Improved digital transmission system for an enhanced ATSC 8-VSB system

• US 20020194570A1
• Filed: 04/22/2002
• Published: 12/19/2002
• Est. Priority Date: 04/02/2001
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Birru, Dagnachew, Gaddam, Vasanth R.
• Granted Patent: US 7,111,221 B2
• Time in Patent Office: Days
• US Class Current: 714/792
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002

Abstract

A digital transmission system and method that improves upon the ATSC A/53 HDTV signal transmission standard includes: a first forward error correction (FEC) unit for encoding packets belonging to each of robust and normal data bit streams; a robust processor unit for receiving robust packets comprising priority data and processing the packets for generating the robust bit stream; a trellis encoder unit for producing a stream of trellis encoded data bits corresponding to bits of the normal and robust streams, the encoder employing mapping of encoded data bits of said robust packets into symbols according to one or more symbol mapping schemes; and, an optional second forward error correction (FEC) encoding unit for ensuring backward compatibility with a receiver device by reading in only packets of the robust bit stream and enabling generation of parity bytes only for the robust stream packets; and, a transmitter device for transmitting the robust bit streams in a backwards compatible manner, separately or in conjunction with said normal bit stream over a fixed bandwidth communications channel to a receiver device, wherein an existing receiver device is capable of receiving and processing packets of the robust bit stream as null packets.

Claims

1. A digital signal transmission system for transmitting encoded data packets including normal packets for transmission as a normal bit stream and robust packets comprising information for transmission as a robust bit stream, said system comprising:

a first forward error correction (FEC) unit for encoding packets belonging to each said robust and normal data bit streams;

a robust processor unit for receiving robust packets comprising priority data and processing said packets for generating said robust bit stream;

a trellis encoder unit for producing a stream of trellis encoded data bits corresponding to bits of said normal and robust streams, said encoder employing means for mapping encoded data bits of said robust packets into symbols according to one or more symbol mapping schemes;

an optional second forward error correction (FEC) encoding unit for ensuring backward compatibility with a receiver device by reading in only packets of said robust bit stream and enabling generation of parity bytes only for the robust stream packets; and

,

a transmitter device for transmitting said robust bit streams in a backwards compatible manner, separately or in conjunction with said normal bit stream over a fixed bandwidth communication channel to a receiver device,

wherein a receiver device includes an existing receiver device capable of receiving and processing packets of said robust bit stream as null packets.

2. The digital signal transmission system as claimed in claim 1, wherein said receiver device includes a new receiver device capable of receiving and processing packets of said robust bit stream at a lower TOV compared to the standard bit-stream.

3. The digital signal transmission system as claimed in claim 1, wherein said robust processor unit for processing said robust packets comprises:

a device for receiving said robust packets and interleaving said robust packets of an input data stream; and

,

a packet formatter device for processing robust packets in accordance with a symbol mapping scheme employed for said robust packets and, whether backward compatibility with an existing receiver device is optioned;

said formatter device including means for reading robust bytes from the robust interleaver and generating two or more data blocks corresponding to each robust packet to facilitate robust encoding in said trellis encoder unit.

4. The digital signal transmission system as claimed in claim 3, wherein said packet formatter further comprises:

means for arranging information bits of each said robust byte into least significant bit (LSB) positions of said two or more data blocks for robust encoding in said trellis encoder unit,

wherein remaining bits in most significant bit (MSB) positions are subsequently determined based on a symbol mapping scheme employed.

5. The digital signal transmission system as claimed in claim 4, wherein said packet formatter further comprises:

means for inserting a plurality of placeholder bytes at various locations in each said two or more data blocks, said placeholder bytes for eventually receiving said parity bytes provided by said second FEC encoding unit when optioned to ensure backward compatibility.

6. The digital signal transmission system as claimed in claim 5, wherein said packet formatter further comprises:

means for inserting three header bytes in each data block for identifying the packet at a receiver device, wherein placeholder bytes include a pre-specified location in each said two or more data blocks for eventually receiving said three header bytes.

7. The digital signal transmission system as claimed in claim 5, wherein said placeholder bytes are inserted at one or more locations comprising byte positions dispersed throughout each data block, said one or more locations of placeholders bytes in each said data block are located to result in placement of parity bytes in contiguous byte positions at the end of that packet when interleaved.

8. The digital signal transmission system as claimed in claim 6, further including parity byte generator device for de-interleaving bytes obtained from after trellis encoding for robust packets when optioned to ensure backward compatibility, said generator further obtaining parity byte location information for each robust packet, generating said parity bytes from said second FEC unit, and placing said parity bytes in said robust packet at said placeholder locations.

9. The digital signal transmission system as claimed in claim 1, further including multiplexor device for multiplexing normal stream packets with the robust packets according to a pre-defined algorithm.

10. The digital signal transmission system as claimed in claim 1, wherein said one or more symbol mapping schemes includes one selected from the group comprising:

a pseudo 2-VSB symbol mapping scheme, 4-VSB symbol mapping scheme, and H-VSB mapping scheme.

11. The digital signal transmission system as claimed in claim 1, wherein said parity bytes are mapped into one of 8-VSB levels according to Advanced Television Systems Committee (ATSC) standard 8-VSB bit stream standard.

13. The method for transmitting digital signals as claimed in claim 12, wherein said receiver device includes a new receiver device capable of receiving and processing packets of said robust bit stream at a lower TOV compared to the standard bit-stream.

