An apparatus and method are provided for a mobile communication system. The method includes 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. 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 the symbol groups are mapped to the OFDM symbols and the multiple antennas in an alternating pattern in accordance with the symbol group index.