Methods and systems for encoding and decoding for LDPC codes
地域：
Shenzhen, Guangdong
摘要
Methods and devices are disclosed for encoding source words and decoding codewords with LDPC matrices. The Methods and devices use a LDPC matrix Hn of lifting factor Z. The LDPC matrix Hn comprises a plurality of submatrices, each submatrix having a size of Z×Z, and at least one submatrix has m1 diagonals of “1” m1 is an integer>=2.
說(shuō)明書
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The present application is a continuation of, and claims the benefit of and priority to, International Application No. PCT/CN2016/090775 entitled “METHODS AND SYSTEMS FOR ENCODING AND DECODING FOR LDPC CODES” filed Jul. 20, 2016, the contents of which are incorporated herein by reference.
The present application relates to mobile air interface technologies, in particular to methods and systems for encoding and decoding for binary low density parity check (LDPC) codes.
An LDPC encoder at a transmitter is used for encoding source words to generate codewords. An LDPC decoder at a receiver is used for decoding the received codewords. LDPC codes of various rates have been adopted in the IEEE 802.11ad standard.
Several rate 7/8 LDPC codes have been proposed in IEEE 802.11REVmc. However, the proposed LDPC codes either have not been optimized in terms of error rate performance or have a different codeword length from that of the LDPC codes in the IEEE 802.11ad standard. The differences in codeword length may impact the implementation of the blocking and de-blocking processes at the transmitter and at the receiver respectively.
權(quán)利要求
The invention claimed is:1. A method, performed at a transmitter, for encoding a source word, comprising:receiving a 1×K source word row vector ū; and generating a 1×N codeword vector c =ū·G, whereinG is a K×N generator matrix, and wherein G is derived from a parity check matrix Hn, the parity check matrix Hn having a lifting factor Z, wherein Z is an integer greater than 0, and wherein the parity check matrix Hn comprises a plurality of submatrices, each submatrix having a size Z×Z, and wherein at least one submatrix has m1 cyclically shifted diagonals of “1”, and wherein m1 is an integer>=2; and wirelessly transmitting a signal including the generated codeword vector; wherein the parity check matrix Ha is generated bypartitioning a first M×N parity check matrix H, with the lifting factor of Z, wherein M=I×Z, N=J×Z, and wherein I and J are integers, I>2 and J>0, into square submatrices having a size of Z×Z, wherein the first M×N parity check matrix H contains (M/Z) rows×(N/Z) columns of the submatrices; selecting m1 rows from the M/Z rows of the submatrices of the first M×N parity check matrix H; and adding the m1 rows of the submatrices of the first M×N parity check matrix H as a row of submatrices of the parity check matrix Hn, and m1 is a integer>=2. 2. The method of claim 1 , wherein the parity check matrix Hn=[P(n?k)×kI(n?k)], where P(n?k)×k is a binary matrix and I(n?k) is an identity matrix of order n?k; and wherein the generator matrix G is derived from the parity check matrix Hn such that GHnT=0, where “T” denotes a matrix transpose. 3. The method of claim 1 , further comprising adding m2 rows from the remaining rows of the submatrices of the first M×N parity check matrix H as a second new row of submatrices of the parity check matrix Hn, and m2 is an integer>=1. 4. The method of claim 3 , wherein N=672, Z=42, K=588, and the parity check matrix Hn comprises 84 rows×672 columns. 5. The method of claim 1 , further comprising:adding m2 rows from remaining (M/Z?m1) rows of the submatrices of the first M×N parity check matrix H as a second submatrix row of the parity check matrix Hn; adding m3 rows from remaining (M/Z?m1?m2) rows of the submatrices of the first M×N parity check matrix H as a third submatrix row of the parity check matrix Hn; and adding m4 rows from remaining (M/Z?m1?m2?m3) rows of the submatrices of the first M×N parity check matrix H as a fourth submatrix row of the parity check matrix Hn, wherein N=1344, Z=42, m1, m2, m3, and m4 are integers, m1+m2+m3+m4=<M/Z, m1>1 m2>=1, m3>=1, and m4>=1. 6. The method of claim 1 , wherein the first M×N parity check matrix H is a code rate 3/4 Low LDPC matrix specified in 802.11ad, wherein the first M×N parity check matrix H=168 rows×672 columns, and Z=42, and wherein the parity check matrix Hn is generated with parameters m1=2 and m2=2, Z=42. 7. The method of claim 6 , wherein the parity check matrix Hn is
