LDPC Codeword Shortening and Puncturing for WLAN Throughput
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Solution Overview
Problem
In wireless local area networks (WLANs), existing LDPC coding systems face challenges in balancing block size and iteration number to optimize error correction and decoding speed, leading to inefficiencies in high data rate transmissions and increased network overhead due to prolonged decoding latency.
Innovation Solution
The implementation of a system and method for LDPC coding that computes the number of available bits in OFDM codewords, determines the length of LDPC codewords, and adjusts the number of shortening and puncture bits to optimize encoding and decoding processes, thereby reducing decoding latency and improving error correction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If larger blocklength LDPC codes are used, then error correcting capability improves, but decoding speed decreases due to fewer iterations per unit time
Solution Approach 1:
The patent implements dynamic adaptation of LDPC code blocklength and iteration number based on channel conditions and QoS requirements. The base station can select from multiple code configurations (different blocklengths and code rates) and adjust the number of decoding iterations dynamically, allowing the system to optimize between error correction capability and decoding speed in real-time according to current network conditions.
Solution Approach 2:
The system changes key parameters of the LDPC coding scheme including blocklength (n), code rate (R), and number of iterations. By adjusting these parameters, the system can adapt to different channel conditions and quality of service requirements, resolving the contradiction between using larger blocklengths for better error correction and maintaining decoding speed.
2Reliability
If more iterations are performed, then decoder performance improves, but decoding latency increases
Solution Approach 1:
The patent implements dynamic control of the number of decoding iterations based on channel conditions and quality of service requirements. The base station can adjust the iteration number adaptively, stopping the iterative decoding process early when convergence is achieved or when QoS requirements are met, thereby reducing unnecessary decoding latency while maintaining adequate decoder performance.
Solution Approach 2:
The system performs a sufficient number of iterations to achieve the required decoder performance and error correction capability, but not necessarily the maximum possible iterations. By determining the optimal iteration count based on channel conditions and QoS requirements, the system avoids excessive iterations that would increase latency without providing proportional performance improvements.
3Ease of manufacture
If fixed block size is used, then encoding simplicity is maintained, but adaptability to different data rates and packet sizes is reduced
Solution Approach 1:
The patent implements dynamic selection of LDPC code blocklength and code rate based on data rate requirements and packet sizes. The base station can choose from multiple pre-defined code configurations with different blocklengths (e.g., 1944, 1296, 648 bits) and code rates, allowing the system to adapt to varying transmission conditions while maintaining relatively simple encoding procedures through standardized code structures.
Solution Approach 2:
The system changes the blocklength and code rate parameters of the LDPC code according to data rate and packet size requirements. This allows the encoding scheme to be adapted to different transmission scenarios while maintaining the systematic structure and relative simplicity of LDPC encoding through parameter adjustment rather than fundamental structural changes.
Data Source
AI summary
Methods and systems of low density parity check coded (LDPCC) coding are disclosed herein in which a set of LDPC codes ensure reliable transmission for channels in which modulation symbols may undergo attenuation in a random fashion. Methods and systems of LDPC coding disclosed herein include choosing a code blocklength and concatenating codewords into which a data packet can be encoded. To optimize the coding scheme, first, codeword shortening is performed to ensure an integer number of codewords for a desired packet length. The codewords may then be punctured or repeated to ensure an integer number of channel symbols per codeword. Shortening and puncturing repetition methods are implemented to yield minimum overhead while keeping the effective coding rate low.