LDPC Codeword Matrix Layout for Frequency-Reuse Cloud Broadcast
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Solution Overview
Problem
Current terrestrial TV broadcasting systems face co-channel interference, leading to inefficient spectrum reuse and the occurrence of 'white space,' which reduces spectrum efficiency, and require error correction codes that function effectively in negative Signal to Noise Ratio (SNR) environments.
Innovation Solution
The development of a Low Density Parity Check (LDPC) encoder and decoder that uses a parity check matrix structure combining a first parity check matrix for a higher code rate with a second parity check matrix for a lower code rate, incorporating zero, identity, and dual diagonal matrices, to encode and decode input information efficiently in a negative SNR environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction codes are used in terrestrial cloud broadcast systems, then the system can operate in negative SNR environments, but the complexity of the code structure increases and performance deteriorates
Solution Approach 1:
The parity check matrix is divided into multiple sub-matrices, each with specific structures (identity matrices, zero matrices, and structured sub-matrices). This segmentation allows the encoder to process different segments independently, reducing overall computational complexity while maintaining error correction capability in negative SNR environments.
Solution Approach 2:
The patent employs parameterized matrix structures where certain sub-matrices have fixed patterns (such as identity matrices and zero matrices) while others contain variable parameters. This approach simplifies the encoding process by reducing the number of independent parameters that need to be processed, thereby lowering complexity while preserving reliability.
2Productivity
If frequency reuse is implemented to improve spectrum efficiency, then co-channel interference increases, but this leads to signal reception difficulties in overlapping areas
Solution Approach 1:
The patent applies error correction coding with a specifically structured parity check matrix before transmission. This pre-processing step adds redundancy to the signal in advance, cushioning against the effects of co-channel interference and enabling reliable reception in overlapping frequency reuse areas where noise power exceeds signal power.
3Adaptability or versatility
If a single frequency network is established to enable cloud broadcast, then frequency reuse is facilitated, but the requirement for robust error correction in negative SNR environments increases system complexity
Solution Approach 1:
The parity check matrix is designed with different local structures in different regions of the matrix. Certain sub-matrices have identity or zero patterns that simplify local computations, while other regions contain structured sub-matrices optimized for error correction. This local quality differentiation reduces overall system complexity while maintaining the adaptability required for frequency reuse in single frequency networks.
Data Source
AI summary
Provided is an LDPC (Low Density Parity Check) code for terrestrial cloud broadcast. A method of encoding input information based on an LDPC (Low Density Parity Check) includes receiving information and encoding the input information with an LDPC codeword using a parity check matrix, wherein the parity check matrix may have a structure obtained by combining a first parity check matrix for an LDPC code having a higher code rate than a reference value with a second parity check matrix for an LDPC code having a lower code rate than the reference value.