Embodiments of the present invention provide a data sending and receiving method, an apparatus, and a system. The method can be executed by a microwave device, which includes: obtaining a control word (CW) and a first antenna-carrier (A×C) from a common public radio interface (CPRI) frame; modulating the CW to obtain in-phase/quadrature (I/Q) data of the CW; determining a first timeslot in which the first A×C does not carry antenna-carrier I/Q data; writing a preset synchronization sequence, first information, and a random number in the first timeslot to generate a second A×C; and combining the second A×C with the I/Q data of the CW to generate a microwave air interface frame, and sending the microwave air interface frame in a time division multiplexing manner.