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