Mobile Broadcast Signal Encoding for Robust VSB Reception
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Solution Overview
Problem
The Vestigial Sideband (VSB) transmission mode used in digital broadcasting in North America and Korea is prone to performance deterioration in poor channel environments, especially with portable and mobile receivers, requiring enhanced resistance to channel changes and noise.
Innovation Solution
A transmitting system that includes an SNS client, transmitter, RS frame encoder, CRC encoder, group formatter, interleaver, and trellis encoder to process and transmit digital broadcast signals, with SNS messages integrated into the signaling table and RS frames, enabling robust encoding and error correction for improved reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If VSB transmission mode is used for digital broadcasting, then the system is compatible with existing standards in North America and Korea, but receiving performance deteriorates in poor channel environments and mobile conditions
Solution Approach 1:
The mobile service data transmission is segmented into multiple RS frames belonging to different ensembles, each with independent error correction codes. This segmentation allows the receiver to successfully decode data from at least one ensemble even when others fail in poor channel conditions
Solution Approach 2:
The system uses composite encoding by combining multiple error correction schemes (RS encoding with different parameters across ensembles) to create a more robust transmission system that maintains compatibility with VSB while adding resilience against channel impairments
2Reliability
If additional encoding is performed on mobile service data, then error correction capability and receiving performance are improved, but system complexity and processing overhead increase
Solution Approach 1:
The encoding system is divided into multiple independent RS frame encoders, each processing a portion of the mobile service data with different encoding parameters. This modular segmentation makes the complex encoding process more manageable and allows selective use of encoding strength based on channel conditions
Solution Approach 2:
Different ensembles use different RS encoding parameters (different block lengths and code rates) to provide varying levels of error protection. This parameter variation allows the system to achieve high reliability without uniformly applying maximum complexity to all data streams
3Reliability
If known data sequences are inserted in data groups, then receiving performance and channel estimation accuracy are enhanced, but transmission bandwidth and data throughput are reduced
Solution Approach 1:
Known data sequences are inserted only in specific local positions within data groups where they are most needed for channel estimation and equalization, rather than uniformly throughout the entire transmission. This localized insertion minimizes bandwidth consumption while maintaining receiving performance
Data Source
AI summary
The invention relates to a transmitting system, comprising an SNS client that receives SNS messages from at least one SNS server, and a transmitter which transmits a broadcast signal, including the SNS messages and mobile service data, for a mobile broadcast. The transmitter includes: an RS frame encoder, which performs RS encoding and CRC encoding on the mobile service data for the mobile broadcast so as to build RS frames, and divides each RS frame into a plurality of portions; a group-forming unit, which forms data groups that contain each of the plurality of portions, and which adds known data sequences and signaling data to each data group; an inter-leaver for interleaving data of the data groups; and a trellis encoding unit for trellis-encoding the interleaved data.