LDPC Framing Structure for Rapid Digital Broadcast Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional frame synchronization methods in digital satellite broadcasting systems, particularly those using Low Density Parity Check (LDPC) codes, face challenges in achieving rapid and reliable synchronization without incurring significant overhead or increasing receiver complexity, especially in low signal-to-noise environments.
Innovation Solution
A framing module that maps codewords to signal constellations, splits the data stream, and combines it with a physical layer signaling code, allowing for rapid frame acquisition using a simple frame detector and peak search process, embedding framing information within the LDPC coded frame to facilitate synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional frame synchronization methods are used in LDPC coded systems, then decoding can be performed prior to synchronization, but frame synchronization cannot be achieved rapidly and reliably in low signal-to-noise environments
Solution Approach 1:
The patent embeds a unique word and physical layer signaling code at the beginning of each LDPC coded frame before the main data payload. This preliminary framing structure allows the receiver to perform frame synchronization and modulation/coding scheme identification before decoding the main payload, resolving the contradiction by preparing synchronization information in advance without increasing receiver complexity
Solution Approach 2:
The patent introduces a physical layer signaling code as an intermediary element that carries modulation and coding scheme information. This intermediary allows the receiver to identify the correct decoding parameters before processing the main data, enabling reliable synchronization in low SNR environments without requiring complex receiver architecture
2Measurement precision
If additional framing overhead is added to assist with synchronization, then synchronization accuracy improves, but throughput decreases
Solution Approach 1:
The patent segments the frame into distinct components: a unique word for synchronization, a physical layer signaling code for modulation/coding information, and the main LDPC coded payload. This segmentation allows each component to serve its specific function efficiently, with the unique word and signaling code providing accurate frame detection while minimizing overhead by carrying only essential synchronization information
Solution Approach 2:
The patent uses parameter changes in the physical layer signaling code to convey modulation and coding scheme information. By encoding this information in a compact form within the signaling code, the system achieves accurate frame detection and parameter identification without adding significant overhead, thus maintaining high throughput
3Device complexity
If fixed modulation and coding schemes are used, then system complexity is reduced, but adaptability to varying channel conditions deteriorates
Solution Approach 1:
The patent introduces dynamic modulation and coding scheme selection through the physical layer signaling code, which indicates the actual modulation and coding parameters used in each frame. This allows the system to adapt to varying channel conditions by switching between different modulation and coding schemes while maintaining relatively simple receiver architecture, as the signaling code guides the decoding process
Data Source
AI summary
An approach is provided for supporting frame synchronization in a digital broadcast and interactive system. A transmitter includes an encoder that outputs a Low Density Parity Check (LDPC) codeword. The transmitter also includes a framing module generates a LDPC coded frame in response to the LDPC codeword, and appends a physical layer signaling field to the LDPC codeword for specifying modulation and coding information associated with the LDPC coded frame. The physical layer signaling field is encoded with a Forward Error Correction (FEC) code and has an embedded framing structure to assist with frame synchronization. The above arrangement is particularly suited to a digital satellite broadcast system.