Multi-dimensional space Gray code maps for multi-dimensional phase modulation as applied to LDPC (Low Density Parity Check) coded modulation

• US 7,436,902 B2
• Filed: 06/12/2004
• Issued: 10/14/2008
• Est. Priority Date: 06/13/2003
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Shen, Ba-Zhong, Lee, Tak K., Tran, Hau Thien, Cameron, Kelly Brian
• Primary Examiner(s): Payne; David C.
• Assistant Examiner(s): Wong; Linda
• Application Number:
  US10/866,542
• Publication Number:
  US 20040258177A1
• Time in Patent Office: 1,585 Days
• Field of Search: 375/259, 375/260, 375/265, 375/268, 375/262, 375/264, 375/341, 375/333, 375/301, 375/302, 375/308, 375/320, 375/322, 375/323, 375/329, 375/330, 375279-280, 375/271, 375/273, 332/103, 332/108, 332/112, 332/115, 332/119, 332/120, 332/144, 332/145, 332/149, 332/161
• US Class Current: 375/308
• CPC Class Codes: H03M 13/1117 using approximations for check node processing, e.g. an outgoing message is depending on the signs and the minimum over the magnitudes of all incoming messages according to the min-sum rule
• CPC Class Codes: H03M 13/112 with correction functions for the min-sum rule, e.g. using an offset or a scaling factor
• CPC Class Codes: H03M 13/255 with Low Density Parity Check [LDPC] codes
• 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 1/0058 Block-coded modulation
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 25/03184 Details concerning the metric
• CPC Class Codes: H04L 25/03318 Provision of soft decisions
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178
• CPC Class Codes: H04L 27/183 Multiresolution systems
• CPC Class Codes: H04L 27/186 in which the information is carried by both the individual signal points and the subset to which the individual signal points belong, e.g. coset coding or related schemes
• CPC Class Codes: H04L 27/2053 using more than one carrier, e.g. carriers with different phases
• CPC Class Codes: H04L 27/2604 Multiresolution systems by means of multiresolution subcarriers H04L27/183, H04L27/3488

Abstract

Multi-dimensional space Gray code maps for multi-dimensional phase modulation as applied to LDPC (Low Density Parity Check) coded modulation. A novel approach is provided within LDPC coded modulation communication systems that employ multi-dimensional phase modulation, using m-D (multi-dimensional) Gray code maps, to provide for improved performance when compared to communication systems employing 1-D (single-dimensional) Gray code maps. This approach can generate all possible m-D Gray code maps for a 2m-D M PSK modulation system. For example, all of the 2-D Gray code maps may be generated for a communication system using 4-D 8 PSK modulation system (where m=2, and M=8). A variety decoding processing approaches may be employed to perform LDPC coded modulation decoding of multi-dimensional space Gray code mapped signals. The slightly increased decoding complexity (when compared to decoding 1-D Gray code mapped signals) is the computation of symbol metrics and their decomposition to bit metrics.

Claims

1. An encoder that is operable to generate a multi-dimensional space Gray code mapped LDPC (Low Density Parity Check) coded modulation signal, the encoder comprising:

an LDPC encoder that is operable to encode a plurality of information bits thereby generating an LDPC codeword that includes a plurality of LDPC coded bits;

wherein the plurality of LDPC coded bits is arranged into a plurality of symbols such that each symbol has a predetermined plurality (n) of bits, wherein n is an integer;

a multi-dimensional space Gray code mapper that is operable to map each symbol of the plurality of symbols to a 2m-D (2m-dimensional) M PSK (Phase Shift Key) modulation using an m-D (m-dimensional) cycle Gray code map thereby generating a sequence of discrete-valued modulation symbols that comprise a digital format of the multi-dimensional space Gray code mapped LDPC coded modulation signal, wherein m and M are integers; and

wherein;

the m-D cycle Gray code map is a one to one and onto map that maps a first matrix, that includes each symbol of the plurality of symbols, to a second matrix that includes a plurality of 2m-D M PSK Gray code mapped symbols;

the sequence of discrete-valued modulation symbols is composed of elements of the second matrix that are output from the multi-dimensional space Gray code mapper according to a predetermined order; and

each symbol of the sequence of discrete-valued modulation symbols includes at least two pairs of I, Q (In-phase, Quadrature) values that are output from the multi-dimensional space Gray code mapper sequentially as a function of time.

2. The encoder of claim 1, further comprising:

an interleaver, interposed between the LDPC encoder and the multi-dimensional space Gray code mapper, that interleaves the plurality of LDPC coded bits of the LDPC codeword thereby generating the plurality of symbols.

3. The encoder of claim 1, wherein:

the 2m-D M PSK modulation includes a first 1-D (1-dimensional) M PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping; and

the 2m-D M PSK modulation includes a second 1-D M PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping.

