Variable code rate and signal constellation turbo trellis coded modulation codec

• US 7,093,187 B2
• Filed: 10/04/2002
• Issued: 08/15/2006
• Est. Priority Date: 05/31/2002
• Status: Active Grant

• Current Assignee: Broadcom Corporation (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Shen, Ba-Zhong, Tran, Hau Thien, Cameron, Kelly Brian
• Primary Examiner(s): Lamarre, Guy J.
• Application Number:
  US10/264,486
• Publication Number:
  US 20030223506A1
• Time in Patent Office: 1,411 Days
• Field of Search: 714790-792, 714/796, 714/786, 714/755, 375/265, 375/295, 375/298, 375/316, 375/279, 375/308, 375/329
• US Class Current: 714/792
• CPC Class Codes: G11B 20/18 Error detection or correction; Testing , e.g. of drop-outs
• CPC Class Codes: H03M 13/1102 Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
• CPC Class Codes: H03M 13/256 with trellis coding, e.g. with convolutional codes and TCM
• CPC Class Codes: H03M 13/258 with turbo codes, e.g. Turbo Trellis Coded Modulation [TTCM]
• CPC Class Codes: H03M 13/27 using interleaving techniques
• CPC Class Codes: H03M 13/2767 Interleaver wherein the permutation pattern or a portion thereof is stored
• CPC Class Codes: H03M 13/2771 Internal interleaver for turbo codes H03M13/2714 and H03M13/2725 take precedence
• CPC Class Codes: H03M 13/2785 Interleaver using in-place interleaving, i.e. writing to and reading from the memory is performed at the same memory location
• CPC Class Codes: H03M 13/2957 Turbo codes and decoding
• CPC Class Codes: H03M 13/4123 implementing the return to a predetermined state
• CPC Class Codes: H03M 13/4161 implementing path management
• CPC Class Codes: H03M 13/45 Soft decoding, i.e. using symbol reliability information H03M13/41 takes precedence
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0066 Parallel concatenated codes
• CPC Class Codes: H04L 1/0068 by puncturing
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27

Abstract

Variable code rate and signal constellation turbo trellis coded modulation (TTCM) codec. A common trellis is employed at both ends of a communication system (in an encoder and decoder) to code and decode data at different rates. The encoding employs a single TTCM encoder whose output bits may be selectively punctured to support multiple modulations (constellations and mappings) according to a rate control sequence. A single TTCM decoder is operable to decode each of the various rates at which the data is encoded by the TTCM encoder. The rate control sequence may include a number of rate controls arranged in a period that is repeated during encoding and decoding. Either one or both of the encoder and decoder may adaptively select a new rate control sequence based on operating conditions of the communication system, such as a change in signal to noise ratio (SNR).

Claims

1. An apparatus, comprising:

a rate control sequencer that provides a rate control sequence that includes a plurality of modulations, each modulation within the plurality of modulations includes a constellation and a mapping, each modulation of the plurality of modulations includes a bandwidth efficiency, the rate control sequence includes a plurality of rate controls arranged in a period;

an encoder that encodes a plurality of input bits according to the plurality of rate controls of the rate control sequence thereby generating a plurality of encoded symbols, the plurality of encoded symbols having an average bandwidth efficiency; and

a decoder that decodes the plurality of encoded symbols according to the plurality of rate controls of the rate control sequence.

2. The apparatus of claim 1, wherein the encoder encodes the plurality of input bits thereby generating a plurality of encoded input bits;

and

the encoder further includes a puncturing functional block that punctures at least one encoded input bit of the plurality of encoded input bits according to one of the rate controls of the plurality of rate controls of the rate control sequence to generate at least one encoded symbol of the plurality of encoded symbols.

3. The apparatus of claim 1, wherein one input bit of the plurality of input bits is provided to the decoder as an uncoded bit.

4. The apparatus of claim 1, wherein the plurality of input bits are provided serially to the encoder.

5. The apparatus of claim 1, wherein one modulation of the plurality of modulations includes at least one of 8 Phase Shift Keying (PSK) modulation, Quadrature Phase Shift Keying (QPSK) modulation, 16 Quadrature Amplitude Modulation (QAM), and 16 Amplitude Phase Shift Keying (APSK) modulation.

6. The apparatus of claim 1, wherein a first modulation of the plurality of modulations includes a 16 Quadrature Amplitude Modulation (QAM);

and

a second modulation of the plurality of modulations includes a 16 Amplitude Phase Shift Keying (APSK) modulation.

7. The apparatus of claim 1, wherein one modulation of the plurality of modulations includes a Quadrature Phase Shift Keying (QPSK) modulation having constellation points that are titled with respect to axes of an I,Q (in-phase and quadrature) plane.

