NB-LDPC Coding in OTFS for Low Error Floor Transmission

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Solution Overview

Problem

Traditional error correction codes in wireless communication systems, such as LDPC codes, often fail to meet the stringent bit error rate (BER) requirements of next-generation wireless networks due to excessive computational complexity, which is not feasible for battery-powered devices like IoT and machine-to-machine communication devices.

Innovation Solution

The implementation of non-binary low-density parity-check (NB-LDPC) codes with a parity-check matrix formulated to include non-binary entries, used in conjunction with OTFS modulation, which reduces error triggering events and achieves extremely low error floors (10−11 or 10−12) without significantly increasing computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional LDPC codes are used for error correction, then implementation is simpler, but bit error rate performance does not meet stringent requirements of next-generation wireless networks

Engineering Contradiction:
Improvebit error rateVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the fundamental parameter of the LDPC code from binary to non-binary (q-ary) representation. By using symbols from a finite field GF(q) instead of binary bits, the code achieves better error correction performance with lower bit error rates while maintaining manageable computational complexity through efficient field arithmetic operations.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent combines OTFS modulation with non-binary LDPC coding to create a composite error correction system. This integration leverages the time-frequency domain processing of OTFS with the algebraic structure of NB-LDPC codes over GF(q), achieving synergistic error correction performance that meets stringent reliability requirements.

Inventive Principle:
Principle #40Composite materials

2Reliability

If non-binary LDPC codes are used to achieve low error rates, then reliability improves, but computational complexity increases significantly

Engineering Contradiction:
Improveerror floorVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent achieves extremely low error floors (10^-11 or 10^-12) by formulating the parity-check matrix with non-binary entries from GF(q). The key to managing complexity lies in using efficient field arithmetic operations and optimized decoding algorithms that exploit the algebraic structure of non-binary fields, preventing complexity from becoming prohibitive.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent transitions from binary to non-binary domain, effectively adding an algebraic dimension to the error correction process. By operating in the extended GF(q) field rather than binary GF(2), the system gains additional degrees of freedom in error correction while using structured parity-check matrices to control computational burden.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If conventional error correction codes are used, then device complexity is manageable, but they fail to meet stringent BER requirements of next-generation wireless networks

Engineering Contradiction:
ImproveBER performanceVSAvoidcoding complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent fundamentally changes the coding parameter from binary to non-binary representation over GF(q). This parameter change enables the code to achieve superior BER performance required for next-generation networks while the use of structured parity-check matrices and efficient field arithmetic keeps the coding complexity manageable for practical implementation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The non-binary LDPC code framework provides universal error correction capability that can adapt to different communication requirements. By using the algebraic structure of GF(q) and structured parity-check matrices, the same coding framework can serve multiple functions including error correction, achieving low BER, and maintaining complexity control across different application scenarios.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS11632133B2Forward error correction using non-binary low density parity check codes
Publication Date: 2023.04.18 COHERE TECHNOLOGIES INC
  • US11632133B2 patent drawing
  • US11632133B2 patent drawing
  • US11632133B2 patent drawing

AI summary

Methods, systems and devices for forward error correction in orthogonal time frequency space (OTFS) communication systems using non-binary low-density parity-check (NB-LDPC) codes are described. One exemplary method for forward error correction includes receiving data, encoding the data via a non-binary low density parity check (NB-LDPC) code, wherein the NB-LDPC code is characterized by a matrix with binary and non-binary entries, modulating the encoded data to generate a signal, and transmitting the signal. Another exemplary method for forward error correction includes receiving a signal, demodulating the received signal to produce data, decoding the data via a NB-LDPC code, wherein the NB-LDPC code is characterized by a matrix with binary and non-binary entries, and providing the decoded data to a data sink.