LDPC Encoder Structure for Co-Channel Interference Robustness
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Solution Overview
Problem
Current terrestrial TV broadcasting systems face significant co-channel interference issues, leading to white spaces where frequency reuse is not possible, resulting in deteriorated spectrum efficiency, especially in areas within three times the service radius.
Innovation Solution
A new Low Density Parity Check (LDPC) code with a length of 64800 and a code rate of 7/15 is developed, utilizing an LDPC encoding technique that efficiently performs encoding using a sequence corresponding to a parity check matrix, allowing for robust reception and efficient frequency reuse by eliminating white spaces through LDPC encoding and decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional broadcasting frequency allocation is used, then co-channel interference is avoided, but spectrum efficiency deteriorates due to white spaces
Solution Approach 1:
The patent converts the harmful co-channel interference into a beneficial feature by designing LDPC codes specifically optimized for single frequency network operations where co-channel signals are intentionally transmitted. The code structure and parity check matrix are designed to exploit the statistical properties of co-channel interference rather than merely defending against it, enabling receivers to successfully decode signals even in the presence of overlapping transmissions from multiple broadcasters.
Solution Approach 2:
The patent changes key parameters of the LDPC code including code length (64800 bits), code rate (7/15), and the specific structure of the parity check matrix to optimize performance for single frequency network applications. These parameter changes enable the code to achieve superior error correction performance in the presence of co-channel interference compared to conventional codes, allowing frequency reuse within 3 times the service radius.
2Loss of energy
If frequency reuse is implemented to eliminate white spaces, then spectrum efficiency improves, but co-channel interference increases
Solution Approach 1:
The patent transforms co-channel interference from a harmful factor into a manageable condition by designing LDPC codes that are specifically optimized for single frequency network operations. The code structure exploits the statistical properties of co-channel signals to achieve successful decoding, enabling frequency reuse while maintaining reception quality despite the presence of interfering signals from multiple broadcasters.
Solution Approach 2:
The LDPC code acts as an intermediary mechanism between the transmitted signals and the receiver, mediating the effect of co-channel interference. The parity check matrix and code structure serve as a filter that separates desired signal information from interfering signals, enabling the receiver to extract clean data even when multiple broadcasters transmit on the same frequency simultaneously.
3Reliability
If LDPC encoding with optimized parameters is used, then error correction performance improves, but encoding complexity increases
Solution Approach 1:
The patent segments the 64800-bit codeword into structured components including a 30240-bit systematic part and parity bits, with the parity check matrix organized in a quasi-cyclic structure. This segmentation allows the encoder to process data in manageable blocks using repeating patterns, reducing the computational burden compared to fully random LDPC codes while maintaining excellent error correction performance.
Solution Approach 2:
The patent optimizes encoding complexity by carefully selecting code parameters including code length (64800), code rate (7/15), and the specific structure of the parity check matrix with defined dimensions and patterns. These parameter choices enable efficient implementation using quasi-cyclic properties and structured algorithms, achieving a balance between error correction performance and computational complexity suitable for practical broadcasting applications.
Data Source
AI summary
A low density parity check (LDPC) encoder, an LDPC decoder, and an LDPC encoding method are disclosed. The LDPC encoder includes first memory, second memory, and a processor. The first memory stores an LDPC codeword having a length of 64800 and a code rate of 7/15. The second memory is initialized to 0. The processor generates the LDPC codeword corresponding to information bits by performing accumulation with respect to the second memory using a sequence corresponding to a parity check matrix (PCM).