LDPC Base Graph With Single Punctured Node for Fast Convergence
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Solution Overview
Problem
Existing wireless communication systems face challenges in achieving fast convergence and improved asymptotic performance for LDPC codes, particularly in high-throughput applications where the use of two punctured nodes can slow down convergence.
Innovation Solution
The implementation of LDPC coding techniques using a base graph with a single punctured node that has one or more double-edge elements, along with a lifting procedure that involves replacing edges with identity matrices and using larger lifting sizes or removing edges to prevent short cycles.
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 punctured node is segmented into multiple degrees by introducing double-edge elements, where the first degree connects to first check nodes and the second degree connects to second check nodes. This segmentation allows different degrees to serve different functional purposes, enabling fast convergence through the first degree while maintaining asymptotic performance through the second degree.
Solution Approach 2:
Different check nodes are assigned different local qualities based on their connection degree to the punctured node. First check nodes receive connections with a first degree while second check nodes receive connections with a second degree. This local quality differentiation optimizes the decoding process by providing varied connectivity patterns that simultaneously improve convergence speed and asymptotic performance.
2Reliability
If lifting size is increased, then code performance is improved, but computational complexity increases
Solution Approach 1:
The lifting size parameter is changed from traditional values to larger values (e.g., Z ≥ 384), which transforms the code structure to achieve better performance. This parameter change is complemented by the introduction of double-edge elements with specific degree distributions, allowing the system to achieve improved code performance while managing computational complexity through optimized degree assignments.
3Quantity of substance
If double-edge elements are added to punctured node, then total degree is increased, but graph density increases
Solution Approach 1:
The increased graph density from double-edge elements is managed by applying local quality principles, where different check nodes have different connection degrees. First check nodes are connected with a first degree while second check nodes are connected with a second degree, creating a heterogeneous graph structure that distributes the increased total degree in an optimized manner, preventing uniform density increase across the entire graph.
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.