Non-Binary LDPC Coding for Lower-SNR Error Correction

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Solution Overview

Problem

Conventional communication systems face challenges in achieving optimal performance due to high signal-to-noise ratios required for low bit error rates, as they do not adequately utilize the Shannon channel capacity, limiting data transmission efficiency.

Innovation Solution

The implementation of non-binary low density parity check (NB-LDPC) codes, which utilize a finite Galois field and bipartite graphs to encode and decode signals, allowing for improved error correction and increased spectral efficiency by using a generator matrix and NB-LDPC matrix for encoding and decoding processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional FEC/ECC coding is used, then error correction capability is provided, but high signal-to-noise ratio is required to achieve low bit error rates

Engineering Contradiction:
Improvebit error rateVSAvoidsignal-to-noise ratio
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the fundamental parameter of the coding system from binary to non-binary (using Galois fields GF(q) where q>2). This parameter change enables the code to achieve the same bit error rate performance at lower signal-to-noise ratios by utilizing a larger alphabet size, which provides better error discrimination capability and moves the operating point closer to the Shannon channel capacity limit.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If conventional binary LDPC codes are used, then error correction is achieved, but spectral efficiency is limited

Engineering Contradiction:
Improvespectral efficiencyVSAvoidcode structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent changes the code structure parameter from binary (2-ary) to non-binary (q-ary where q>2). This parameter change increases spectral efficiency by transmitting more information per symbol, as each non-binary symbol carries log2(q) bits of information compared to 1 bit in binary codes, thereby improving productivity without fundamentally changing the LDPC code architecture.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If non-binary LDPC codes are implemented, then Shannon channel capacity is approached, but encoding and decoding complexity increases

Engineering Contradiction:
Improvechannel capacity utilizationVSAvoidencoding and decoding operations
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the field parameter from binary to non-binary Galois fields, which enables approaching Shannon capacity by better matching the code characteristics to the channel statistics. The increased complexity is managed through efficient algorithms that exploit the algebraic structure of Galois fields, particularly using properties of primitive elements and discrete logarithms to simplify the arithmetic operations required for encoding and decoding.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9692451B2Non-binary low density parity check (NB-LDPC) codes for communication systems
Publication Date: 2017.06.27 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD
  • US9692451B2 patent drawing
  • US9692451B2 patent drawing
  • US9692451B2 patent drawing

AI summary

A communication device (alternatively, device) includes a processor configured to support communications with other communication device(s) and to generate and process signals for such communications. In some examples, the device includes a communication interface and a processor, among other possible circuitries, components, elements, etc. to support communications with other communication device(s) and to generate and process signals for such communications. The device receives a non-binary low density parity check (NB-LDPC) coded signal. The device then decodes the NB-LDPC coded signal using a NB-LDPC matrix to generate estimates of information bits encoded therein. The NB-LDPC matrix is characterized by a base proto-matrix having elements that represent sub-matrices, and the elements are selected from a finite Galois field that includes symbols. In another example, the device encodes other information bits using a generator matrix to generate another NB-LDPC coded signal and then transmits this other NB-LDPC coded signal.