VSB Broadcast Reference Sequence for Multipath Equalization
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Solution Overview
Problem
The existing ATSC VSB digital broadcast system suffers from poor receiving performance in multi-path fading channel environments due to the low frequency of the field sync signal, making it difficult for the equalizer to estimate and correct channel distortions effectively, especially in Doppler fading channels.
Innovation Solution
A digital broadcast transmitter/receiver system is developed that inserts a known supplementary reference sequence (SRS) into the VSB data stream, allowing the receiver to utilize this sequence for synchronization and equalization, improving channel estimation and correcting multi-path fading. This is achieved by inserting stuff bytes with specific known data into the transport stream, which are then used for trellis encoding and parity generation, enhancing the system's ability to handle dynamic channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field sync signal is used for synchronization and equalization in the ATSC VSB system, then the system maintains compatibility with the standard broadcasting framework, but the receiving performance deteriorates in multi-path fading channels due to the low frequency of the field sync signal
Solution Approach 1:
The patent divides the synchronization and equalization function into two parts: the existing field sync signal for basic synchronization, and a newly inserted supplementary reference sequence (SRS) for enhanced equalization training. This segmentation allows the system to maintain standard compatibility while improving receiving performance through additional reference signals specifically designed for multi-path fading compensation.
Solution Approach 2:
The supplementary reference sequence is inserted in advance into the VSB data stream at predetermined positions before transmission. This preliminary action provides the receiver with known reference signals that enable proactive channel estimation and equalization adjustment, rather than waiting for field sync signals that occur less frequently.
2Measurement precision
If the field sync signal frequency is kept low to maintain standard structure, then the system complexity remains manageable, but the equalizer cannot effectively estimate and correct channel distortions in dynamic fading conditions
Solution Approach 1:
The supplementary reference sequence acts as an intermediary element between the transmitter and receiver, providing a dedicated reference signal that facilitates accurate channel estimation. This intermediary sequence is specifically designed for equalization purposes, allowing the receiver to accurately measure and compensate for channel distortions without disrupting the overall signal processing efficiency.
3Reliability
If known data is inserted into the transport stream for equalization training, then the receiving performance improves, but the data stream structure becomes more complex requiring additional processing
Solution Approach 1:
The supplementary reference sequence serves multiple functions simultaneously: it provides synchronization assistance, enables equalization training, and maintains compatibility with the existing transport stream structure. By designing the SRS to fulfill multiple purposes, the patent reduces the need for separate processing mechanisms, thereby limiting the increase in data stream processing complexity.
Data Source
AI summary
A digital broadcast transmitting/receiving system, and a signal processing method thereof, includes a randomizer for randomizing a transport stream into a specified position of which stuff bytes are inserted, a stuff-byte exchanger for replacing the stuff bytes included in data output from the randomizer with specified known data, an RS encoder for performing an RS-encoding of data output from the stuff-byte exchanger, an interleaver for interleaving data output from the RS encoder, a trellis encoder for performing a trellis encoding of data output from the interleaver, an RS parity generator for generating a parity by performing an RS encoding of data output from the RS encoder, and outputting the generated parity to the trellis encoder, and a modulator/RF converter for modulating data output from the trellis encoder and performing an RF up-converting of the modulated data. The digital broadcast receiving performance can be improved even in an inferior multi-path channel by detecting the known data from the received signal and using the known data for synchronization and equalization in a digital broadcast receiver.