Constellation re-arrangement and bit grouping
View Patent ↗Methods and systems for subpacket generation using a convolutional turbo code in hybrid automatic repeat request re-transmissions that includes separating a codeword into subblocks of bits, interleaving the subblocks, and performing a permutation to group the bit streams and rearrange a symbol constellation such that bits are assigned to bit positions based on a number of re-transmissions.
1. A method for subpacket generation comprising:
separating a codeword into subblocks of bits to produce at least one data subblock and at least one parity subblock;
interleaving the subblocks into bit streams;
grouping the bit streams by multiplexing sequences of similar type; and
performing a permutation to group the bit streams and rearrange a symbol constellation such that bits are assigned, using a processor, to bit positions based on a number of re-transmissions;
wherein the permutation and grouping steps for data bit streams are performed by the following functions:
A i z ( j )=(( j+z )mod c/ 2+[2 j/C ]* c/ 2+( i mod C ))mod C,j= 0 , . . . ,C− 1 ,i= 0, . . . ,[ N/C ]−1
B i z ( j )=(( j+z )mod c/ 2+[2 j/C ]* c/ 2+(( i+ 1+δ)mod C ))mod C,j= 0 , . . . ,C− 1 ,i= 0, . . . ,[ N/C ]−1
where z represents the re-arrangement version number, i represents a bit position within a symbol, C is the modulation order, N is the length of an input sequence for A or B, and δ is set to 1 for 64-QAM and to 0 for other modulation schemes.
2. The method of claim 1 , wherein the step of performing a permutation includes cyclically bit-shifting each group to the right by one bit.
3. The method of claim 1 , wherein the permutation and grouping steps for parity bit streams are performed by the following functions:
Y 1 /Y 2 i z ( j )=(( j+z )mod C/ 2+[2 j/C ] *C/ 2+(( i+ 1)mod C ))mod C,j= 0 , . . . ,C− 1 ,i= 0, . . . ,[2 N/C ]−1
W 2 /W 1 i z ( j )=(( j+z )mod C/ 2+[2 j/C ]* C/ 2+(( i+ 1)mod C ))mod C,j= 0 , . . . ,C− 1 ,i= 0, . . . ,[2 N/C ]−1
where z represents the re-arrangement version number, j represents a bit position within a symbol, C is the modulation order, and N is the length of an input sequence for A or B.
4. The method of claim 1 , wherein the symbol constellation is based on 64 quadrature amplitude modulation and individual bit groups are assigned to respective I and Q portions of a resulting symbol.
5. The method of claim 1 , wherein the codeword is formed according to a code of rate ⅓ that includes two parity subblocks for each data subblock.
6. The method of claim 5 , wherein the step of separating includes separating the codeword into one data subblock and two parity subblocks.
7. The method of claim 1 , wherein the permuting step is performed for hybrid automatic repeat request re-transmissions using alternating permutation schemes.