Dual Stream DTV Transceiver Using 4-VSB Robust Data
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Solution Overview
Problem
Conventional 8-VSB Digital Television (DTV) transceivers experience degraded reception performance due to channel distortion, multipath effects, and increased signal-to-noise ratio (SNR) in indoor and mobile environments, leading to inferior decoding performance and backward compatibility issues.
Innovation Solution
A dual stream DTV transceiver system that transmits normal data as 8-VSB and robust data as 4-VSB, using specific symbol mappings {−5, −3, 1, 7} or {−7, −1, 3, 5}, which reduces SNR and improves decoding performance without increasing average power, allowing for improved reception of both normal and robust data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If 8-VSB modulation is used for DTV transmission, then backward compatibility with existing receivers is maintained, but reception performance degrades in indoor and mobile environments due to channel distortion and multipath effects
Solution Approach 1:
The data stream is segmented into two separate streams: normal data transmitted using conventional 8-VSB modulation for backward compatibility, and robust data transmitted using 4-VSB modulation for improved reception performance. This segmentation allows each stream to be optimized for its specific purpose without compromising the other.
Solution Approach 2:
Different modulation schemes are applied to different portions of the data stream based on their specific requirements. Normal data uses 8-VSB where compatibility is paramount, while robust data uses 4-VSB where reception reliability is critical. This local differentiation of quality characteristics resolves the contradiction between compatibility and performance.
2Reliability
If 4-VSB robust data with symbol mapping {−7, −5, 5, 7} is used, then decoding performance improves in challenging channels, but average power increases
Solution Approach 1:
The symbol mapping parameters for robust data are changed from the conventional {−7, −5, 5, 7} to the optimized {−5, −3, 1, 7} or {−7, −1, 3, 5}. This parameter change reduces the average power of robust data to match that of normal 8-VSB data while maintaining the improved decoding performance in challenging channel conditions.
3Measurement precision
If robust data is transmitted to improve reception in mobile environments, then decoding accuracy increases, but overall system complexity increases
Solution Approach 1:
The system is segmented into two parallel processing paths: one for normal data using standard 8-VSB demodulation and another for robust data using 4-VSB demodulation with specific symbol mapping. This segmentation allows the receiver to handle robust data with enhanced processing only when necessary, rather than increasing complexity across the entire system.
Solution Approach 2:
The dual stream approach creates a universal system that can operate in multiple modes: it maintains compatibility with legacy 8-VSB receivers for normal operation, while simultaneously providing enhanced robust data transmission for challenging environments. The system adapts its functionality based on channel conditions and receiver capabilities.
Data Source
AI summary
The present invention relates to a Vestigial Side Band (VSB) Digital Television (DTV) in agreement with the DTV standards (A/53) of the Advanced Television System Committee (ATSC), and to a method thereof. More particularly, it provides 4-VSB DTV transceiver that improves reception performance of a receiver by transmitting and receiving dual streams formed of normal data and robust data without increasing average power, regardless of a mixing ratio of the normal and robust data. The 4-VSB DTV transceiver of the present research includes an encoding unit for encoding the robust data to be mapped to one of two groups having 4 levels {−5, −3, 1, 7} and {−7, −1, 3, 5}.