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 orthogonal frequency division multiplexing (OFDM) symbols using resource elements as units, the method comprising:
determining indexes of resource element groups (REGs) in which repetitive patterns of the PHICH are transmitted; and
mapping the PHICH to the OFDM symbols according to the determined indexes,
wherein an index ( n i ) of the REG in an OFDM symbol of index l′ i is determined by using one of the following equation 1 or 2:
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
equation
1
where N ID cell denotes a cell ID, n′ l′ i denotes the number of available resource element groups in the OFDM symbol of index l′ i , n′ 0 denotes the number of available resource element groups in an OFDM symbol of index 0, and m′ denotes an index of a PHICH group,
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
equation
2
where N ID cell denotes a cell ID, n′ l′ i denotes the number of available resource element groups in the OFDM symbol of index l′ i , n′ 1 denotes the number of available resource element groups in an OFDM symbol of index 1, and m′ denotes an index of a PHICH group.
2. The method of claim 1 , wherein the PHICH is transmitted in groups of a plurality of PHICH, each group consisting of two or four resource elements.
3. The method of claim 1 , wherein the PHICH is transmitted in groups of a plurality of PHICH, and the index of an OFDM symbol in which an i-th repetitive pattern of a PHICH group is transmitted is determined by using the following equation:
l
i
′
=
{
0
normal
PHICH
duration
,
all
subframes
i
extended
PHICH
duration
,
non
-
MBSFN
subframes
(
⌊
m
′
/
2
⌋
+
i
+
1
)
mod
2
extended
PHICH
duration
,
MBSFN
subframes
where m′ denotes an index of a PHICH group.
4. The method of claim 1 , wherein the PHICH is transmitted in groups of a plurality of PHICH, and the index of an OFDM symbol in which an i-th repetitive pattern of a PHICH group is transmitted satisfies the following equation:
l
i
′
=
{
0
normal
PHICH
duration
,
all
subframes
i
extended
PHICH
duration
,
non
-
MBSFN
subframes
(
⌊
m
′
/
2
⌋
+
i
+
1
)
mod
2
extended
PHICH
duration
,
MBSFN
subframes
where m′ denotes an index of a PHICH group.
5. A method of transmitting ACK/NACK signal by a transmitting end in a wireless communication system, the method comprising:
spreading the ACK/NACK signal using a plurality of spreading codes, wherein the plurality of spreading codes have a spreading factor (SF) of 4;
multiplexing the spread ACK/NACK signal by code division multiplexing (CDMA) to construct a physical hybrid ARQ indicator channel (PHICH) group;
mapping the PHICH group to a resource element group (REG) of a first orthogonal frequency division multiplexing (OFDM) symbol;
mapping the PHICH group to a resource element group (REG) of a second orthogonal frequency division multiplexing (OFDM) symbol; and
transmitting the PHICH group to a receiving end,
wherein the PHICH group is transmitted a total of 3 times, and
wherein an index ( n i ) of the REG to which the PHICH group is mapped in an OFDM symbol of index l′ i is determined by 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, n′ l′ i denotes the number of available resource element groups in the OFDM symbol of index l′ i within a subframe, and n′ 0 denotes the number of available resource element groups in an OFDM symbol of index 0 within the subframe, and m′ denotes an index of a PHICH group.
6. The method of claim 5 , wherein the number of available REGs in an OFDM symbol is defined as the number of REGs to which a physical control format indicator channel (PCFICH) is not allocated among a total REGs.
7. The method of claim 5 , wherein the index of OFDM symbol to which the PHICH group is mapped is an integer of 0 to 2.
8. The method of claim 5 , wherein the PHICH group is transmitted via multi-antennas.
9. A method of transmitting ACK/NACK signal by a transmitting end in a wireless communication system, the method comprising:
spreading the ACK/NACK signal using a plurality of spreading codes, wherein the plurality of spreading codes have a spreading factor (SF) of 2;
multiplexing the spread ACK/NACK signal by code division multiplexing (CDMA) to construct a plurality of physical hybrid ARQ indicator channel (PHICH) groups;
mapping two consecutive PHICH groups contiguously in a resource element group (REG) of a first orthogonal frequency division multiplexing (OFDM) symbol;
mapping the two consecutive PHICH groups contiguously in a resource element group (REG) of a second orthogonal frequency division multiplexing (OFDM) symbol; and
transmitting the two consecutive PHICH groups to a receiving end,
wherein location of the REG to which the two consecutive PHICH groups are mapped in said second OFDM symbol is determined by using a ratio between the number of available REGs in said first OFDM symbol and the number of available REGs in said second OFDM symbol.
10. The method of claim 9 , wherein the number of available REGs in an OFDM symbol is defined as the number of REG to which a physical control format indicator channel (PCFICH) is not allocated among a total REGs.
11. The method of claim 9 , wherein the location of REG to which the two consecutive PHICH groups are mapped in said second OFDM symbol is determined by further using Cell ID.
12. The method of claim 9 , wherein the two consecutive PHICH groups are transmitted a total of 3 times.
13. The method of claim 12 , wherein the two consecutive PHICH groups are transmitted through 2 OFDM symbols and the said first OFDM symbol is an OFDM symbol of symbol 1 within a subframe.
14. The method of claim 13 , wherein an index ( n i ) of the REG to which the two consecutive PHICH groups are mapped in an OFDM symbol of index l′ i is determined by 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, n′ l′ i denotes the number of available resource element groups in the OFDM symbol of index l′ i within a subframe, n′ 1 denotes the number of available resource element groups in an OFDM symbol of index 1 within the subframe, and m′ denotes an index of two consecutive PHICH groups.
15. The method of claim 14 , wherein the index l′ i of OFDM symbol to which the two consecutive PHICH groups are mapped is defined as (└m′/2┘+i+1)mod 2 where i denotes an integer of 0 to 2 and m′ denotes an index of two consecutive PHICH groups.
16. The method of claim 9 , wherein the two consecutive PHICH groups are transmitted via multi-antennas.
17. A method for receiving a physical hybrid automatic repeat request indicator channel (PHICH) from a transmitting end, the method comprising:
receiving orthogonal frequency division multiplexing (OFDM) symbols from the transmitting end, wherein the OFDM symbols including resource element groups (REGs) in which repetitive patterns of the PHICH are mapped,
wherein an index ( n i ) of the REG in an OFDM symbol of index l′ i satisfies one of the following equation 1 or 2:
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
equation
1
where N ID cell denotes a cell ID, n′ l′ i denotes the number of available resource element groups in the OFDM symbol of index l′ i , n′ 0 denotes the number of available resource element groups in an OFDM symbol of index 0, and m′ denotes an index of a PHICH group,
equation 2
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, n′ l′ i denotes the number of available resource element groups in the OFDM symbol of index l′ i , n′ 1 denotes the number of available resource element groups in an OFDM symbol of index 1 within the subframe, and m′ denotes an index of a PHICH group.
18. The method of claim 17 , wherein the PHICH is transmitted in groups of a plurality of PHICH, each group consisting of two or four resource elements.