4. The encoder of claim 1, wherein:

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits;

m is equal to 2 and M is equal to 8 such that the multi-dimensional space Gray code mapper that maps each 6 bit symbol of the plurality of symbols to a 4-D 8 PSK modulation using a 2-D (2-dimensional) Gray code map;

the 4-D 8 PSK modulation includes a first 1-D (1-dimensional) 8 PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping;

the 4-D 8 PSK modulation includes a second 1-D 8 PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping; and

each symbol of the discrete-valued modulation symbols includes two pairs of I, Q values.

5. The encoder of claim 1, wherein:

the LDPC encoder employs a rate 5/6 LDPC code;

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits; and

each symbol within the plurality of symbols includes a redundancy bit.

6. The encoder of claim 1, wherein:

the multi-dimensional space Gray code mapper is operable to generate an LDPC codeword matrix whose elements include each n bit symbol of the plurality of symbols; and

the LDPC codeword matrix is the first matrix.

7. The encoder of claim 1, wherein:

the encoder is implemented within a communication device; and

the communication device is implemented within at least one of a satellite communication system, an HDTV (High Definition Television) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, a fiber-optic communication system, a WLAN (Wireless Local Area Network) communication system, and a DSL (Digital Subscriber Line) communication system.

8. An encoder that is operable to generate a multi-dimensional space Gray code mapped LDPC (Low Density Parity Check) coded modulation signal, the encoder comprising:

an LDPC encoder that is operable to encode a plurality of information bits thereby generating an LDPC codeword that includes a plurality of LDPC coded bits;

an interleaver that is operable to interleave the plurality of LDPC coded bits of the LDPC codeword thereby generating a plurality of symbols such that each symbol has a predetermined plurality (n) of bits, wherein n is an integer;

a multi-dimensional space Gray code mapper that is operable to map each symbol of the plurality of symbols to a 2m-D (2m-dimensional) M PSK (Phase Shift Key) modulation using an m-D (m-dimensional) cycle Gray code map thereby generating a sequence of discrete-valued modulation symbols that comprise a digital format of the multi-dimensional space Gray code mapped LDPC coded modulation signal, wherein m and M are integers; and

wherein;

the m-D cycle Gray code map is a one to one and onto map that maps a first matrix, that includes each symbol of the plurality of symbols, to a second matrix that includes a plurality of 2m-D M PSK Gray code mapped symbols;

the sequence of discrete-valued modulation symbols is composed of elements of the second matrix that are output from the multi-dimensional space Gray code mapper according to a predetermined order;

each symbol of the sequence of discrete-valued modulation symbols includes at least two pairs of I, Q (In-phase, Quadrature) values that are output from the multi-dimensional space Gray code mapper sequentially as a function of time;

the 2m-D M PSK modulation includes a first 1-D (1-dimensional) M PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping; and

the 2m-D M PSK modulation includes a second 1-D M PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping.

9. The encoder of claim 8, wherein:

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits;

m is equal to 2 and M is equal to 8 such that the multi-dimensional space Gray code mapper that maps each 6 bit symbol of the plurality of symbols to a 4-D 8 PSK modulation using a 2-D (2-dimensional) Gray code map;

the 4-D 8 PSK modulation includes a first 1-D (1-dimensional) 8 PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping;

the 4-D 8 PSK modulation includes a second 1-D 8 PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping; and

each symbol of the discrete-valued modulation symbols includes two pairs of I, Q values.

10. The encoder of claim 8, wherein:

the LDPC encoder employs a rate 5/6 LDPC code;

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits; and

each symbol within the plurality of symbols includes a redundancy bit.

11. The encoder of claim 8, wherein:

the multi-dimensional space Gray code mapper is operable to generate an LDPC codeword matrix whose elements include each n bit symbol of the plurality of symbols; and

the LDPC codeword matrix is the first matrix.

12. The encoder of claim 8, wherein:

the encoder is implemented within a communication device; and

the communication device is implemented within at least one of a satellite communication system, an HDTV (High Definition Television) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, a fiber-optic communication system, a WLAN (Wireless Local Area Network) communication system, and a DSL (Digital Subscriber Line) communication system.