8. The apparatus of claim 1, wherein a first modulation of the plurality of modulations includes a Quadrature Phase Shift Keying (QPSK) modulation having constellation points located further from an origin of the I,Q (in-phase and quadrature) plane than constellation points of a second modulation of the plurality of modulations that also includes a Quadrature Phase Shift Keying (QPSK) modulation.

9. The apparatus of claim 1, wherein the encoder is a systematic encoder.

10. The apparatus of claim 1, wherein the encoder is a non-systematic encoder.

11. The apparatus of claim 1, wherein the plurality of encoded symbols are transmitted from the encoder to the decoder via an Additive White Gaussian Noise (AWGN) communication channel.

12. The apparatus of claim 1, wherein the encoder is contained within a satellite transmitter;

and

the decoder is contained within a satellite receiver.

13. The apparatus of claim 1, wherein the apparatus is contained within at least one of a satellite communication system, a high definition television (HDTV) communication system, a cellular communication system, a cellular communication system, a microwave communication system, a point-to-point radio communication system, a uni-directional TTCM communication system, a bi-directional TTCM communication system, and a one to many TTCM communication system.

14. An apparatus, comprising:

a rate control sequencer that provides a rate control sequence that includes a plurality of modulations, each modulation within the plurality of modulations includes a constellation and a mapping, each modulation of the plurality of modulations includes a bandwidth efficiency, the rate control sequence includes a plurality of rate controls arranged in a period; and

an encoder that encodes a plurality of input bits according to the plurality of rate controls of the rate control sequence thereby generating a plurality of encoded symbols, the plurality of encoded symbols having an average bandwidth efficiency.

15. The apparatus of claim 14, further comprising a decoder that decodes the plurality of encoded symbols according to the plurality of rate controls of the rate control sequence.

16. The apparatus of claim 15, wherein the plurality of encoded symbols are transmitted from the encoder to the decoder via an Additive White Gaussian Noise (AWGN) communication channel.

17. The apparatus of claim 15, wherein the encoder is contained within a satellite transmitter;

and

the decoder is contained within a satellite receiver.

18. The apparatus of claim 15, wherein one input bit of the plurality of input bits is provided to the decoder as an uncoded bit.

19. The apparatus of claim 14, wherein one modulation of the plurality of modulations includes at least one of 8 Phase Shift Keying (PSK) modulation, Quadrature Phase Shift Keying (QPSK) modulation, 16 Quadrature Amplitude Modulation (QAM), and 16 Amplitude Phase Shift Keying (APSK) modulation.

20. The apparatus of claim 14, wherein the encoder encodes the plurality of input bits thereby generating a plurality of encoded input bits;

and

the encoder further includes a puncturing functional block that punctures at least one encoded input bit of the plurality of encoded input bits according to one of the rate controls of the plurality of rate controls of the rate control sequence to generate at least one encoded symbol of the plurality of encoded symbols.

21. The apparatus of claim 14, wherein the plurality of input bits are provided serially to the encoder.

22. The apparatus of claim 14, wherein a first modulation of the plurality of modulations includes a 16 Quadrature Amplitude Modulation (QAM);

and

a second modulation of the plurality of modulations includes a 16 Amplitude Phase Shift Keying (APSK) modulation.

23. The apparatus of claim 14, wherein one modulation of the plurality of modulations includes a Quadrature Phase Shift Keying (QPSK) modulation having constellation points that are titled with respect to axes of an I,Q (in-phase and quadrature) plane.

24. The apparatus of claim 14, wherein a first modulation of the plurality of modulations includes a Quadrature Phase Shift Keying (QPSK) modulation having constellation points located further from an origin of the I,Q (in-phase and quadrature) plane than constellation points of a second modulation of the plurality of modulations that also includes a Quadrature Phase Shift Keying (QPSK) modulation.

25. The apparatus of claim 14, wherein the encoder is a systematic encoder.

26. The apparatus of claim 14, wherein the encoder is a non-systematic encoder.

27. An apparatus, comprising:

a rate control sequencer that provides a rate control sequence that includes a plurality of modulations, each modulation within the plurality of modulations includes a constellation and a mapping, each modulation of the plurality of modulations includes a bandwidth efficiency, the rate control sequence includes a plurality of rate controls arranged in a period; and

a decoder that decodes a plurality of encoded symbols according to the plurality of rate controls of the rate control sequence; and

wherein the plurality of encoded symbols having an average bandwidth efficiency.

28. The apparatus of claim 27, further comprising an encoder that encodes a plurality of input bits according to the plurality of rate controls of the rate control sequence thereby generating the plurality of encoded symbols.

29. The apparatus of claim 28, wherein the plurality of encoded symbols are transmitted from the encoder to the decoder via an Additive White Gaussian Noise (AWGN) communication channel.

