LDPC Parity-Check Matrix Layout for Lower Coding Complexity
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Solution Overview
Problem
Conventional low-density parity check (LDPC) codes face challenges such as increased complexity, difficulty in determining an optimal code structure for short frame sizes, and high memory requirements, limiting their efficiency and flexibility in wireless communication systems.
Innovation Solution
A method and apparatus for generating LDPC codes using a parity check matrix divided into information and parity parts, with specific diagonal structures and shifted identity matrices, allowing for simpler coding and reduced memory usage, enabling flexible frame lengths and efficient decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDPC codes are used, then coding performance approaches Shannon capacity limit, but coding complexity increases
Solution Approach 1:
The parity check matrix is segmented into an information part matrix and a parity part matrix, with the parity part further divided into P×P subblocks. This segmentation allows for structured placement of shifted identity matrices along diagonals, simplifying the encoding process while maintaining the performance benefits of LDPC codes.
2Reliability
If conventional LDPC codes are used, then excellent error performance is achieved, but memory requirements increase
Solution Approach 1:
The patent changes the structural parameters of the parity part matrix by organizing it into P×P subblocks with shifted identity matrices placed along diagonals. This parameter change reduces the memory required to store and process the parity check matrix while preserving the error performance characteristics of LDPC codes.
3Reliability
If conventional LDPC codes are used, then good frame error rate is achieved, but flexibility in frame length is reduced
Solution Approach 1:
The patent introduces a dynamic structure where the parity part matrix is organized into P×P subblocks with shifted identity matrices. The shift amount and matrix dimensions can be adjusted based on the required frame length, providing flexibility while maintaining good frame error rate performance through the structured diagonal arrangement.
Data Source
AI summary
A low density parity check (LDPC) code generating method and apparatus are provided. A parity check matrix with (N−K) rows for check nodes and N columns for variable nodes are formed to encode an information sequence of length K to a codeword of length N. The parity check matrix is divided into an information part matrix with K columns and a parity part matrix with (N−k) columns. The parity part is divided into P×P subblocks. P is a divisor of (N−K). First and second diagonals are defined in the parity part matrix and the second diagonal is a shift of the first diagonal by f subblocks. Shifted identity matrices are placed on the first and second diagonals and zero matrices are filled elsewhere. An odd number of delta matrices each having only one element of 1 are placed in one subblock column of the parity part matrix. The parity check matrix is stored.