13. A communication device that is operable to generate a multi-dimensional space Gray code mapped LDPC (Low Density Parity Check) coded modulation signal, the communication device comprising:

an LDPC encoder that is operable to encode a plurality of information bits thereby generating an LDPC codeword that includes a plurality of LDPC coded bits;

an interleaver that interleaves the plurality of LDPC coded bits of the LDPC codeword thereby generating a plurality of symbols such that each symbol has a predetermined plurality (n) of bits, wherein n is an integer;

a multi-dimensional space Gray code mapper that is operable to map each symbol of the plurality of symbols to a 2m-D (2m-dimensional) M PSK (Phase Shift Key) modulation using an m-D (m-dimensional) cycle Gray code map thereby generating a sequence of discrete-valued modulation symbols that comprise a digital format of the multi-dimensional space Gray code mapped LDPC coded modulation signal, wherein m and M are integers;

wherein the m-D cycle Gray code map is a one to one and onto map that maps a first matrix, that includes each symbol of the plurality of symbols, to a second matrix that includes a plurality of 2m-D M PSK Gray code mapped symbols;

wherein the sequence of discrete-valued modulation symbols is composed of elements of the second matrix that are output from the multi-dimensional space Gray code mapper according to a predetermined order;

wherein each symbol of the sequence of discrete-valued modulation symbols includes at least two pairs of I, Q (In-phase, Quadrature) values that are output from the multi-dimensional space Gray code mapper sequentially as a function of time;

a DAC (Digital to Analog Converter) that is operable to generate a continuous-time baseband signal using each pair of I, Q values of the at least two pairs of I, Q values corresponding to each symbol of the sequence of discrete-valued modulation symbols; and

a channel modulator that is operable to transform the continuous-time baseband signal to a continuous-time transmit signal and to launch the continuous-time transmit signal into a communication channel to which the communication device is communicatively coupled.

14. The communication device of claim 13, wherein:

channel modulator is operable to perform any one of amplification, filtering, and frequency conversion to the continuous-time baseband signal thereby ensuring that the continuous-time transmit signal comports to the communication channel into which the continuous-time transmit signal is launched.

15. The communication device of claim 13, wherein:

the 2m-D M PSK modulation includes a first 1-D (1-dimensional) M PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping; and

the 2m-D M PSK modulation includes a second 1-D M PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping.

16. The communication device of claim 13, wherein:

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits;

m is equal to 2 and M is equal to 8 such that the multi-dimensional space Gray code mapper that maps each 6 bit symbol of the plurality of symbols to a 4-D 8 PSK modulation using a 2-D (2-dimensional) Gray code map;

the 4-D 8 PSK modulation includes a first 1-D (1-dimensional) 8 PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping;

the 4-D 8 PSK modulation includes a second 1-D 8 PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping; and

each symbol of the discrete-valued modulation symbols includes two pairs of I, Q values.

17. The communication device of claim 13, wherein:

the LDPC encoder employs a rate 5/6 LDPC code;

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits; and

each symbol within the plurality of symbols includes a redundancy bit.

18. The communication device of claim 13, wherein:

the multi-dimensional space Gray code mapper is operable to generate an LDPC codeword matrix whose elements include each n bit symbol of the plurality of symbols; and

the LDPC codeword matrix is the first matrix.

19. The communication device of claim 13, wherein:

the communication device is implemented within at least one of a satellite communication system, an HDTV (High Definition Television) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, a fiber-optic communication system, a WLAN (Wireless Local Area Network) communication system, and a DSL (Digital Subscriber Line) communication system.

20. A method for generating a multi-dimensional space Gray code mapped LDPC (Low Density Parity Check) coded modulation signal, the method comprising:

encoding a plurality of information bits according to an LDPC code thereby generating an LDPC codeword that includes a plurality of LDPC coded bits;

arranging the plurality of LDPC coded bits into a plurality of symbols such that each symbol has a predetermined plurality (n) of bits, wherein n is an integer;

multi-dimensional space Gray code mapping each symbol of the plurality of symbols to a 2m-D (2m-dimensional) M PSK (Phase Shift Key) modulation using an m-D (m-dimensional) cycle Gray code map thereby generating a sequence of discrete-valued modulation symbols that comprise a digital format of the multi-dimensional space Gray code mapped LDPC coded modulation signal, wherein m and M are integers, wherein each symbol of the sequence of discrete-valued modulation symbols includes at least two pairs of I, Q (In-phase, Quadrature) values;

employing the m-D cycle Gray code map, that is a one to one and onto map, to map a first matrix, that includes each symbol of the plurality of symbols, to a second matrix that includes a plurality of 2m-D M PSK Gray code mapped symbols; and

outputting each pair of I, Q values of the at least two pairs of I, Q values corresponding to each symbol of the sequence of discrete-valued modulation symbols sequentially as a function of time, wherein the sequence of discrete-valued modulation symbols is composed of elements of the second matrix output there from according to a predetermined order.

21. The method of claim 20, further comprising:

interleaving the plurality of LDPC coded bits of the LDPC codeword thereby generating the plurality of symbols.

22. The method of claim 20, wherein:

the 2m-D M PSK modulation includes a first 1-D (1-dimensional) M PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping; and

the 2m-D M PSK modulation includes a second 1-D M PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping.

