Variable length burst transmission over the physical layer of a multilayer transmission format

• US 6,285,681 B1
• Filed: 04/13/1998
• Issued: 09/04/2001
• Est. Priority Date: 10/24/1995
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Hou, Victor T., Anderson, Steven E., Kolze, Thomas J.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Duong, Frank
• Application Number:
  US09/059,113
• Time in Patent Office: 1,240 Days
• Field of Search: 370/282, 370/294, 370/321, 370/337, 370/347, 370/395, 370/430, 370/436, 370/437, 370/442, 370/458, 370/473, 370/478, 370/480, 370/486, 370/487, 370/498, 348/7, 348/10, 348/12, 375/222, 375/261, 375/298, 455/3.1, 455/5.1, 714/755, 714/774
• US Class Current: 370/442
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0006 by adapting the transmission format
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0018 based on latency requirement
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 2012/5607 Radio
• CPC Class Codes: H04L 2012/5645 Connectionless
• CPC Class Codes: H04L 2012/5647 Cell loss
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

Apparatus is provided for communicating data packets in variable length bursts over a physical layer in a multilayer data communication scheme. Each burst contains information data (40, 50, 60, 64, 74, 78, 82) and overhead (30, 32, 34, 36, 38, 42, 44, 62, 66, 76, 80, 84). The overhead includes forward error control (FEC) data (42, 62, 66, 76, 80, 84). Different burst modes (FIG. 2, 3, 4, 5) are provided to enable a trade-off to be made between bandwidth efficiency and data transmission robustness. The burst modes provide different combinations of modulation (such as QPSK and 16-QAM), symbol rates, FEC coding levels and frame and preamble structure. The apparatus is particularly suitable for use in upstream communications over hybrid fiber coax cable television plants.

Claims

1. Apparatus for communicating data packets in variable length bursts over a physical layer in a multilayer data communication scheme, each burst containing (i) information data and (ii) overhead including forward error control (FEC) data, said apparatus comprising:

a programmable block processor for grouping said information data into blocks according to a selected one of a plurality of available grouping modes;

a programmable FEC encoder for encoding said blocks with said FEC data according to a selected one of a plurality of possible coding levels; and

an interface associated with said block processor and said FEC encoder for;

selecting a burst mode that uses a particular grouping mode provided by said block processor and a particular coding level established by said FEC encoder to achieve an associated transmission bandwidth efficiency and burst transmission robustness over said physical layer for bursts containing said blocks.

2. Apparatus in accordance with claim 1 further comprising a programmable modulator for modulating the encoded blocks for transmission according to one of a plurality of available modulation modes, said modulator being responsive to the burst mode selected via said interface for providing a particular one of said modulation modes.

3. Apparatus in accordance with claim 2 wherein said modulation modes include QPSK and QAM.

4. Apparatus in accordance with claim 1 wherein said bursts are transmitted using time and frequency division multiple access (F/TDMA) with frequency agility over a communication channel.

5. Apparatus in accordance with claim 1 wherein each of said grouping modes is associated with a particular symbol rate for the transmission of symbols carried by said bursts.

6. Apparatus in accordance with claim 5 wherein:

said block processor blocks protocol data units (PDUs) containing said information data into units independent of the PDU length and provides a preamble of a selected length in response to the burst mode selected via said interface; and

said FEC encoder encodes data from said units into a number of codewords dictated by the selected burst mode.

7. Apparatus in accordance with claim 6 wherein said FEC encoder is programmable to provide codewords of different lengths.

8. Apparatus in accordance with claim 6 further comprising an interleaver for interleaving codeword symbols whenever said FEC encoder encodes said blocks into two or more codewords.

9. Apparatus in accordance with claim 6 further comprising a programmable modulator for modulating the encoded blocks for transmission according to one of a plurality of available modulation modes, said modulator being responsive to the burst mode selected via said interface for providing a particular one of said modulation modes.

10. Apparatus in accordance with claim 9 wherein said modulation modes include QPSK and QAM.

11. Apparatus in accordance with claim 6 wherein said block processor allows a final unit derived from the PDUs whose data is contained in a burst to be shorter than previous units contained in the burst.

12. Apparatus in accordance with claim 1 wherein said blocks comprise asynchronous transfer mode (ATM) cells, and said block processor allocates a particular number of said cells to each block based on the burst mode selected via said interface.

13. Apparatus in accordance with claim 12 wherein said block processor allocates either 1, 2 or 4 cells per block depending on the burst mode selected via said interface.

14. Apparatus in accordance with claim 1 wherein said burst mode is additionally selected to achieve an associated latency for bursts containing said blocks.

15. Apparatus in accordance with claim 1 wherein:

said block processor provides modes of varying burst length, each having one codeword per burst; and

said bursts are convolutionally,coded using at least one of a convolutional FEC code and trellis coded modulation.

16. Apparatus in accordance with claim 15 wherein said convolutional coding is provided as an inner code concatenated with an error-correcting outer code.

17. A method for communicating data packets in variable length bursts over a physical layer in a multilayer data communication scheme, each burst containing (i) information data and (ii) overhead including forward error control (FEC) data, comprising the steps of:

providing a plurality of different burst modes, each specifying an information data grouping mode and an FEC coding level;

selecting one of said burst modes;

grouping said information data into blocks according to the grouping mode specified by the selected burst mode; and

encoding said blocks with said FEC data according to the coding level specified by the selected burst mode;

wherein said burst mode is selected to achieve an associated transmission bandwidth efficiency and burst transmission robustness over said physical layer for bursts containing said blocks.

18. A method in accordance with claim 17 wherein said burst mode is additionally selected to achieve an associated latency for bursts containing said blocks.

19. A method in accordance with claim 18 wherein the burst mode is selected based on a trade-off between at least two of bandwidth efficiency, burst transmission robustness and latency.

20. A method in accordance with claim 19 wherein said trade-off comprises at least one of the following:

(a) a trade-off between robustness and efficiency by varying a block code length and code rate;

(b) a trade-off between robustness and efficiency by varying a preamble length;

(c) a trade-off between latency and efficiency by bundling protocol data units (PDUs);

(d) a trade-off between efficiency and robustness at the cost of latency by lengthening and bundling codewords for short PDUs; and

(e) a trade-off between efficiency and robustness by shortening codewords for long PDUs and coarse slot boundaries.