ATSC Data Packet Synchronization via Dummy Byte Signaling
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Solution Overview
Problem
In ATSC-M/H transmission systems, there is a delay in post-processing due to the delay in arrival of the VSB frame initialization packet (VFIP), which affects data transmission effectiveness and synchronization between the head-end and transmitters.
Innovation Solution
The system introduces signaling information in specific dummy bytes of data packets to indicate whether a packet belongs to an ATSC-M/H group, allowing for correct time-alignment and synchronization of data packets between the head-end and transmitters without additional bandwidth usage, using placeholders that do not affect the transmission channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VSB frame initialization packet (VFIP) is transmitted once every 20 VSB Frames from head-end to transmitter, then transmitters can synchronize VSB super frame structure, but post-processing delay increases due to waiting for VFIP arrival
Solution Approach 1:
The patent applies preliminary action by inserting signaling information about VSB data field start positions into the transport stream data packets before transmission. This allows transmitters to know in advance when to expect and process upcoming data fields, eliminating the need to wait for periodic VFIP packets. The signaling information is embedded in the data flow itself, enabling proactive synchronization rather than reactive waiting.
2Productivity
If signaling information is inserted into transport stream to indicate VSB data field start positions, then synchronized mapping is achieved without delay, but data transmission bandwidth is reduced
Solution Approach 1:
The patent extracts unused dummy bytes from the transport stream packet structure to carry signaling information. Specifically, it utilizes the 4 dummy bytes that are already part of the ATSC transport stream format for mobile data, replacing their default content with synchronization signaling information. This extraction approach allows signaling to be added without requiring additional bandwidth beyond what is already allocated for mobile data transmission.
3Device complexity
If dummy bytes are replaced with signaling data, then synchronization information is transmitted without additional bandwidth usage, but the transmission channel structure is modified
Solution Approach 1:
The patent applies universality by making the dummy bytes serve dual functions: they maintain their original role as padding bytes for data alignment while simultaneously carrying signaling information about VSB data field positions. This multi-functionality allows the same transmission channel structure to support both data transmission and synchronization without requiring separate dedicated signaling channels or modifying the fundamental ATSC transport stream format.
Data Source
AI summary
Mapping data packets of a first data stream into data fields of a second data stream at several transmitters is provided by generating a first data stream with first data packets containing data associated with stationary receivers and second data packets containing data associated with mobile receivers in a head-end, where second data packets at the start of a group of consecutively transmitted second data packets contain placeholders into which signaling information is filled. A first data stream is transmitted from the head-end to each transmitter. Each transmitter extracts signaling information from the second data packets indicating in which data slot and in which data sub-frame of a received data frame the second data packet is transferred. Each transmitter inserts synchronization data in a specific data packet in each data slot containing second data packets. The first and second data packets are mapped consecutively into the second data stream.