A data transmission method is disclosed. The method includes: processing, by a network device, first data to obtain at least one first modulation symbol that is in a first antenna port set, where the first antenna port set includes at least one first antenna port; and sending, by the network device, the at least one first modulation symbol to a terminal device in a first subframe by using a first carrier, where the at least one first modulation symbol is different from at least one second modulation symbol that a network device sends to the terminal device in the first subframe by using the first carrier and that is in a second antenna port set, and the second antenna port set includes at least one second antenna port.