8. A method, performed at a receiver, for decoding a codeword, comprising:wirelessly receiving a signal having a 1×N row vector S; and decoding the 1×N row vector S with a parity check matrix Hn that is used in an encoding process; and generating a 1×N vector c =[c1, . . . , cn] such that Hnc T=0 to recover a 1×K source word row vector ū, where “T” denotes a matrix transpose and whereinthe parity check matrix Hn comprises a plurality of submatrices, the parity check matrix Hn having a lifting factor Z, each submatrix having a size of Z×Z, wherein Z is an integer greater than 0, and wherein at least one submatrix has m1 cyclically shifted diagonals of “1”, and wherein m1 is an integer>=2; and wherein the parity check matrix Hn is generated bypartitioning a first M×N parity check matrix H, with the lifting factor of Z, wherein M=I×Z, N=J×Z, and wherein I and J are integers, I>2 and J>0, into square submatrices of a size Z×Z, wherein the first M×N parity check matrix H contains (M/Z) rows×(N/Z) columns of the submatrices; selecting m1 rows from the M/Z rows of the submatrices of the first M×N parity check matrix H; and adding the m1 rows of the submatrices of the first M×N parity check matrix H as a row of submatrices of the parity check matrix Hn, and m1 is a integer>=2. 9. The method of claim 8 , further comprising adding m2 rows from the remaining rows of the submatrices of the first M×N parity check matrix H as a second new row of submatrices of the parity check matrix Hn, and m2 is an integer>=1. 10. The method of claim 8 , wherein N=672, Z=42, K=588, and the parity check matrix Hn comprises 84 rows×672 columns. 11. The method of claim 8 , further comprising:adding m2 rows from remaining (M/Z?m1) rows of the submatrices of the first M×N parity check matrix H as a second submatrix row of the parity check matrix Hn; adding m3 rows from remaining (M/Z?m1?m2) rows of the submatrices of the first M×N parity check matrix H as a third submatrix row of the parity check matrix Hn; adding m4 rows from remaining (M/Z?m1?m2?m3) rows of the submatrices of the first M×N parity check matrix H as a fourth submatrix row of the parity check matrix Hn; wherein N=1344, Z=42, m1, m2, m3, and m4 are integers, m1+m2+m3+m4=<M/Z, m1>1 m2>=1, m3>=1, and m4>=1. 12. The method of claim 8 , wherein the first M×N parity check matrix H is a code rate 3/4 Low LDPC matrix specified in 802.11ad, wherein the first M×N parity check matrix H=168 rows×672 columns, and Z=42, and wherein the parity check matrix Hn is generated with parameters m1=2 and m2=2, Z=42. 13. The method of claim 12 , wherein the parity check matrix Hn is
14. A system, comprising:a processor, the processor configured to cause the system to: receive, at a codeword generator, a 1×K source word row vector ū; and generate, at the codeword generator, a 1×N codeword vector c =ū·G, whereinG is a K×N generator matrix, and wherein G is derived from a parity check matrix Hn, wherein the parity check matrix Hn has a lifting factor Z, wherein Z is an integer greater than 0, the parity check matrix Hn comprises a plurality of submatrices, each submatrix having a size Z×Z, and wherein at least one submatrix has m1 cyclically shifted diagonals of “1”, and wherein m1 is an integer>=2; and wirelessly transmit a signal including the generated codeword vector; wherein the parity check matrix Hn is generated bypartitioning a first M×N parity check matrix H, with the lifting factor of Z, wherein M=I×Z, N=J×Z, and wherein I and J are integers, I>2 and J>0, into square submatrices of a size Z×Z, wherein the first M×N parity check matrix H contains (M/Z) rows×(N/Z) columns of the submatrices; selecting m1 rows from the M/Z rows of the submatrices of the first M×N parity check matrix H; and adding the m1 rows of the submatrices of the first M×N parity check matrix H as a row of submatrices of the parity check matrix Hn, and m1 is a integer>=2. 15. The system of claim 14 , wherein the parity check matrix Hn=[P(n?k)×kI(n?k)], where P(n?k)×k is a binary matrix and I(n?k) is an identity matrix of order n?k; and wherein the generator matrix G is derived from the parity check matrix Hn such that GHnT=0, where “T” denotes a matrix transpose. 16. The system of claim 14 , wherein the system is a station, an access point, or a wireless transceiver unit. 17. A system, comprising:a receiver configured to wirelessly receive a signal, the signal having a 1×N row vector S; a processor, the processor configured to cause the system to: decode the row vector S with a parity check matrix Hn that is used in an encoding process; and generate a 1×N vector c =[c1, . . . , cn] such that Hnc T=0, where “T” denotes a matrix transpose,and wherein the parity check matrix Hn comprises a plurality of submatrices, the parity check matrix Hn having a lifting factor Z, each submatrix having a size of Z×Z, wherein Z is an integer greater than 0, and wherein at least one submatrix has m1 cyclically shifted diagonals of “1”, and wherein m1 is an integer>=2; wherein the parity check matrix Hn is generated bypartitioning a first M×N parity check matrix H, with the lifting factor of Z, wherein M=I×Z, N=J×Z, and wherein I and J are integers, I>2 and J>0, into square submatrices of a size Z×Z, wherein the first M×N parity check matrix H contains (M/Z) rows×(N/Z) columns of the submatrices; selecting m1 rows from the M/Z rows of the submatrices of the first M×N parity check matrix H; and adding the m1 rows of the submatrices of the first M×N parity check matrix H as a row of submatrices of the parity check matrix Hn, and m1 is a integer>=2. 18. The system of claim 17 , wherein the system is a station, an access point, or a wireless transceiver unit.
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