LDPC HARQ Retransmission for Variable-Length 5G Codewords
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Solution Overview
Problem
Existing LDPC codes face challenges in supporting variable lengths and code rates, particularly in 5G communication systems, due to limitations in existing lifting methods that restrict length compatibility and code design flexibility.
Innovation Solution
The proposed method involves designing a parity check matrix using modified lifting processes and exponent conversion techniques that allow for variable lengths without performance degradation, enabling LDPC coding and decoding for variable-length codewords and supporting hybrid automatic repeat request (HARQ) schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing lifting methods are used for LDPC code design, then the code structure is simple and easy to implement, but the length compatibility and code design flexibility are restricted
Solution Approach 1:
The patent applies parameter changes by modifying the lifting process parameters and introducing exponent conversion techniques. Specifically, it changes the lifting size parameter from fixed to variable, and introduces exponent values that can be adjusted to achieve different code lengths and rates, thereby improving length compatibility while maintaining manageable complexity
Solution Approach 2:
The patent implements dynamics by making the lifting process adaptive rather than static. The lifting size and exponent values are dynamically selected based on the desired code length and rate requirements, allowing the LDPC code structure to flexibly adapt to different transmission scenarios without requiring completely different code designs
2Adaptability or versatility
If variable-length codewords are supported through modified lifting processes, then code design flexibility and adaptability improve, but the complexity of encoding and decoding processes increases
Solution Approach 1:
The patent manages the increased complexity by systematically changing parameters through exponent conversion. Instead of redesigning the entire encoding/decoding architecture for each variable length, it modifies specific parameters (exponent values and lifting sizes) within the existing framework, making the complexity manageable through parameterization rather than structural redesign
Solution Approach 2:
The modified lifting process serves multiple functions: it can generate LDPC codes of various lengths, support different code rates, and maintain compatibility with existing decoding algorithms. This multi-functionality reduces the need for separate specialized processes for each code configuration, thereby controlling overall system complexity
3Productivity
If LDPC codes are optimized for high data throughput in 5G systems, then transmission speed and capacity increase, but error correction capabilities may be compromised
Solution Approach 1:
The patent optimizes the balance between throughput and reliability by adjusting code rate parameters and lifting sizes. Higher code rates are used for throughput-critical transmissions, while lower code rates are selected for reliability-critical scenarios. The exponent conversion technique allows fine-grained parameter adjustment to achieve the optimal trade-off for each specific transmission condition
Solution Approach 2:
The system dynamically selects code parameters based on channel conditions and service requirements. When channel conditions are good, higher code rates are used to maximize throughput. When conditions deteriorate, the system adaptively switches to lower code rates with stronger error correction capabilities, maintaining the optimal balance between throughput and reliability in real-time
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.