14. The method for transmitting digital signals as claimed in claim 12, wherein said step of processing said robust packets comprises:

receiving said robust packets and interleaving said robust packets of an input data stream; and

,

formatting said robust packets in accordance with a symbol mapping scheme employed for said robust packets and whether backward compatibility with a receiver device is optioned, wherein said formatting step includes the step of reading robust bytes from the interleaver and generating two or more data blocks corresponding to each robust packet to facilitate robust encoding in said trellis encoder unit.

15. The method for transmitting digital signals as claimed in claim 14, wherein said formatting step further includes the step of:

arranging information bits of each said robust byte into least significant bit (LSB) positions of said two or more data blocks for robust encoding in said trellis encoder unit, and subsequently determining remaining bits in most significant bit (MSB) positions are based on a symbol mapping scheme employed.

16. The method for transmitting digital signals as claimed in claim 14, wherein said packet formatting step further comprises the step of inserting a plurality of placeholder bytes at various locations in each said two or more data blocks, said placeholder bytes for eventually receiving said parity bytes provided by said second FEC encoding unit when optioned to ensure backward compatibility.

17. The method for transmitting digital signals as claimed in claim 16, wherein said packet formatting step further comprises the step of inserting three header bytes in each data block for identifying the packet at a receiver device, wherein placeholder bytes include a pre-specified location in each said two or more data blocks for eventually receiving said three header bytes.

18. The method for transmitting digital signals as claimed in claim 16, wherein said plurality of placeholder bytes are inserted at one or more locations comprising byte positions dispersed throughout each data block, said one or more locations of placeholders bytes in each said data block are located to result in placement of parity bytes in contiguous byte positions at the end of that packet in a subsequent interleaving step.

19. The method for transmitting digital signals as claimed in claim 17, further including the steps of:

de-interleaving bytes obtained from after trellis encoding for robust packets when optioned to ensure backward compatibility,

obtaining parity byte location information for each robust packet,

generating said parity bytes from said second FEC unit, and

placing said parity bytes in said robust packet at said placeholder locations.

20. The method for transmitting digital signals as claimed in claim 12, further including the step of multiplexing normal stream packets with the robust packets according to a pre-defined algorithm.

21. The method for transmitting digital signals as claimed in claim 12, wherein said step of mapping trellis encoded data bits of said robust packets into symbols includes utilizing a symbol mapping scheme selected from the group comprising:

a pseudo 2-VSB symbol mapping scheme, 4-VSB symbol mapping scheme, and H-VSB mapping scheme.

12. A method for transmitting digital signals comprising encoded data packets including normal packets for transmission as a normal bit stream and robust packets comprising information for transmission as a robust bit stream, said method comprising the steps of:

a) encoding packets belonging to each said robust and normal data bit streams in a first forward error correction (FEC) unit;

b) receiving robust packets comprising priority data and processing said packets for generating said robust bit stream;

c) producing a stream of trellis encoded data bits corresponding to bits of said normal and robust streams, and mapping trellis encoded data bits of said robust packets into symbols according to one or more symbol mapping schemes;

d) optionally ensuring backward compatibility with a receiver device by reading in only packets of said robust bit stream and enabling generation of parity bytes only for the robust stream packets in a second forward error correction (FEC) encoding unit; and

,

e) transmitting said robust bit stream in a backwards compatible manner, separately or in conjunction with said normal bit stream over a fixed bandwidth communications channel to a receiver device, wherein an existing receiver device is capable of receiving and processing packets of said robust bit stream as null packets.

22. A high-definition digital television signal transmission system for transmitting encoded MPEG-compatible data packets for receipt by a digital television receiver device, said packets including normal packets for transmission as a normal bit stream and robust packets comprising information for transmission as a robust bit stream, said system comprising:

a first forward error correction (FEC) encoding unit for formatting packets belonging to each said robust and normal data bit streams;

a robust processor unit for receiving robust packets comprising priority data and processing said packets for generating said robust bit stream;

a trellis encoder unit for producing a stream of trellis encoded data bits corresponding to bits of said normal and robust streams, said encoder employing means for mapping encoded data bits of said robust packets into symbols according to one or more symbol mapping schemes;

an optional second forward error correction (FEC) encoding unit for ensuring backward compatibility with a receiver device by reading in only packets of said robust bit stream and enabling generation of parity bytes only for the robust stream packets; and

,

a digital television signal transmitter device for transmitting said robust bit streams in a backwards compatible manner, separately or in conjunction with said normal bit stream over a fixed bandwidth communications channel to said receiver device, and,

means for transmitting bits for receipt by said receiver device including information to enable the receiver to correctly decode the robust packets symbols according to the symbol mapping scheme employed,

wherein an existing receiver device is capable of receiving and processing packets of said robust bit stream as null packets and a new receiver device is capable of receiving and processing packets of said robust bit stream at a lower TOV compared to the standard bit-stream.

23. The high-definition digital television signal transmission system as claimed in claim 22, wherein said transmitted bits for receipt by said receiver device includes information bits characterizing a digital signal transmission mode according to a number of robust packets, a type of modulation, and a level of redundancy inserted for trellis encoding.

24. The high-definition digital television signal transmission system as claimed in claim 22, wherein each said transmitted information bit is spread spectrum encoded prior to transmission, said bits encoded for transmission in a reserved bit portion of a data field sync segment.

25. The high-definition digital television signal transmission system as claimed in claim 22,wherein said mode information bits represent a symbol mapping technique employed for said robust packets, said symbol mapping techniques including one selected from 2-VSB, 4-VSB and H-VSB symbol mapping modes, and, an indication of whether said optional second FEC encoding unit was utilized.