Apparatus and method for transmitting/receiving the hybrid-ARQ ACK/NACK signal in mobile communication system

1. A method for a mobile communication system, the method comprising:

receiving a signal;

determining location information of symbol groups; and

acquiring the symbol groups, to which an orthogonal sequence is applied, from the signal, based on the location information,

wherein the symbol groups are mapped to orthogonal frequency division multiple (OFDM) symbols and multiple antennas based on a symbol group index and a physical HARQ indicator channel (PHICH) group index, and

wherein the symbol groups are mapped to the OFDM symbols and the multiple antennas in an alternating pattern in accordance with the symbol group index.

2. The method of claim 1 , wherein the symbol groups are alternately mapped to a first OFDM symbol and a second OFDM symbol in order to be mapped to the OFDM symbols.

3. The method of claim 1 , wherein a size of the symbol group index is three (3).

4. The method of claim 1 , wherein the symbol groups are mapped to the multiple antennas in an alternating pattern, based on the symbol group index and the PHICH group index, and

wherein the multiple antennas include four antennas.

5. The method of claim 4 , wherein at least one of complex conjugation and sign reversal is applied to map the symbol groups to the multiple antennas.

6. The method of claim 4 , wherein the symbol groups are mapped to the OFDM symbols according to:

PHICH group

symbol group

symbol

antenna mapping

index g

index r

index n

pattern

0

0

0

A

0

1

1

B

0

2

0

A

1

0

0

B

1

1

1

A

1

2

0

B

2

0

1

A

2

1

0

B

2

2

1

A

3

0

1

B

3

1

0

A

3

2

1

B

. . .

. . .

. . .

. . .

7. The method of claim 1 , wherein the symbol groups, to which the orthogonal sequence is applied, include symbol groups generated by spreading symbol groups with an orthogonal sequence according to a spreading factor, and

wherein the spreading factor is four (4).

8. The method of claim 1 , wherein the symbol groups are mapped to four consecutive resource elements in a frequency domain, in order to be mapped to the OFDM symbols.

9. The method of claim 1 , wherein if a start symbol of the OFDM symbols, to which the symbol groups are mapped, is defined as n=0, a symbol index n for the transmission of the symbol groups is mapped in the order [010].

10. The method of claim 1 , wherein if a start symbol of the OFDM symbols, to which the symbol group are mapped, is defined as n=1, a symbol index n for the transmission of the symbol groups is mapped in the order [101].

11. The method of claim 1 , wherein an alternating pattern based on the symbol index is changed for every at least two consecutive PHICH groups among a plurality of PHICH groups.

12. The method of claim 1 , wherein the symbol groups are mapped to the OFDM symbols according to:

PHICH group

symbol group

index g

index r

symbol index n

0

0

0

0

1

1

0

2

0

1

0

0

1

1

1

1

2

0

2

0

1

2

1

0

2

2

1

3

0

1

3

1

0

3

2

1

. . .

. . .

. . .

13. An apparatus for a mobile communication system, the apparatus comprising:

a receiver for receiving a signal; and

a controller for determining location information of symbol groups, and acquiring the symbol groups, to which an orthogonal sequence is applied, from the signal, based on the location information,

wherein the symbol groups are mapped to orthogonal frequency division multiple (OFDM) symbols and multiple antennas based on a symbol group index and a physical HARQ indicator channel (PHICH) group index, and

wherein the symbol groups are mapped to the OFDM symbols and the multiple antennas in an alternating pattern in accordance with the symbol group index.

14. The apparatus of claim 13 , wherein the symbol groups are alternately mapped to a first OFDM symbol and a second OFDM symbol in order to be mapped to the OFDM symbols.

15. The apparatus of claim 13 , wherein a size of the symbol group index is three (3).

16. The apparatus of claim 13 , wherein the symbol groups are mapped to the multiple antennas in an alternating pattern based on the symbol group index and the PHICH group index, and

wherein the multiple antennas include four antennas.

17. The apparatus of claim 16 , wherein at least one of complex conjugation and sign reversal is applied to map the symbol groups to the multiple antennas.

18. The apparatus of claim 16 , wherein the symbol groups are mapped to the OFDM symbols according to:

PHICH group

symbol group

antenna mapping

index g

index r

symbol index n

pattern

0

0

0

A

0

1

1

B

0

2

0

A

1

0

0

B

1

1

1

A

1

2

0

B

2

0

1

A

2

1

0

B

2

2

1

A

3

0

1

B

3

1

0

A

3

2

1

B

. . .

. . .

. . .

. . .

19. The apparatus of claim 13 , wherein the symbol groups, to which the orthogonal sequence is applied, include symbol groups generated by spreading symbol groups with an orthogonal sequence according to a spreading factor, and

wherein the spreading factor is four (4).

20. The apparatus of claim 13 , wherein the symbol groups are mapped to four consecutive resource elements in a frequency domain, in order to be mapped to the OFDM symbols.

21. The apparatus of claim 13 , wherein if a start symbol of the OFDM symbols, to which the symbol groups are mapped, is defined as n=0, a symbol index n for the transmission of the symbol groups is mapped in the order [010].

22. The apparatus of claim 13 , wherein if a start symbol of the OFDM symbols, to which the symbol groups are mapped, is defined as n=1, a symbol index n for the transmission of the symbol groups is mapped in the order [101].

23. The apparatus of claim 13 , wherein an alternating pattern based on the symbol index is changed for every at least two consecutive PHICH groups among a plurality of PHICH groups.

24. The apparatus of claim 13 , wherein the symbol groups are mapped to the OFDM symbols according to:

PHICH group

symbol group

index g

index r

symbol index n

0

0

0

0

1

1

0

2

0

1

0

0

1

1

1

1

2

0

2

0

1

2

1

0

2

2

1

3

0

1

3

1

0

3

2

1

. . .

. . .

. . .