LDPC Code Structure for Negative-SNR Terrestrial 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 creation of 'white spaces,' which necessitate a technology that can operate in negative Signal to Noise Ratio (SNR) environments and improve error correction for terrestrial cloud broadcast signals in single frequency networks.
Innovation Solution
The development of an 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 negative SNR conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional terrestrial TV broadcasting is used, then frequency reuse is limited to areas beyond three times service coverage, but this creates white spaces and reduces spectrum efficiency
Solution Approach 1:
The patent applies parameter changes by modifying the LDPC code structure (parity check matrix configuration, code rates, block lengths) to enable operation in negative SNR environments. This allows the system to maintain reliable communication while operating in single frequency networks, thereby enabling frequency reuse in previously unusable white space areas and improving spectrum efficiency.
2Productivity
If LDPC codes with higher code rates are used, then transmission capacity increases, but error correction performance in negative SNR environments deteriorates
Solution Approach 1:
The patent implements dynamics by providing multiple LDPC code configurations with different code rates (e.g., 1/2, 2/3, 3/4, 4/5) and block lengths that can be dynamically selected based on channel conditions. This allows the system to adaptively choose appropriate code rates to balance transmission capacity and error correction performance in negative SNR environments.
Solution Approach 2:
The patent changes parameters by defining specific parity check matrices with different structures (e.g., combining identity matrices, zero matrices, and dual diagonal matrices) and configuring different code rates and block lengths. These parameter variations enable the system to achieve both high transmission capacity and reliable error correction in challenging broadcast environments.
3Reliability
If complex LDPC code structures are used to improve error correction, then performance in negative SNR environments improves, but system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the LDPC code into systematic parts and parity parts with specific structures. The parity check matrix is segmented into sections with defined patterns (identity matrices, zero matrices, dual diagonal matrices), which simplifies the encoding and decoding processes while maintaining error correction performance in negative SNR environments.
Solution Approach 2:
The patent optimizes parameters by carefully configuring the parity check matrix structure and code rates to achieve the best balance between error correction performance and computational complexity. Specific parameter sets are defined for different code rates and block lengths, allowing the system to achieve reliable operation in negative SNR without excessive complexity.
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.