A method and apparatus in a user equipment transmit a subframe shared by multiple users through a dual-antenna transmission scheme by using space-time coding. A first and a second plurality of modulation symbols are generated. A third and a fourth plurality of modulation symbols are generated by performing Alamouti coding on each pair of modulation symbols in each of the first and second pluralities of modulation symbols. A spread matrix is generated for each modulation symbol such that the first and third pluralities of modulation symbols are mapped to a first slot of the subframe, and the second and third pluralities of modulation symbols are mapped to a second slot of the subframe. The subframe is transmitted such that the first and second pluralities of modulation symbols are transmitted via a first antenna, and the third and fourth pluralities of modulation symbols are transmitted via a second antenna.