Lifted LDPC Code Representation for Lower Encoding Complexity
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently encoding and decoding data at high rates, particularly in multiple-access technologies like 5G NR, where errors in binary data transmission can lead to unusable data and require retransmission, necessitating improved encoding methods for reliable communication.
Innovation Solution
The implementation of compactly described lifted low-density parity-check (LDPC) codes, which involve selecting lifting size values and sets of lifting values to generate lifted LDPC codes, allowing for efficient encoding and decoding by interconnecting edges in multiple copies of a base parity check matrix, thereby enhancing error correction capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction coding is used in wireless communication systems, then data transmission reliability is improved, but encoding and decoding complexity increases, reducing communication efficiency
Solution Approach 1:
The patent applies segmentation by dividing the LDPC code structure into a base graph and multiple lifted copies. The base graph is segmented into variable node sets and check node sets, with each lifted copy containing corresponding segments. This segmentation allows the encoder and decoder to process smaller, more manageable units while maintaining the overall error correction capability, thereby reducing computational complexity without sacrificing reliability.
Solution Approach 2:
The patent utilizes parameter changes by varying the lifting size parameter to generate different code rates and block lengths from a single base graph. By changing the lifting size parameter, the system can adapt to different communication requirements without redesigning the entire code structure, thus reducing encoding/decoding complexity while maintaining reliability across various transmission conditions.
2Productivity
If high data rates are supported in multiple-access technologies, then communication productivity is improved, but error correction capabilities must be enhanced, increasing system complexity
Solution Approach 1:
The patent implements universality by designing a single base graph that can serve multiple functions through different lifting operations. The same base graph can generate LDPC codes for various data rates and block lengths by applying different lifting sizes, making the error correction system universal and adaptable to high data rate requirements without increasing fundamental system complexity.
Solution Approach 2:
The patent applies preliminary action by pre-defining the base graph structure with optimized variable node and check node connections before actual data transmission. This preliminary design of the base graph allows for efficient encoding and decoding operations during high-rate communication, as the complex error correction structure is prepared in advance rather than computed in real-time.
3Adaptability or versatility
If lifted LDPC codes are generated using multiple lifting size values, then code adaptability is improved, but the number of required parity check matrices increases, consuming more memory resources
Solution Approach 1:
The patent applies copying by creating multiple lifted copies of a single base graph instead of storing multiple different parity check matrices. Each lifted copy is generated by applying a lifting operation to the base graph with specific lifting size values. This copying approach allows the system to support multiple code rates and block lengths (improving adaptability) while only storing one base graph in memory, significantly reducing memory resource requirements.
Data Source
AI summary
Certain aspects of the present disclosure generally relate to techniques for compactly describing lifted low-density parity-check (LDPC) codes. A method by a transmitting device generally includes selecting a first lifting size value and a first set of lifting values; generating a first lifted LDPC code by applying the first set of lifting values to interconnect edges in copies of a parity check matrix (PCM) having a first number of variable nodes and a second number of check nodes; determining a second set of lifting values for generating a second lifted LDPC code for a second lifting size value based on the first lifted PCM and the first set of lifting values; encoding a set of information bits based the first lifted LDPC code or the second lifted LDPC code to produce a code word; and transmitting the code word.