30. The apparatus of claim 28, wherein the encoder encodes the plurality of input bits thereby generating a plurality of encoded input bits;

and

the encoder further includes a puncturing functional block that punctures at least one encoded input bit of the plurality of encoded input bits according to one of the rate controls of the plurality of rate controls of the rate control sequence to generate at least one encoded symbol of the plurality of encoded symbols.

31. The apparatus of claim 27, wherein a first modulation of the plurality of modulations includes a 16 Quadrature Amplitude Modulation (QAM);

and

a second modulation of the plurality of modulations includes a 16 Amplitude Phase Shift Keying (APSK) modulation.

32. The apparatus of claim 27, wherein one modulation of the plurality of modulations includes a Quadrature Phase Shift Keying (QPSK) modulation having constellation points that are titled with respect to axes of an I,Q (in-phase and quadrature) plane.

33. The apparatus of claim 27, wherein a first modulation of the plurality of modulations includes a Quadrature Phase Shift Keying (QPSK) modulation having constellation points located further from an origin of the I,Q (in-phase and quadrature) plane than constellation points of a second modulation of the plurality of modulations that also includes a Quadrature Phase Shift Keying (QPSK) modulation.

34. A method, comprising:

encoding a plurality of input bits according to a plurality of rate controls of a rate control sequence thereby generating a plurality of encoded symbols, the plurality of encoded symbols having an average bandwidth efficiency; and

decoding the plurality of encoded symbols according to the plurality of rate controls of the rate control sequence; and

wherein each modulation of the plurality of modulations includes a bandwidth efficiency, each modulation within the plurality of modulations includes a constellation and a mapping, the rate control sequence includes a plurality of rate controls arranged in a period.

35. The method of claim 34, wherein a rate control sequencer provides the rate control sequence that includes the plurality of modulations.

36. The method of claim 34, further comprising transmitting the plurality of encoded symbols across an Additive White Gaussian Noise (AWGN) communication channel.

37. The method of claim 34, further comprising transmitting one input bit of the plurality of input bits across an Additive White Gaussian Noise (AWGN) communication channel as an uncoded bit.

38. The method of claim 34, further comprising;

encoding the plurality of input bits thereby generating a plurality of encoded input bits; and

puncturing at least one encoded input bit of the plurality of encoded input bits according to one of the rate controls of the plurality of rate controls of the rate control sequence to generate at least one encoded symbol of the plurality of encoded symbols.

39. The method of claim 34, wherein one modulation of the plurality of modulations includes at least one of 8 Phase Shift Keying (PSK) modulation, Quadrature Phase Shift Keying (QPSK) modulation, 16 Quadrature Amplitude Modulation (QAM), and 16 Amplitude Phase Shift Keying (APSK) modulation.

40. The method of claim 34, wherein a first modulation of the plurality of modulations includes a 16 Quadrature Amplitude Modulation (QAM);

and

a second modulation of the plurality of modulations includes a 16 Amplitude Phase Shift Keying (APSK) modulation.

41. The method of claim 34, wherein one modulation of the plurality of modulations includes a Quadrature Phase Shift Keying (QPSK) modulation having constellation points that are titled with respect to axes of an I,Q (in-phase and quadrature) plane.

42. The method of claim 34, wherein a first modulation of the plurality of modulations includes a Quadrature Phase Shift Keying (QPSK) modulation having constellation points located further from an origin of the I,Q (in-phase and quadrature) plane than constellation points of a second modulation of the plurality of modulations that also includes a Quadrature Phase Shift Keying (QPSK) modulation.

43. The method of claim 34, wherein the encoding of the plurality of input bits is performed using a systematic encoder.

44. The method of claim 34, wherein the encoding of the plurality of input bits is performed using a non-systematic encoder.

45. The method of claim 34, wherein the encoding of the plurality of input bits is performed using an encoder that is contained within a satellite transmitter;

and

the decoding of the plurality of encoded symbols is performed using a decoder that is contained within a satellite receiver.

46. The method of claim 45, wherein the encoder is contained within at least one of a satellite transmitter, a high definition television (HDTV) transmitter, a mobile transmitter, a base station transmitter, a transmitter, and a transceiver.

47. The method of claim 45, wherein the decoder is contained within at least one of a satellite receiver, a high definition television (HDTV) set top box receiver, a mobile receiver, a base station receiver, a receiver, and a transceiver.

48. The method of claim 34, wherein the method is performed within at least one of a satellite communication system, a high definition television (HDTV) communication system, a cellular communication system, a cellular communication system, a microwave communication system, a point-to-point radio communication system, a uni-directional TTCM communication system, a bi-directional TTCM communication system, and a one to many TTCM communication system.