An apparatus and method are provided for transmitting a symbol group in a mobile communication system. The method includes generating the symbol group to which an orthogonal sequence is applied; mapping the generated symbol group to an orthogonal frequency division multiple (OFDM) symbol and a multiple antenna array based on a symbol group index and a physical hybrid automatic repeat request (HARQ) indicator channel (PHICH) group index; and transmitting the mapped symbol group. The generated symbol group is mapped to the OFDM symbol and the multiple antenna array in an alternating pattern in accordance with the symbol group index.