QC-LDPC Shift Coefficient Layout for Harmful Cycle Avoidance
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Solution Overview
Problem
Existing LDPC code designs for New Radio (NR) face challenges in avoiding harmful cycles with high ACE values, particularly in high-rate parts of rate-compatible codes, where ACE constraints are difficult to fulfill, leading to potential errors in block-error rate performance.
Innovation Solution
The proposed solution involves a lifting method with different ACE constraints for various code rates and cycle lengths, allowing for higher connectivity in larger shift sizes, and optimizing ACE constraints for each shift size separately to improve block-error rate performance by ensuring short cycles have higher connectivity than longer, less harmful cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single shift coefficient design is specified for each shift size, then storage requirements are reduced, but the ability to optimize ACE constraints for different code rates is limited
Solution Approach 1:
The patent creates a universal shift coefficient design that serves multiple code rates simultaneously. A single base matrix with carefully selected shift coefficients can be used across different code rates (e.g., 1/2, 2/3, 3/4, 4/5, 5/6, 6/7, 7/8, 8/9) without requiring separate designs for each rate, thereby reducing storage while maintaining optimization for each rate's specific ACE constraints
Solution Approach 2:
The patent changes the parameters of the shift coefficients in the base matrix to accommodate different code rates. By selecting shift coefficients that work across multiple rates and using code extension techniques, the system adapts the same base design to different operational conditions (code rates) without requiring multiple complete designs
2Reliability
If ACE constraints are made stricter to avoid harmful cycles, then cycle connectivity improves, but the difficulty of finding valid shift coefficients increases
Solution Approach 1:
The patent applies partial action by focusing ACE constraint optimization on the most critical aspects rather than attempting to optimize all possible cycles equally. The design targets harmful short cycles specifically while accepting that not all cycle configurations can be perfectly optimized, making the design process more tractable while still achieving improved reliability
Solution Approach 2:
The patent applies different ACE constraint levels to different parts of the code structure. Rather than applying a uniform strict constraint across all cycles, the design focuses stricter constraints on short harmful cycles while allowing more flexibility for longer cycles, creating a differentiated approach that improves connectivity where it matters most without making the overall design intractable
3Reliability
If different ACE constraints are applied for different code rates, then performance is optimized for each rate, but the complexity of the lifting method increases
Solution Approach 1:
The patent segments the code structure into a base matrix and extended portions, where different ACE constraints can be applied to different segments. The base matrix is designed with constraints appropriate for lower code rates, while code extension techniques allow higher code rates to inherit and build upon this foundation, creating a hierarchical segmentation that manages complexity
4Reliability
If larger shift sizes are used to provide more freedom in coefficient selection, then the ability to avoid harmful cycles improves, but the size of the parity-check matrix increases
Solution Approach 1:
The patent makes the effective shift size dynamic by using code extension techniques. The base matrix uses a moderate shift size that works for lower code rates, while higher code rates effectively utilize larger shift patterns through the extension process. This dynamic approach allows the system to benefit from larger shift sizes when needed (for higher rates) without permanently increasing the base matrix size
Data Source
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AI summary
According to some embodiments, a method for use in a wireless transmitter of a wireless communication network comprises encoding information bits using a parity check matrix (PCM) and transmitting the encoded information bits to a wireless receiver. The parity check matrix (PCM) is optimized according to two or more approximate cycle extrinsic message degree (ACE) constraints. In some embodiments, a first portion of the PCM is optimized according to a first ACE constraint and a second portion of the PCM is optimized according to a second ACE constraint.