Method for mapping physical hybrid automatic repeat request indicator channel
View Patent ↗A method for mapping a physical hybrid automatic repeat request indicator channel (PHICH) is described. The method for mapping a PHICH includes determining an index of a resource element group transmitting a repetitive pattern of the PHICH, according to a ratio of the number of available resource element groups in a symbol in which the PHICH is transmitted and the number of available resource element groups in a first or second OFDM symbol, and mapping the PHICH to the symbol according to the determined index. In transmitting the PHICH, since efficient mapping is performed considering available resource elements varying with OFDM symbols, repetition of the PHICH does not generate interference between neighbor cell IDs and performance is improved.
1. A method of a base station including a processor and a transmitter for transmitting a signal comprising acknowledgement/negative acknowledgement (ACK/NACK) mapped in at least two orthogonal frequency division multiplexing (OFDM) symbols, the method comprising:
determining, at the processor, an index of a first resource element group (REG) in a first OFDM symbol based on a first ratio calculated using a number of available resource element groups (REGs) in the first OFDM symbol and a number of available REGs in a second OFDM symbol, the index of the first REG corresponding to a frequency domain location;
mapping, at the processor, the ACK/NACK to the first REG in the first OFDM symbol according to the determined index of the first REG; and
transmitting, at the transmitter, the signal comprising the mapped ACK/NACK,
wherein available REGs are REGs not assigned to Physical Control Format Indicator Channel (PCFICH).
2. The method of claim 1 , wherein an index of the first OFDM symbol corresponds to an OFDM symbol index l′=0, and an index of the second OFDM symbol corresponds to an OFDM symbol index l′=1.
3. The method of claim 2 , wherein the first ratio is calculated as the number of available REGs in the first OFDM symbol to the number of available REGs in the second OFDM symbol.
4. The method of claim 2 , further comprising:
mapping the ACK/NACK to a second REG in the second OFDM symbol and to a third REG in the second OFDM symbol.
5. The method of claim 4 , wherein an index ( n i ) of an i- th REG to which the ACK/NACK is mapped is determined using the following equation:
n
_
i
=
{
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
)
mod
n
l
i
′
′
,
i
=
0
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
+
⌊
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
1
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
+
⌊
2
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
2
where an index of the second REG in the second OFDM symbol corresponds to the index ( n 0 ) of the i- th REG when i=0, the index of the first REG in the first OFDM symbol corresponds to the index ( n 1 ) of the i- th REG when i=1, an index of the third REG in the second OFDM symbol corresponds to the index ( n 2 ) of the i- th REG when i=2, N ID cell denotes a cell ID, l′ i denotes an index of an OFDM symbol comprising the i- th REG when i=0, 1, or 2, n′ l′ i denotes a number of available REGs in an OFDM symbol having an index l′ i , n′ 1 denotes a number of available REGs in an OFDM symbol having an index l′=1, and m′ is determined based on an index of a physical hybrid automatic repeat request indicator channel (PHICH) group.
6. The method of claim 2 , further comprising:
mapping the ACK/NACK to a second REG in the first OFDM symbol and to a third REG in the second OFDM symbol.
7. The method of claim 6 , wherein an index ( n i ) of an i- th REG to which the ACK/NACK is mapped is determined using the following equation:
n
_
i
=
{
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
)
mod
n
l
i
′
′
,
i
=
0
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
+
⌊
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
1
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
+
⌊
2
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
2
where the index of the first REG in the first OFDM symbol corresponds to the index ( n 0 ) of the i- th REG when i=0, an index of the third REG in the second OFDM symbol corresponds to the index ( n 1 ) of the i- th REG when i=1, an index of the second REG in the first OFDM symbol corresponds to the index ( n 2 ) of the i- th REG when i=2, N ID cell denotes a cell ID, l′ i denotes an index of an OFDM symbol comprising the i- th REG when i=0, 1, or 2, n′ l′ i denotes a number of available REGs in an OFDM symbol having an index l′ i , n′ 1 denotes a number of available REGs in an OFDM symbol having an index l′=1, and m′ is determined based on an index of a physical hybrid automatic repeat request indicator channel (PHICH) group.
8. The method of claim 1 , wherein an index of the first OFDM symbol corresponds to an OFDM symbol index l′=1, and an index of the second OFDM symbol corresponds to an OFDM symbol index l′=0.
