LDPC HARQ Retransmission Using Variable-Length Codewords
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Solution Overview
Problem
Current 5G communication systems face challenges in overcoming noise, fading, and inter-symbol interference, which degrade link performance, particularly in high-speed digital communication and broadcasting systems, limiting the reliability and throughput of next-generation mobile communication and digital broadcasting.
Innovation Solution
The implementation of low density parity check (LDPC) encoding and decoding methods that support variable-length codewords and hybrid automatic repeat request (HARQ) transmission, using a designed parity check matrix to generate and transmit bit sequences, and decode received signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction codes are used in 5G communication systems, then basic transmission functionality is maintained, but link performance is significantly degraded by noise, fading, and inter-symbol interference
Solution Approach 1:
The patent applies parameter changes by implementing LDPC encoding with variable code rates and lengths. The system dynamically adjusts encoding parameters (code rate, block length) based on channel conditions to overcome noise, fading, and inter-symbol interference. The LDPC code structure with configurable parity check matrices allows optimization of error correction performance under different transmission conditions, directly addressing the link performance degradation issue.
2Adaptability or versatility
If fixed-length codewords are used in HARQ transmission, then implementation is simpler, but adaptability to variable transmission rates and lengths is limited
Solution Approach 1:
The patent implements dynamics by enabling variable-length codeword generation and rate matching in LDPC encoding. The system dynamically selects codeword lengths and rates based on transmission requirements and channel conditions. The rate matching process adapts the encoded bit sequence length to match the required transmission block size, providing flexibility for HARQ retransmissions with different redundancy versions while managing encoding complexity through structured parity check matrices.
Data Source
AI summary
The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). The present disclosure discloses a method for effective retransmission when HARQ is applied to data encoded with a low density parity check (LDCP) code. A data transmission method of the transmitter may include: initially transmitting data encoded with an LDPC code to a receiver; receiving a negative acknowledgement (NACK) from the receiver; determining retransmission related information for data retransmission; and retransmitting, in response to the NACK, LDPC-encoded data based on the retransmission related information.