23. The method of claim 20, wherein:

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits;

m is equal to 2 and M is equal to 8 such that each 6 bit symbol of the plurality of symbols is multi-dimensional space Gray code mapped to a 4-D 8 PSK modulation using a 2-D (2-dimensional) Gray code map;

the 4-D 8 PSK modulation includes a first 1-D (1-dimensional) 8 PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping;

the 4-D 8 PSK modulation includes a second 1-D 8 PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping; and

each symbol of the discrete-valued modulation symbols includes two pairs of I, Q values.

24. The method of claim 20, wherein:

the LDPC code is a rate 5/6 LDPC code;

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits; and

each symbol within the plurality of symbols includes a redundancy bit.

25. The method of claim 20, further comprising:

generating an LDPC codeword matrix whose elements include each n bit symbol of the plurality of symbols; and

wherein;

the LDPC codeword matrix is the first matrix.

26. The method of claim 20, wherein:

the method is performed within an encoder;

the encoder is implemented within a communication device; and

the communication device is implemented within at least one of a satellite communication system, an HDTV (High Definition Television) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, a fiber-optic communication system, a WLAN (Wireless Local Area Network) communication system, and a DSL (Digital Subscriber Line) communication system.

27. A method for transmit processing a multi-dimensional space Gray code mapped LDPC (Low Density Parity Check) coded modulation signal, the method comprising

encoding a plurality of information bits according to an LDPC code thereby generating an LDPC codeword that includes a plurality of LDPC coded bits;

interleaving the plurality of LDPC coded bits of the LDPC codeword thereby generating a plurality of symbols such that each symbol has a predetermined plurality (n) of bits, wherein n is an integer;

multi-dimensional space Gray code mapping each symbol of the plurality of symbols to a 2m-D (2m-dimensional) M PSK (Phase Shift Key) modulation using an m-D (m-dimensional) cycle Gray code map thereby generating a sequence of discrete-valued modulation symbols that comprise a digital format of the multi-dimensional space Gray code mapped LDPC coded modulation signal, wherein m and M are integers, wherein each symbol of the sequence of discrete-valued modulation symbols includes at least two pairs of I, Q (In-phase, Quadrature) values;

employing the m-D cycle Gray code map, that is a one to one and onto map, to map a first matrix, that includes each symbol of the plurality of symbols, to a second matrix that includes a plurality of 2m-D M PSK Gray code mapped symbols;

outputting each pair of I, Q values of the at least two pairs of I, Q values corresponding to each symbol of the sequence of discrete-valued modulation symbols sequentially as a function of time, wherein the sequence of discrete-valued modulation symbols is composed of elements of the second matrix output there from according to a predetermined order;

generating a continuous-time baseband signal using each pair of I, Q values of the at least two pairs of I, Q values corresponding to each symbol of the sequence of discrete-valued modulation symbols

channel modulating the continuous-time baseband signal thereby generating a continuous-time transmit signal; and

launching the continuous-time transmit signal into a communication channel.

28. The method of claim 27, wherein:

the channel modulating of the continuous-time baseband signal involves performing any one of amplification, filtering, and frequency conversion to the continuous-time baseband signal thereby ensuring that the continuous-time transmit signal comports to the communication channel into which the continuous-time transmit signal is launched.

29. The method of claim 27, wherein:

the 2m-D M PSK modulation includes a first 1-D (1-dimensional) M PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping; and

the 2m-D M PSK modulation includes a second 1-D M PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping.

30. The method of claim 27, wherein:

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits;

m is equal to 2 and M is equal to 8 such that each 6 bit symbol of the plurality of symbols is multi-dimensional space Gray code mapped to a 4-D 8 PSK modulation using a 2-D (2-dimensional) Gray code map;

the 4-D 8 PSK modulation includes a first 1-D (1-dimensional) 8 PSK shaped constellation whose constellation points are mapped according to a first 1-D space Gray code mapping;

the 4-D 8 PSK modulation includes a second 1-D 8 PSK shaped constellation whose constellation points are mapped according to a second 1-D space Gray code mapping; and

each symbol of the discrete-valued modulation symbols includes two pairs of I, Q values.

31. The method of claim 27, wherein:

the LDPC code is a rate 5/6 LDPC code;

n is equal to 6 such that each symbol of the plurality of symbols includes 6 bits; and

each symbol within the plurality of symbols includes a redundancy bit.

32. The method of claim 27, further comprising:

generating an LDPC codeword matrix whose elements include each n bit symbol of the plurality of symbols; and

wherein;

the LDPC codeword matrix is the first matrix.

33. The method of claim 27, wherein:

the method is performed within a communication device; and

the communication device is implemented within at least one of a satellite communication system, an HDTV (High Definition Television) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, a fiber-optic communication system, a WLAN (Wireless Local Area Network) communication system, and a DSL (Digital Subscriber Line) communication system.