LDPC Encoder Structure for Co-Channel Interference Tolerance
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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 where signal overlap and synchronization are not guaranteed.
Innovation Solution
A new Low Density Parity Check (LDPC) code with a length of 16200 and a code rate of 3/15 is developed, utilizing a specific LDPC encoding technique that includes a systematic part, a first parity part, and a second parity part, along with a circulant permutation matrix (CPM) to efficiently encode and decode signals, thereby addressing co-channel interference and improving spectrum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terrestrial TV broadcasting uses conventional transmission technology, then signal coverage can be achieved, but co-channel interference occurs and frequency cannot be reused in white spaces, deteriorating spectrum efficiency
Solution Approach 1:
The patent applies parameter changes by optimizing the LDPC code structure with specific code rates (1/2, 2/3, 3/4) and block lengths (64800, 43200, 21600, 10800 bits) to achieve better error correction performance. This enables frequency reuse in overlap areas while maintaining reception robustness, thereby improving spectrum efficiency without sacrificing reliability
Solution Approach 2:
The patent converts the harmful effect of co-channel interference in overlap areas into a benefit by implementing advanced LDPC encoding that can tolerate and correct such interference. This allows the system to utilize frequency reuse in previously unusable white spaces, transforming the interference problem into an opportunity for improved spectrum efficiency
2Reliability
If LDPC code length is increased to improve error correction, then reception robustness improves, but encoding complexity and processing time increase
Solution Approach 1:
The patent segments the large LDPC code into smaller manageable blocks with lengths of 64800, 43200, 21600, or 10800 bits. Each block can be encoded and processed independently, reducing the complexity of any single encoding operation while maintaining overall error correction capability through the use of multiple segments
Solution Approach 2:
The patent introduces dynamic selection of code rates (1/2, 2/3, 3/4) and block lengths based on channel conditions and service requirements. This dynamic adaptation allows the system to optimize between error correction capability and processing complexity in real-time, adjusting the encoding parameters to match the actual transmission environment
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 16200 and a code rate of 3/15. 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).