LDPC Channel Encoding with Lifting for Variable 5G Code Blocks
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Solution Overview
Problem
Current LDPC encoding/decoding methods struggle to support various input lengths and coding rates, particularly for short information word lengths and fixed coding rates, in 5G communication systems, where noise, fading, and intersymbol interference degrade link performance.
Innovation Solution
The proposed method involves designing LDPC codes using a lifting technique and considering trapping set characteristics, with a channel encoding method that identifies a block size and shift value sequence for LDPC encoding and decoding, employing a permutation matrix of size ZXZ, where the shift value sequence is predetermined for circular shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional LDPC encoding/decoding methods are used, then implementation is straightforward, but they cannot support various input lengths and coding rates
Solution Approach 1:
The patent designs a universal LDPC base matrix that can generate code blocks of various lengths and coding rates through systematic lifting operations. The base matrix structure enables it to serve multiple functions across different communication scenarios, supporting both short and long packet transmissions with various coding rates without requiring separate encoding schemes for each case.
Solution Approach 2:
The patent employs lifting factor as a variable parameter to transform the base matrix into code blocks of different sizes. By changing the lifting factor, the system can adapt to various input lengths and coding rates. The design also optimizes shift values and column permutation patterns as adjustable parameters to maintain good decoding performance across different configurations.
2Reliability
If LDPC codes are designed for short information word lengths (about 100 bits or less), then they can handle short packets, but maintaining good performance with fixed coding rates becomes difficult
Solution Approach 1:
The patent applies local optimization to the base matrix structure, particularly in the arrangement of columns and the selection of shift values for specific blocks. This local quality enhancement ensures that short packet transmissions achieve good error correction performance while maintaining the overall versatility of the code design for different coding rates.
Solution Approach 2:
The patent performs preliminary design and optimization of the base matrix structure before actual encoding operations. By pre-optimizing the base matrix with appropriate column permutations and shift values, the system ensures good performance for short packets across various fixed coding rates without requiring real-time adjustments during encoding.
3Adaptability or versatility
If lifting factor is increased to support various code block lengths, then adaptability improves, but decoding performance may deteriorate due to trapping sets
Solution Approach 1:
The patent identifies trapping sets as harmful structures that degrade decoding performance, and converts this problem into an opportunity for optimization. By systematically analyzing and avoiding trapping set configurations in the base matrix design, the patent transforms the potential harm of lifting operations into a benefit where the resulting codes maintain excellent decoding performance across various block lengths.
Solution Approach 2:
The patent incorporates performance feedback from simulation and analysis of trapping sets into the base matrix design process. By using feedback from decoding performance evaluation, the design optimizes the base matrix structure to avoid configurations that create harmful trapping sets, thereby maintaining reliable decoding performance while supporting various code block lengths through lifting.
Data Source
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AI summary
A pre-5th-generation (pre-5G) or 5G communication system for supporting higher data rates beyond a 4th-generation (4G) communication system, such as long term evolution (LTE) is provided. A channel encoding method in a communication or broadcasting system includes identifying an input bit size, determining a block size (Z), determining a low density parity check (LDPC) sequence to perform LDPC encoding, and performing the LDPC encoding based on the LDPC sequence and the block size.