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 for mapping a physical hybrid automatic repeat request indicator channel (PHICH) to at least one orthogonal frequency division multiplexing (OFDM) symbol,
each OFDM symbol comprising a plurality of resource element groups,
each resource element group being comprised of four resource elements, the method comprising:
determining indexes of resource element groups in which the PHICH is transmitted; and
mapping the PHICH to at least one OFDM symbols according to the determined indexes,
wherein said indexes are determined according to ratio n′ l′ i /n′ 0 or ratio n′ l′ i /n′ i in OFDM symbol, having index l′ i ,
n′ l′ i is the number of available resource element groups in the OFDM symbol, having index l′ i , n′ 0 is the number of available resource element groups in OFDM symbol, having index 0, of a sub-frame, n′ 1 is the number of available resource element groups in OFDM symbol, having index 1, of the sub-frame,
available resource element groups in the OFDM symbol, having index l′ i , are resource element groups which can be used for PHICH transmission in the OFDM symbol, having index l′ i .
2. The method of claim 1 , wherein the indexes are determined according to a value obtained by multiplying a cell identifier (ID) by the ratio n′ l′ i /n′ 0 or the ratio n′ l′ i /n′ 1 .
3. The method of claim 1 , wherein, if the PHICH is transmitted through one or three OFDM symbols, the indexes of the resource element groups in which the PHICH is repeatedly transmitted three times are 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 N ID cell denotes a cell ID, i denotes an index of the repetition of the PHICH, n′ l′ i /n′ 0 denotes the ratio between the number of available resource element groups in the OFDM symbol l′ i and the number of available resource element groups in the OFDM symbol, having index 0, of the sub-frame, and m′ denotes an index of a PHICH group including the PHICH.
4. The method of claim 1 , wherein, if the PHICH is transmitted through two OFDM symbols, the indexes of the resource element groups in which the PHICH is repeatedly transmitted three times are 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 N ID cell denotes a cell ID, i denotes an index of the repetition of the PHICH, n′ l′ i /n′ 1 denotes the ratio between the number of available resource element groups in the OFDM symbol l′ i and the number of available resource element groups in the OFDM symbol, having index 1, of the sub-frame, and m′ denotes an index of a PHICH group including the PHICH.
5. A base station for mapping a physical hybrid automatic repeat request indicator channel (PHICH) to at least one orthogonal frequency division multiplexing (OFDM) symbol,
each OFDM symbol comprising a plurality of resource element groups,
each resource element group being comprised of four resource elements, the base station comprising:
a processor configured to determine indexes of resource element groups in which the PHICH is transmitted, and map the PHICH to at least one OFDM symbols according to the determined indexes,
wherein said indexes are determined according to ratio n′ l′ i /n′ 0 or ratio n′ l′ i /n′ 1 in OFDM symbol, having index l′ i ,
n′ l′ i is the number of available resource element groups in the OFDM symbol, having index l′ i , n′ 0 is the number of available resource element groups in OFDM symbol, having index 0, of a sub-frame, n′ 1 is the number of available resource element groups in OFDM symbol, having index 1, of the sub-frame,
available resource element groups in the OFDM symbol, having index l′ i , are resource element groups which can be used for PHICH transmission in the OFDM symbol, having index l′ i .
6. The base station of claim 5 , wherein the indexes are determined according to a value obtained by multiplying a cell identifier (ID) by the ratio n′ l′ i /n′ 0 or the ratio n′ l′ i /n′ 1 .
7. The base station of claim 5 , wherein, if the PHICH is transmitted through one or three OFDM symbols, the indexes of the resource element groups in which the PHICH is repeatedly transmitted three times are 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 N ID cell denotes a cell ID, i denotes an index of the repetition of the PHICH, n′ l′ i /n′ 0 denotes the ratio between the number of available resource element groups in the OFDM symbol l′ i and the number of available resource element groups in the OFDM symbol, having index 0, of the sub-frame, and m′ denotes an index of a PHICH group including the PHICH.
8. The base station of claim 5 , wherein, if the PHICH is transmitted through two OFDM symbols, the indexes of the resource element groups in which the PHICH is repeatedly transmitted three times are 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 N ID cell denotes a cell ID, i denotes an index of the repetition of the PHICH, n′ l′ i /n′ 1 denotes the ratio between the number of available resource element groups in the OFDM symbol l′ i and the number of available resource element groups in the OFDM symbol, having index 1, of the sub-frame, and m′ denotes an index of a PHICH group including the PHICH.
9. A mobile station for decoding a physical hybrid automatic repeat request indicator channel (PHICH) mapped to at least one orthogonal frequency division multiplexing (OFDM) symbol,
each OFDM symbol comprising a plurality of resource element groups,
each resource element group being comprised of four resource elements, the mobile station comprising:
a processor configured to determine indexes of resource element groups in which the PHICH is transmitted, and decode the PHICH mapped to at least one OFDM symbols according to the determined indexes,
wherein said indexes are determined according to ratio n′ l′ i /n′ 0 or ratio n′ l′ i /n′ 1 in OFDM symbol, having index l′ i ,
n′ l′ i is the number of available resource element groups in the OFDM symbol, having index l′ i , n′ 0 n is the number of available resource element groups in OFDM symbol, having index 0, of a sub-frame, n′ 1 is the number of available resource element groups in OFDM symbol, having index 1, of the sub-frame,
available resource element groups in the OFDM symbol, having index l′1, are resource element groups which can be used for PHICH transmission in the OFDM symbol, having index l′ i .
10. The mobile station of claim 9 , wherein the indexes are determined according to a value obtained by multiplying a cell identifier (ID) by the ratio n′ l′ i /n′ 0 or the ratio n′ l′ i /n′ 1 .
11. The mobile station of claim 9 , wherein, if the PHICH is transmitted through one or three OFDM symbols, the indexes of the resource element groups in which the PHICH is repeatedly transmitted three times are 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 N ID cell denotes a cell ID, i denotes an index of the repetition of the PHICH, n′ l′ i /n′ 0 denotes the ratio between the number of available resource element groups in the OFDM symbol l′ i and the number of available resource element groups in the OFDM symbol, having index 0, of the sub-frame, and m′ denotes an index of a PHICH group including the PHICH.
12. The mobile station of claim 9 , wherein, if the PHICH is transmitted through two OFDM symbols, the indexes of the resource element groups in which the PHICH is repeatedly transmitted three times are 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 N ID cell denotes a cell ID, i denotes an index of the repetition of the PHICH, n′ l′ i /n′ 1 denotes the ratio between the number of available resource element groups in the OFDM symbol l′ i and the number of available resource element groups in the OFDM symbol, having index 1, of the sub-frame, and m′ denotes an index of a PHICH group including the PHICH.