LDPC Parity Puncturing in Transmitters for Decoding Efficiency
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Solution Overview
Problem
Current signal transmitters and receivers face challenges in providing improved performance for digital broadcasting services, particularly in high definition digital television and portable broadcasting, due to limitations in efficiently managing parity bits during signal transmission.
Innovation Solution
A transmitter system that includes an LDPC encoder, a puncturer, and a mapper, which calculates the number of parity bits to be punctured based on specific ratios and minimum values, and punctures those bits to improve decoding performance, allowing for flexible robustness levels and efficient transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all parity bits are transmitted, then decoding reliability is improved, but transmission efficiency deteriorates due to increased bandwidth consumption
Solution Approach 1:
The patent extracts and removes a portion of the parity bits from the transmitted signal. Specifically, it punctures the last portion of parity bits (e.g., bits from index N_punc to N_ldpc_parity-1) while retaining the first portion (bits from index 0 to N_punc-1). This selective removal reduces the number of transmitted bits while maintaining sufficient decoding capability, thereby improving transmission efficiency without completely sacrificing reliability.
Solution Approach 2:
The patent introduces a puncturing parameter N_punc that controls the number of parity bits to be removed. By adjusting this parameter, the system can dynamically change the trade-off between reliability and transmission efficiency. The receiver uses this same parameter to correctly identify which bits were punctured and performs appropriate puncturing during decoding, enabling flexible adaptation to different channel conditions and service requirements.
2Productivity
If parity bits are punctured to improve transmission efficiency, then bandwidth usage is reduced, but decoding performance may deteriorate
Solution Approach 1:
The patent applies different treatment to different portions of parity bits. The first portion of parity bits (indices 0 to N_punc-1) is transmitted and used for decoding, while the last portion (indices N_punc to N_ldpc_parity-1) is punctured and not transmitted. This local differentiation ensures that the most critical parity information is preserved while less critical portions are removed, maintaining decoding performance while improving efficiency.
Solution Approach 2:
The transmitter performs preliminary puncturing of parity bits before transmission based on pre-agreed parameters. The receiver, knowing the puncturing pattern through the parameter N_punc, performs corresponding preliminary preparation in the decoding process by identifying which bits to expect and which were removed. This pre-planned approach ensures smooth operation without real-time negotiation overhead.
Data Source
AI summary
A transmitter is provided. The transmitter includes: a Low Density Parity Check (LDPC) encoder configured to encode outer-encoded bits to generate an LDPC codeword including LDPC information bits and parity bits; a puncturer configured to puncture some of the parity bits included in the LDPC codeword; and a mapper configured to map the LDPC codeword except the punctured parity bits to symbols for transmission to a receiver, wherein the puncturer calculates a number of parity bits to be punctured among the parity bits included in the LDPC codeword based on a number of the outer-encoded bits, a number of the LDPC information bits, and a minimum number of parity bits to be punctured among the parity bits included in the LDPC codeword.