This application relates to the mobile communications field, and in particular, to a data sending method in a wireless communications system. A first device generates a signal before DFT transform is performed including 2×M signal elements. The 2×M signal elements include elements in two element groups A and B, the elements in the two element groups respectively meet same-number repetition and inverse-number repetition characteristics, and the 2×M signal elements further include another element group C that does not need to meet the same-number repetition/inverse-number repetition characteristics. The element in the element group A and an element in the element group C are multiplexed before DFT, and there is an interval, so that the element group A is not interfered by the element group B or the element group C.