Lifted LDPC Code Representation for High-Rate Wireless Encoding
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently encoding and decoding data at high rates, particularly in multiple-access technologies like 5G NR, where errors in binary data transmission can lead to unusable data and require retransmissions, necessitating improved encoding methods for reliable communication.
Innovation Solution
The implementation of compactly described lifted low-density parity-check (LDPC) codes, which involve selecting lifting size values and sets of lifting values to generate lifted LDPC codes, allowing for efficient encoding and decoding by interconnecting edges in multiple copies of a base parity check matrix, enabling error correction and improved data transmission reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction coding is used in wireless communication systems, then data transmission reliability is improved, but encoding and decoding complexity increases, reducing productivity
Solution Approach 1:
The patent segments the LDPC code structure into a base graph (protograph) and lifting operations. The base graph contains a small number of nodes and edges that define the code structure, while lifting replicates and interconnects these nodes to achieve the desired code length. This segmentation allows efficient representation of long codes through compact base graphs combined with lifting parameters, significantly reducing encoding complexity while maintaining reliability
Solution Approach 2:
The patent utilizes lifting size parameters to transform the base graph into lifted graphs of various sizes. By changing the lifting size parameter, the same base graph can generate LDPC codes of different lengths, eliminating the need to store multiple different base graphs. This parameter-based transformation reduces memory requirements and processing complexity while maintaining code performance
2Adaptability or versatility
If multiple different base graphs are stored to support various code lengths and rates, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent makes a single base graph universal by applying lifting operations with different lifting sizes to generate multiple code lengths from the same base structure. The base graph serves multiple functions: it can generate short, medium, and long codes of various rates by adjusting the lifting parameter. This multi-functionality eliminates the need to store separate base graphs for different code specifications, reducing device complexity while maintaining adaptability
Solution Approach 2:
The patent implements a nested structure where a compact base graph (inner layer) is replicated and interconnected through lifting to form larger lifted graphs (outer layers). The base graph is nested within the lifted graph structure, and the same base graph can be nested at different lifting levels to achieve various code lengths. This nesting approach allows efficient memory usage where the small base graph is stored once and algorithmically expanded to support multiple code configurations
Data Source
AI summary
Certain aspects of the present disclosure generally relate to techniques for compactly describing lifted low-density parity-check (LDPC) codes. A method by a transmitting device generally includes selecting a first lifting size value and a first set of lifting values; generating a first lifted LDPC code by applying the first set of lifting values to interconnect edges in copies of a parity check matrix (PCM) having a first number of variable nodes and a second number of check nodes; determining a second set of lifting values for generating a second lifted LDPC code for a second lifting size value based on the first lifted PCM and the first set of lifting values; encoding a set of information bits based the first lifted LDPC code or the second lifted LDPC code to produce a code word; and transmitting the code word.