LDPC Base Graph Lifting for Faster Convergence
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Solution Overview
Problem
Existing LDPC coding techniques with two punctured nodes in wireless communications systems suffer from slow convergence, which hampers high-throughput applications, despite providing improved asymptotic performance.
Innovation Solution
Implementing a base graph with a single punctured node having double-edge elements and performing a lifting procedure using larger lifting sizes or removing edges to prevent short cycles, while storing lifting values in a matrix, to enhance convergence and asymptotic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two punctured nodes are used in LDPC coding, then asymptotic performance is improved, but convergence speed deteriorates
Solution Approach 1:
The patent extracts one punctured node from the traditional two-punctured-node configuration, retaining only a single punctured node in the base graph. This reduction eliminates the convergence speed penalty while preserving the essential error-correction functionality through the remaining punctured node combined with double-edge elements.
Solution Approach 2:
The patent introduces double-edge elements that create asymmetric connectivity patterns in the base graph. These double edges provide additional redundant paths for information propagation during decoding, compensating for the reduced number of punctured nodes and maintaining asymptotic performance while enabling faster convergence.
2Speed
If lifting size is increased to improve convergence, then asymptotic performance is improved, but device complexity increases
Solution Approach 1:
The patent optimizes the lifting size parameter to a specific range that balances convergence speed and implementation complexity. By carefully selecting lifting sizes that are not excessively large, the patent achieves fast convergence while keeping the complexity of the lifting procedure and memory requirements manageable for practical implementations.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A transmitting device may perform a lifting procedure on a base graph including multiple variable nodes and multiple check nodes to obtain a lifted graph. The lifting procedure may include replacing each edge between multiple variable nodes and multiple check nodes of the base graph with a respective identity matrices with respective circular shift values. The base graph may include a punctured variable node which corresponds to each of one or more check nodes of the plurality of check nodes via multiple edges. The transmitting device may encode multiple information nodes and multiple parity nodes according to the lifted graph. The transmitting device may transmit a signal including multiple information bits and multiple parity bits based on encoding the multiple information nodes and the multiple parity nodes.