9. The method of claim 8 , further comprising:
mapping the ACK/NACK to a second REG in the second OFDM symbol;
determining an index of a third REG in a third OFDM symbol based on a second ratio calculated using the number of available REGs in the second OFDM symbol and a number of available REGs in the third OFDM symbol; and
mapping the ACK/NACK to the third REG in the third OFDM symbol according to the determined index of the third REG.
10. The method of claim 9 , wherein the first ratio is calculated as the number of available REGs in the first OFDM symbol to the number of available REGs in the second OFDM symbol, and
the second ratio is calculated as the number of available REGs in the third OFDM symbol to the number of available REGs in the second OFDM symbol.
11. The method of claim 9 , wherein an index ( n i ) of an i- th REG to which the ACK/NACK is mapped is determined using the following equation:
n
_
i
=
{
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
0
′
)
⌋
+
m
′
)
mod
n
l
i
′
′
,
i
=
0
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
0
′
)
⌋
+
m
′
+
⌊
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
1
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
0
′
)
⌋
+
m
′
+
⌊
2
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
2
where the index of the second REG in the second OFDM symbol corresponds to the index ( n 0 ) of the i- th REG when i=0, the index of the first REG in the first OFDM symbol corresponds to the index ( n 1 ) of the i- th REG when i=1, the index of the third REG in the third OFDM symbol corresponds to the index ( n 2 ) of the i- th REG when i=2, N ID cell denotes a cell ID, l′ i denotes an index of an OFDM symbol comprising the i- th REG when i=0, 1, or 2, n′ l′ i denotes a number of available REGs in an OFDM symbol having an index l′ i , n′ 0 denotes a number of available REGs in an OFDM symbol having an index l′=0, and m′ is determined based on an index of a physical hybrid automatic repeat request indicator channel (PHICH) group.
12. The method of claim 1 , wherein the number of available REGs in the first OFDM symbol is defined as a number of REGs not assigned to PCFICH in the first OFDM symbol, and
the number of available REGs in the second OFDM symbol is defined as a number of REGs not assigned to PCFICH in the second OFDM symbol.
13. An apparatus to transmit a signal comprising acknowledgement/negative acknowledgement (ACK/NACK) mapped in at least two orthogonal frequency division multiplexing (OFDM) symbols, the apparatus comprising:
a processor configured to determine an index of a first resource element group (REG) in a first OFDM symbol based on a first ratio calculated using a number of available resource element groups (REGs) in the first OFDM symbol and a number of available REGs in a second OFDM symbol, and to map acknowledgement/negative acknowledgement (ACK/NACK) to the first REG according to the determined index of the first REG, the index of the first REG corresponding to a frequency domain location; and
a transmitter to transmit the signal comprising the mapped ACK/NACK.
14. The apparatus of claim 13 , wherein the number of available REGs in the first OFDM symbol is defined as a number of REGs not assigned to Physical Control Format Indicator Channel (PCFICH) in the first OFDM symbol, and
the number of available REGs in the second OFDM symbol is defined as a number of REGs not assigned to PCFICH in the second OFDM symbol.
15. The apparatus of claim 13 , wherein an index of the first OFDM symbol corresponds to an OFDM symbol index l′=0, and an index of the second OFDM symbol corresponds to an OFDM symbol index l′=1, and
wherein the processor is configured to map the ACK/NACK to a second REG in the second OFDM symbol and to a third REG in the second OFDM symbol.
16. The apparatus of claim 15 , wherein an index ( n i ) of an i- th REG to which the ACK/NACK is mapped is determined using the following equation:
n
_
i
=
{
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
)
mod
n
l
i
′
′
,
i
=
0
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
+
⌊
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
1
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
+
⌊
2
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
2
where an index of the second REG in the second OFDM symbol corresponds to the index ( n 0 ) of the i- th REG when i=0, the index of the first REG in the first OFDM symbol corresponds to the index ( n 1 ) of the i- th REG when i=1, an index of the third REG in the second OFDM symbol corresponds to the index ( n 2 ) of the i- th REG when i=2, N ID cell denotes a cell ID, l′ i denotes an index of an OFDM symbol comprising the i- th REG when i=0, 1, or 2, n′ l′ i denotes a number of available REGs in an OFDM symbol having an index l′ i , n′ 1 denotes a number of available REGs in an OFDM symbol having an index l′=1, and m′ is determined based on an index of a physical hybrid automatic repeat request indicator channel (PHICH) group.
