VSB Transport Packet Formatting With SRS for Fading Channel Reception
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Solution Overview
Problem
The existing ATSC VSB digital terrestrial broadcasting system experiences deteriorated receiving performance in multi-path fading and Doppler 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.
Innovation Solution
A method for formatting digital broadcast transport stream packets by inserting a known supplementary reference sequence (SRS) into the adaptation field of the packet, which is used for synchronization and channel equalization, maintaining compatibility with existing systems and improving receiver performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the field sync signal frequency is kept low to maintain compatibility with existing ATSC VSB systems, then system compatibility is preserved, but receiving performance deteriorates in multi-path fading and Doppler fading channel environments
Solution Approach 1:
The patent divides the synchronization function into two parts: the original field sync signal for basic system compatibility, and a new supplementary reference sequence (SRS) inserted in the adaptation field for improved equalization. This segmentation allows each component to serve its specific purpose without compromising the other.
Solution Approach 2:
The supplementary reference sequence (SRS) acts as an intermediary element inserted into the adaptation field of transport stream packets. It provides additional known data that mediates between the low-frequency field sync signal and the equalizer's need for more frequent reference points, enabling better channel estimation without changing the fundamental system structure.
2Reliability
If the field sync signal frequency is increased to improve equalization performance, then receiving performance in fading channels improves, but compatibility with existing systems deteriorates
Solution Approach 1:
The patent applies local quality by inserting the supplementary reference sequence specifically in the adaptation field portion of the transport stream, rather than changing the overall field sync signal structure. This localized modification provides enhanced reference data where needed while preserving the global system compatibility.
Solution Approach 2:
The supplementary reference sequence is inserted in advance into the adaptation field before the data is transmitted through the channel. This preliminary placement of known data allows the receiver to perform better equalization without requiring any changes to the existing field sync signal timing or frequency.
3Reliability
If known data (SRS) is inserted into the adaptation field to improve synchronization and equalization, then receiving performance improves, but device complexity increases
Solution Approach 1:
The adaptation field, which already exists in the MPEG-2 transport stream structure for various purposes, is repurposed to also carry the supplementary reference sequence. This multi-functional use of the adaptation field avoids adding new complex structures while providing the needed SRS functionality.
Solution Approach 2:
The system uses its own existing adaptation field structure to carry the supplementary reference sequence, rather than requiring external or additional complex signaling mechanisms. The adaptation field essentially serves itself by taking on the additional role of SRS carrier.
Data Source
AI summary
A method of formatting a digital broadcast transport stream packet, a digital broadcast transmitter, and a signal processing method thereof, includes constructing a transport stream packet that includes a stuffing region for an insertion of a known supplementary reference signal (SRS) data therein, randomizing the packet that includes the stuffing region is randomized, and the SRS data is inserted into the stuffing region of the randomized packet. Adding a parity for an error correction to the packet into which the SRS data has been inserted, the packet to which the parity has been added is interleaved, and a trellis encoding of the interleaved packet is performed. Inserting a segment sync signal and a field sync signal into the trellis-encoded packet, and a vestigial side band (VSB) modulation and an RF conversion of the packet are performed to transmit the VSB-modulated and RF-converted packet.