LDPC Shift Coefficients for New Radio via ACE Constraints
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Solution Overview
Problem
Existing LDPC code designs for New Radio (NR) face challenges in setting ACE constraints for the full parity-check matrix, which allow harmful cycles in the high-rate part of rate-compatible LDPC codes, especially during code extension, and it is difficult to find cyclic shifts that satisfy tough ACE constraints for large cycles while avoiding short cycles with lower connectivity.
Innovation Solution
A lifting method with different approximate cycle extrinsic message degree (ACE) constraints for different code rates and cycle lengths, optimizing ACE constraints for each shift size separately to ensure short cycles have higher connectivity than longer cycles, and specifying separate constraints for systematic and parity bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single ACE constraint is applied to the full parity-check matrix, then the constraint is easy to implement, but harmful cycles are allowed in the high-rate part of rate-compatible LDPC codes
Solution Approach 1:
The patent segments the parity-check matrix into multiple submatrices corresponding to different code rates. Each submatrix has its own ACE constraint, allowing differentiated control over cycle properties in different rate regions. This segmentation enables the high-rate part to have stricter constraints while the low-rate part has more relaxed constraints, resolving the contradiction between single-constraint simplicity and multi-rate performance.
Solution Approach 2:
The patent applies different ACE constraint values to different submatrices based on their specific rate requirements. Each submatrix receives a locally optimized constraint that matches its operational characteristics, rather than applying a uniform global constraint. This local quality approach ensures that each part of the code gets the appropriate level of cycle control for its specific function.
2Reliability
If tough ACE constraints are applied to avoid short cycles, then connectivity is improved, but it becomes difficult to find cyclic shifts that satisfy the constraints for large cycles
Solution Approach 1:
The patent implements dynamic ACE constraints that adapt to the specific submatrix and code rate being constructed. Rather than applying a static tough constraint throughout, the system dynamically adjusts constraint stringency based on local requirements. This allows easier satisfaction of constraints in regions where connectivity is already adequate while maintaining strict constraints where needed, reducing the overall difficulty of finding valid cyclic shifts.
Solution Approach 2:
The patent changes the ACE constraint parameter values across different submatrices and code rates. By varying the constraint parameter locally rather than keeping it fixed, the system finds a balance between avoiding harmful short cycles and allowing feasible long cycles. This parameter variation makes it possible to satisfy constraints without excessive computational difficulty.
3Reliability
If one shift coefficient design is specified for each shift size, then optimal performance is achieved for each shift size, but storage requirements increase in both transmitter and receiver
Solution Approach 1:
The patent creates a universal shift coefficient design that works across multiple shift sizes through a systematic mapping rule. Instead of storing separate designs for each shift size, a single base design is defined and then adapted to different shift sizes using a consistent transformation. This multi-functional approach allows the same shift coefficient pattern to serve multiple shift size requirements, eliminating the need for separate storage of each design while maintaining optimal performance characteristics.
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.