Transmitting spread signal in communication system

1. A method for transmitting a spread signal at a base station in a mobile communication system, the method comprising:

spreading a signal using a plurality of spreading codes, wherein the plurality of spreading codes have a spreading factor of 4;

coding the spread signal for multiple antenna transmission;

multiplexing the coded spread signal by code division multiplexing for each antenna;

transmitting the multiplexed signal via four neighboring frequency resources of one orthogonal frequency-division multiplexing (OFDM) symbol of a first antenna set comprising two antennas; and

transmitting the same multiplexed signal via four neighboring frequency resources of one OFDM symbol of a second antenna set comprising two antennas,

wherein the multiplexed signal transmitted via the first antenna set and the multiplexed signal transmitted via the second antenna set are transmitted via different OFDM symbols,

wherein the multiplexed signal transmitted via the first antenna set and the multiplexed signal transmitted via the second antenna set are separated from each other by a plurality of subcarriers in a frequency domain,

wherein the spread signal is coded between the two antennas in each of the first antenna set and the second antenna set as shown in Table 1:

TABLE 1

neighboring frequency resources in

one OFDM symbol

antenna A

f 1 (a 1 )

f 2 (a 2 )

f 1 (a 3 )

f 2 (a 4 )

antenna B

f 3 (a 2 )

f 4 (a 1 )

f 3 (a 4 )

f 4 (a 3 )

wherein antenna A and antenna B represent the two antennas in each of the first antenna set and second antenna set, f 1 (x)=x, f 2 (x)=x, f 3 (x)=−x* and f 4 (x)=x*, and a 1 to a 4 represent each element of the spread signal, and

wherein the spread signal is an ACK/NACK signal for indicating whether or not uplink signal is successfully received.

2. The method of claim 1 , wherein frequency switching transmitting diversity (FSTD) is applied in a way of transmitting the multiplexed signal alternately by the first antenna set and second antenna set repeatedly.

3. The method of claim 2 , wherein the multiplexed signal is transmitted a total of 3 times using the first antenna set and second antenna set alternately.

4. The method of claim 1 , wherein the first antenna set comprises a first antenna and a second antenna of a four-antenna group.

5. The method of claim 4 , wherein the second antenna set comprises a third antenna and a fourth antenna of the four-antenna group.

6. The method of claim 1 , wherein the first antenna set comprises a first antenna and a third antenna of a four-antenna group.

7. The method of claim 6 , wherein the second antenna set comprises a second antenna and a fourth antenna of the four-antenna group.

8. A method for receiving a spread signal at a user equipment in a mobile communication system, the method comprising:

receiving a multiplexed signal via four neighboring frequency resources of one orthogonal frequency-division multiplexing (OFDM) symbol, the multiplexed signal being received from a first antenna set comprising two antennas of a transmitting end; and

receiving the same multiplexed signal via four neighboring frequency resources of one OFDM symbol, the same multiplexed signal being received from a second antenna set comprising two antennas of the transmitting end,

wherein the multiplexed signal received from the first antenna set and the multiplexed signal received from the second antenna set are received via different OFDM symbols,

wherein the multiplexed signal originates from a coded spread signal using code division multiplexing for each antenna,

wherein the coded spread signal originates from a spread signal coded between the two antennas in each of the first antenna set and the second antenna set as shown in Table 1:

TABLE 1

neighboring frequency resources in

one OFDM symbol

antenna A

f 1 (a 1 )

f 2 (a 2 )

f 1 (a 3 )

f 2 (a 4 )

antenna B

f 3 (a 2 )

f 4 (a 1 )

f 3 (a 4 )

f 4 (a 3 )

wherein antenna A and antenna B represent the two antennas in each of the first antenna set and second antenna set, f 1 (x)=x, f 2 (x)=x, f 3 (x)=−x* and f 4 (x)=x*, and a 1 to a 4 represent each element of the spread signal,

wherein the spread signal originates from spreading a signal using a plurality of spreading codes, wherein the plurality of spreading codes have a spreading factor of 4,

wherein the multiplexed signal received via the first antenna set and the multiplexed signal received via the second antenna set are separated from each other by a plurality of subcarriers in a frequency domain,

wherein the spread signal is an ACK/NACK signal for indicating whether or not uplink signal is successfully received.

9. The method of claim 8 , wherein frequency switching transmitting diversity (FSTD) is applied in receiving the multiplexed signal alternately from the first antenna set and second antenna set repeatedly.

10. The method of claim 9 , wherein the multiplexed signal is received a total of 3 times using the first antenna set and second antenna set alternately.

11. The method of claim 8 , wherein the first antenna set comprises a first antenna and a second antenna of a four-antenna group.

12. The method of claim 11 , wherein the second antenna set comprises a third antenna and a fourth antenna of the four-antenna group.

13. The method of claim 8 , wherein the first antenna set comprises a first antenna and a third antenna of a four-antenna group.

14. The method of claim 13 , wherein the second antenna set comprises a second antenna and a fourth antenna of the four-antenna group.