An apparatus and method are provided for a mobile communication system. The method includes generating a symbol group to which an orthogonal sequence is applied; determining one of a first orthogonal frequency division multiplexing (OFDM) symbol and a second OFDM symbol for mapping the generated symbol group based on a symbol group index and a physical hybrid automatic repeat request indicator channel (PHICH) group index; mapping the generated symbol group to the determined symbol; and transmitting the mapped symbol group.