17. The apparatus of claim 13 , wherein an index of the first OFDM symbol corresponds to an OFDM symbol index l′=0, and an index of the second OFDM symbol corresponds to an OFDM symbol index l″=1, and
wherein the processor is configured to map the ACK/NACK to a second REG in the first OFDM symbol and to a third REG in the second OFDM symbol.
18. The apparatus of claim 17 , wherein an index ( n i ) of an i- th REG to which the ACK/NACK is mapped is determined using the following equation:
n
_
i
=
{
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
)
mod
n
l
i
′
′
,
i
=
0
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
+
⌊
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
1
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
1
′
)
⌋
+
m
′
+
⌊
2
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
2
where the index of the first REG in the first OFDM symbol corresponds to the index ( n 0 ) of the i- th REG when i=0, an index of the third REG in the second OFDM symbol corresponds to the index ( n 1 ) of the i- th REG when i=1, an index of the second REG in the first OFDM symbol corresponds to the index ( n 2 ) of the i- th REG when i=2, N ID cell denotes a cell ID, l′ i denotes an index of an OFDM symbol comprising the i- th REG when i=0, 1, or 2, n′ l′ i denotes a number of available REGs in an OFDM symbol having an index l′ i , n′ 1 denotes a number of available REGs in an OFDM symbol having an index l′=1, and m′ is determined based on an index of a physical hybrid automatic repeat request indicator channel (PHICH) group.
19. The apparatus of claim 13 , wherein an index of the first OFDM symbol corresponds to an OFDM symbol index l′=1, and an index of the second OFDM symbol corresponds to an OFDM symbol index l′=0,
wherein the processor is configured to map the ACK/NACK to a second REG in the second OFDM symbol, to determine an index of a third REG in a third OFDM symbol based on a second ratio calculated using the number of available REGs in the second OFDM symbol and a number of available REGs in the third OFDM symbol, and to map the ACK/NACK to the third REG in the third OFDM symbol according to the determined index of the third REG, and
wherein an index ( n i ) of an i- th REG to which the ACK/NACK is mapped is determined using the following equation:
n
_
i
=
{
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
0
′
)
⌋
+
m
′
)
mod
n
l
i
′
′
,
i
=
0
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
0
′
)
⌋
+
m
′
+
⌊
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
1
(
⌊
(
N
ID
cell
·
n
l
i
′
′
/
n
0
′
)
⌋
+
m
′
+
⌊
2
n
l
i
′
′
/
3
⌋
)
mod
n
l
i
′
′
,
i
=
2
where an index of the second REG in the second OFDM symbol corresponds to the index ( n 0 ) of the i- th REG when i=0, the index of the first REG in the first OFDM symbol corresponds to the index ( n 1 ) of the i- th REG when i=1, the index of the third REG in the third OFDM symbol corresponds to the index ( n 2 ) of the i- th REG when i=2, N ID cell denotes a cell ID, l′ i is denotes an index of an OFDM symbol comprising the i- th REG when i=0, 1, or 2, n′ l′ i denotes a number of available REGs in an OFDM symbol having an index l′ i , n′ 0 denotes a number of available REGs in an OFDM symbol having an index l′=0, and m′ is determined based on an index of a physical hybrid automatic repeat request indicator channel (PHICH) group.
20. A method of a base station including a processor and a transmitter for transmitting a signal comprising acknowledgement/negative acknowledgement (ACK/NACK) mapped in at least two orthogonal frequency division multiplexing (OFDM) symbols, the method comprising:
determining, by the processor, an index of a first resource element group (REG) in a first OFDM symbol based on a first ratio calculated using a number of available resource element groups (REGs) in the first OFDM symbol and a number of available REGs in a second OFDM symbol, the index of the first REG corresponding to a frequency domain location;
mapping, by the processor, the ACK/NACK to the first REG in the first OFDM symbol according to the determined index of the first REG;
mapping, by the processor, the ACK/NACK to a second REG in the second OFDM symbol and to a third REG, the third REG being included in the first OFDM symbol, the second OFDM symbol, or a third OFDM symbol; and
transmitting, by the transmitter, the signal comprising the mapped ACK/NACK,
wherein a number of available REGs in an OFDM symbol is defined as a number of REGs not assigned to Physical Control Format Indicator Channel (PCFICH) in an OFDM symbol.