelihood calculation into two distinct parts: a first likelihood value calculated using a first formula, and a second likelihood value calculated using a second formula. This segmentation allows each formula to be optimized for specific purposes, reducing overall computational complexity while maintaining accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different likelihood calculation formulas (different local qualities) to different aspects of the calculation. The first formula is used for calculating the first likelihood value, and the second formula is used for calculating the second likelihood value, allowing each to be optimized for its specific function rather than using a single complex formula for all cases.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP2950493B1Bit likelihood calculation device and bit likelihood calculation method

Publication Date: 2019.05.15 MITSUBISHI ELECTRIC CORP

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AI summary

To obtain a bit-likelihood calculating apparatus that has fewer approximation errors and is capable of reducing the computational complexity and the amount of memory. The bit-likelihood calculating apparatus includes an initial-bit-likelihood calculating unit 210 obtaining an inter-transmission-signal-point distance corresponding to a value of N, a region number indicating a determination region of a transmission signal point nearest from data, and inter-nearest-point distance from a transmission signal point of initial bit = 0 nearest to the data and a transmission signal point of initial bit = 1 nearest to the data, and calculating likelihood of initial bit of the data serving as initial term of a recurrence formula for recursively calculating bit likelihood, an i-th-bit-likelihood calculating unit 230 calculating, when N is 2 or larger, difference between inter-nearest-point distance with respect to (i-1)th bit and inter-nearest-point distance with respect to i-th bit and calculating likelihood of i-th bit of the data from likelihood of (i-1)th bit and the difference using the recurrence formula, and a processing-step control unit 220 controlling calculation processing for bit likelihood by the i-th-bit-likelihood calculating unit 230 based on the value of N.